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PSD 136

Animal-care Facility Piping Systems

Continuing Education from Plumbing Systems & Design Kenneth G.Wentink, PE, CPD, and Robert D. Jackson

NOVEMBER/DECEMBER 2006

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CONTINUING EDUCATION

Animal-care Facility Piping Systems

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INTRODUCTION This chapter discusses various piping systems uniquely associated with the physical care, health, and well-being of laboratory animals. Included are various utility systems for animal watering, water treatment, room and floor cleaning, equipment washing, cage flushing and drainage, and other specialized piping required for laboratory and experimental work within the facility. Other systems involved with general laboratory and facility work, such as those for compressed gases and plumbing, are discussed in their respective chapters.

General It is expected that a facility involved with long-term studies will have different operating and animal drinking-water quality requirements than one used for medical research. For critical studies, the various utility systems shall incorporate design features necessary to ensure reliability and provide a consistent environment. As many variables as are practical (or desirable) shall be eliminated to ensure the accuracy of the ongoing experiments being conducted. Regardless of the facility type, different users and owners have individual priorities based on experiences, operating philosophies, and corporate cultures that must be established prior to the start of the final design phase of a project.

Codes and Standards

1. The local codes applicable to plumbing systems must be observed in the design and installation of ordinary plumbing fixtures and potable water and drainage lines for the facility. 2. 10-CFR-58 is the code (by the agencies of the federal government) for good laboratory practice for nonclinical laboratory studies. 3. 21-CFR-211, cGMP, requires compliance with FDA protocols for pharmaceutical applications. 4. NIH publication 86-23, Guide for the Care and Use of Laboratory Animals. 5. American Association for Accrediation of Laboratory Animal Care (AAALAC). Inspection and accreditation by the AAALAC is accepted by the NIH as assurance that the facility is in compliance with Public Health Services (PHS) standards.

Animal Drinking-Water Systems The purpose of the animal drinking-water system is to produce, distribute, and maintain an uninterruptible supply of drinking water with a specific and consistent range of purity to all animals in a facility. There are two general types of systems: an automated central-distribution system and individual water bottles.

System Types The great majority of animals used by laboratories for medical and product research are mice, rats, guinea pigs, rabbits, cats, dogs, and primates. Smaller animals and primates are kept in stacked cages, often on racks. Medium-sized animals, such as dogs, goats, and pigs, are kept in kennels or pens. Larger floor areas are required for barnyard animals such as cows. Watering can be done either by an automatic, reduced-pressure, central system, which pipes water from the source directly to each cage, kennel or pen; or by separate drinking bottles or watering devices manually placed in individual cages or pens. Automated, Central Supply-and-Distribution System The purpose of an automated, central, drinking-water supply system is to automatically treat and distribute drinking water. Ancillary devices are used to flush the system and maintain a uniform and acceptable level of purity. The system consists of a raw or treated water source, a purification system, medicinal and disinfection injection equipment if necessary, pressure-reducing stations, and a distribution piping network consisting of a low-pressure room-distribution piping system and a rack-manifold pipe terminating in a drinking valve for each cage or pen for the animals. Also necessary is an automated flushing system for the room-distribution piping activated by a flush-sequence panel, and a monitoring system to automatically provide monitoring of such items as drinkingwater pressure, flow, and possible leakage. Animals in cages are kept in animal rooms. Cages are usually placed in multi-tiered, portable or permanent cage racks, which contain a number of cages. The cage rack has an integral piping system installed, called a “rack manifold,” that distributes the water to all cages. The rack manifold could be installed by the manufacturer or in the facility by operating personnel. The rack manifold receives its water from the room-distribution piping. The connection between the room-distribution piping and the rack manifold is made by means of a detachable recoil hose generally manufactured from Polypropylene (PP), nylon, or Ethylene-Propylene Diene Monomer (EPDM). This hose is flexible, generally 3⁄8 in. (12 mm) in size and coiled to conserve space. It will stretch to a length of about 6 ft 0 in. (2 m). Each end is provided with a quick-disconnect fitting used to attach the hose to both the room-distribution piping and the rack manifold. To maintain drinking-water quality, a method of flushing the room-distribution piping and the rack manifold shall be provided. Ancillary equipment includes flushing and sanitizing systems to wash the recoil hose and the cage rack-piping interior. Water Bottles Drinking water bottles are individual units with an integral drinking tube that are placed by hand on a bracket in each cage.

Reprinted from Pharmaceutical Facilities Plumbing Systems, Chapter 7: “Animal-care Facility Piping Systems,” by Michael Frankel. © American Society of Plumbing Engineers.   Plumbing Systems & Design 

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These bottles could be filled either by hand or automatically via the operating cost of the proposed system, the species of aniSimpo PDF Merge and Split Unregistered Versionmals - http://www.simpopdf.com a bottle filler. housed in the facility, and the animal-housing methods. Automatic bottle fillers should be considered to reduce the The overall objective is to eliminate as many variables as postime necessary to fill bottles and minimize water spillage. Bottle sible for the entire period of time the studies or experiments are fillers are available with manifolds to fit any size bottles. They conducted. can be supplied with purified water from a central water supply The most often-used treatment for drinking water is reverse and—with separate, programmable proportioners—could osmosis. Other possible treatment methods are distillation acidify, chlorinate, and medicate the water as required. The and deionization. A discussion of these purification methods bottle filler automates the filling procedure so that the bottles appears in the chapter “Water Systems.” are correctly positioned during filling and stops the flow when Reverse Osmosis the water reaches a predetermined level. When a higher-quality water is required and other types of puriFlushing System In order to maintain drinking-water quality, the drinking-water distribution system should be flushed periodically. This is accomplished by having the same drinking water that is normally distributed to the animals flow through the piping system at an elevated flow rate, pressure, and velocity. The water is sent to drain and not recovered. This is initiated automatically at the drinking-water pressure-reducing station by the addition of separate regulating valves and pressure-regulating arrangements. Different flushing arrangements are possible, depending on the cost, facility protocol, and purity desired. One method flushes only the main runs by the addition of a solenoid valve at the end of the main run and the provision of a return line to drain from this point. Another method is to flush the mains and the room-distribution piping by adding the solenoid valve at the end of each room-distribution branch with the return line to drain from each room. A third method flushes the entire system, including the rack manifold, by adding a solenoid valve on each cage connection to the room-distribution pipe, which flushes the recoil hose and the rack manifold. It is accepted practice to replace all the drinking water in the room-distribution piping system at regular intervals, a minimum of twice daily. To approximate the amount of water in the pipe, allow 1 gal (4 L) for each 33 ft 0 in. (10 m) of pipe. General practice is to flush the system with water at about 15 psi (90 kPa) at a rate of 15 gpm (60 L/min). If the drinking water is not purified, it is recommended that the piping be flushed at least twice daily for about 2 min. For purified water, flush once daily for about 1 min. Flushing can be done manually by means of a valve in the pressure-reducing station enclosure or automatically by the addition of a bypass and solenoid valve around the low-pressure assembly to the pressure-reducing station. The sequence and duration of the automatic flush cycle is controlled from a flush-sequencer panel. Figure 7-1 

fied water are not available in a facility, reverse osmosis (RO) is normally selected. Since the amount of water is usually small, a package type unit mounted on a skid is provided and connected directly to the water supply. The RO system is flexible and, when used in combination with DI water supply, will provide water that is virtually contamination free. Disinfection and Medication of Drinking Water Disinfection chemical mixtures are added to the animal drinking-water supply to eliminate and control bacterial contamination in the central and room-distribution piping system. Medication is added to conform with experimental protocols if necessary. These mixtures are usually introduced into the piping system by a self-contained, central, proportioning (injector) unit using facility water pressure. Medication is added to the drinking water using the same proportioning equipment that adds disinfectant. All equipment is available in a wide range of sizes and materials. A schematic detail of a typical central proportioner is illustrated in Figure 7-1. Chlorination  Chlorination is a recognized biocidal treatment that leaves a residual of chlorine in the entire central-distribution system. Hyperchlorinated water is not as corrosive as acidified water and could be used with brass/copper distribution system components. Accepted practice is to provide a pH higher than 4, with a residual range of free chlorine between 5 and 12 ppm. Free chlorine in water dissipates in time with light, heat, and reaction with organic contaminants, making it ineffective when water bottles are used. Chlorine creates toxic compounds in reaction with some water contaminants and medications. Acidification  Acidification has an advantage over chlorination in that it is more stable and lasts longer in the system. The disadvantage is that corrosion-resistant materials must be used. The pH range should be between 2.5 and 3 in order to be effecTypical Central Proportioning Unit

Drinking-Water Treatment Systems The purpose of the drinking-water treatment system is to remove impurities from the raw-water supply to achieve the water quality required by the animals in the facility. In addition, disinfectant and medication can be added to the water during treatment if required. Systems Description There are no generally recognized and accepted standards for animal drinking-water quality. Purity and consistency requirements depend on the incoming water quality, the established protocol of the end user, the importance of either the initial or NOVEMBER/DECEMBER 2006 

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CONTINUING EDUCATION: Animal-care Facility Piping Systems tive. A pH lower than 2.5 will cause the water to become “sour” Simpo PDF Merge and Split Unregistered Version and the animals will not drink it. At a pH above 3, the mixture is not considered an effective germicide.

Figure 7-2  Reverse “S” Configuration Watering Manifold - http://www.simpopdf.com

Drinking-Water System Components and Selection Pressure-Reducing Station The pressure-reducing station reduces the normal pressure of the raw-water supply to a level required for the animal-room drinking-water distribution system. As an option, a secondary system can be added to provide a higher pressure in the roomdistribution system for flushing. The pressure and flow rate depend on the type and number of animals to be supplied. Also usually included are a 5-µ water filter, a pressure gauge, and a backflow preventer. Timing devices that automatically control flushing duration are controlled by a remote flush-sequencer panel, which controls all flushing sequencing operations. The recommended pressures for animal-room piping distribution to various animals are as follows: 3-5 psig (20.4-34 kPa) 3-5 psig 3-5 psig 6-12 psig (41-81.6 kPa)

The secondary pressure-reducing assembly used to provide automatically room-distribution pipe-flushing water operates at a pressure of 15 psig (102 kPa). This assembly is installed as a bypass around the low-pressure assembly. Manual operation at a lower cost could also be provided. This additional pressure for a short period of time will not cause the animals any difficulty if they decide to drink during the flushing cycle. One pressure-reducing station can be connected to as many as 35 interconnect stations to small animal-rack manifolds, often referred to as “drops.” This allows 1 station to control more than 1 animal room. The pressure-reducing station is a preassembled unit complete with all the various valves, fittings, and reducing valves required for a specific project. All the components are installed in a cabinet, which requires only mounting and utility connections. Drinking Valves Drinking valves are used by the animals to obtain water from the distributionsystem piping. An internal mechanism keeps the valve normally closed; the animal drinking from the valve must open it by some action, such as moving the entire valve or operating a small lever inside the body of the valve with the tongue. Many different kinds of valve are available to supply any type of animal that may be kept in the facility. The valves can be mounted on cages, on the rack manifold, or on the walls of pens and kennels at varying heights with the use of special brackets.

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Animal-Rack Manifold Configurations The configuration of the piping on the animal rack plays an important part in the effectiveness and efficiency of the filling and flushing of the drinking-water system. The two most oftenused configurations are the reverse “S” and the “H.” The reverse “S,” illustrated in Figure 7-2, is the most often-used configuration. It has two basic styles based on the valve location in the flush drain line. One style has a supply control valve at the top and the other has a drain valve at the bottom. Either location is acceptable, with the deciding factor being the ease of operating the valve where the rack is installed. This configuration has the advantage of eliminating dead legs and offers more convenience to facility personnel when they fill the piping after washing. The vent is a manually operated air bleed used when the cage rack is reconnected to the room-distribution pipe. It is opened until water is discharged, thereby eliminating any air pockets in the manifold. This manifold style provides a positive exchange of water during flushing with a minimum usage of time and water.

Figure 7-3  Typical Room Distribution, On-Line, Rack Manifold Flushing System

NOVEMBER/DECEMBER 2006

Source: Courtesy of Edstrom Industries.

Small animals, such as Rats and mice Primates Dogs and cats Swine and piglets

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This configuration is used far more than any The pipe sizes in other areas of the Figure 7-4  Standard “S” Configuration Manifold Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com other manifold style. It is easily converted animal facility are determined based on to automatic flushing by the installation of the requirements of maximum flow rate at solenoid devices on the valve. It is recomthe necessary pressure to supply the flushmended when micro-isolator cage systems ing velocity. Maximum flow rate depends are installed. The complete, on-line, rackon the flush sequencing, and the pressure manifold flushing system is illustrated in drop depends on overcoming pressure Figure 7-3. This cage system has the advanloss through the equipment connected to tage of the complete isolation of individual the branch being sized—such as pressurecages, with the accompanying capability reducing stations, solenoid valves, and for additional flushing and disinfection of recoil hoses—and friction loss through the the piping ­system. piping network. Allowance must be made One variation of the reverse “S” is the to provide a sufficiently high flow rate and standard “S,” illustrated in Figure 7-4. This water velocity to efficiently provide the configuration has the advantage of comflushing action desired. plete on-line flushing and lower initial cost Cleaning and Drainage Systems of the manifold. Disadvantages are the and Practices need for extra supports on the cage rack General and the need for venting to be done manKeeping the animal rooms and cages ually or by the animals after being placed clean is an extremely important facet of facility practice. The in service. This configuration is no longer recommended. The “H” style, illustrated in Figure 7-5, although rigidly cleaning of the animal room is accomplished either by sponging installed and with positive venting, is not suitable for on-line the walls, floors, and ceiling or by hosing down the room. Cage flushing. Because of this, it is rarely used except for larger ani- racks can be cleaned by washing them with a hose or by placing mals, which will consume all the water in the rack piping mani- them in a large washing machine. Cages are cleaned in a cage washer. Pens and kennels are hosed down. Floors in pens are fold. The most common piping materials are CPVC and 304L stain- cleaned with hoses and the bedding with feces is pushed into less steel. CPVC conforms to ASTM D 2846, is 0.875 outside trenches with floor drains. In specialized areas, such as holding or isolation rooms where diameter (OD) with 0.188 in. minimum wall thickness. Joining process is done with solvent cement socket joints. The drinking only small animals are kept, it is common practice to have pervalves are installed with a proprietary, drilled and tapped fit- manent cage racks or have the portable racks remain in the ting. The 304L stainless steel tubing is 0.50 OD with a 0.036 in. animal room. The litter is put into bags and brought to other minimum wall thickness. Fittings are made with O-ring joints areas for disposal. The cage racks are manually wiped down and socket fittings or compression type fittings. The mounting of and no rack washer is required. A sink is usually provided in both pipe materials is accomplished by the use of 304 SS stain- the animal room for the convenience of the cleaning personnel. Individual water bottles, if provided, could be washed in the less-steel clamps and fasteners. sink. The cages are removed and washed separately in a cage System Sizing Methods washer. This type of animal room usually does not require a The water consumption of small animals in cages is very low. floor drain if the entire room will be sponged down. If hosing is It is also probable that the animal room will not be used to full practiced, a floor drain is required. capacity. Because of this low consumption flow rate, the flushRabbits and guinea pigs have a tendency to spray urine and ing-water flow rate of the system is the critical factor in sizing feces. This requires that the racks be hosed down in the room. A the piping. Typically, the animal-room piping distribution netwash station with a hose reel and detergent injection capability work is a header uniformly sized at ½ in. (50 mm) throughout to hose down the cage racks and the room itself is usually placed the animal room. in individual rooms. Citric acid is often used as a cleaning agent for rabbits. Figure 7-5  Standard “H” Configuration Manifold Hose Stations Hose stations usually consist of a mixing valve with cold water and steam to make hot water or hot water alone, a length of flexible hose, and an adjustable spray nozzle. Hot and cold water are also used. It can be exposed or provided with an enclosure when an easily cleaned surface is required. Cleaning-Agent Systems Cleaning agents are used to clean and/or disinfect the walls, ceiling, and floor of a room and to add agent to the cage wash water. When used to clean rooms, the equipment used for this purpose is commonly called a “facility detergent system.” When used to add agent to the cage washing water it is often called a “cage-washing detergent system.” These are separate systems and are not capable of providing agent to each other. NOVEMBER/DECEMBER 2006 

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CONTINUING EDUCATION: Animal-care Facility Piping Systems Figure 7-6  Single-Station Detergentand System Simpo PDF Merge Split

supply has to be changed. A typical central-supply deter-

Unregistered Version - http://www.simpopdf.com gent-dispensing system is illustrated in Figure 7-7.

The cage-washing detergent system is usually located in the wet area of the cage-washing facility and, with the use of a detergent pump, could be used as a central system to supply cage and bottle washers. A typical schematic detail of a cage-washing system is illustrated in Figure 7-8. It is common practice to have a central system or a wallmounted cleaning-agent dispenser unit along with the hose station. Separate, portable units could be used when cross contamination between animal rooms is a consideration. A typical, wall-mounted, cleaning-agent system consists of separate water and cleaning-agent tanks; a water pump; and a special, coaxial hose that sprays a proportioned mixture of the water and cleaning agent. Compressed air is often used to provide pressure. Cage-Flushing Water System The removal of animal waste from cages can be done by several methods. One method removes the waste along with the bedding at the time cages are removed from the animal room to be washed. Another method uses an independent rack-flush system to automatically remove animal waste from cages on racks while the animals and cages remain in the animal room. The independent rack flush is a separate system that uses chlorinated water automatically distributed to each animal room. The cages and racks are constructed so that the animal droppings fall through the cage floor onto a sloping pan below each tier of cages. Each tier is cascaded at the end onto the sloping pan below. Eventually, the lowest pan spills into a drain trough in the animal room. The flushing schedule is decided by facility personnel. The water supply could be a reservoir placed on the rack that is filled with water and automatically discharged onto the pans at preset intervals. These preset intervals are determined based on experience and generally range from once to three times daily. Another method uses a solenoid valve to automatically discharge water onto the pans; the valve is sequenced by a timer set to alternate fill and dump cycles. The timer could be either

A single-station detergent-dispensing system is used when rooms are cleaned with mops or squeegees. It consists of a wallmounted unit having a holder for detergent concentrate and an injector unit. A container filled with detergent concentrate is placed in the holder and is used to supply agent to the injector that dispenses a metered amount of agent when a hose bibb is opened to fill the pail or container. These rooms usually have sinks and mop racks inside to be used only for these rooms. A typical schematic detail of a single-station detergent system is illustrated in Figure 7-6. When used to supply a single or multiple-spray hose for cleaning floors and walls, a central system could be installed to supply several rooms within a facility by means of a detergent pump that dispenses agent. A 55-gal drum of agent should be used to reduce the number of times the Figure 7-8  Typical Cage-Washing Detergent System

Figure 7-7  Central-Supply Detergent System

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Figure 7-9  Typical Cage-Rack Utility Connections Simpo PDF Merge and Split Unregistered

disposed of as regular garbage. Regular gar-

Version - http://www.simpopdf.com bage disposal is the most common method of disposal. It involves collecting, moving, and storage of the waste into large containers until regular garbage collection is made. This is very labor intensive. Discharge into the drainage system must first be accepted by the local authorities and responsible code officials. This requires the bedding to be water soluble, that it shall not float, and provision be made to thoroughly mix the bedding with water. This mixture is called a “slurry.” Experience has shown, if done properly, discharge into an adequately sized drain line—minimum size 6 in. (150 mm)—has caused no problems, since the effluent has the same general characteristics of water. A self-contained waste-disposal system is available that is capable of disposing of animal bedding and waste. The system consists of a pulping unit to grind the waste into a slurry and sanitize it, a water extractor to remove most of the water from the slurry, and the interconnecting piping system that transports the slurry from the pulper to the extractor and recirculates the water removed from the extractor back to the pulping unit for reuse. The solid waste is removed as garbage. Manufacturers are available for assistance in the design and equipment selection for this specialized system. The system has the advantages of reducing water use, reducing operating costs by eliminating the handling of the waste by operating personnel, compacting the waste to about 20% of the space required for standard garbage not compacted, and reducing the possibility of contamination by isolation of the disposal equipment. The disadvantage is its high initial cost.

centrally located or installed separately in each animal room. Larger cages, such as those for primates, are usually stacked no more than two cages high. Current practice is to have these cages manually cleaned by personnel who hose down the pans directly into floor or wall troughs. Water is supplied to each cage rack by means of a recoil hose, which has a different quick-disconnect end than that of the drinking water recoil hose to avoid cross connection. Refer to Figure 7‑9 for a detail Figure 7-10  Typical Waste-Disposal System of a typical cage-rack utility connection arrangement. Solid-Waste Disposal Solid waste consists of bedding, feces, animal carcasses, and other miscellaneous waste, including straw and sawdust used for larger farm animals. Bedding comprises the largest quantity of this solid waste. It is necessary to determine the quantity of bedding before a decision can be made as to the most cost-effective method to dispose of it. Bedding can be disposed of by incineration, as regular garbage, or into the sewer system. Incinerators are costly, require compliance with many regulatory agencies and multiple permits, and often result in objections from adjoining property owners. Incineration is the preferred method of disposing of carcasses and large quantities of contaminated waste. Carcasses could also be autoclaved and

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CONTINUING EDUCATION: Animal-care Facility Piping Systems This system could consist of single or multiple units of dif- Equipment Washing Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com ferent capacities. It requires water intermittently for pulping at Most facilities contain washing and sanitizing machines to wash the rate of about 10 to 30 gpm (63 to 190 L/min). Hose bibbs cages, cage racks, and bottles, if used. There are two commonly should be installed for washdown. The pipe should be sized for used types of cage washer: the batch type and conveyer (tunnel) a maximum velocity of 8 fps (1.75 m/s), with typical slurry lines type. Batch washers require manual loading and unloading and ranging between 2 and 4 in. (50 and 200 mm) and return lines are used where a small number of cages and racks are washed. generally 2 in. (50 mm) in size. The extractor discharges into a The conveyer type is similar to a commercial dishwasher, where drain that should be 4 or 6 in. (100 or 150 mm) depending on the cages and racks are loaded on a conveyer and automatically the flow. A typical schematic diagram of a multiple installation moved through the machine for the washing and sanitizing is illustrated in Figure 7-10. cycles. Room-Waste Disposal The rooms in which animals are kept must be designed to allow proper drainage practices and in accordance with the anticipated cleaning procedures of the facility. Floor drains, drainage trenches (or troughs) at room sides, adequate and consistent floor pitch to drains or troughs, and floor surfaces are all important considerations. There are several considerations to be taken into account in locating floor drains. Experience has shown that placing drains in the center of a room is not acceptable because it is difficult to hose solids down a drain in this location. Another reason is that the floor must be pitched to the drain and if a cage rack is defective, it should roll to the side of the room. The best location is in a corner or at the side. Floor drains without troughs can be considered if the floors will only be squeegeed rather than hosed down. They should also be considered in contagious areas where contamination between rooms must be avoided. Gratings must have openings smaller than the wheels of racks or cages. In rooms where washdown and cage-rack flushing are expected, the provision of a floor trough should be considered. Troughs are often provided at opposite ends of the room to minimize the amount of floor drop due to pitch. Accepted practice uses a minimum floor pitch of 1⁄8 in./ft of floor run. The floor is pitched to the troughs to facilitate cleaning and also to provide an easy method to dispose of waste generated from the rack-flush system. It is common practice to provide an automatic or manual trough-flushing system with nozzles or jets to wash down the trough sides and eliminate as much of the contamination remaining in the trough as possible. Wall troughs, similarly to roof gutters, are located at a higher elevation. This type of trough arrangement is sometimes provided in addition to or in lieu of floor troughs if the arrangement of elevated cages and racks make it an effective drainage method. Experience has shown that prefabricated drain troughs in floors are preferred over those built on the wall as part of the architectural construction. The floor troughs are drained by means of a floor drain placed in a low point at one end. The troughs are usually pitched at ¼ in./ft of run to the drain. The drain should be constructed of acidresistant materials and have a grate that can be easily removed. For small animal rooms where bedding is not disposed of in the room, a 4-in. (100-mm) drain is considered adequate. In most other locations, it is recommended that a 6-in. (150-mm) drain be provided. A flushing-rim type drain should be considered to flush all types of waste into the drainage system. Floor drains should have the capability of being sealed by the replacement of the grates with solid covers during periods when the room may not be in service.   Plumbing Systems & Design 

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Equipment Sanitizing Maintaining drinking-water quality requires that the recoil hoses and rack manifolds be not merely washed but internally sanitized. This is most often done at the same time the cages are washed. Separate rack-manifold and recoil-hose flush stations are available for this purpose and are usually installed in the cage-wash area. Washing can be done manually or automatically. The hoses are flushed for 1 to 2 min with 4 gpm (16 L/min) of water. Chlorine is injected into the water by a chlorine-injection station (proportioner) set to deliver 10 to 20 ppm into the flush water. Ten scfm of oil-free compressed air at 60 psig is blown through the hoses to dry them. If chlorine is used as a disinfectant, a contact time of 30 min is recommended before evacuation and drying. Periodic sanitizing of the room-distribution piping system is required for maintaining good water quality. Sanitizing is done prior to system flushing. To accomplish this, a portable sanitizer is used to manually inject a sanitizing solution directly into the piping system. In order to do this, an injection port is required at the inlet to the pressure-reducing station. The portable sanitizer usually consists of a 20-gal (90-L) polyethylene tank with a submersible pump inside and a flexible hose used to connect the tank to the injection port. The disinfecting solution is a mixture of chlorine and water with 20 ppm of chlorine. The mixture should maintain a contact time in the piping of 30 to 45 min. Drainage-System Sizing As mentioned previously, for individual animal rooms where bedding is not disposed of in the drainage system, a 4-in. drain is acceptable. In general, a 6-in. drain is considered good practice. The size of the drainage system piping should be a minimum of 6 in., with a ¼-in. pitch when possible and the piping sized to flow ½ to 2⁄3 full in order to accommodate unexpected inflow.

Monitoring Systems The monitoring of various animal-utility systems is critical to keep within a range of values consistent with the protocol of the experiments being conducted at the facility. This is accomplished by a central monitoring system that includes many measurements from HVAC and electrical systems. For the animal drinking-water system, parameters such as water pressure, flow rates, leakage, pH, and temperature in various areas of the facility are helpful for maintenance, monitoring, and alarms.

Systems Design Considerations The amount of exposed piping inside any animal room should be minimized. The exception is the animal drinking-water system, which is usually exposed on the walls of the room. This piping should be installed using standoffs to permit proper cleaning of the wall and around the pipe. The piping material used for all systems should be selected with consideration given to the facility cleaning methods and PSDMAGAZINE.ORG

type of disinfectant. Where sterilization is required and cleaning Simpo PDF Merge and Split Unregistered Version very frequent, stainless-steel pipe should be considered. If insulation is used on piping, it should be protected with a stainless steel jacket to permit adequate cleaning. Pipe penetrations should be sealed with a high-grade, impervious, and fire-resistant sealant. Escutcheons should not be used because they allow the accumulation of dirt and bacteria behind them. ✺

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CONTINUING EDUCATION Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com Continuing Education from Plumbing Systems & Design Kenneth G.Wentink, PE, CPD, and Robert D. Jackson

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The technical article you must read to complete the exam is located at www.psdmagazine.org. The following exam and application form also may be downloaded from the Web site. Reading the article and completing the form will allow you to apply to ASPE for CEU credit. For most people, this process will require approximately one hour. If you earn a grade of 90 percent or higher on the test, you will be notified that you have logged 0.1 CEU, which can be applied toward the CPD renewal requirement or numerous regulatory-agency CE programs. (Please note that it is your responsibility to determine the acceptance policy of a particular agency.) CEU information will be kept on file at the ASPE office for three years. Note: In determining your answers to the CE questions, use only the material presented in the corresponding continuing education article. Using information from other materials may result in a wrong answer.

About This Issue’s Article The November/December 2006 Continuing Education article is “Animal-care Facility Piping Systems,” Chapter 7 of Pharmaceutical Facilities Plumbing Systems by Michael Frankel. This chapter discusses the various piping systems uniquely associated with the physical care, health, and wellbeing of laboratory animals. Included are utility systems for animal watering, water treatment, room and floor cleaning, equipment washing, cage flushing and drainage, and other specialized piping required for laboratory and experimental work within the facility. You may locate this article at www.psdmagazine.org. Read the article, complete the following exam, and submit your answer sheet to the ASPE office to potentially receive 0.1 CEU.

CE Questions—“Animal-care Facility Piping Systems” (PSD 136)

PSD 136

Do you find it difficult to obtain continuing education units (CEUs)? Through this special section in every issue of PS&D, ASPE can help you accumulate the CEUs required for maintaining your Certified in Plumbing Design (CPD) status.

1. What comprises the largest solid waste item from animal cages? a.  bedding, b.  feces, c.  carcasses, d.  miscellaneous waste

c. is the guide for the care and use of laboratory animals d. is the code for good laboratory practice for non-clinical laboratory studies

2. This chapter discusses various piping systems uniquely associated with the physical care, health, and well-being of ___________. a.  laboratory workers, b.  laboratory animals, c.  animal watering, d.  cage cleaning

8. Select the true statement below. a. There are no generally recognized and accepted standards for animal drinking water. b. Drinking valves are not used by animals to obtain water from the distribution system. c. Water pressure, minimum and maximum, for the various animals to be served is mandated in the plumbing code. d. Reverse osmosis (RO) systems are inappropriate for animal drinking water systems.

3. A single-station detergent-dispensing system is used when rooms are ___________. a. hosed down b. cleaned with mops or squeegees c. cleaned with steam d. none of the above 4. To maintain drinking water quality, ___________. a. a water purification system must be designed b. the water system must be allowed to run continuously c. there must be chlorine injection d. the drinking water distribution system must be flushed periodically 5. Floor drains should not be placed ___________ where animals are kept. a. under cages in rooms b. in the center of the room c. at the back edge of cages in rooms d. none of the above 6. A pulping unit is used to ___________. a. separate water from solid waste b. determine the pH of the waste c. determine the temperature of the waste d. grind the waste into a slurry 7. 10-CFR-58 ___________. a. is the federal code that must be followed when keeping animals for research b. requires compliance with FDA protocols for pharmaceutical applications 10  Plumbing Systems & Design 

NOVEMBER/DECEMBER 2006

9. The recommended water pressure for dogs and cats is ___________. a.  6–12 psig, b.  20.4–34 kPa, c.  more than for rats and mice, d.  none of the above

10. What flow rate and pressure of oil-free air is used to dry the interior of hoses? a. 5 scfm at 30 psig b. 10 scfm at 30 psig c. 5 scfm at 60 psig d. 10 scfm at 60 psig

11. What type of piping material should be used on systems that require frequent sterilization? a. cast iron b. copper c. galvanized d. stainless steel 12. The water consumption of small animals in cages is ___________. a. based on a flushing system to maintain fresh water in the piping at all times b. established by experience c. very low d. none of the above

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Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com Plumbing Systems & Design Continuing Education Application Form This form is valid up to one year from date of publication. The PS&D Continuing Education program is approved by ASPE for up to one contact hour (0.1 CEU) of credit per article. Participants who ear a passing score (90 percent) on the CE questions will receive a letter or certification within 30 days of ASPE’s receipt of the application form. (No special certificates will be issued.) Participants who fail and wish to retake the test should resubmit the form along with an additional fee (if required). 1.  Photocopy this form or download it from www.psdmagazine.org. 2.  Print or type your name and address. Be sure to place your ASPE membership number in the appropriate space. 3.  Answer the multiple-choice continuing education (CE) questions based on the corresponding article found on www.psdmagazine.org and the appraisal questions on this form. 4.  Submit this form with payment ($35 for nonmembers of ASPE) if required by check or money order made payable to ASPE or credit card via mail (ASPE Education Credit, 8614 W. Catalpa Avenue, Suite 1007, Chicago, IL 60656) or fax (773-695-9007). Please print or type; this information will be used to process your credits. Name _ __________________________________________________________________________________________________ Title _______________________________________________ ASPE Membership No.____________________________________ Organization _ ____________________________________________________________________________________________ Billing Address ____________________________________________________________________________________________ City_ _______________________________________ State/Province________________________ Zip _ ____________________ Country____________________________________________ E-mail_________________________________________________ Daytime telephone_ _________________________________ Fax___________________________________________________ I am applying for the following continuing education credits:

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Animal-care Facility Piping Systems (PSD 136)

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Animal-care Facility Piping Systems (PSD 136) Was the material new information for you? ❏ Yes ❏ No Was the material presented clearly? ❏ Yes ❏ No Was the material adequately covered? ❏ Yes ❏ No Did the content help you achieve the stated objectives? ❏ Yes ❏ No Did the CE questions help you identify specific ways to use ideas presented in the article? ❏ Yes ❏ No How much time did you need to complete the CE offering (i.e., to read the article and answer the post-test questions)?___________________

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Plumbing Systems & Design  11

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PSD 143

Recirculating Domestic Hot Water Systems

Continuing Education from Plumbing Systems & Design Haig Demergian, PE, CPD

DECEMBER 2007

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CONTINUING EDUCATION

Recirculating Domestic Hot Water Systems

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INTRODUCTION It has been determined through field studies that the correct sizing and operation of water heaters depend on the appropriateness of the hot water maintenance system. If the hot water maintenance system is inadequate, the water heater sizing criteria are wrong and the temperature of the hot water distributed to the users of the plumbing fixtures is below acceptable standards. Additionally, a poorly designed hot water maintenance system wastes large amounts of energy and potable water and creates time delays for those using the plumbing fixtures. This chapter addresses the criteria for establishing an acceptable time delay in delivering hot water to fixtures and the limitations of the length between a hot water recirculation system and plumbing fixtures. It also discusses the temperature drop across a hot water supply system, types of hot water recirculation system, and pump selection criteria, and gives extensive information on the insulation of hot water supply and return piping.

Background

culated, dead-end branches to periodically used plumbing fixtures. The new allowable distances for uncirculated, dead-end branches represent a trade-off between the energy utilized by the hot water maintenance system and the cost of the insulation, on the one hand, and the cost of energy to heat the excess cold water makeup, the cost of wasted potable water, and extra sewer surcharges, on the other hand. Furthermore, engineers should be aware that various codes now limit the length between the hot water maintenance system and plumbing fixtures. They also should be aware of the potential for liability if an owner questions the adequacy of their hot water system design. What are reasonable delays in obtaining hot water at a fixture? For anything beside very infrequently used fixtures (such as those in industrial facilities or certain fixtures in office buildings), a delay of 0 to 10 sec is normally considered acceptable for most residential occupancies and public fixtures in office buildings. A delay of 11 to 30 sec is marginal but possibly acceptable, and a time delay longer than 31 sec is normally considered unacceptable and a significant waste of water and energy. Therefore, when designing hot water systems, it is prudent for the designer to provide some means of getting hot water to the fixtures within these acceptable time limits. Normally this means that there should be a maximum distance of approximately 25 ft (7.6 m) between the hot water maintenance system and each of the plumbing fixtures requiring hot water, the distance depending on the water flow rate of the plumbing fixture at the end of the line and the size of the line. (See Tables 1, 2, and 3.) The plumbing designer may want to stay under this length limitation because the actual installation in the field may differ slightly from the engineer’s design, and additional delays may be caused

In the past, the plumbing engineering community considered the prompt delivery of hot water to fixtures either a requirement for a project or a matter of no concern. The plumbing engineer’s decision was based primarily on the type of facility under consideration and the developed length from the water heater to the farthest fixture. Previous reference material and professional common practices have indicated that, when the distance from the water heater to the farthest fixture exceeds 100 ft (30.48 m) water should be circulated. However, this recommendation is subjective, and, unfortunately, some engineers and contractors use the 100-ft (30.48-m) criterion as the maximum length for all uncirculated, uninsulated, dead-end hot water branches to fixtures in order to cut the cost of hot water distribution piping. These long, uninsulated, dead-end Table 1 Water Contents and Weight of Tube or Piping per Linear Foot branches to fixtures create considerable problems, such as a Nominal Copper Pipe Copper Pipe Steel Pipe lack of hot water at fixtures, inadequately sized water heater Diameter Type L Type M Schedule 40 assemblies, and thermal temperature escalation in showers. Water Wgt. Water Wgt. Water Wgt. (in.)a (gal/ft) (lb/ft) (gal/ft) (lb/ft) (gal/ft) (lb/ft) The 100-ft (30.48-m) length criterion was developed in 1973 ½ 0.012 0.285 0.013 0.204 0.016 0.860 after the Middle East oil embargo, when energy costs were the paramount concern and water conservation was given little ¾ 0.025 0.445 0.027 0.328 0.028 1.140 consideration. Since the circulation of hot water causes a loss 1 0.043 0.655 0.045 0.465 0.045 1.680 of energy due to radiation and convection in the circulated 1¼ 0.065 0.884 0.068 0.682 0.077 2.280 system and such energy losses have to be continually replaced 1½ 0.093 1.14 0.100 0.940 0.106 2.720 by water heaters, the engineering community compromised a Pipe sizes are indicated for mild steel pipe sizing. between energy loss and construction costs and developed Table 1(M) Water Contents and Weight of Tube or Piping per Meter the 100-ft (30.48-m) maximum length criterion.

Nominal Diameter

Length and Time Criteria Recently, due to concern about not only energy conservation but also the extreme water shortages in parts of the country, the 100-ft (30.48-m) length criteria has changed. Water wastage caused by the long delay in obtaining hot water at fixtures has become as critical an issue as the energy losses caused by hot water temperature maintenance systems. To reduce the wasting of cooled hot water significantly, the engineering community has reevaluated the permissible distances for uncir-

(mm)a DN15 DN20 DN25 DN32 DN40 a

Copper Pipe Type L Water Wgt. (L) (kg) 0.045 0.129 0.095 0.202 0.163 0.297 0.246 0.401 0.352 0.517

Copper Pipe Type M Water Wgt. (L) (kg) 0.049 0.204 0.102 0.328 0.170 0.465 0.257 0.682 0.379 0.940

Steel Pipe Schedule 40 Water Wgt. (L) (kg) 0.061 0.390 0.106 0.517 0.170 0.762 0.291 1.034 0.401 1.233

CPVC Pipe Schedule 40 Water Wgt. (gal/ft) (lb/ft) 0.016 0.210 0.028 0.290 0.045 0.420 0.078 0.590 0.106 0.710

CPVC Pipe Schedule 40 Water Wgt. (L) (kg) 0.061 0.099 0.106 0.132 0.170 0.191 0.295 0.268 0.401 0.322

Pipe sizes are indicated for mild steel pipe sizing.

Reprinted from Domestic Water Heating Design Manual, Second Edition, Chapter 14: “Recirculating Domestic Hot Water Systems.” © American Society of Plumbing Engineers , 2003.

2  Plumbing Systems & Design 

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Results of Delays in Delivering Hot Water to Fixtures

Table 2  Approximate Fixture and Appliance Water Flow Rates Maximum Flow Ratesa Fittings GPM L/Sec Lavatory faucet 2.0 1.3   Public non-metering 0.5 0.03   Public metering 0.25 gal/cycle 0.946 L/cycle Sink faucet 2.5 0.16 Shower head 2.5 0.16 Bathtub faucets   Single-handle 2.4 minimum 0.15 minimum   Two-handle 4.0 minimum 0.25 minimum Service sink faucet 4.0 minimum 0.25 minimum Laundry tray faucet 4.0 minimum 0.25 minimum Residential dishwasher 1.87 aver 0.12 aver Residential washing machine 7.5 aver 0.47 aver

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As mentioned previously, when there is a long delay in obtaining hot water at the fixture, there is significant wastage of potable water as the cooled hot water supply is simply discharged down the drain unused. Furthermore, plumbing engineers concerned about total system costs should realize that the cost of this wasted, previously heated water must include: the original cost for obtaining potable water, the cost of previously heating the water, the final cost of the waste treatment of this excess potable water, which results in larger sewer surcharges (source of supply to end disposal point), and the cost of heating the new cold water to bring it up to the required temperature. Furthermore, if there is a long delay in obtaining hot water at the fixtures, the faucets are turned on for long periods of time to bring the hot water supply at the fixture up to the desired temperature. This can cause the water heating system to run out of a Unless otherwise noted. hot water and make the heater sizing inadequate, because the heater is unable to heat all the extra cold water brought Table 3  Approximate Time Required to Get Hot Water to a Fixture into the system through the wastage of the water discharged Delivery Time (sec) down the drain. In addition, this extra cold water entering Fixture Flow Rate (gpm) 0.5 1.5 2.5 4.0 the hot water system reduces the hot water supply temperature. This exacerbates the problem of insufficient hot water Piping Length (ft) 10 25 10 25 10 25 10 25 because to get a proper blended temperature more lower Copper ½ in. 25 63a 8 21 5 13 3 8 temperature hot water will be used to achieve the final mixed   Pipe ¾ in. 48a 119a 16 40a 10 24 6 15 water temperature. (See Chapter 1, Table 1.1.) Additionally, Steel Pipe ½ in. 63a 157a 21 52a 13 31a 8 20 this accelerates the downward spiral of the temperature of   Sched. 40 ¾ in. 91a 228a 30 76a 18 46a 11 28 the hot water system. CPVC Pipe ½ in. 64a 159a 21 53a 13 32a 8 20 Another problem resulting from long delays in getting hot   Sched. 40 ¾ in. 95a 238a 32 79a 19 48a 12 30 water to the fixtures is that the fixtures operate for longer than Note: Table based on various fixture flow rates, piping materials, and dead-end branch lengths. Calculations are based expected periods of time. Therefore, the actual hot water on the amount of heat required to heat the piping, the water in the piping, and the heat loss from the piping. Based on demand is greater than the demand normally designed for. water temperature of 140°F and an air temperture of 70°F. Therefore, when sizing the water heater and the hot water a Delays longer than 30 sec are not acceptable. piping distribution system, the designer should be aware that the lack of a proper hot water maintenance system can Table 3(M)  Approximate Time Required to Get Hot Water to a Fixture seriously impact the required heater size. Delivery Time (sec)

Fixture Flow Rate (L/sec) Piping Length (m) Copper   Pipe Steel Pipe   Sched. 40 CPVC Pipe   Sched. 40

0.03 DN15 DN22 DN15 DN20 DN15 DN20

3.1 25 48a 63a 91a 64a 95a

0.10 7.6 63a 119a 157a 228a 159a 238a

3.1 8 16 21 30 21 32

0.16 7.6 21 40a 52a 76a 53a 79a

3.1 5 10 13 18 13 19

Methods of Delivering Reasonably Prompt Hot Water Supply

0.25 7.6 13 24 31a 46a 32a 48a

3.1 3 6 8 11 8 12

7.6 8 15 20 28 20 30

Note: Table based on various fixture flow rates, piping materials, and dead-end branch lengths. Calculations are based on the amount of heat required to heat the piping, the water in the piping, and the heat loss from the piping. Based on water temperature of 60°C and an air temperture of 21.1°C. a Delays longer than 30 sec are not acceptable.

by either the routing of the pipe or other problems. Furthermore, with the low fixture discharge rates now mandated by national and local laws, it takes considerably longer to obtain hot water from non-temperature maintained hot water lines than it did in the past, when fixtures had greater flow rates. For example, a public lavatory with a 0.50 or 0.25 gpm (0.03 or 0.02 L/sec) maximum discharge rate would take an excessive amount of time to obtain hot water from 100 ft (30.48 m) of uncirculated, uninsulated hot water piping. (See Table 3.) This table gives conservative approximations of the amount of time it takes to obtain hot water at a fixture. The times are based on the size of the line, the fixture flow rate, and the times required to replace the cooled off hot water, to heat the pipe, and to offset the convection energy lost by the insulated hot water line.

Hot water maintenance systems are as varied as the imaginations of the plumbing engineers who create them. They can be grouped into three basic categories, though any actual installation may be a combination of more than one of these types of system. The three basic categories are 1.  Circulation systems. 2.  Self-regulating heat trace systems. 3. Point-of-use water heaters (include booster water heaters).

Circulation Systems for Commercial, Industrial, and Large Residential Projects

A circulation system is a system of hot water supply pipes and hot water return pipes with appropriate shutoff valves, balancing valves, circulating pumps, and a method of controlling the circulating pump. The diagrams for six basic circulating systems are shown in Figures 1 through 6.

Self-Regulating Heat Trace Over approximately the last 20 years, self-regulating heat trace has come into its own because of the problems of balancing circulated hot water systems and energy loss in the return piping. For further discussion of this topic, see Chapter 15.

DECEMBER 2007 

Plumbing Systems & Design  3

CONTINUING EDUCATION: Recirculating Domestic Hot Water Systems Point-of-Use Heaters

Fixture 1  Upfeed Hot Water System with Heater at Bottom of System.

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This concept is applicable when there is a single fixture or group of fixtures that is located far from the temperature maintenance system. In such a situation, a small, instantaneous, pointof-use water heater—an electric water heater, a gas water heater, or a small under-fixture storage type water heater of the magnitude of 6 gal (22.71 L)—can be provided. (See Figure 7.) The point-of-use heater will be very cost-effective because it will save the cost of running hot water piping to a fixture that is a long distance away from the temperature maintenance system. The plumbing engineer must remember, however, that when a water heater is installed there are various code and installation requirements that must be complied with, such as those pertaining to T & P relief valve discharge. Instantaneous electric heaters used in pointof-use applications can require a considerable amount of power, and may require 240 or 480 V service.

Potential Problems in Circulated Hot Water Maintenance Systems

* See text for requirements for strainers.

Figure 2  Downfeed Hot Water System with Heater at Top of System.

The following are some of the potential problems with circulated hot water maintenance systems that must be addressed by the plumbing designer.

Water Velocities in Hot Water Piping Systems For copper piping systems, it is very important that the circulated hot water supply piping and especially the hot water return piping be sized so that the water is moving at a controlled velocity. High velocities in these systems can cause pinhole leaks in the copper piping in as short a period as six months or less.

Balancing Systems It is extremely important that a circulated hot water system be balanced for its specified flows, including all the various individual loops within the circulated system. Balancing is required even though an insulated circulated line usually requires very little flow to maintain satisfactory system temperatures. If the individual hot water circulated loops are not properly balanced, the circulated water will tend to shortcircuit through the closest loops, creating high velocities in that piping system. Furthermore, the short-circuiting of the circulated hot water will result in complaints about the long delays in getting hot water at the remotest loops. If the hot water piping is copper, high velocities can create velocity erosion which will destroy the piping system. Because of the problems inherent in manually balancing hot water circulation systems, many professionals incorporate factory preset flow control devices in their hot water systems. While the initial cost of such a device is higher than the cost of a manual balancing valve, a

4  Plumbing Systems & Design 

DECEMBER 2007

* See text for requirements for strainers.

Figure 3  Upfeed Hot Water System with Heater at Bottom of System.

* See text for requirements for strainers.

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Figure 4  Downfeed Hot Water System with Heater at Top of System.

preset device may be less expensive when the balancing the entire hot water system is included. When using a preset flow control device, however, the plumbing designer has to be far more accurate in selecting the control device’s capacity as there is no possibility of field adjustment. Therefore, if more or less hot water return flow is needed during the field installation, a new flow control device must be installed and the old one must be removed and discarded.

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Isolating Portions of Hot Water Systems

* See text for requirements for strainers.

Figure 5  Combination Upfeed and Downfeed Hot Water System with Heater at Bottom of System.

It is extremely important in circulated systems that shutoff valves be provided to isolate an entire circulated loop. This is done so that if individual fixtures need modification, their piping loop can be isolated from the system so the entire hot water system does not have to be shut off and drained. The location of these shutoff valves should be given considerable thought. The shutoff valves should be accessible at all times, so they should not be located in such places as the ceilings of locked offices or condominiums.

Maintaining the Balance of Hot Water Systems

Note: This piping system increases the developed length of the HW system over the upfeed systems shown in Figures 1 and 3. * See text for requirements for strainers.

Figure 6  Combination Downfeed and Upfeed Hot Water System with Heater at Top of System.

To ensure that a balanced hot water system remains balanced after the shutoff valves have been utilized, the hot water return system must be provided with a separate balancing valve in addition to the shutoff valve or, if the balancing valve is also used as the shutoff valve, the balancing valve must have a memory stop. (See the discussion of “balancing valves with memory stops” below.) With a memory stop on the valve, plumbers can return a system to its balanced position after working on it rather than have the whole piping system remain unbalanced, which would result in serious problems.

Providing Check Valves at the Ends of Hot Water Loops The designer should provide a check valve on each hot water return line where it joins other hot water return lines. This is done to ensure that a plumbing fixture does not draw hot return water instead of hot supply water, which could unbalance the hot water system and cause delays in obtaining hot water at some fixtures.

A Delay in Obtaining Hot Water at Dead-End Lines Keep the delay in obtaining hot water at fixtures to within the time (and branch length) parameters given previously to avoid unhappy users of the hot water system and to prevent lawsuits.

Flow Balancing Devices Note: This piping system increases the developed length of the HW system over the downfeed systems shown in Figures 2 and 4. * See text for requirements for strainers.

The following are the more common types of balancing device. DECEMBER 2007 

Plumbing Systems & Design  5

CONTINUING EDUCATION: Recirculating Domestic Hot Water Systems Fixed Orifices and Venturis

Figure 7  Instantaneous Point-of-Use Water Heater Piping Diagram.

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Source: Courtesy of Chronomite Laboratories, Inc.

These can be obtained for specific flow rates and simply inserted into the hot water return piping system. (See Figure 8.) However, extreme care should be taken to locate these devices so they can be removed and cleaned out, as they may become clogged with the debris in the water. It is recommended, therefore, that a strainer with a blowdown valve be placed ahead of each of these devices. Additionally, a strainer with a fine mesh screen can be installed on the main water line coming into the building to help prevent debris buildup in the individual strainers. Also, a shutoff valve should be installed before and after these devices so that an entire loop does not have to be drained in order to service a strainer or balancing device.

Factory Preset Automatic Flow Control Valves The same admonition about strainers and valves given for “fixed orifices and venturis” above applies to the installation and location of these devices. (See Figure 9.)

Flow Regulating Valves These valves can be used to determine the flow rate by reading the pressure drop across the valve. They are available from various manufacturers. (See Figure 10.)

Balancing Valves with Memory Stops These valves can be adjusted to the proper setting by installing insertable pressure measuring devices (Pete’s Plugs, etc.) in the piping system, which indicate the flow rate in the pipe line. (See Figure 11.)

Sizing Hot Water Return Piping Systems and Recirculating Pumps The method for selecting the proper size of the hot water return piping system and the recirculating pump is fairly easy, but it does require engineering judgment. First, the plumbing engineer has to design the hot water supply and hot water return piping systems, keeping in mind the parameters for total developed length,1 prompt delivery of hot water to fixtures, and velocities in pipe lines. The plumbing engineer has to make assumptions about the sizes of the hot water return piping. After the hot water supply and hot water return systems are designed, the designer should make a piping diagram of the hot water supply system and the assumed return system showing piping sizing and approximate lengths. From this piping diagram the hourly heat loss occurring in the circulated portion of the hot water supply and return systems can be determined. (See Table 4 for minimum required insulation thickness and Table 5 for approximate piping heat loss.) Next determine the heat loss in the hot water storage tank if one is provided. (See Table 6 for approximate tank heat loss.) Calculate the total hot water system energy loss (tank heat loss plus piping heat loss) in British thermal units per hour (watts). This total hot water system energy loss is represented by q in Equation 1 below. Note: Heat losses from storage type water heater tanks are not normally included in the hot water piping system heat loss because the water heater capacity takes care of this loss, whereas pumped hot water has to replace the piping convection losses in the piping system. (1) q =  60rwc∆T [q =  3600rwc∆T]

6  Plumbing Systems & Design 

DECEMBER 2007

where

60 = min/h 3600 = sec/h q = piping heat loss, Btu/h (kJ/h) r = flow rate, gpm (L/sec) w = weight of heated water, lb/gal (kg/L) c = specific heat of water, Btu/lb/°F (kJ/kg/K) ∆T = change in heated water temperature (temperature of leaving water minus temperature of incoming water, represented in this manual as Th – Tc, °F [K])

Therefore

q = c (gpm × 8.33 lb/gal)(60 min/h)(°F temperature drop) = 1(gpm) × 500 × °F temperature drop [q = c (L/sec • 1kg/L)(3600 sec/h)(K temperature drop) = 1(L/sec) • 15 077 kJ/L/sec/K • K temperature drop] system heat loss (Btu/h) 500 × °F temperature drop system heat loss (kJ/h) L/sec  ≈ 15 077 • K temperature drop In sizing hot water circulating systems, the designer should note that the greater the temperature drop across the system, the less water is required to be pumped through the system and, therefore, the greater the savings on pumping costs. However, if the domestic hot water supply starts out at 140°F (60°C) with, say, a 20°F (6.7°C) temperature drop across the supply system, the fixtures near the end of the circulating hot water supply loop could be provided with a hot water supply of only 120°F (49°C). In addition, if the hot water supply delivery temperature is 120°F (49°C) instead of 140°F (60°C), the plumbing fixtures will use greater volumes of hot water to get the desired blended water temperature (see Chapter 1, Table 1.1). Therefore, the recommended hot water system temperature drop should be of the magnitude of 5°F (3°C). This means that if the hot water supply starts out from the water heater at a temperature between 135 and 140°F (58 and 60°C), the lowest hot water supply temperature provided by the hot water supply system could (2)  gpm  ≈

[

]

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Figure 9  Preset Self-Limiting Flow Control Cartridge.

Figure 8  Fixed Orifices and Venturi Flow Meters.

Source: Courtesy of Gerand Engineering Co.

Source: Courtesy of Griswold Controls.

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be between 130 and 135°F (54 and 58°C). With multiple temperature distribution systems, it is recommended that the recirculation system for each temperature distribution system be extended back to the water heating system separately and have its own pump. Using Equation 2, we determine that, if there is a 5°F (3°C) temperature drop across the hot water system, the number to divide into the hot water circulating system heat loss (q) to obtain the minimum required hot water return circulation rate in gpm (L/sec) is 2500 (500 × 5°F), (45 213 [15 071 • 3°C]). For a 10°F (6°C) temperature drop that number is 5000 (from Equation 2, 500 × 10°F = 5000) (90 426 [from Equation 2, 15 071 • 6°C = 90 426]). However, this 10°F (6°C) temperature drop may produce hot water supply temperatures that are lower than desired. After Equation 2 is used to establish the required hot water return flow rate, in gpm (L/sec), the plumbing designer can size the hot water return piping system based on piping flow rate velocities and the available pump heads. It is quite common that a plumbing designer will make wrong initial assumptions about the sizes

of the hot water return lines to establish the initial heat loss figure (q). If that is the case, the plumbing engineer will have to correct the hot water return pipe sizes, redo the calculations using the new data based on the correct pipe sizing, and verify that all the rest of the calculations are now correct.

EXAMPLE 1 — CALCULATION TO DETERMINE REQUIRED CIRCULATION RATE 1. Assume that the hot water supply piping system has 800 ft (244 m) of average size 1 ¼ in. (DN32) pipe. From Table 5, determine the heat loss per linear foot (meter). To find the total heat loss, multiply length times heat loss per foot (meter):

800 ft × 13 Btu/h/ft  =  10,400 Btu/h supply piping losses (244 m • 12.5 W =  3050 W supply piping losses) 2. Assume that the hot water return piping system for the system in no. 1 above has 100 ft (30.5 m) of average ½ in. (DN15) piping and 100 ft (30.5 m) of average ¾ in. (DN20) pipe. From Table 5 determine the heat loss per linear foot (meter): 100 ft × 8 Btu/h/ft  =  800 Btu/h piping loss (30.5 m • 7.7 W/m  =  235 W piping loss) 100 ft × 10 Btu/h/ft  = 1000 Btu/h piping loss 1800 Btu/h piping loss

(30.5 m

•

9.6 W/m  =

293 W piping loss 528 W piping loss

)

3. Determine the hot water storage tank heat loss. Assume the system in no. 1 above has a 200-gal (757-L) hot water storage DECEMBER 2007 

Plumbing Systems & Design  7

CONTINUING EDUCATION: Recirculating Domestic Hot Water Systems Figure 10  Adjustable Orifice Flow Control Valve.

Source: ITT Industries. Used with permission.

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tank. From Table 6 determine the heat loss of the storage tank @ 759 Btu/h (222 W). 4. Determine the hot water system’s total heat losses by totaling the various losses: A. Hot water supply piping losses 10,400 Btu/h B. Hot water return piping losses 1,800 Btu/h C. Hot water storage tank losses 759 Btu/h Total system heat losses 12,959 Btu/h Total system piping heat losses (A + B) = 12,200 Btu/h [A. Hot water supply piping losses 3050 W B. Hot water return piping losses 527 W C. Hot water storage tank losses 222 W Total system heat losses 3799 W Total system piping heat losses (A + B) = 3577 W] From Equation 2, using a system piping loss of 12,200 Btu/h (3577 W) and a 5°F (3°C) temperature drop,

Source: Courtesy of Milwaukee Valve Co.



Figure 11  Adjustable Balancing Valve with Memory Stop.

12,200 Btu/h = 4.88 gpm (say 5 gpm) 5°F temperature difference × 500 required hot water return circulation rate 3577 W = 0.29 (say 0.3) L/sec 3 3°C temp. difference • 4188.32 kJ/m required hot water return circulation

Recalculation of Hot Water System Losses 1. Assume that the hot water supply piping system has 800 ft (244 m) of average size 1¼ in. (DN32) pipe. From Table 5 determine the heat loss per linear foot (meter): 800 ft × 13 Btu/h/ft  = 10,400 Btu/h piping loss (244 m • 12.5 W/m  =  3050 W piping loss) 2. Assume that the hot water return piping system for the system in no. 1 above has 100 ft (30.5 m) of average ½ in. (DN15) pipe, 25 ft (7.6 m) of average ¾ in. (DN22) pipe, and

8  Plumbing Systems & Design 

DECEMBER 2007

75 ft (22.9 m) of average 1 in. (DN28) pipe. From Table 5, determine the heat loss per linear foot (meter): 100 ft × 8 Btu/h/ft = 25 ft × 10 Btu/h/ft = 75 ft × 10 Btu/h/ft =

800 Btu/h piping loss 250 Btu/h piping loss 750 Btu/h piping loss 1800 Btu/h piping loss

[30.5 m • 7.7 W/m = 235 W piping loss PSDMAGAZINE.ORG

Table 4  Minimum Pipe Insulation Thickness Simpo PDF Merge and Split Unregistered Version Required Insulation Thickness for Piping (in.) Runouts 2a 8 in. or in. or Less 1 in. or Less 1¼–2 in. 2½–4 in. 5 & 6 in. Larger ½ 1 1 1½ 1½ 1½ Note: Data based on fiberglass insulation with all-service jacket. Data will change depending on actual type of insulation used. Data apply to recirculating sections of hot water systems and the first 3 ft from the storage tank of uncirculated systems. a Uncirculated pipe branches to individual fixtures (not exceeding 12 ft in length). For lengths longer than 12 ft, use required insulation thickness shown in table.

Table 4(M)  Minimum Pipe Insulation Thickness Required Insulation Thickness for Piping (mm) Runouts DN32 aor DN25 or DN32– DN65– DN125 & Less Less DN50 DN100 DN150 13 25 25 40 40

DN200 or Larger 40

Note: D ata based on fiberglass insulation with all-service jacket. Data will change depending on actual type of insulation used. Data apply to recirculating sections of hot water systems and the first 0.9 m from the storage tank of uncirculated systems. a Uncirculated pipe branches to individual fixtures (not exceeding 3.7 m in length). For lengths longer than 305 mm, use required insulation thickness shown in table.

Table 5  Approximate Insulated Piping Heat Loss and Surface Temperature Surface Nominal Pipe Insulation Heat Loss Temperature Size (in.) Thickness (in.) (Btu/h/ linear ft) (°F) ½ 1 8 68 ¾ 1 10 69 1 1 10 69 1¼ 1 13 70 1½ 1 13 69 2 or less ½a 24 or less 74 2 1 16 70 2½ 1½ 12 67 3 1½ 16 68 4 1½ 19 69 6 1½ 27 69 8 1½ 32 69 10 1½ 38 69 Note: Figures based on average ambient temperature of 65°F and annual average wind speed of 7.5 mph. a Uncirculating hot water runout branches only.

Table 5(M)  Approximate Insulated Piping Heat Loss and Surface Temperature Surface Nominal Pipe Insulation Heat Loss Temperature Size (mm) Thickness (mm) (W/m) (°C) DN15 25 7.7 20 DN20 25 9.6 21 DN25 25 9.6 21 DN32 25 12.5 21 DN40 25 12.5 21 DN50 or less 13a 23.1 or less 23 DN50 25 15.4 21 DN65 38 11.5 19 DN80 38 15.4 20 DN100 38 18.3 21 DN150 38 26.0 21 DN200 38 30.8 21 DN250 38 36.5 21 Note: Figures based on average ambient temperature of 18°C and annual average wind speed of 12 km/h. a Uncirculating hot water runout branches only.

Table 6  Heat Loss from Various Size Tanks with

- http://www.simpopdf.com Various Insulation Thicknesses

Insulation Approx. Energy Loss Thickness Tank Size from Tank at Hot Water a (in.) (gal) Temperature 140°F (Btu/h) 1 50 468 1 100 736 2 250 759 3 500 759 3 1000 1273 Source: From Sheet Metal and Air Conditioning Contractors National Association (SMACNA) Table 2 data. a For unfired tanks, federal standards limit the loss to no more than 6.5 Btu/h/ft2 of tank surface.

Table 6(M)  Heat Loss from Various Size Tanks with Various Insulation Thicknesses Insulation Approx. Energy Loss Thickness Tank Size from Tank at Hot Watera (mm) (L) Temperature 60°C (W) 25.4 200 137 25.4 400 216 50.8 1000 222 76.2 2000 222 76.2 4000 373 Source: From Sheet Metal and Air Conditioning Contractors National Association (SMACNA) Table 2 data. a For unfired tanks, federal standards limit the loss to no more than 1.9 W/m2 of tank surface.

7.6 m • 9.6 W/m = 73 W piping loss 22.9 m • 9.6 W/m = 220 W piping loss 528 W piping loss] 3. Determine the hot water storage tank heat loss. Assume the system in no. 1 above has a 200-gal (757-L) hot water storage tank. From Table 6 determine the heat loss of the storage tank @ 759 Btu/h (222 W). 4. Determine the system’s total heat losses: A. Hot water supply losses 10,400 Btu/h B. Hot water return losses 1,800 Btu/h C. Hot water storage tank losses 759 Btu/h Total system heat losses 12,959 Btu/h Total system piping heat losses (A + B) = 12,200 Btu/h [A. Hot water supply losses B. Hot water return losses C. Hot water storage tank losses Total system heat losses Total system piping heat losses (A + B) =

3050 W 528 W 222 W 3800 W 3578 W]

Note: The recalculation determined that the hot water system heat losses remained unchanged and that 4.88 (say 5) gpm (0.29 [say 0.3] L/sec) is the flow rate that is required to maintain the 5°F (3°C) temperature drop across the hot water supply system. It should be stated that engineers use numerous rules of thumb to size hot water return systems. These rules of thumb are all based on assumptions, however, and are not recommended. It is recommended that the engineer perform the calculations for each project to establish the required flow rates because, with all the various capacities of the pumps available today, exact sizing is possible, and any extra circulated flow caused by the plumbing engineer using a rule of thumb equates to higher energy costs, to the detriment of the client.

Establishing the Head Capacity of the Hot Water Circulating Pump DECEMBER 2007 

Plumbing Systems & Design  9

CONTINUING EDUCATION: Recirculating Domestic Hot Water Systems The hot water return circulating pump is selected based on the It can be used very successfully for residential and commercial Simpo PDFreturn Merge and(inSplit Unregistered - http://www.simpopdf.com required hot water flow rate gpm [L/sec]), calculatedVersion using applications. Equation 2, and the system’s pump head. The pump head is nor- 2. A thermostatic aquastat is a device that is inserted into the mally determined by the friction losses through only the hot water hot water return line. When the water in the hot water return return piping loops and any losses through balancing valves. The hot system reaches the distribution temperature, it shuts off the water return piping friction losses usually do not include the friction circulating pump until the hot water return system temperalosses that occur in the hot water supply piping. The reason for this is ture drops by approximately 10°F [5.5°C]. With this method, that the hot water return circulation flow is needed only to keep the when there is a large consumption of hot water by the plumbhot water supply system up to the desired temperature when there ing fixtures, the circulating pump does not operate. is no flow in the hot water supply piping. When people use the hot 3. A time clock is used to turn the pump on during specific hours water at the fixtures, there is usually sufficient flow in the hot water of operation when people are using the fixtures. The pump supply piping to keep the system hot water supply piping up to the would not operate, for example, at night in an office building desired temperature without help from the flow in the hot water when nobody is using the fixtures. return piping. 4. Often an aquastat and a time clock are used in conjunction The only exception to the rule of ignoring the friction losses in the so that during the hours a building is not operating the time hot water supply piping is a situation where a hot water return pipe clock shuts off the circulating pump, and during the hours the is connected to a relatively small hot water supply line. “Relatively building is in use the aquastat shuts off the pump when the small” here means any hot water supply line that is less than one system is up to the desired temperature. pipe size larger than the hot water return line. The problems created by this condition are that the hot water supply line will add Air Elimination additional friction to the head of the hot water circulating pump, In any hot water return circulation system it is very important that and the hot water circulating pump flow rate can deprive the last there be a means of eliminating any entrapped air from the hot plumbing fixture on this hot water supply line from obtaining its water return piping. Air elimination is not required in the hot water required flow. It is recommended, therefore, that in such a situation supply piping because the discharge of water from the fixtures will the hot water supply line supplying each hot water return piping eliminate any entrapped air. If air is not eliminated from the hot connection point be increased to prevent these potential problems, water return lines, however, it can prevent the proper circulation i.e., use ¾ in. (DN22) hot water supply piping and ½ in. (DN15) hot of the hot water system. It is imperative that a means of air elimiwater return piping, or 1 in. (DN28) hot water supply piping and ¾ nation be provided at all high points of a hot water return system. The plumbing engineer must always give consideration to precisely in. (DN22) hot water return piping, etc. When selecting the hot water circulating pump’s head, the where the air elimination devices are to be located and drained. For designer should be sure to calculate only the restrictions encoun- example, they should not be located in the unheated attics of buildtered by the circulating pump. A domestic hot water system is nor- ings in cold climates. If the plumbing engineer does not consider mally considered an open system (i.e., open to the atmosphere). the location of these devices and where they will drain, the result When the hot water circulating pump is operating, however, it is may be unsightly piping in a building or extra construction costs. assumed that the piping is a closed system. Therefore, the designer Insulation should not include static heads where none exists. For example, in The use of insulation is very cost-effective. It means paying one time Figure 1, the hot water circulating pump has to overcome only the to save the later cost of significant energy lost by the hot water supply friction in the hot water return piping not the loss of the static head and return piping system. Also, insulation decreases the stresses pumping the water up to the fixtures because in a closed system on the piping due to thermal expansion and contraction caused the static head loss is offset by the static head gain in the hot water by changes in water temperature. Furthermore, the proper use of return piping. insulation eliminates the possibility of someone getting burned by a hot, uninsulated water line. See Table 5 for the surface temperaHot Water Circulating Pumps Most hot water circulating pumps are of the centrifugal type and are tures of insulated lines (versus 140°F [60°C] for bare piping). It is recommended that all hot water supply and return piping be available as either in-line units for small systems or base-mounted insulated. This recommendation exceeds some code requirements. units for large systems. Because of the corrosiveness of hot water See Table 4 for the minimum required insulation thicknesses for all systems, the pumps should be bronze, bronze fitted, or stainless systems. steel. Conventional, iron bodied pumps, which are not bronze If the insulated piping is installed in a location where it is subfitted, are not recommended. jected to rain or other water, the insulation must be sealed with a Control for Hot Water Circulating Pumps watertight covering that will maintain its tightness over time. Wet There are three major methods commonly used for controlling hot insulation not only does not insulate, it also releases considerable water circulating pumps: manual, thermostatic (aquastat), and heat energy from the hot water piping, thus wasting energy. Furtime clock control. Sometimes more than one of these methods are thermore, the insulation on any outdoor lines that is not sealed used on a system. watertight can be plagued by birds or rodents, etc., pecking at the 1. A manual control runs the hot water circulating pump contin- insulation to use it for their nests. In time, the entire hot water uously when the power is turned on. A manual control should supply and/or return piping will have no insulation. Such bare hot be used only when hot water is needed all the time, 24 h a day, water supply and/or return piping will waste considerable energy or during all the periods of a building’s operation. Otherwise, and can seriously affect the operation of the hot water system and it is not a cost-effective means of controlling the circulating water heaters. pump because it will waste energy. The minimum required insulation thicknesses given in Table 4 are based on insulation having thermal resistivity (R) in the range of Note: The method for applying the “on demand” concept for 4.0 to 4.6 ft2 × h × (°F/Btu) × in. (0.028 to 0.032 m2 • [°C/W] • mm) on a controlling the hot water circulating pump is a manual control. flat surface at a mean temperature of 75°F (24°C). Minimum insula-

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tion thickness shall be increased for materials having R values less 14. American Society of Plumbing Engineers. 2000. Energy conPDF Merge (0.028 and Split Unregistered Version - http://www.simpopdf.com • mm) or may be thanSimpo 4.0 ft2 × h × (°F/Btu) × in. m2 • [°C/W] servation in plumbing systems. Chapter 7 in ASPE Data Book, 2 reduced for materials having R values greater than 4.6 ft  × h × (°F/ Volume 1. Btu) × in. (0.032 m2 • [°C/W] • mm). 15. American Water Works Association. 1985. Internal corrosion 1. For materials with thermal resistivity greater than 4.6 of water distribution systems. Research Foundation cooperaft2 × h × (°F/Btu) × in. (0.032 m2 • [°C/W] • mm), the minimum tive research report. insulation thickness may be reduced as follows: 16. Cohen, Arthur. Copper Development Association. 1978. Copper for hot and cold potable water systems. Heating/ 4.6 × Table 4 thickness =  New minimum thickness Piping/Air Conditioning Magazine. May. Actual R 17. Cohen, Arthur. Copper Development Association. 1993. His0.032 • Table 4 thickness =  New minimum thickness Actual R torical perspective of corrosion by potable waters in building systems. Paper no. 509 presented at the National Association 2. For materials with thermal resistivity less than 4.0 ft2 × h × (°F/ of Corrosion Engineers Annual Conference. Btu) × in. (0.028 m2 • [°C/W] • mm), the minimum insulation 18. Copper Development Association. 1993. Copper Tube Handthickness shall be increased as follows: book. 4.0 × Table 4 thickness =  New minimum thickness 19. International Association of Plumbing and Mechanical OffiActual R cials. 1985. Uniform Plumbing Code Illustrated Training Manual. 0.028 • Table 4 thickness =  New minimum thickness Actual R 20. Konen, Thomas P. 1984. An experimental study of competing systems for maintaining service water temperature in residenConclusion tial buildings. In ASPE 1984 Convention Proceedings. In conclusion, an inappropriate hot water recirculation system can 21. Konen, Thomas P. 1994. Impact of water conservation on have serious repercussions for the operation of the water heater interior plumbing. In Technical Proceedings of the 1994 ASPE and the sizing of the water heating system. In addition, it can cause Convention. the wastage of vast amounts of energy, water, and time. Therefore, 22. Saltzberg, Edward. 1988. The plumbing engineer as a forensic it is incumbent upon the plumbing designer to design a hot water engineer. In Technical Proceedings of the 1988 ASPE Convention. recirculation system so that it conserves natural resources and is in 23. Saltzberg, Edward. 1993. To combine or not to combine: An accordance with the recommendations given in this chapter. ✺ in–depth review of standard and combined hydronic heating systems and their various pitfalls. Paper presented at the Bibliography American Society of Plumbing Engineers Symposium, Octo1. American Society of Heating, Refrigerating, and Air Condiber 22–23. tioning Engineers. 1993. Pipe sizing. Chapter 33 in Fundamen24. Saltzberg, Edward. 1996. The effects of hot water circulation tals Handbook. systems on hot water heater sizing and piping systems. Tech2. American Society of Heating, Refrigerating, and Air Condinical presentation given at the American Society of Plumbing tioning Engineers. 1993. Thermal and water vapor transmisEngineers convention, November 3–6. sion data. Chapter 22 in Fundamen­tals Handbook. 25. Saltzberg, Edward. 1997. In press. New methods for analyzing 3. American Society of Heating, Refrigerating, and Air Condihot water systems. Plumbing Engineer Magazine. tioning Engineers. 1995. Service water heating. Chapter 45 in 26. Saltzberg, Edward. 1997. In press. Prompt delivery of hot Applications Handbook. water at fixtures. Plumbing Engineer Magazine. 4. American Society of Heating, Refrigerating, and Air Con27. Sealine, David A., Tod Windsor, Al Fehrm, and Greg Wilcox. ditioning Engineers. Energy conservation in new build1988. Mixing valves and hot water temperature. In Technical ing design. ASHRAE Standards, 90A–1980, 90B–1975, and Proceedings of the 1988 ASPE Convention. 90C–1977. 28. Sheet Metal and Air Conditioning Contractors National Asso5. American Society of Heating, Refrigerating, and Air Condiciation. 1982. Retrofit of Building Energy Systems and Processes. tioning Engineers. Energy efficient design of new low rise 29. Steele, Alfred. Engineered Plumbing Design. 2d ed. residential buildings. ASHRAE Standards, 90.2–1993. 30. Steele, Alfred. 1988. Temperature limits in service hot water 6. American Society of Heating, Refrigerating, and Air Condisystems. In Technical Proceedings of the 1988 ASPE Convention. tioning Engineers. New information on service water heating. 31. Wen-Yung, W. Chan, and Milton Meckler. 1983. Pumps and Technical Data Bulletin. Vol. 10, No. 2. pump systems. In American Society of Plumbing Engineers 7. American Society of Mechanical Engineers. Plumbing fixture Handbook. fittings. ASME A112.18.1M–1989. 8. American Society of Plumbing Engineers. 2000. Cold water systems. Chapter 5 in ASPE Data Book, Volume 2. 9. American Society of Plumbing Engineers. 1989. Piping systems. Chapter 10 in ASPE Data Book. 10. American Society of Plumbing Engineers. 1989. Position paper on hot water temperature limitations. 11. American Society of Plumbing Engineers. 1989. Service hot water systems. Chapter 4 in ASPE Data Book. 12. American Society of Plumbing Engineers. 1990. Insulation. Chapter 12 in ASPE Data Book. 13. American Society of Plumbing Engineers. 1990. Pumps. Chapter 11 in ASPE Data Book.

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DECEMBER 2007 

Plumbing Systems & Design  11

Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com Continuing Education from Plumbing Systems & Design Haig Demergian, PE, CPD

Now Online!

The technical article you must read to complete the exam is located at www.psdmagazine.org. Just click on “Plumbing Systems & Design Continuing Education Article and Exam” at the top of the page. The following exam and application form also may be downloaded from the website. Reading the article and completing the form will allow you to apply to ASPE for CEU credit. If you earn a grade of 90 percent or higher on the test, you will be notified that you have logged 0.1 CEU, which can be applied toward CPD renewal or numerous regulatory-agency CE programs. (Please note that it is your responsibility to determine the acceptance policy of a particular agency.) CEU information will be kept on file at the ASPE office for three years. Note: In determining your answers to the CE questions, use only the material presented in the corresponding continuing education article. Using information from other materials may result in a wrong answer.

About This Issue’s Article The December 2007 continuing education article is “Recirculating Domestic Hot Water Systems,” Chapter 14 of Domestic Water Heating Design Manual, Second Edition. This chapter addresses the criteria for establishing an acceptable time delay in delivering hot water to fixtures and the limitations of the length between a hot water recirculation system and plumbing fixtures. It also discusses the temperature drop across a hot water supply system, types of hot water recirculation system, and pump selection criteria, and gives extensive information on the insulation of hot water supply and return piping. You may locate this article at www.psdmagazine.org. Read the article, complete the following exam, and submit your answer sheet to the ASPE office to potentially receive 0.1 CEU.

PSD 143

Do you find it difficult to obtain continuing education units (CEUs)? Through this special section in every issue of PS&D, ASPE can help you accumulate the CEUs required for maintaining your Certified in Plumbing Design (CPD) status.

CE Questions—“Recirculating Domestic Hot Water Systems” (PSD 143) 1. If the balancing valve is also used as the shutoff valve, the balancing valve must have a ___________. a. long stem b. flanged end c. memory stop d. none of the above 2. The water content of 1-inch Type L copper pipe is __________ gal/ft. a. 0.060 b. 0.052 c. 0.043 d. 0.039 3. Hot water recirculation systems with circulating pumps are installed in large buildings to __________. a. maintain constant hot water pressure at fixtures b. provide a reasonably prompt hot water supply to fixtures c. both of the above d. neither of the above 4. The approximate heat loss of a tank with 1-inch insulation holding 100 gallons of 140°F hot water is __________ Btu/h. a.  736, b.  137, c.  468, d.  1,273 5. The minimum recommended fiberglass pipe insulation thickness for a 2-inch diameter potable hot water pipe is __________. a. ¾ inch b. 1 inch c. 1½ inches d. 2 inches 6. The approximate heat loss of 1-inch copper pipe with 1-inch insulation (assuming 65°F ambient temperature) is __________ Btu/h per foot. a.  8, b.  10, c.  12, d.  14

12  Plumbing Systems & Design 

DECEMBER 2007

7. The total estimated heat loss of 520 feet of 1½-inch copper pipe, with 1-inch fiberglass insulation, is __________ Btu/h. a.  6,000, b.  6,320, c.  6,760, d.  7,520

8. The approximate time to deliver hot water to a 1.5-gpm fixture 25 feet from the water heater, using ¾-inch copper supply pipe, is __________ seconds. a.  25, b.  30, c.  40, d.  50 9. The gpm of a hot water circulating pump for a system with a total calculated heat loss of 10,000 Btu/h and 5°F allowable temperature drop between hot water supply and return is __________. a.  3, b.  4, c.  7, d.  9 10. The heat required to raise 35 gpm from 50°F to 140°F is __________ Btu/h. a. 895,000 b. 1,270,000 c. 1,575,000 d. 1,625,000

11. Why it is necessary to provide a pressure relief valve on potable hot water systems? a. to relieve the water, which expands during the heating process b. to protect the water heater and piping from excessive pressure c. both of the above d. neither of the above

12. Automatic air vents for air elimination shall be installed on the high points of __________. a. hot water supply piping b. hot water return piping c. cold water supply piping d. none of the above

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Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com Plumbing Systems & Design Continuing Education Application Form This form is valid up to one year from date of publication. The PS&D Continuing Education program is approved by ASPE for up to one contact hour (0.1 CEU) of credit per article. Participants who earn a passing score (90 percent) on the CE questions will receive a letter or certification within 30 days of ASPE’s receipt of the application form. (No special certificates will be issued.) Participants who fail and wish to retake the test should resubmit the form along with an additional fee (if required). 1.  Photocopy this form or download it from www.psdmagazine.org. 2.  Print or type your name and address. Be sure to place your ASPE membership number in the appropriate space. 3. Answer the multiple-choice continuing education (CE) questions based on the corresponding article found on www.psdmagazine.org and the appraisal questions on this form. 4.  Submit this form with payment ($35 for nonmembers of ASPE) if required by check or money order made payable to ASPE or credit card via mail (ASPE Education Credit, 8614 W. Catalpa Ave., Suite 1007, Chicago, IL 60656) or fax (773-695-9007). Please print or type; this information will be used to process your credits. Name _ __________________________________________________________________________________________________ Title _______________________________________________ ASPE Membership No.____________________________________ Organization _ ____________________________________________________________________________________________ Billing Address ____________________________________________________________________________________________ City_ _______________________________________ State/Province________________________ Zip _ ____________________ Country____________________________________________ E-mail_ _________________________________________________ Daytime telephone_ _________________________________ Fax___________________________________________________

I am applying for the following continuing education credits: I certify that I have read the article indicated above.

❏ ASPE Member Each examination: $25

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Payment: ❏ Personal Check (payable to ASPE) $____________ ❏ Business or government check $ _________ ❏ DiscoverCard ❏ VISA ❏ MasterCard ❏ AMEX $____________ Signature Expiration date: Continuing education credit will be given for this examination through DECEMBER 31, 2008. Applications received after that date will not be processed.

PS&D Continuing Education Answer Sheet

If rebilling of a credit card charge is necessary, a $25 processing fee will be charged. ASPE is hereby authorized to charge my CE examination fee to my credit card Account Number Expiration date Signature

Recirculating Domestic Hot Water Systems (PSD 143) Questions appear on page 12. Circle the answer to each question. Q 1. A B C D Q 2. A B C D Q 3. A B C D Q 4. A B C D Q 5. A B C D Q 6. A B C D Q 7. A B C D Q 8. A B C D Q 9. A B C D Q 10. A B C D Q 11. A B C D Q 12. A B C D

Cardholder’s name (Please print)

Appraisal Questions

Recirculating Domestic Hot Water Systems (PSD 143) Was the material new information for you?  ❏ Yes ❏ No Was the material presented clearly?  ❏ Yes ❏ No Was the material adequately covered?  ❏ Yes ❏ No Did the content help you achieve the stated objectives?  ❏ Yes ❏ No Did the CE questions help you identify specific ways to use ideas presented in the article?  ❏ Yes ❏ No 6. How much time did you need to complete the CE offering (i.e., to read the article and answer the post-test questions)?___________________ 1. 2. 3. 4. 5.

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Plumbing Systems & Design  13

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PSD 140

Flow in Water Piping

Continuing Education from Plumbing Systems & Design Kenneth G.Wentink, PE, CPD, and Robert D. Jackson

JULY/AUGUST 2007

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CONTINUING EDUCATION

Flow in Water Piping

Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com Hydraulics can be defined as the study of the principles and laws that govern the behavior of liquids at rest or in motion. Hydrostatics is the study of liquids at rest and hydrokinetics is the study of liquids in motion. Although this text deals exclusively with water, all the data developed can be applied to any liquid.

Physical Properties of Water The weight of water, or its density, varies with its temperature and purity. Water has its greatest specific weight (weight per cubic foot) at a temperature of 39.2°F. If this phenomenon did not occur, lakes would start freezing from the bottom up instead of from the top down. Table 1 tabulates densities of pure water at various temperatures. For the normal Table 1  Density of Pure Water at Various range of tempera- Temperatures tures met in plumbTemperature Density Temperature Density ing systems, the den°F lbm/ft3 °F lbm/ft3 32 62.416 100 61.988 sity of water is very 35 62.421 120 61.719 close to 62.4 lbm/ft3 39.2 62.424 140 61.386 and this value can be 40 62.423 160 61.006 used for all calcula50 62.408 180 60.586 tions without any 60 62.366 200 60.135 significant error. 70 62.300 212 59.843 Viscosity can be 80 62.217 defined as the internal friction, or internal resistance, to the relative motion of fluid particles. It can also be defined as the property by which fluids offer a resistance to a change of shape under the action of an external force. Viscosity varies greatly from one liquid to another. It approaches the conditions of a solid for highly viscous liquids and approaches a gas for the slightly viscous liquids. Viscosity decreases with rising temperatures. For example, #6 oil is a solid at low temperatures and begins to flow as it is heated. Water is perfectly elastic, compressing when pressure is imposed and returning to its original condition when the pressure is removed. The compressibility of water may be expressed as 1/K, where K is the coefficient of compressibility and is equal to 43,200,000 lb/ft2. It can be seen that if a pressure of 100 lb/ft2 were applied, the volumetric change would be 100∕43,200,000. The change is of such negligible significance that water is always treated as incompressible for all calculations in plumbing design. The temperature at which water boils varies with the pressure to which it is subjected. At sea level—14.7 psi—water boils at 212°F. At an elevation above sea level, where the atmospheric pressure is less than 14.7 psi, water will boil at a lower temperature. In a closed system, such as that found in the domestic hot water system where the pressure is generally around 50 psi above atmospheric pressure, the water will not boil until a temperature of 300°F is reached.

Types of Flow When water is moving in a pipe, two types of flow can exist. One type is known by the various names of streamline, laminar, or viscous. The second is called turbulent flow. At various viscosities (various temperatures), there is a certain critical velocity for every pipe size above which turbulent flow occurs and below which laminar flow occurs. This critical velocity occurs within a range of Reynolds numbers from approximately 2100 to 4000. Reynolds formula is: Equation 1

ρ Re =  DV µgc

where Re = Reynolds number, dimensionless D = Pipe diameter, ft V = Velocity of flow, ft/sec ρ = Density, lbm/ft3 µ = Absolute viscosity, lbf · sec/ft2 gc = Gravitational constant, 32.2 lbm·ft/lbf·sec2 Within the limits of accuracy required for plumbing design, it can be assumed that the critical velocity occurs at a Reynolds number of 2100. In laminar flow, the roughness of the pipe wall has a negligible effect on the flow but the viscosity has a very significant effect. In turbulent flow, the viscosity has an insignificant effect but the roughness of the pipe wall has a very marked effect on the flow. Very rarely is a velocity of less than 4 ft/sec employed in plumbing design. The Reynolds number for a 3 in. pipe and a velocity of flow of 4 ft/sec would be

Re =

(0.250ft)(4ft/sec)(62.4lbm/ft3) = 82,500 (2.35 × 10–5 lbf·sec/ft2)(32.2 lbm·ft/lbf·sec2

(which is well above the critical number of 2,100) It can be seen that all plumbing design is with turbulent flow and only when very viscous liquids or extremely low velocities are encountered does the plumbing engineer deal with laminar flow. Critical velocities of ½, 1, and 2-in. pipe at 60°F are 0.61, 0.31, and 0.15 ft/sec, respectively, and at 140°F they are 0.25, 0.13, and 0.06 ft/sec, respectively.

Velocity of Flow When the velocity of flow is measured across the section of pipe from the center to the wall, it is found that there is a variation in the velocity, with the greatest velocity at the center and a minimum velocity at the walls. The average velocity for the entire cross-section is approximately 84% of the velocity as measured at the center. The plumbing engineer is concerned only with the average velocity, and all formulas are expressed in average velocity. Whenever and wherever the term velocity is used, it is the average velocity of flow that is meant. Since water is incompressible within the range of pressures met in plumbing design, a definite relationship can be expressed between the quantity flowing past a given point in a given time

Reprinted from Engineered Plumbing Design II, Chapter 11: “Flow in Water Piping,” by A. Calvin Laws, PE, CPD. © American Society of Plumbing Engineers.   Plumbing Systems & Design 

JULY/AUGUST 2007

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and the velocity of flow. This can be expressed as (Equation 3- g = gravitational acceleration, 32.2 ft/sec2 Simpo PDF Merge and Split Unregistered Version - ghttp://www.simpopdf.com 2 2): c = gravitational constant, 32.2 lbm·ft/lbf·sec Q = AV V = velocity, ft/sec where When the body weighs 1 lb the formula becomes Q = quantity of flow (volumetric flow rate), ft3/sec Equation 6 A = cross-sectional area of flow, ft2 V2 EK = 2g V = velocity of flow, ft/sec c The units employed in this flow formula are inconvenient for where use in plumbing design. The plumbing engineer deals in gallons EK = kinetic energy per pound weight per minute and inches for pipe sizes. Converting to these terms, Static Head the flow rate becomes (Equation 8-8): At any point below the surface of water that is exposed to atmospheric pressure, the pressure (head) is produced by the weight q = 2.448 d2V of the water above that point. The pressure is equal and effective where in all directions at this point and is proportional to the depth q = quantity of flow (flow rate), gpm below the surface. This pressure is variously called static head, d = diameter of pipe, in. static pressure, hydrostatic head, or hydrostatic pressure. It is the V = velocity of flow, ft/sec measure of the potential energy. Because pressure is a function Potential Energy of the weight of the water, it is possible to convert the static head One of the most fundamental laws of thermodynamics is that expressed as feet of head into pounds per square inch. (See energy can be neither created nor destroyed; it can only be con- Table 2.) verted from one form to another. The energy of a body due to The pressure developed by the weight of a column of water 1 its elevation above a given level is called its potential energy in in.2 in cross-sectional area and h ft high may be expressed as relation to that datum. Work had to be performed to raise the body to that elevation and this work is equal to the product of Equation 7 γ × h p =  144 the weight of the body and the height it was raised. This can be expressed as: where p = pressure, lbf/in2 Equation 2 γ = specific weight of water, lbf/ft3 EP = w h =  mgh gc h = static head, ft where At 50°F, the pressure expressed in pounds per square inch for EP = potential energy, ft lbf a 1-ft column of water is then: w = weight of the body, lbf h = height raised, ft g = gravitational acceleration, 32.2 ft/s2 Table 2  Heads of Water in Feet Corresponding to Pressure in Pounds per Square Inch gc = gravitational constant, 32.2 lbm·ft/ PSI 0 1 2 3 4 5 6 7 8 9 lbf·s2 0 2.3 4.6 6.9 9.2 11.6 13.9 16.2 18.5 20.8 10 23.1 25.4 27.7 30.0 32.3 34.7 37.0 39.3 41 .6 43.9 When the weight is equal to 1 lb the for20 46.2 48.5 50.8 53.1 55.4 57.8 60.1 62.4 64.7 67.0 mula becomes 30 69.3 71.6 73.9 76.2 78.5 80.9 83.2 85.5 87.8 90.1 Equation 3 40 92.4 94.7 97.0 99.3 101.6 104.0 106.3 108.6 110.9 113.2 50 115.5 117.8 120.1 122.4 124.7 127.1 129.4 131.7 134.0 136.3 EP = hg gc 60 138.6 140.9 143.2 145.5 147.8 150.2 152.5 154.8 157.1 159.4 where 70 161.7 164.0 166.3 168.6 170.9 173.3 175.6 177.9 180.2 182.5 EP = potential energy per pound weight 80 184.8 187.1 189.4 191.7 194.0 196.4 198.7 201.0 203.3 205.6 90 207.9 210.2 212.5 214.8 217.1 219.5 221.8 224.1 226.4 228.7 Kinetic Energy 100 231.0 233.3 235.6 237.9 240.2 242.6 244.9 247.2 249.5 251.8 The energy of a body due to its motion is 110 254.1 256.4 258.7 261.0 263.3 265.7 268.0 270.3 272.6 274.9 called kinetic energy and is equal to one-half 120 277.2 279.5 281.8 284.1 286.4 288.8 291.1 293.4 295.7 298.0 its mass and the square of its velocity. Mass 130 300.3 302.6 304.9 307.2 309.5 311.9 314.2 316.5 318.8 321.1 140 323.4 325.7 328.0 330.3 332.6 335.0 337.3 339.6 341.9 344.2 is equal to the weight of the body divided by 150 346.5 348.8 351.1 353.4 355.7 358.1 360.4 362.7 365.0 367.3 its acceleration imposed by gravity. 160 369.6 371.9 374.2 376.5 378.8 381.2 383.5 385.8 388.1 390.4 Equation 4 170 392.7 395.0 397.3 399.6 401.9 404.3 406.6 408.9 411.2 413.5 wgc m =  g 180 415.8 418.1 420.4 422.7 425.0 427.4 429.7 432.0 434.3 436.6 c 190 438.9 441.2 443.5 445.8 448.1 450.5 452.8 455.1 457.4 459.7 Equation 5 200 462.0 464.3 466.6 468.9 471.2 473.6 475.9 478.2 480.5 482.8 2 wg 210 485.1 487.4 489.7 492.0 494.3 496.7 499.0 501.3 503.6 505.9 w × V2 EK = ½ ×  gc c × V = gc 2g 220 508.2 510.5 512.8 515.1 517.4 519.8 522.1 524.4 526.7 529.0 230 531.3 533.6 535.9 538.2 540.5 542.9 545.2 547.5 549.8 552.1 where 240 554.4 556.7 559.0 561.3 563.6 566.0 568.3 570.6 572.9 575.2 EK = kinetic energy, ft lbf 250 577.5 579.8 582.1 584.4 586.7 589.1 591.4 593.7 596.0 598.3 w = weight of body, lbf m = mass of the body, lbm

Notes: 1. To use the chart, find the point corresponding to the specific pressure (psi) by adding incremental values in the top line to the base values in the extreme left column. For example, to find head in ft. corresponding to 25 psi, follow the line of figures to the right of 20 psi and read 57.8 ft under 5 psi. 2. Head values in the body of the chart were calculated by multiplying psi by 2.31. To convert ft of head to psi, multiply by 0.433, or use the chart in reverse.

JULY/AUGUST 2007 

Plumbing Systems & Design  

CONTINUING EDUCATION: Flow in Water Piping 62.408



g = gravitational constant, 32.2 lbm·ft/lbf·sec2

c p =Merge × 1 = 0.433 lbf/in Simpo PDF Split Unregistered Version - http://www.simpopdf.com 144 and

2

Conversely, the height of a column of water that will impose a pressure of 1 lb/in.2 is

h = p × 144 γ 144 = 2.31 ft h = 1 × 62.408

The term Pgc/ρg is equal to the static head or height of the liquid column. Substituting in the equation it becomes Equation 12

To convert from feet of head to pounds per square inch, multiply the height by 0.433. To convert pounds per square inch to feet of head, multiply the pounds per square inch by 2.31.

Velocity Head

Zg + h + V2 = E T gc 2gc

For any two points in a system, we may then write: Equation 13

Z1g V12 Z2g V22 + h  + = + h  + 1 2 gc gc 2gc 2gc

Figure 1 illustrates the application of this equation.

In a piping system with the water at rest, the water has potential energy. When the water is flowing it has kinetic energy as well as potential energy. To cause the water to flow some of the available potential energy must be converted to kinetic energy. The decrease in the potential energy, or static head, is called the velocity head. In a freely falling body, the body is accelerated by the action of gravity at a rate of 32.2 ft/sec2. The height of the fall and the velocity at any moment may be expressed as: Equation 8

h = gt 2

2

Equation 9

Friction When water flows in a pipe, friction is produced by the rubbing of water particles against each other and against the walls of the pipe. This friction generates heat, which is dissipated in the form of a rise in the temperature of the water and the piping. This temperature rise in plumbing systems is insignificant and can safely be ignored in plumbing design. It requires a potential energy of 778 ft-lbf to raise 1 lb of water 1°F. The friction produced by flowing water also causes a pressure loss along the line of flow, which is called friction head. By utilizing Bernoulli’s equation this friction head loss can be expressed as:

V = gt or t = V g

where h = velocity head, ft t = time, sec g = gravitational acceleration, 32.2 ft/sec2 V = velocity, ft/sec Substituting t = V/g in the first equation,

Figure 11-1  Bernoulli's Theorem (Disregarding Friction)

2 g h =  2 × V2 g

Equation 10

V2 h =  2g

The foregoing illustrates the conversion of the potential energy of a body (static head) due to its height into kinetic energy (velocity head). The velocity head, V2/2g, is a measure of the decrease in static head expressed in feet of column of water.

Bernoulli’s Theorem As previously stated, energy can be neither created nor destroyed. Bernoulli developed an equation to express this conservation of energy as it is applied to a flowing liquid. The liquid is assumed to be frictionless and incompressible. Equation 11

Zg + Pgc + V2 = E T gc ρg 2gc

where ET = total energy ft·lbf/lbm Z = height of point above datum, ft P = pressure, lbf/ ft2 ρ = density, lbm/ft3 V = velocity, ft/sec g = gravitational acceleration, 32.2 ft./sec2   Plumbing Systems & Design 

JULY/AUGUST 2007

Z1g V12 Z2g V22 gc + h1 + 2gc = gc + h2 + 2gc

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[

][

]

Figure 11-2  Toricelli's Theorem

Simpo Version - http://www.simpopdf.com Z1gPDF Merge V12 and Split Z2g Unregistered V22

hF = 

gc

+ h1 + 

2gc

Flow from Outlets

 - 

gc

+ h2 +

2gc

Experiments to determine the velocity of flow from an outlet in the side of an open tank were performed by Toricelli in the 17th century. The result of these experiments was expounded in the theorem: “Except for minor frictional effects, the velocity is the same as if the fluid had fallen freely from the surface through a vertical distance to the outlet.” This can be expressed as: Equation 15

V = √2gh

It is graphically shown in Figure 2. If friction, size, and shape of the opening and entrance losses are disregarded, the ideal velocity is the same as the maximum velocity and is equal to the velocity attained by free fall. The actual velocity, however, is always less than the ideal. All the factors, previously ignored, when taken into consideration can be expressed as the coefficient of discharge, CD. The actual velocity can then be written: Equation 16

V = CD √2gh

For most outlets encountered in a plumbing system an average coefficient of discharge of 0.67 can be safely applied.

Flow in Piping The velocity of flow at any point in a system is due to the total energy at that point. This is the sum of the potential and kinetic energy, less the friction head loss. The static head is the potential energy, but some of it was converted to kinetic energy to cause flow and some of it was used to overcome friction. It is for these reasons that the pressure during flow is always less than the static pressure. The pressure measured at any point while water is flowing is called the flow pressure. This is the pressure that is read on a pressure gauge installed in the piping. The kinetic energy of water flowing in a plumbing system is extremely small. Very rarely is the design velocity for water flow in plumbing systems greater than 8 ft/sec. The kinetic energy (velocity head) at this velocity is V2/2g or 8 ∕64.4. This is equal to 1 ft or 0.433 psi, which is less than 0.5 psi. It can be seen that such an insignificant pressure can be safely ignored in all calculations. The maximum rate of discharge from an outlet can now be determined from the flow pressure and the diameter of the outlet (using Equations 8-2 to 8-5):

d = diameter of outlet, in. V1 = ideal velocity, ft/sec h = flow pressure, ft p = flow pressure, psi If 0.67 is used for the coefficient of discharge, then, per Equation 6-1,

qD = 13.17d2 √h and

2

qD = CD q1 qD = CD × 2.448 d2V1 qD = CD × 2.448d2 √2gh qD = CD × 19.65d2 √h or Equation 17

qD = CD × 29.87d2 √p

where qD = actual quantity of discharge, gpm q1 = ideal quantity of discharge, gpm CD = coefficient of discharge, dimensionless

Equation 18

qD = 20d2 √p

Friction in Piping As stated previously, whenever flow occurs, there is a continuous loss of pressure along the piping in the direction of flow. The amount of this head loss because of friction is affected by 1. 2. 3. 4.

Density and temperature of the fluid Roughness of the pipe Length of run Velocity of the fluid

Experiments have demonstrated that the friction head loss is inversely proportional to the diameter of the pipe, proportional to the roughness and length of the pipe, and varies approxi-

JULY/AUGUST 2007 

Plumbing Systems & Design  

CONTINUING EDUCATION: Flow in Water Piping mately with the square of the velocity. Darcy expressed this rela- Equation 24 Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com tionship as: q = 40.1 d2½ 2 h =  fLV or D × 2g

Equation 19

ρfLV2 p = 144D × 2g c

where h = friction head loss, ft p = friction head loss, lbf/in2 ρ = density of fluid, lbm/ft3 f = coefficient of friction, dimensionless L = length of pipe, ft D = diameter of pipe, ft V = velocity of flow, ft/sec gc = gravitational constant, 32.2 lbm ft/lbf sec2 Values for the coefficient of friction are given in Table 3. It can be seen from Table 3 that steel pipe is much rougher than brass, lead or copper. It follows that there will be a greater head loss in steel pipe than in the other material. Table 3  Average Values for Coefficient of Friction, f Nominal Brass, Copper, Galvanized Pipe Size, in. or Lead Iron or Steel ½ 0.022 0.044 ¾ 0.021 0.040 1 0.020 0.038 1¼ 0.020 0.036 1½ 0.019 0.035 2 0.018 0.033 2½ 0.017 0.031 3 0.017 0.031 4 0.016 0.030

For ease of application for the plumbing engineer, the formula for friction head loss can be reduced to a simpler form. Assuming an average value for the coefficient of friction of 0.02 for brass and copper and 0.04 for steel, the formula becomes: For brass and copper Equation 20 Equation 21

h = 0.000623q2 × L5 d p = 0.00027q2 × L5 d

Equation 25 and for steel Equation 26 Equation 27

( hL )

½

( )

q = 60.8 d2½ p L

½

( )

q = 28.3 d2½ h L

½

( )

q = 43.0 d2½ p L

where q = quantity of flow, gpm d = diameter of pipe, in. h = pressure, ft p = pressure, psi L = length of pipe, ft

½

The terms h/L and p/L represent the loss of head due to friction for 1 ft of pipe length and is called the uniform friction loss. Values of d2½ for various diameters of pipe and various materials are given in Table 4. In all water flow formulas, the term L (length of run in feet) is always the equivalent length of run (ELR).Every fitting and valve imposes more frictional resistance than the pipe itself.To take this additional friction head loss into account, the fitting or valve is converted to an equivalent length of pipe of the same size that will impose an equal friction loss, e.g., a 4-in. elbow is equivalent to 10 ft of 4-in. pipe.Thus, if the measured length of run of 4-in. piping with one elbow is 15 ft, then the equivalent length of run is 15 + 10 = 25 ft.The length of pipe measured Table 4  Values of d2½ Nominal Brass or Size, In. Copper Pipe ½ 0.31 ¾ 0.61 1 1.16 1¼ 2.19 1½ 3.24 2 6.17 2½ 9.88 3 16.41 4 32.00

Copper Copper Galvanized Type K Type L Iron or Steel 0.20 0.22 0.31 0.48 0.55 0.62 0.99 1.06 1.13 1.73 1.80 2.24 2.67 2.78 3.29 5.37 5.55 6.14 9.25 9.54 9.58 14.41 14.87 16.48 29.23 30.13 32.53

and for steel

Table 5  Equivalent Pipe Length for Valves and Fittings Gate Nominal Valve Angle Globe Swing L 2 h = 0.00124q  × 5 Pipe Size Full Valve Full Valve Full Check Full d inches Open Open Open Open Equation 23 ½ 0.35 9.3 18.6 4.3 p = 0.00539q2 × L5 ¾ 0.44 11.5 23.1 5.3 d 1 0.56 14.7 29.4 6.8 These formulas can be rearranged in another 1¼ 0.74 19.3 38.6 8.9 useful form: 1½ 0.86 22.6 45.2 10.4 For brass and copper 2 1.10 29.0 58.0 13.4 2½ 1.32 35.0 69.0 15.9 3 1.60 43.0 86.0 19.8 4 2.10 57.0 113.0 26.0 5 2.70 71.0 142.0 33.0 6 3.20 85.0 170.0 39.0 8 4.30 112.0 224.0 52.0 Equation 22

  Plumbing Systems & Design 

JULY/AUGUST 2007

45° Elbow 0.78 0.97 1.23 1.6 1.9 2.4 2.9 3.6 4.7 5.9 7.1 9.4

Long Sweep Elbow or Run of Tee 1.11 1.4 1.8 2.3 2.7 3.5 4.2 5.2 6.8 8.5 10.2 13.4

Std. Elbow 1.7 2.1 2.6 3.5 4.1 5.2 6.2 7.7 10.2 12.7 15.3 20.2

Std. Tee Thru Side Outlet 3.3 4.2 5.3 7.0 8.1 10.4 12.4 15.5 20.3 25.4 31.0 40.0

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along the centerline of pipe and fittings is the developed length. Simpo PDF Merge and Split Unregistered Version Table 5 shows equivalent lengths of pipe for valves and fittings of various sizes. Note that the larger the pipe size, the more significant the equivalent length of run becomes. In the design phase of piping systems, the size of the piping is not known and the equivalent lengths cannot be accurately determined. A rule of thumb that has worked exceptionally well is to assume 50% of the developed length as an allowance for fittings and valves. Once the sizes are determined, the accuracy of the assumption can be checked. All equipment imposes a friction head loss and must be carefully considered in the design and operation of a system. The pressure drop through any piece of equipment can be obtained from the manufacturer. The knowledgeable engineer is careful to specify the maximum pressure drop he/she will permit through a piece of equipment.

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CONTINUING EDUCATION Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com Continuing Education from Plumbing Systems & Design Kenneth G.Wentink, PE, CPD, and Robert D. Jackson

Now Online!

The technical article you must read to complete the exam is located at www.psdmagazine.org. The following exam and application form also may be downloaded from the website. Reading the article and completing the form will allow you to apply to ASPE for CEU credit. For most people, this process will require approximately one hour. If you earn a grade of 90 percent or higher on the test, you will be notified that you have logged 0.1 CEU, which can be applied toward the CPD renewal requirement or numerous regulatory-agency CE programs. (Please note that it is your responsibility to determine the acceptance policy of a particular agency.) CEU information will be kept on file at the ASPE office for three years. Note: In determining your answers to the CE questions, use only the material presented in the corresponding continuing education article. Using information from other materials may result in a wrong answer.

About This Issue’s Article

The July/August 2007 continuing education article is “Flow in Water Piping,” Chapter 11 of Engineered Plumbing Design II by A. Cal Laws, PE, CPD. This chapter discusses hydraulics, which can be defined as the study of the principles and laws that govern the behavior of liquids at rest or in motion, hydrostatics, the study of liquids at rest, and hydrokinetics, or the study of liquids in motion. Although this text deals exclusively with water, all the data developed can be applied to any liquid. The chapter delves into the physical properties of water, types of flow, Bernoulli’s and Toricelli’s Theorems, and friction in piping as they relate to sizing piping systems. It provides calculations for finding the Reynolds number, velocity of flow, potential and kinetic energy, pressure, velocity head, and Bernoulli’s Theorem, among others. You may locate this article at www.psdmagazine.org. Read the article, complete the following exam, and submit your answer sheet to the ASPE office to potentially receive 0.1 CEU.

CE Questions—“Flow in Water Piping” (PSD 140) 1. The average coefficient of friction (f) in a 2-inch steel pipe is _________. a. 0.037 b. 0.035 c. 0.033 d. 0.031 2. Friction is created by the flow of water in piping. This friction generates _________. a. pressure drop b. pressure increase c. heat d. none of the above 3. Number six (6) oil _________. a. is not part of this chapter b. is a solid at low temperatures c. begins to flow when heated d. b and c only

PSD 140

Do you find it difficult to obtain continuing education units (CEUs)? Through this special section in every issue of PS&D, ASPE can help you accumulate the CEUs required for maintaining your Certified in Plumbing Design (CPD) status.

7. How much potential energy is required to raise 1 pound of water 1°F? a.  728 ft-lbf, b.  778 ft-lbf, c.  828 ft-lbf, d.  878 ft-lbf

8. The pressure at any point below the surface of water exposed to atmospheric pressure is referred to as ______. a. static head b. hydrostatic pressure c. specific pressure d. a or b 9. What is the equivalent pipe length for a 4-inch fully open globe valve? a. 113.0 b. 142.0 c. 170.0 d. 224.0

4. Water is _________. a. not compressible b. perfectly elastic c. greatly compressible d. none of the above

10. The critical velocity of water _________. a. in ½-inch, 1-inch, and 2-inch pipe is less than 0.5 fps at temperatures of 60°F to 140°F b. is represented by a Reynolds number of 82,500 c. is Re=DVp/ugc d. is greater than 20 ft/sec for all pipe 10 inches and smaller at temperatures of 60°F to 140°F

5. Experiments to determine the velocity of flow from an outlet were performed by _________ in the 17th century. a. Bernoulli b. Reynolds c. Toricelli d. Hunter

11. The static pressure is always _________ the pressure during flow. a. less than b. greater than c. the same as d. none of the above

6. Velocity head (V2/2g) _________. a. is a measure of the decrease in static head b. is of no consequence to the plumbing engineer c. must be understood to control water hammer d. is responsible for most pipe fitting failures

12. Water in motion _________. a. has used its potential energy b. has only kinetic energy c. has both kinetic and potential energy d. none of the above

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Simpo PDFSystems Merge and Unregistered Version - http://www.simpopdf.com Plumbing &Split Design Continuing Education Application Form This form is valid up to one year from date of publication. The PS&D Continuing Education program is approved by ASPE for up to one contact hour (0.1 CEU) of credit per article. Participants who ear a passing score (90 percent) on the CE questions will receive a letter or certification within 30 days of ASPE’s receipt of the application form. (No special certificates will be issued.) Participants who fail and wish to retake the test should resubmit the form along with an additional fee (if required). 1.  Photocopy this form or download it from www.psdmagazine.org. 2.  Print or type your name and address. Be sure to place your ASPE membership number in the appropriate space. 3.  Answer the multiple-choice continuing education (CE) questions based on the corresponding article found on www.psdmagazine.org and the appraisal questions on this form. 4.  Submit this form with payment ($35 for nonmembers of ASPE) if required by check or money order made payable to ASPE or credit card via mail (ASPE Education Credit, 8614 W. Catalpa Avenue, Suite 1007, Chicago, IL 60656) or fax (773-695-9007). Please print or type; this information will be used to process your credits. Name _ __________________________________________________________________________________________________ Title _______________________________________________ ASPE Membership No.____________________________________ Organization _ ____________________________________________________________________________________________ Billing Address ____________________________________________________________________________________________ City_ _______________________________________ State/Province________________________ Zip _ ____________________ Country____________________________________________ E-mail_________________________________________________ Daytime telephone_ _________________________________ Fax___________________________________________________

I am applying for the following continuing education credits: I certify that I have read the article indicated above.

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Flow in Water Piping (PSD 140)

Questions appear on page . Circle the answer to each question. Q 1. A B C D Q 2. A B C D Q 3. A B C D Q 4. A B C D Q 5. A B C D Q 6. A B C D Q 7. A B C D Q 8. A B C D Q 9. A B C D Q 10. A B C D Q 11. A B C D Q 12. A B C D

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Appraisal Questions Flow in Water Piping (PSD 140) Was the material new information for you?  ❏ Yes ❏ No Was the material presented clearly?  ❏ Yes ❏ No Was the material adequately covered?  ❏ Yes ❏ No Did the content help you achieve the stated objectives?  ❏ Yes ❏ No Did the CE questions help you identify specific ways to use ideas presented in the article?  ❏ Yes ❏ No 6. How much time did you need to complete the CE offering (i.e., to read the article and answer the post-test questions)?___________________ 1. 2. 3. 4. 5.

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Plumbing Systems & Design  

Fuel Gas Piping Systems

PSD 144

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Continuing Education from Plumbing Systems & Design Diane M. Wingard, CPD

JANUARY/FEBRUARY 2008

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CONTINUING EDUCATION

Fuel Gas Piping Systems

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LOW AND MEDIUM-PRESSURE NG SYSTEMS This chapter describes fuel-gas systems on consumer sites from the property line to the final connection with the most remote gas appliance or piece of equipment. The system is intended to provide sufficient pressure and volume for all uses. Since NG is a nonrenewable energy resource, the engineer should design for its efficient use. The direct utilization of NG is preferable to the use of electrical energy when electricity is obtained from the combustion of gas or oil. However, in many areas, the gas supplier and /or governmental agencies may impose regulations that restrict the use of natural gas. Refer to the chapter “Energy Conservation in Plumbing Systems” in Plumbing Engineering Design Handbook Volume 1 for information on appliance efficiencies and energy conservation recommendations. The composition, specific gravity, and heating value of NG (NG) vary depending on the well (or field) from which the gas is gathered. NG is a mixture of gases, most of which are hydrocarbons, and the predominant hydrocarbon is methane. Some natural gases contain significant quantities of nitrogen, carbon dioxide, or sulfur (usually as H2S). Natural gases containing sulfur or carbon dioxide are apt to be corrosive. These corrosive substances are usually eliminated by treatment of the NG before it is transmitted to the customers. Readily condensable petroleum gases also are usually extracted before the NG is put into the pipeline to prevent condensation during transmission. The physical properties of both NG and liquefied

petroleum gas (LPG) are given in Table 1. NG and LPG are colorless and odorless, so an additive is added to the gases to detect a leak.

General NG is obtained from a franchised public utility obligated to provide gas to all who request this service. There are different types of services a utility may provide, each with a different cost. They include the following: 1. Firm Service. This service provides constant supply of gas under all conditions. 2. Interruptible Service. This service allows the utility to stop gas supply under certain conditions and proper notification and to start service when the conditions no longer exist. The most common reason for this interruption is when the ambient temperature falls below a predetermined point. 3. Light or Heavy Process Service. This service is provided for process or other industrial use. The quantity of gas must meet utility company requirements. 4. Commercial or Industrial Service. This type of service is used for heating and cooling loads for this class of building. 5. Transportation Gas Service. This is used when the gas is purchased directly from the producer (or wellhead) and not directly from the utility company. The gas actually is carried in the utility company mains, and there is a charge for this use. There are many gases used as a fuel gas. Where easily and cheaply available, two major fuel gases, NG and LPG, are preferred. Other gases are used because of availability. For properties of gases commonly available throughout the world, refer to Table 2.

Approvals

Table 1  Average Physical Properties of Natural Gas and Propane Formula Molecular weight Melting (or freezing) point, °F Boiling point, °F Specific gravity of gas (air = 1.00) Specific gravity of liquid 60°F/60°F (water = 1.00) Latent heat of vaporization at normal boiling point, Btu/lb Vapor pressure, lb/in2, gauge at 60°F Pounds per gallon of liquid at 60°F Gallons per pound of liquid at 60°F Btu per pound of gas (gross) Btu per ft3 gas at 60°F and 30 in mercury Btu per gallon of gas at 60°F Cubic feet of gas (60°F, 30 in Hg)/gal of liquid Cubic feet of gas (60°F, 30 in Hg)/lb of liquid Cubic feet of air required to burn 1 ft3 gas Flame temperature, °F Octane number (isooctane = 100) Flammability limit in air, upper Flammability limit in air, lower

Propane C3H8 44.097 – 305.84 – 44 1.52 0.588 183 92 4.24 0.237 21591 2516 91547 36.39 8.58 23.87 3595 125 9.50 2.87

Natural gas (methane) CH4 16.402 – 300.54 – 258.70 0.60 0.30 245 2.51 23000 1050 ± 59.0 23.6 9.53 3416 15.0 5.0

The American Gas Association, the National Fire Protection Association, and the American National Standards Association do not approve, inspect, or certify installations, procedures, equipment, or materials. The acceptability of all such items must comply with the authority having jurisdiction (AHJ).

System Operating Pressure The gas pressure in the piping system downstream of the meter is usually 5 to 14 in. (125 to 356 mm) of water column (wc). Under these conditions, good engineering practice limits the pressure losses in the piping to a range between 0.2 to 0.5 in. (5 to 13 mm) wc. However, local codes may dictate a more stringent pressure drop maximum; these should be consulted before the system is sized. Most appliances require approximately 3.5 in. (89 mm) wc. The designer must be aware that large appliances, such as boilers, may require high gas pressures to operate properly. Where appliances require high pressures or where long distribution lines are involved, it may be necessary to use higher pressures at the meter outlet to satisfy the appliance requirements or provide for greater pressure losses in the piping system, thereby allowing economy of pipe size. Systems often are designed with meter outlet pressures of 3 to 5 psi (20.7 to 34.5 kPa) and with pressure regulators to reduce the pressure for appliances as required. A

Reprinted from Plumbing Engineering Design Handbook, Volume 2: Plumbing Systems, Chapter 7: “Fuel Gas Piping Systems.” © American Society of Plumbing Engineers , 2005.

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Table 2  Physical and Combustion Properties of Commonly Available Fuel Gases Heating value Specific Btu/ft3 Btu/lb Heat release, Btu Specific Density, volume No. Gas Gross Net Gross Net Per ft3 air Per lb air gravity lb per ft3 ft3/lb 1 Acetylene 1,498 1,447 21,569 20,837 125.8 1677 0.91 0.07 14.4 2 Blast furnace gas 92 92 1,178 1,178 135.3 1804 1.02 0.078 12.8 3 Butane 3,225 2,977 21,640 19,976 105.8 1411 1.95 0.149 6.71 4 Butylene (hutene) 3,077 2,876 20,780 19,420 107.6 1435 1.94 0.148 6.74 5 Carbon monoxide 323 323 4,368 4,368 135.7 1809 0.97 0.074 13.5 6 Carburetted water gas 550 508 11,440 10,566 119.6 1595 0.63 0.048 20.8 7 Coke oven gas 574 514 17,048 15,266 115.0 1533 0.44 0.034 29.7 8 Digester (sewage) gas 690 621 11,316 10,184 107.6 1407 0.80 0.062 16.3 9 Ethane 1,783 1,630 22,198 20,295 106.9 1425 1.05 0.080 12.5 10 Hydrogen 325 275 61,084 51,628 136.6 1821 0.07 0.0054 186.9 11 Methane 1,011 910 23,811 21,433 106.1 1415 0.55 0.042 23.8 12 Natural (Birmingham, AL) 1,002 904 21,844 19,707 106.5 1420 0.60 0.046 21.8 13 Natural (Pittsburgh, PA) 1,129 1,021 24,161 21,849 106.7 1423 0.61 0.047 21.4 14 Natural (Los Angeles, CA) 1,073 971 20,065 18,158 106.8 1424 0.70 0.054 18.7 15 Natural (Kansas City, MO) 974 879 20,259 18,283 106.7 1423 0.63 0.048 20.8 16 Natural (Groningen, Netherlands) 941 849 19,599 17,678 111.9 1492 0.64 0.048 20.7 17 Natural (Midlands Grid, U.K.) 1,035 902 22,500 19,609 105.6 1408 0.61. 0.046 21.8 18 Producer (Wellman-Galusha) 167 156 2,650 2,476 128.5 1713 0.84 0.065 15.4 19 Propane 2,572 2,365 21,500 19,770 108 1440 1.52 0.116 8.61 20 Propylene (Propane) 2,332 2,181 20,990 19,030 108.8 1451 1.45 0.111 9.02 21 Sasol (South Africa) 500 443 14,550 13,016 116.3 1551 0.42 0.032 31.3 22 Water gas (bituminous) 261 239 4,881 4,469 129.9 1732 0.71 0.054 18.7

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majority of times, the utility company will reduce the incoming pressure to a figure that is requested by the design engineer at the start of the project. The maximum allowable operating pressure for NG piping systems inside a building is based on NFPA 54: National Fuel Gas Code, except when approved by the AHJ or when insurance carriers have more limiting requirements. NG systems are not permitted to have more than 5 psig (34.5 kPa) unless all the following are met: 1. The AHJ will allow a higher pressure. 2. The distribution piping is welded. 3. Pipe runs are enclosed for protection and located in a ventilated place that will not allow gas to accumulate. 4. The pipe is installed in areas only used for industrial processes, research, warehouse, or mechanical equipment rooms. The maximum LPG pressure of 20 psig (138 kPa) is allowed, provided the building is used only for research or industrial purposes and is constructed in accordance with NFPA 58: Liquefied Petroleum Gas Code, Chapter 7.

Efficiency The difference between the input and the output of any equipment is the heat lost in the burner, the heat exchanger, and the flue gases. Water heating and space heating equipment are usually 75 to 85% efficient, and ratings are given for both input and output. Cooking and laundry equipment also is usually 75 to 85% efficient, and ratings are given for the input that take into consideration the internal losses. When only the output required for the appliance is known, it will be necessary to increase the volume of gas to account for the loss of efficiency.

Codes and Standards The local code in the area where the project is located is the primary code to be used. Often, this code refers to NFPA 54. Other codes and standards that may be applicable are ANSI/NFPA 30: Flammable and Combustible Liquids Code, ANSI/NFPA 58, ANSI Z83.3: Gas Utilization Equipment for Large Boilers, ANSI/UL 144: Pressure Regulating Valves for LPG, NFPA 88A: Standard for Parking Structures, and American Gas Association standards. Insurance carriers such as Industrial Risk Insurers and FM Global also have standards, which may be in many respects stricter than the applicable code.

Gas Meters Meters are required in all services. To achieve greatest accuracy, the pressure into the meter must be regulated. Requirements for various utilities differ regarding the placement and arrangement of the meter assembly. The assembly could consist of filters, valves, regulators, and relief valves. It could be placed indoors, on a slab outdoors aboveground, or underground in an outdoor pit. The plumbing contractor is usually responsible for a pit, if required, a slab, telephone outlet, and electrical outlet adjacent to the meter. The utility company almost always supplies the meter. The utility company usually runs the service on the consumer’s site up to the meter, terminating with a shutoff valve.

Pressure Regulating Valves A pressure regulator is a device for reducing a variable high inlet pressure to a constant lower outlet pressure. The line regulator is used to reduce supply line pressure from generally 25–50 psig (170–345 kPa) to an intermediate pressure of about 3–5 psig (21–35 kPa). If used, it is usually placed outside before the meter and selected by the utility company. If installed inside the building, a relief vent will be necessary. An intermediate regulator is used to JANUARY/FEBRUARY 2008 

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CONTINUING EDUCATION: Fuel Gas Piping Systems further reduce the pressure from 3–5 psig (21–35 kPa) to one that to design and specify gas vents. This is done by either the HVAC Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com can be used by terminal equipment, which is approximately 7 in. department or the manufacturer. (178 mm) wc. Different types of valves may require a relief vent. An Where the ratings of the appliances are not known, they shall appliance regulator connects the supply to the terminal equipment comply with the typical demand of appliances by types as indicated and may be provided by the equipment manufacturer, usually on in NFPA 54. gas trains where equipment has one. Types of appliance regulaAllowable Gas Pressure tors are a zero governer, a backpressure regulator, and a differential The gas outlet pressure in the piping system downstream of the regulator. meter that is supplied by the utility is mostly in the range of 4–14 When regulators are installed inside a building and require a in. (102–356 mm) wc, with approximately 7 in. (178 mm) wc being vent, these vents often must be routed to the atmosphere. The vents a common figure. Good engineering practice limits the pressure from individual regulators may not be combined. When bottled gas losses in the piping to approximately 0.2–0.5 in. (5–12.7 mm) wc is used, the tank can have as much as 150 psi (1034.6 kPa) pressure depending on the outlet pressure, with 0.3 in. (7.6 mm) wc being to be reduced to the burner design pressure of 11 in. (279.4 mm) the most commonly used number. However, local codes may dicwc. The regulator normally is located at the tank for this pressure tate a more stringent pressure drop maximum. The AHJ should reduction. be consulted before the system is sized. Most appliances require Pressure Control Valves approximately 3.5 in. (89 mm) wc; however, the designer must be An excess flow valve is a device that shuts off the flow of gas if there is a much larger flow through the pipe or service than designed Table 3  Approximate Gas Demand for Common Appliances a for. In some parts of the country, particularly in areas where earthInput, quakes may occur, excessive flow valves are necessary to guard Appliance Btu/h (mJ/h) against the possibility of a break during such an event. In other Commercial kitchen equipment cases, where danger exists for equipment such as large boilers, Small broiler 30,000 (31.7) installation should be considered. Large broiler 60,000 (63.3) A low pressure cutoff shall be installed between the meter and Combination broiler and roaster 66,000 (69.6) appliance where the operation of a device, such as a gas compressor, appliance, or a boiler, could produce a vacuum or dangerous Coffee maker, 3-burner 18,000 (19) vacuum condition in the piping system. Coffee maker, 4-burner 24,000 (25.3)

Deep fat fryer, 45 lb (20.4 kg) of fat Deep fat fryer, 75 lb (34.1 kg) of fat Doughnut fryer, 200 lb (90.8 kg) of fat 2-deck baking and roasting oven 3-deck baking oven Revolving oven, 4 or 5 trays Range with hot top and oven Range with hot top Range with fry top and oven Range with fry top Coffee urn, single, 5-gal (18.9 L) Coffee urn, twin, 10-gal. (37.9 L) Coffee urn, twin, 15-gal (56.8 L) Stackable convection oven, per section of oven Residential equipment Clothes dryer (Type I) Range Stove-top burners (each) Oven 30-gal (113.6-L) water heater 40 to 50-gal (151.4 to 189.3-L) water heater Log lighter Barbecue Miscellaneous equipment Commercial log lighter Bunsen burner Gas engine, per horsepower (745.7 W) Steam boiler, per horsepower (745.7 W)

Appliance Control Valves An appliance shutoff valve shall be installed at all gas appliances prior to any flexible hose used to connect the appliance to the building gas supply.

Interlocks An automatic interlock, connected to the automatic fire extinguishing system, is required to shut off the gas supply to all equipment in a kitchen when there is a discharge in the event of a fire. In earthquake-prone areas, an interlock is required to shut off the supply of gas if the disturbance may rupture the pipe or separate pipe from any equipment.

Appliances Appliances are listed by types and categories that shall be used in the design of vents. These vents shall be sized and located in accordance with NFPA 54. Most manufacturers of gas appliances rate their equipment by the gas consumption values that are used to determine the maximum gas flow rate in the piping. Table 3 shows the approximate gas consumption for some common appliances. To find the flow rate of gas required, use the consumption from the manufacturer and divide by 1,000. If the equipment is a water heater, multiply the figure by the weight of water (8.48 lbs). The products of combustion from an appliance must be safely exhausted to the outside. This is accomplished with a gas vent system in most cases. Where an appliance has a very low rate of gas consumption (e.g., Bunsen burner or countertop coffee maker) or where an appliance has an exhaust system associated with the appliance (e.g., gas clothes dryer or range) and the room size and ventilation are adequate, a separate gas vent system may not be required. Current practice usually dictates the use of factory-fabricated and listed vents for small to medium-size appliances. Large appliances and equipment may require specially designed venting or exhaust systems. It is not the plumbing engineer’s responsibility

Commercial clothes dryer (Type 2) a

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50,000 (52.8) 75,000 (79.1) 72,000 (76) 100,000 (105.5) 96,000 (101.3) 210,000 (221.6) 90,000 (95) 45,000 (47.5) 100,000 (105.5) 50,000 (52.8) 28,000 (29.5) 56,000 (59.1) 84,000 (88.6) 60,000 (63.3) 35,000 (36.9) 65,000 (68.6) 40,000 (42.2) 25,000 (26.4) 30,000 (31.7) 50,000 (52.8) 25,000 (26.4) 50,000 (52.8) 50,000 (52.8) 5,000 (5.3) 10,000 (10.6) 50,000 (52.8) See manufacturer’s data.

The values given in this table should be used only when the manufacturer’s data are not available.

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aware that large appliances, such as boilers, may require higher roof and away from doors, windows, and fresh-air intakes. It also Simpo to PDF Merge andWhere Splitappliances Unregistered Versionshould - http://www.simpopdf.com gas pressures operate properly. require higher be located on a side of the building that is not protected pressures or where long distribution lines are involved, it may be from the wind. Refer to NFPA 54 and local codes for vent locations. necessary to use higher pressures at the meter outlet to satisfy Altitude Derating Factor the appliance requirements or provide for greater pressure losses NG has a reduced density at a higher altitude that must be allowed in the piping system. If greater pressure at the meter outlet can for when the project location is more than 2,000 feet above sea level. be attained, a greater pressure drop can be allowed in the piping This altitude correction factor shall be multiplied by the gas input at system. If the greater pressure drop design can be used, a more ecosea level to determine the correct input at full load capacity. Refer nomical piping system is possible. to Figure 1 to determining the derating factor for NG.

Laboratory Usage NG is the primary gas used in laboratories at lab benches for Bunsen burners. Where NG is not available, propane gas is used, but this generally requires the manufacturer to be advised due to the Bunsen burner requiring a smaller orifice. Typical Bunsen burners consume either 5 cfh (0.15 m3/h) (small burners) or 10 cfh (0.30 m3/h) (large burners).The maximum pressure at the burner should not exceed 14 in. (355.6 mm) wc. 10 cfh (0.30 m3/h) is more commonly used. Some local codes require laboratory gas systems, especially those in schools or universities, to be supplied with emergency gas shutoff valves on the supply to each laboratory. The valve normally should be closed and opened only when the gas is being used. It should be located inside the laboratory and used in conjunction with shutoff valves at the benches or equipment, which may be required by other codes. The designer should ensure locations meet local code requirements. The following diversities, found in Table 4, shall be applied where flow will be from Bunsen burners:

Table 4  Laboratory Diversity Factors Laboratory Number of Diversity Flow3 cfh Outlets Factor (m /h) 1–8 100 9 (0.26) 9–16 90 15 (0.43) 17–29 80 24 (0.68) 30–79 60 48 (1.36) 80–162 50 82 (2.32) 163–325 45 107 (3.03) 326–742 40 131 (3.71) 743–1,570 30 260 (7.36) 1,571–2,900 25 472 (13.37) 2,901 and up 20 726 (20.56) Branch piping that serves one or two laboratory classrooms should be sized for 100% usage regardless of the number of outlets. Use factors should be modified to suit special conditions and must be used with judgment after consultation with the owner and /or user.

Gas Regulator Relief Vents Guidelines for the use of relief vents from pressure regulators, also referred to as gas-train vents, can be found in the latest editions of NFPA 54 and FM Global Loss Prevention Data Sheet 6-4: Oil- and Gas-Fired Single-Burner Boilers, as well as in other publications of industry standards, such as those issued by Industrial Risk Insurers and the American Gas Association. It should be noted that when the pressure regulators discharge, large amounts of fuel gas may be released. It is not uncommon for a local fire department to be summoned to investigate an odor of gas caused by a gas-train vent discharge. Every attempt should be made to locate the terminal point of the vents above the line of the

Figure 1  Altitude Correction Factor

The Altitude Correction Factor (ACF) should be multiplied by the gas input at sea level to determine the corrected input. Sizing of the equipment is then performed utilizing this corrected input multiplied by the full load efficency.

Piping System Materials The following piping materials are the most often used for both NG and propane. Pipe Steel (galvanized, plastic-wrapped, or black), brass, and copper. Black steel is the most commonly used pipe. Cast-iron pipe shall not be used. Tubing Semi-rigid copper type K or L. Plastic pipe and tubing (polyethylene) Plastic pipe may be used outside and underground only.

Flexible hose Corrugated stainless steel tubing Indoor Indoor gas hose connectors may be used with laboratory or shop and other equipment that requires mobility during operation or installation, if listed for this application. A shutoff valve must be installed where the connector is attached to the building piping. The connector must be of minimum length but shall not exceed 6 ft (1.8 m). The connector must not be concealed and must not extend from one room to another nor pass through wall partitions, ceilings, or floors. Outdoor Outdoor gas hose connectors may be used to connect portable outdoor gas-fired appliances, if listed for this application. A shutoff valve or a listed quick-disconnect device must be installed where the connector is attached to the supply piping and in such a manner as to prevent the accumulation of water or foreign matter. JANUARY/FEBRUARY 2008 

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CONTINUING EDUCATION: Fuel Gas Piping Systems This connection must be made only in the outdoor area where the Gas boosters for natural or liquefied petroleum gas Boosters Simpo Merge and Split Unregistered Versionfor- http://www.simpopdf.com appliance is toPDF be used. natural or utility-supplied gas are hermetically sealed and are Fittings and joints for low-pressure piping, 3 psi (21 kPa) or equipped to deliver a volumetric flow rate (user defined but within less Steel pipe may be threaded, flanged, or welded. Cast or mal- the booster’s rated capacity) to an elevated pressure beyond the leable iron threaded fittings are the most commonly used. Tubing supply pressure. The outlet pressure usually remains at a constant may be soldered or brazed using wrought copper or copper alloy differential above the supply pressure within a reasonable range. fittings and no flux. Brazing alloy must not contain phosphorous. The discharge pressure is the sum of the incoming gas pressure and Fittings and joints for high pressure piping greater than 3 psi the booster-added pressure at the chosen flow rate. The incoming (21 kPa) Steel pipe and fittings 4 in. (100 mm) and larger shall be gas pressure usually has an upper safety limit as stipulated by the welded. hermetic gas booster manufacturer. Therefore, in the engineering Tubing joints Tubing usually is needed for the flexible connec- literature from the manufacturer, the engineer may find cautions tions to equipment. For pressures normally encountered in the uti- or warnings about the upper limits of incoming pressure, usually lization of NG and LPG, the most often used joints are screwed. about 5 psi (34.5 kPa).

Design Considerations

Materials of construction

The fact that LPG vapors are heavier than air has a practical bearing on several items. For one thing, LPG systems are located in such a manner that the hazard of escaping gas is kept at a minimum. Since the heavier-than-air gas tends to settle in low places, the vent termination of relief valves must be located at a safe distance from openings into buildings that are below the level of such valves. With many gas systems, both the gas pressure regulator and the fuel containers are installed adjacent to the building they serve. This distance must be a least 3 ft (0.91 m) measured horizontally. However, the required clearances vary according to the tank size and the adjacent activities. The designer should refer to the local code and NFPA 54 for these clearances. When LPG piping is installed in crawl spaces or in pipe tunnels, the engineer may consider a sniffer system, which automatically shuts down the gas supply, sounds an alarm, and activates an exhaust system to purge the escaping gas from the area upon detection of gas in the space due to a breach in the piping system.

Housing and rotor Boosters used for fuel gas must be Underwriters Laboratories (UL) listed for the specific duty intended and shall be hermetically sealed. Casings on standard boosters usually are constructed of carbon steel, depending on the equipment supplier. Booster casings are also available in stainless steel and aluminum. Inlet and outlet connections are threaded or flanged, depending on the pipe size connection and the manufacturer selected, and the casings are constructed leak tight. Drive impellers are contained within the casing and always manufactured of a spark-resistant material such as aluminum. Discharge-type check valves are furnished on the booster inlet and on the booster bypass. It is important that these valves are listed and approved for use on the gas service at hand. The fan, control panel, valves, piping, and interelectrical connections can be specified as a skid-mounted package at the discretion of the designer. This allows for UL listing of the entire package rather than of individual components. Electrical components  Motor housings for gas booster systems are designed for explosion-proof (XP) construction and are rated per National Electrical Manufacturers Association (NEMA) Class 1, Division 1, Group D classification with thermal overload protection. A factory UL-listed junction box with a protected, sealed inlet is necessary for wiring connections.

GAS BOOSTERS A gas booster is a pump that increases the pressure of gas. It is used when there is insufficient pressure available from the gas utility or LPG storage device to supply the necessary pressure to the equipment at hand. It is important to note that the gas service must be capable of the volumetric flow rate required at the boosted level. A booster cannot overcome an inadequate volumetric supply.

Figure 2 Variations of a Basic Simplex Booster System: (A) Standby Generator Application with Accumulator Tank Having a Limitation on Maximum Pressure 6  Plumbing Systems & Design 

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(B)

(C) Figure 2 Variations of a Basic Simplex Booster System: (B) Dual Booster System for Critical Systems Like Those in Hospitals, (C) Heat Exchanger Loop­ Example—Required for High Flow Range with Low Minimum Flow. Other electrical ancillary equipment  Boosters are equipped with low pressure switches that monitor the incoming gas pressure. The switch is designed to shut down the booster should the utilitysupplied pressure fall below a preset limit. The set point is usually about 3 in. (76 mm) wc, but the designer should verify the limit with the local gas provider. The switch must be UL listed for use with the gas service at hand. When the switch opens, it de-energizes the motor control circuit and simultaneously outputs both audible and visual signals, which require manual resetting. The booster can be equipped with an optional high/low gas pressure switch. This feature equips the booster to run only when adequate supply pressure

is available. The switch shuts the booster down at the maximum discharge setpoint pressure at the output line pressure. Minimum gas flow  Gas boosters normally require a minimum gas flow that serves as an internal cooling medium. For example, a booster sized at a flow rate of 10,000 cfh (283.2 m3/h) has an inherent minimum turndown based on the minimum flow required to cool the unit. This rate, in the example, may be 2,000 cfh (566.3 m3/h) (see Figure 2). Should the unit be required to run below this turndown rate, additional supplemental cooling systems must be incorporated into the booster design. The heat exchangers normally rated for this use are water cooled. JANUARY/FEBRUARY 2008 

Plumbing Systems & Design  7

CONTINUING EDUCATION: Fuel Gas Piping Systems Intrinsic safety  Electrical connections are made through a Simpo PDF Merge andtoSplit Unregistered Version sealed, explosion-proof conduit the XP junction box on the booster unit. Control panels are rated NEMA 4 for outdoor use and NEMA 12 for indoor use unless the booster system is to be located in a hazardous area, which may have additional requirements. The panel, as an assembly, must display a UL label specific for its intended use. 4.

Gas laws for boosters Pressure/volume relationships The gas laws apply to the relationship of the incoming gas supply and the boosted service. The standard law for compressed gas relationships is as follows:

Equation 1 PV = RT where P = Pressure, psi or in. wc (kPa or mm wc) V = Volume, cfh (m3/h) R = Constant for the gas/air mixture used T = Temperature, °F (°C) Usually the temperature of the gas remains relatively constant and can be ignored in the relationship. Therefore, the pressure times the volume is proportional to a constant R. Further, the pressure/volume ratios before and after the booster are proportional, that is:

Equation 2 P1V1 = P2V2 where P1 = Pressure at a point prior to the booster P2 = Pressure at a point after the booster For almost every case, the volumetric rating of gas-fired equipment is in Btu/h, which can readily be converted to cfh. In the booster application, sizing criteria should be approached from a standard cfh (scfh) not an actual cfh (acfh) rating. Gas temperatures and density  As stated, the temperature of the gas is usually constant. However, in the event that the gas is to be heated or cooled, the previously mentioned gas laws are affected by temperature. Gas density changes affect the constant but usually do not affect the relationship since the same mixture is boosted across the fan. High-rise building issues  Consideration must be given to the rise effect in available gas pressure as gas rises in the piping through a high-rise building. Therefore, if the gas system supplies a kitchen on the first level and a boiler in the penthouse of a 50-story building, it may be necessary to boost the supply to the kitchen but not to the boiler. The gas rises to the penthouse through the piping system because of the density differential; its rising is dependent on this stack effect, which is directly related to the piping system layout. Design considerations  Although a gas booster is a basic mechanical piece of equipment, there are significant design considerations that should be taken into account when applying it: 1. Indoor vs. outdoor location.  This may be driven by local code or the end user. An indoor location involves a lower initial cost and lower costs for long-term maintenance. Outdoor locations are inherently safer. 2. Access.  The location should be accessible for installation, inspection, and maintenance. The unit should not be so accessible as to create a security issue. Keep the equipment out of traffic patterns and protect it from heavy equipment. 3. Minimum and maximum flow rates.  Boosters usually have a minimum flow rate that must be maintained so that the

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booster’s motor is kept cool. When specifying a booster,

http://www.simpopdf.com always indicate the minimum flow required in addition to other design parameters. Cooling devices and bypass loops may be required if the application requires a turndown in flow (lowest flow expected) that is higher than the booster’s minimum flow. Controls and interlocking.  Determine how the application should be controlled and what demands the application will put on the system. The control philosophy, method of electrically interlocking the system to the gas-fired equipment, and physical hardware will vary based on the application.

For some specific examples, see the schematics in Figure 2, which shows variations of a basic simplex booster system for an emergency generator. In Figure 2(A), the regulator controls maximum delivered pressure, and a combination high/low pressure switch on the tank cycles the booster to ensure emergency startup pressure within a design deadband for the generator. Oversized piping, in this case, can be substituted for the tank itself. Provide adequate volume so that the generator can fire and deliver standby power back to the booster system to continue operation during main power interrupt. In Figure 2(B), a dual booster system, the booster is controlled in a lead/lag control scenario. Should one booster fail, the second is started automatically. Unit operation is rotated automatically via the control panel to share the duty and to keep both units in operating order. The booster with a heat exchanger loop shown in Figure 2(C) has a potential of up to 15 psi (103.4 kPa) and down to 28 in. (711.2 mm) wc supply pressure. The system automatically diverts gas around the booster if there is sufficient supply pressure. While these illustrations obviously do not cover all the potential applications, they are provided to give the system designer some guidance. Sizing a gas booster  A gas booster’s main purpose is to elevate the pressure of a volume of gas to overcome a supply pressure deficiency. When sizing a booster, an engineer needs to understand the following terms and issues: Maximum design flow (Qmax)  The sum of all gas loads at the maximum capacity rating (MCR) for all equipment downstream of the booster that could possibly be required to operate simultaneously. Minimum design flow (Qmin)  The minimum volumetric flow that could exist while the booster is operating. This flow is not always associated with the smallest Btu/h-rated piece of equipment. For example, when evaluating a 75,000,000 Btu/h (22 MW) boiler with a 10:1 turndown ratio in comparison to a 1.0 Btu/h (0.3 W) hot water heater that is on/off in operation, the larger Btu/h (W)-rated boiler has the smaller flow of 0.75 Btu/h (0.2 W) at its minimum firing rate. Turndown (TD) ratio  The ratio of the MCR input to the equipment’s minimum, or low-fire, input. For example, a 100 Btu/h (29.3 W) burner that can fire at a minimum rate of 20 Btu/h (5.9 W) has a TD ratio of 5:1. Pressure droop and peak consumption  Pressure droop is the inability of a supply system to maintain a steady or consistent inlet pressure as an increase in volumetric flow is demanded. Often, in areas where boosters are applied, the supply pressure in off-peak months when gas is not in such demand can be sufficient to run a system. As the local demand for gas increases, the supply system no longer can provide the gas efficiently and the pressure falls off or droops. It is the booster’s function to overcome the droop (or excessive pressure drop) of the supply system during such times. Flow rate relationships  Do your flows for separate pieces of equipment relate to each other? In other words, do the three boilPSDMAGAZINE.ORG

ers always operate in unison while another process machine always 3. The allowable friction loss through the piping system. Simpo PDF Merge and Split Unregistered Version4. - http://www.simpopdf.com operates off peak and alone? Relationships among the equipment A piping layout that shows all the connected equipment, can significantly affect both maximum and minimum flow rates. allowing determination of the measured length of piping to Test block  A factor of safety added to design criteria. Typically, the furthest connection. This, in turn, gives the equivalent a minimum of 5% added volume and 10% added static pressure length of piping. should be applied to the design criteria. When specifying the equip- 5. The maximum probable demand. ment, ensure that you note both the design and test block condi- 6. A pipe sizing method acceptable to the AHJ or local code. tions. This makes other people working on the system aware and The information needed by both the utility company and the ensures that safety factors are not applied to criteria that already engineer The following are intended to be complete lists of items. include safety factors. Not all items will be necessary for all projects. Minimum inlet pressure (PI-min)  What is the minimum supply The following criteria and information shall be obtained in writpressure in in. (mm) wc gauge? This must be evaluated during peak ing from the public utility company and given to the engineer: flow demands both for the equipment and for the local area. Always 1. BTU content of the gas provided. evaluate during flow, not static, conditions. It is also important to 2. Minimum pressure of the gas at the outlet of the meter. know how high the inlet pressure is expected to rise during off-peak 3. Extent of the installation work done by the utility company periods. A booster is typically rated to about 5 psi (34.5 kPa). It may and the point of connection to the meter by the facility conbe possible to exceed this rating during off-peak demand periods; struction contractor. therefore, a bypass system or other means of protection is required. 4. The location of the utility supply main and the proposed run Often this pressure can be specified by the local gas company as the of pipe on the site by the utility company. This shall be in the minimum guaranteed gas pressure from their supply system. Also, form of a marked-up plan or description of the work. Include the maximum inlet pressure (PI-max) must be determined. the expected date of installation if no gas is available. Maximum outlet pressure (PO-max)  List all maximum and 5. Acceptable location of the meter and /or regulator assembly required supply pressures for the various pieces of equipment being or a request to locate the meter at a particular location. supplied gas from the booster. Determine the differential between 6. Any work required by the owner to allow the meter assembly the highest expected gas pressure supply to the booster (e.g., 8 in. to be installed (such as a meter pit or slab on grade). [203.2 mm] wc) and the lowest maximum supply pressure rating 7. Types of gas service available and the cost of each. to a piece of equipment (e.g., 18 in. [457.2 mm] wc). The booster’s For the utility company to provide this data, the fol­lowing inforpressure gain should not exceed this differential (for the above example, 18 – 8 = 10 in. [457.2 – 203.2 = 254 mm] wc) unless other mation must be provided to them: 1. The total connected load. The utility will use its own diversity means of protecting the downstream equipment are provided. factor to calculate the size of the service line. For the design Outlet pressure protection  There are several ways to protect of the project’s interior piping, the design engineer will select equipment downstream of a booster should it be necessary due the diversity factor involved. to potential over-pressurization during off-peak periods. If all the equipment being serviced operates at nominally the same pressure, 2. Minimum pressure requirements for the most demanding device. install a regulator on the inlet or outlet of the booster to maintain a controlled maximum outlet pressure. If the equipment being ser- 3. Site plan indicating the location of the proposed building on the site and the specific area of the building where the proviced operates at various inlet pressures, it may be best to supply a posed NG service will enter the building. regulator for each piece of equipment. Most often, packaged equip4. Preferred location of the meter/regulator assembly ment is supplied with its own regulator. If this is the case, review the 5. Expected date of the start of construction. equipment regulator’s maximum inlet pressure. To perform an evaluation of system requirements, do the following: 6. Different requirements for pressure. 7. Two site plans, one to be marked up and returned to the engi1. Establish design Qmin and Qmax per the previously discussed neer. definitions while evaluating TD requirements. 8. If any equipment has pilot lights. 2. Establish PI-min and PI-max per the previously discussed defini9. The hours of operation for the different types of equipment. tions. 10. Future equipment and capacities, if any, known at this time. 3. Define maximum inlet pressure requirements to equipment (PI-eq). The pressure available after the meter shall be established in 4. Define piping pressure losses (PPL) from the gas booster locawriting from the utility at the start of the project. If boilers or other tion to each piece of equipment. major equipment is being used, the pressure requirements and the 5. Design flow rate (QD) = Qmin to Qmax, cfh (m3/h). flow rate for that equipment must be provided to the utility. 6. Design pressure boost (DP) = PI-eq + PPL – PI-min. The allowable friction loss through the entire piping system 7. Test block flow (QTB) = (1.05 × Qmin) to (1.05 × Qmax). shall be established by the engineer. This value depends on the 8. Test block pressure boost: 1.10 × DP = PI-eq + PPL – PI-min. pressure provided by the utility company. The most often selected value under average conditions is 0.3 in. (7.6 mm) wc, with a range where of 0.2–0.5 in. (5–13 mm) wc. The residential appliances (range and PPL = Pressure losses, psi (kPa) dryer) require a pressure of 3.5 in. (89 mm) wc. If the pressure from the utility company is around 7 in. (178 mm) wc, a higher friction Interior NG Pipe Sizing To accurately size all elements of the piping system, calculate or loss allowance could be used for economy in pipe sizing. If the pressure from the utility company is 4 in. (102 mm) wc, a 0.2 in. (5 obtain the following information: mm) wc is recommended. 1. The information needed by both the utility company and the A piping layout and the equivalent length of piping  A piping engineer. layout is necessary to show the run of the whole piping system and 2. The gas pressure available after the meter assembly. JANUARY/FEBRUARY 2008 

Plumbing Systems & Design  9

CONTINUING EDUCATION: Fuel Gas Piping Systems Table 5  Equivalent Lengths for Various Valve and Fitting Sizes

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¾ (19.1)

1 (25.4) 1½ (38.1)

Pipe Size, in. (mm) 2 (50.8) 2½ (63.5)

3 (76.2)

4 (101.6)

Equivalent Lengths, ft (m) 2.00 (0.61) 2.50 (0.76) 3.00 (0.91) 4.00 (1.22) 5.50 (1.68) 6.50 (1.98)

90° elbow

1.00 (0.3)

Tee (run)

0.50 (0.15) 0.75 (0.23) 1.00 (0.3)

5 (127)

6 (152.4)

8 (203.2)

9.00 (2.74) 12.0 (3.66)

15.0 (4.57)

1.50 (0.46) 2.00 (0.61) 3.00 (0.91) 3.50 (1.07)

4.50 (1.37) 6.00 (1.83)

7.00 (2.13)

Tee (branch)

2.50 (0.76) 3.50 (1.07) 4.50 (1.37) 5.00 (1.52) 6.00 (1.83) 11.0 (3.35) 13.0 (3.96)

18.0 (5.49) 24.0 (7.32)

30.0 (9.14)

Gas cock (approx.)

4.00 (1.22) 5.00 (1.52) 7.50 (2.29) 9.00 (2.74) 12.0 (3.66) 17.0 (5.18) 20.0 (6.1)

28.0 (8.53) 37.0 (11.28) 46.0 (14.02)

Note: The pressure drop through valves should be taken from manufacturers’ published data rather than using the equivalent lengths, since the various patterns of gas cocks can vary greatly.

all the connected appliances and equipment. The equivalent length of piping is calculated by measuring the actual length of proposed piping from the meter to the furthest connection and then adding 50% of the measured length to find the equivalent length. If a very accurate determination of the equivalent length is necessary, it will be necessary to count the fittings and valves and then add those to the measured length. Refer to Table 5 for the equivalent amount of pipe to be added for various valves and fittings. It is common practice not to use the vertical length in either calculation because NG is lighter than air. It expands at the rate of 1 in. (25.4 mm) wc for each 15 ft of elevation as the gas rises. The increase in pressure due to the height will offset any friction loss in the piping. The maximum probable demand is calculated by the engineer with input from the owner if necessary. The primary usage of gas is for cooking and clothes drying at residences, for Bunsen burners or heating (boilers) in laboratories, or cooling equipment in industrial projects. For residential usage, Figure 3 for large residences

and Figure 4 for smaller projects give a direct reading of the usage in cfh (m3/hr). These direct reading tables give flow rate usage by using the number of apartments. Figure 5 is a riser diagram of multiple dwellings that gives the size of gas risers used for cooking and drying for both single and back-to-back installations. For laboratories, use Table 5 for the diversity factor. For schools, use no diversity factor for individual classrooms. Use no diversity factor for groups of classrooms if information of proposed usage is not conclusive or available from the owner. For industrial usage, a diversity factor generally is not used because of the possibility that all equipment may be in use at one time. For a listing of input requirements for common appliances, refer to Table 3.

NG Pipe Sizing Methods A number of formulas can be used to calculate the capacity of NG piping based on such variables as delivery pressure, pressure drop through the piping system, pipe size, pipe material, and length of piping. These formulas are referenced in numerous current model

Figure 3  Gas Demand for Multiple-unit Dwellings with More Than 50 Apartments

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PSDMAGAZINE.ORG

codes as well as in NFPA 54. The most commonly referenced forof piping is not considered due to the pressure gained as the Merge Split Unregistered Version - http://www.simpopdf.com mulaSimpo for gas PDF pressures underand 1½ psi (10.3 kPa) is the Spitzglass gas rises. This very closely approximates the friction loss in the formula. The other commonly referenced equation for pressures of piping. 1½ psi (10.3 kPa) and more is the Weymouth formula. Using these 2. Select the column showing the distance that is equal to or formulas for sizing is a very cumbersome task, so they are rarely, if more than the equivalent length just calculated. ever, used. However, they were used as a basis for the sizing tables 3. Use the vertical column to locate all gas demand figures for that are included in this chapter and reproduced with permission this particular system. This is the only column to use. Startfrom the NFPA. These tables are regarded as the most conservaing at the most remote outlet, find in the vertical column the tive method for sizing NG pipe. Proprietary tables and calculators calculated gas demand for that design point. If the exact figure are available from various organizations and are considered more is not shown, choose the figure closest to or more than the accurate than those shown here. calculated demand. The tables are based on Schedule 40 steel pipe, cfh of gas, and a 4. Opposite this demand figure selected, in the column at the specific gravity of 0.60. The initial pressures are different, and the left, find the correct size of pipe. friction loss allowable is indicated. The following tables are pro- 5. Proceed for each design point and each section of pipe. For vided: each section of pipe, determine the total gas demand supplied Table 6 pressure less than 2 psi (14 kPa), loss of 0.3 in. (7.5 mm) by that section. wc If the gas used for the system has a different specific gravity than Table 7 pressure less than 2 psi (14 kPa), loss of 0.5 in. (12.5 mm) natural gas, obtain that figure from Table 12 and use this as a multiwc plier for the specific gas selected. Table 8 pressure of 5 psi (35 kPa), loss of 10 percent Table 9 pressure 10 psi (70 kPa), loss of 10 percent Table 10 pressure 20 psi (140 kPa), loss of 10 percent Figure 5  Gas Riser Pipe Sizing for Multiple Dwellings Table 11 pressure 50 psi (350 kPa), loss of 10 percent Note 1 cfh gas = 0.3 m3/hr To determine the size of each section of pipe in a gas supply system using the gas pipe sizing tables, the following method should be used: 1. Measure the length of the pipe from the gas meter location to the most remote outlet on the system. Add a fitting allowance of 50% of the measured length. This now gives you the equivalent length of pipe. For natural gas, the vertical portion

Figure 4  Gas Demand for Multiple-unit Dwellings with Less than 50 Apartments

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Plumbing Systems & Design  11

CONTINUING EDUCATION: Fuel Gas Piping Systems Table 6  Pressure less than 2 psi (14 kPa), loss of 0.3 in. (7.5 mm) wc Pipe Size (in.) 1 3 Nominal ⁄2 ⁄4 1 11⁄4 11⁄2 2 21⁄2 3 4 Actual ID 0.622 0.824 1.049 1.380 1.610 2.067 2.469 3.068 4.026 Length (ft) Capacity in Cubic Feet of Gas per Hour 10 131 273 514 1,060 1,580 3,050 4,860 8,580 17,500 20 90 188 353 726 1,090 2,090 3,340 5,900 12,000 30 72 151 284 583 873 1,680 2,680 4,740 9,660 40 62 129 243 499 747 1,440 2,290 4,050 8,270 50 55 114 215 442 662 1,280 2,030 3,590 7,330 60 50 104 195 400 600 1,160 1,840 3,260 6,640 70 46 95 179 368 552 1,060 1,690 3,000 6,110 80 42 89 167 343 514 989 1,580 2,790 5,680 90 40 83 157 322 482 928 1,480 2,610 5,330 100 38 79 148 304 455 877 1,400 2,470 5,040 125 33 70 131 269 403 777 1,240 2,190 4,460 150 30 63 119 244 366 704 1,120 1,980 4,050 175 28 58 109 224 336 648 1,030 1,820 3,720 200 26 54 102 209 313 602 960 1,700 3,460 250 23 48 90 185 277 534 851 1,500 3,070 300 21 43 82 168 251 484 771 1,360 2,780 350 19 40 75 154 231 445 709 1,250 2,560 400 18 37 70 143 215 414 660 1,170 2,380 450 17 35 66 135 202 389 619 1,090 2,230 500 16 33 62 127 191 367 585 1,030 2,110 550 15 31 59 121 181 349 556 982 2,000 600 14 30 56 115 173 333 530 937 1,910 650 14 29 54 110 165 318 508 897 1,830 700 13 27 52 106 159 306 488 862 1,760 750 13 26 50 102 153 295 470 830 1,690 800 12 26 48 99 148 285 454 802 1,640 850 12 25 46 95 143 275 439 776 1,580 900 11 24 45 93 139 267 426 752 1,530 950 11 23 44 90 135 259 413 731 1,490 1,000 11 23 43 87 131 252 402 711 1,450 1,100 10 21 40 83 124 240 382 675 1,380 1,200 NA 20 39 79 119 229 364 644 1,310 1,300 NA 20 37 76 114 219 349 617 1,260 1,400 NA 19 35 73 109 210 335 592 1,210 1,500 NA 18 34 70 105 203 323 571 1,160 1,600 NA 18 33 68 102 196 312 551 1,120 1,700 NA 17 32 66 98 189 302 533 1,090 1,800 NA 16 31 64 95 184 293 517 1,050 1,900 NA 16 30 62 93 178 284 502 1,020 2,000 NA 16 29 60 90 173 276 488 1,000

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To convert gas pressure to various designations, refer to Table 13.

LIQUEFIED PETROLEUM GAS Liquefied petroleum gas (LPG) is a refined NG developed mainly for use beyond the utilities’ gas mains, but it has proven to be competitive in areas not covered by mains in rural areas. It is chiefly a blend of propane and butane with traces of other hydrocarbons remaining from the various production methods. The exact blend is controlled by the LPG distributor to match the climatic conditions of the area served. For this reason, the engineer must confirm the heat value of the supplied gas. Unlike natural gas, 100 percent propane has a specific gravity of 1.53 and a rating of 2,500 Btu/cf (93 MJ/cm3).

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5 5.047

6 6.065

8 7.981

10 12 10.020 11.938

31,700 21,800 17,500 15,000 13,300 12,000 11,100 10,300 9,650 9,110 8,080 7,320 6,730 6,260 5,550 5,030 4,630 4,310 4,040 3,820 3,620 3,460 3,310 3,180 3,060 2,960 2,860 2,780 2,700 2,620 2,490 2,380 2,280 2,190 2,110 2,030 1,970 1,910 1,850 1,800

51,300 105,000 191,000 303,000 35,300 72,400 132,000 208,000 28,300 58,200 106,000 167,000 24,200 49,800 90,400 143,000 21,500 44,100 80,100 127,000 19,500 40,000 72,600 115,000 17,900 36,800 66,800 106,000 16,700 34,200 62,100 98,400 15,600 32,100 58,300 92,300 14,800 30,300 55,100 87,200 13,100 26,900 48,800 77,300 11,900 24,300 44,200 70,000 10,900 22,400 40,700 64,400 10,100 20,800 37,900 59,900 8,990 18,500 33,500 53,100 8,150 16,700 30,400 48,100 7,490 15,400 28,000 44,300 6,970 14,300 26,000 41,200 6,540 13,400 24,400 38,600 6,180 12,700 23,100 36,500 5,870 12,100 21,900 34,700 5,600 11,500 20,900 33,100 5,360 11,000 20,000 31,700 5,150 10,600 19,200 30,400 4,960 10,200 18,500 29,300 4,790 9,840 17,900 28,300 4,640 9,530 17,300 27,400 4,500 9,240 16,800 26,600 4,370 8,970 16,300 25,800 4,250 8,720 15,800 25,100 4,030 8,290 15,100 23,800 3,850 7,910 14,400 22,700 3,680 7,570 13,700 21,800 3,540 7,270 13,200 20,900 3,410 7,010 12,700 20,100 3,290 6,770 12,300 19,500 3,190 6,550 11,900 18,800 3,090 6,350 11,500 18,300 3,000 6,170 11,200 17,700 2,920 6,000 10,900 17,200

Easy storage for relatively large quantities of energy has led to widespread acceptance and usage of LPG in all areas previously served by utilities providing NG to users, including automotive purposes. In addition, a principal use is for the heating of industrial projects. It does not take the place of NG but provides an alternative energy source when the owners want to use a low, interruptible rate for heating purposes. When used for this purpose, experience has shown that the mixing with air should produce a gas with the heating value of 1,500 Btu/cf (a specific gravity of 1.30) for ease of burning and ignition. Use Table 12 for the factor to be used for sizing.

Storage LPG storage tanks can be provided by the vendor or the customer and are subject to the regulations of the U.S. Department of Transportation (DOT) and the local authority, as well as NFPA standards, PSDMAGAZINE.ORG

Table 7  pressure less than 2 psi (14 kPa), loss of 0.5 in. (12.5 mm) wc Pipe Size (in.) 1 3 Nominal ⁄2 ⁄4 1 11⁄4 11⁄2 2 21⁄2 3 4 5 Actual ID 0.622 0.824 1.049 1.380 1.610 2.067 2.469 3.068 4.026 5.047 Length (ft) Capacity in Cubic Feet of Gas per Hour 10 172 360 678 1,390 2,090 4,020 6,400 11,300 23,100 41,800 20 118 247 466 957 1,430 2,760 4,400 7,780 15,900 28,700 30 95 199 374 768 1150 2,220 3,530 6,250 12,700 23,000 40 81 170 320 657 985 1,900 3,020 5,350 10,900 19,700 50 72 151 284 583 873 1,680 2,680 4,740 9,660 17,500 60 65 137 257 528 791 1,520 2,430 4,290 8,760 15,800 70 60 126 237 486 728 1,400 2,230 3,950 8,050 14,600 80 56 117 220 452 677 1300 2,080 3,670 7,490 13,600 90 52 110 207 424 635 1220 1,950 3,450 7,030 12,700 100 50 104 195 400 600 1160 1,840 3,260 6,640 12,000 125 44 92 173 355 532 1020 1,630 2,890 5,890 10,600 150 40 83 157 322 482 928 1,480 2,610 5,330 9,650 175 37 77 144 296 443 854 1,360 2,410 4,910 8,880 200 34 71 134 275 412 794 1270 2,240 4,560 8,260 250 30 63 119 244 366 704 1120 1,980 4,050 7,320 300 27 57 108 221 331 638 1020 1,800 3,670 6,630 350 25 53 99 203 305 587 935 1,650 3,370 6,100 400 23 49 92 189 283 546 870 1,540 3,140 5,680 450 22 46 83 177 266 512 816 1,440 2,940 5,330 500 21 43 82 168 251 484 771 1,360 2,780 5,030 550 20 41 78 159 239 459 732 1290 2,640 4,780 600 19 39 74 152 228 438 699 1240 2,520 4,560 650 18 38 71 145 218 420 669 1180 2,410 4,360 700 17 36 68 140 209 403 643 1140 2,320 4,190 750 17 35 66 135 202 389 619 1090 2,230 4,040 800 16 34 63 130 195 375 598 1060 2,160 3,900 850 16 33 61 126 189 363 579 1020 2,090 3,780 900 15 32 59 122 183 352 561 992 2,020 3,660 950 15 31 58 118 178 342 545 963 1,960 3,550 1,000 14 30 56 115 173 333 530 937 1,910 3,460 1,100 14 28 53 109 164 316 503 890 1,810 3,280 1,200 13 27 51 104 156 301 480 849 1,730 3,130 1,300 12 26 49 100 150 289 460 813 1,660 3,000 1,400 12 25 47 96 144 277 442 781 1,590 2,880 1,500 11 24 45 93 139 267 426 752 1,530 2,780 1,600 11 23 44 89 134 258 411 727 1,480 2,680 1,700 11 22 42 86 130 250 398 703 1,430 2,590 1,800 10 22 41 84 126 242 386 682 1,390 2,520 1,900 10 21 40 81 122 235 375 662 1,350 2,440 2,000 NA 20 39 79 119 229 364 644 1,310 2,380

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so the plumbing designer has little opportunity to design storage tanks and piping, per se. Normally, the designer starts at the storage supply outlet, and the piping system is generally in a low pressure range of 20 psig to 11 in wc.

6 6.065

8 7.981

67,600 46,500 37,300 31,900 28,300 25,600 23,600 22,000 20,600 19,500 17,200 15,600 14,400 13,400 11,900 10,700 9,880 9,190 8,620 8,150 7,740 7,380 7,070 6,790 6,540 6,320 6,110 5,930 5,760 5,600 5,320 5,070 4,860 4,670 4,500 4,340 4,200 4,070 3,960 3,850

139,000 95,500 76,700 65,600 58,200 52,700 48,500 45,100 42,300 40,000 35,400 32,100 29,500 27,500 24,300 22,100 20,300 18,900 17,700 16,700 15,900 15,200 14,500 14,000 13,400 13,000 12,600 12,200 11,800 11,500 10,900 10,400 9,980 9,590 9,240 8,920 8,630 8,370 8,130 7,910

10 12 10.020 11.938 252,000 173,000 139,000 119,000 106,000 95,700 88,100 81,900 76,900 72,600 64,300 58,300 53,600 49,900 44,200 40,100 36,900 34,300 32,200 30,400 28,900 27,500 26,400 25,300 24,400 23,600 22,800 22,100 21,500 20,900 19,800 18,900 18,100 17,400 16,800 16,200 15,700 15,200 14,800 14,400

399,000 275,000 220,000 189,000 167,000 152,000 13,900 130,000 122,000 115,000 102,000 92,300 84,900 79,000 70,000 63,400 58,400 54,300 50,900 48,100 45,700 43,600 41,800 40,100 38,600 37,300 36,100 35,000 34,000 33,100 31,400 30,000 28,700 27,600 26,600 25,600 24,800 24,100 23,400 22,700

suitable for site mains. The engineer shall obtain or request the pressure provided by the supplier and decide upon the pressure drop in the piping system that would be appropriate. The AHJ shall be consulted regarding acceptance of any pressure selected.

LPG SIZING

STORAGE TANKS

The pressure of LPG is set by the supplier or the engineer. If the piping is to be run on the site, the pressure would be set higher for economy of pipe sizing, and a regulator would be provided to lower the pressure to a value that would be compatible with equipment served. A lower pressure would be used within a building. Propane gas shall be sized in accordance with. Tables 14 and 15 that have been developed by the NFPA. Table 14 is based on an outlet pressure of 11 in. wc.(280 mm) that would be suitable for interior piping. Table 15 is based on a higher outlet pressure more

Small tanks (for example, those for residential cooking and heating) are allowed to be located in close proximity to buildings. Large tanks (e.g., for industrial or multiple building use), however, have strict requirements governing their locations in relation to buildings, public use areas, and property lines. If large leaks occur, the heavier-than-air gas will hug the ground and form a fog. The potential for a hazardous condition could exist. Proper safety precautions and equipment, as well as good judgment, must be utilized when

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Plumbing Systems & Design  13

CONTINUING EDUCATION: Fuel Gas Piping Systems Table Simpo 8  Pressure of 5 psiMerge (35 kPa), loss of 10Split percentUnregistered Version - http://www.simpopdf.com PDF and Pipe Size of Total Equivalent Length of Pipe (ft) Schedule 40 Standard Internal Pipe (in.) Diameter (in.) 50 100 150 200 250 300 400 500 1000 1.00 1.049 1,989 1,367 1,098 940 833 755 646 572 393 1.25 1.380 4,084 2,807 2,254 1,929 1,710 1,549 1,326 1,175 808 1.50 1.610 6,120 4,206 3,378 2,891 2,562 2,321 1,987 1,761 1,210 2.00 2.067 11,786 8,101 6,505 5,567 4,934 4,471 3,827 3,391 2,331 2.50 2.469 18,785 12,911 10,368 8,874 7,865 7,126 6,099 5,405 3,715 3.00 3.068 33,209 22,824 18,329 15,687 13,903 12,597 10,782 9,559 6,568 3.50 3.548 48,623 33,418 26,836 22,968 20,356 18,444 15,786 13,991 9,616 4.00 4.026 67,736 46,555 37,385 31,997 28,358 25,694 21,991 19,490 13,396 5.00 5.047 122,544 84,224 67,635 57,887 51,304 46,485 39,785 35,261 24,235 6.00 6.065 198,427 136,378 109,516 93,732 83,073 75,270 64,421 57,095 39,241 8.00 7.981 407,692 280,204 225,014 192,583 170,683 154,651 132,361 117,309 80,626 10.00 10.020 740,477 508,926 408,686 349,782 310,005 280,887 240,403 213,065 146,438 12.00 11.938 1,172,269 805,694 647,001 553,749 490,777 444,680 380,588 337,309 231,830

1500 316 649 972 1,872 2,983 5,274 7,722 10,757 19,461 31,512 64,745 117,595 186,168

2000 270 555 832 1,602 2,553 4,514 6,609 9,207 16,656 26,970 55,414 100,646 159,336

Pressure 5.0 PSI (35 kPa) Pressure Drop of 10%

Table 9  Pressure 10 psi (70 kPa), loss of 10 percent Pipe Size of Schedule 40 Internal Standard Diameter Pipe (in.) (in.) 50 100 150 1.00 1.049 3,259 2,240 1,789 1.25 1.380 6,690 4,598 3,692 1.50 1.610 10,024 6,889 5,532 2.00 2.067 19,305 13,268 10,655 2.50 2.469 30,769 21,148 16,982 3.00 3.068 54,395 37,385 30,022 3.50 3.548 79,642 54,737 43,956 4.00 4.026 110,948 76,254 61,235 5.00 5.047 200,720 137,954 110,782 6.00 6.065 325,013 223,379 179,382 8.00 7.981 667,777 458,959 368,561 10.00 10.020 1,212,861 833,593 669,404 12.00 11.938 1,920,112 1,319,682 1,059,751

Total Equivalent Length of Pipe (ft) 200 1,539 3,160 4,735 9,119 14,535 25,695 37,621 52,409 94,815 153,527 315,440 572,924 907,010

250 1,364 2,801 4,197 8,082 12,882 22,773 33,343 46,449 84,033 136,068 279,569 507,772 803,866

300 1,236 2,538 3,802 7,323 11,672 20,634 30,211 42,086 76,140 123,288 253,310 460,078 728,361

400 500 1000 1500 2000 1,058 938 644 517 443 2,172 1,925 1,323 1,062 909 3,254 2,884 1,982 1,592 1,362 6,268 5,555 3,818 3,066 2,624 9,990 8,854 6,085 4,886 4,182 17,660 15,652 10,757 8,638 7,393 25,857 22,916 15,750 12,648 10,825 36,020 31,924 21,941 17,620 15,080 65,166 57,755 39,695 31,876 27,282 105,518 93,519 64,275 51,615 44,176 216,800 192,146 132,061 106,050 90,765 393,767 348,988 239,858 192,614 164,853 623,383 552,493 379,725 304,933 260,983

Pressure 10.0 PSI (70 kPa) Pressure Drop of 10%

Table 10  Pressure 20 psi (140 kPa), loss of 10 percent Pipe Size of Total Equivalent Length of Pipe (ft) Schedule 40 Standard Internal Pipe (in.) Diameter (in.) 50 100 150 200 250 300 400 1.00 1.049 5,674 3,900 3,132 2,680 2,375 2,152 1,842 1.25 1.380 11,649 8,006 6,429 5,503 4,877 4,419 3,782 1.50 1.610 17,454 11,996 9,633 8,245 7,307 6,621 5,667 2.00 2.067 33,615 23,103 18,553 15,879 14,073 12,751 10,913 2.50 2.469 53,577 36,823 29,570 25,308 22,430 20,323 17,394 3.00 3.068 94,714 65,097 52,275 44,741 39,653 35,928 30,750 3.50 3.548 138,676 95,311 76,538 65,507 58,058 52,604 45,023 4.00 4.026 193,187 132,777 106,624 91,257 80,879 73,282 62,720 5.00 5.047 349,503 240,211 192,898 165,096 146,322 132,578 113,370 6.00 6.065 565,926 388,958 312,347 267,329 236,928 214,674 183,733 8.00 7.981 1,162,762 799,160 641,754 549,258 486,797 441,074 377,502 10.00 10.020 2,111,887 1,451,488 1,165,596 997,600 884,154 801,108 685,645 12.00 11.938 3,343,383 2,297,888 1,845,285 1,579,326 1,399,727 1,268,254 1,085,462

500 1,633 3,352 5,022 9,672 15,416 27,253 39,903 55,538 100,566 162,840 334,573 607,674 962,025

1000 1,122 2,304 3,452 6,648 10,595 18,731 27,425 38,205 69,118 111,919 229,950 417,651 661,194

1500 901 1,850 2,772 5,338 8,509 15,042 22,023 30,680 55,505 89,875 184,658 335,388 530,962

2000 771 1,583 2,372 4,569 7,282 12,874 18,849 26,258 47,505 76,921 158,043 287,049 454,435

Pressure 20.0 PSI (140 kPa) Pressure Drop of 10%

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PSDMAGAZINE.ORG

Table Simpo 11  Pressure 50 psiMerge (350 kPa),and loss of Split 10 percent PDF Unregistered Version - http://www.simpopdf.com Pipe Size of Total Equivalent Length of Pipe (ft) Schedule 40 Internal Standard Diameter Pipe (in.) (in.) 50 100 150 200 250 300 400 500 1000 1500 2000 1.00 1.049 12,993 8,930 7,171 6,138 5,440 4,929 4,218 3,739 2,570 2,063 1,766 1.25 1.380 26,676 18,335 14,723 12,601 11,168 10,119 8,661 7,676 5,276 4,236 3,626 1.50 1.610 39,970 27,471 22,060 18,881 16,733 15,162 12,976 11,501 7,904 6,348 5,433 2.00 2.067 76,977 52,906 42,485 36,362 32,227 29,200 24,991 22,149 15,223 12,225 10,463 2.50 2.469 122,690 84,324 67,715 57,955 51,365 46,540 39,832 35,303 24,263 19,484 16,676 3.00 3.068 216,893 149,070 119,708 102,455 90,804 82,275 70,417 62,409 42,893 34,445 29,480 3.50 3.548 317,564 218,260 175,271 150,009 132,950 120,463 103,100 91,376 62,802 50,432 43,164 4.00 4.026 442,393 304,054 244,166 208,975 185,211 167,814 143,627 127,294 87,489 70,256 60,130 5.00 5.047 800,352 550,077 441,732 378,065 335,072 303,600 259,842 230,293 158,279 127,104 108,784 6.00 6.065 1,295,955 890,703 715,266 612,175 542,559 491,598 420,744 372,898 256,291 205,810 176,147 8.00 7.981 2,662,693 1,830,054 1,469,598 1,257,785 1,114,752 1,010,046 864,469 766,163 526,579 422,862 361,915 10.00 10.020 4,836,161 3,323,866 2,669,182 2,284,474 2,024,687 1,834,514 1,570,106 1,391,556 956,409 768,030 657,334 12.00 11.938 7,656,252 5,262,099 4,225,651 3,616,611 3,205,335 2,904,266 2,485,676 2,203,009 1,514,115 1,215,888 1,040,643 Table 12  Specific Gravity Multipliers Specific Gravity 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70

Capacity Multiplier 1.310 1.230 1.160 1.100 1.040 1.000 0.962 0.926

Specific Gravity 0.75 0.80 0.85 0.90 1.00 1.10 1.20 1.30

Capacity Multiplier 0.895 0.867 0.841 0.817 0.775 0.740 0.707 0.680

Specific Gravity 1.40 1.50 1.60 1.70 1.80 1.90 2.00 2.10

Capacity Multiplier 0.655 0.633 0.612 0.594 0.577 0.565 0.547 0.535

Table 13  Conversion of Gas Prcssurc to Various Designations Equivalent Pressure per Equivalent Pressure per inches square inch inches square inch kP Water Mercury Pounds Ounces Water Mercury Pounds Ounces 0.002 0.01 0.007 0.0036 0.0577 8.0 0.588 0.289 4.62 0.05 0.20 0.015 0.0072 0.115 9.0 0.662 0.325 5.20 0.07 0.30 0.022 0.0108 0.173 0.10 0.40 0.029 0.0145 0.231 10.0 0.74 0.361 5.77 11.0 0.81 0.397 6.34 0.12 0.50 0.037 0.0181 0.239 12.0 0.88 0.433 0.15 0.60 0.044 0.0217 0.346 13.0 0.96 0.469 7.50 0.17 0.70 0.051 0.0253 0.404 0.19 0.80 0.059 0.0289 0.462 13.6 1.00 0.491 7.86 0.22 0.90 0.066 0.0325 0.520 13.9 1.02 0.500 8.00 14.0 1.06 0.505 8.08 0.25 1.00 0.074 0.036 0.577 0.3 1.36 0.100 0.049 0.785 15.0 1.10 0.542 8.7 0.4 1.74 0.128 0.067 1.00 16.0 1.18 0.578 9.2 0.5 2.00 0.147 0.072 1.15 17.0 1.25 0.614 9.8 0.72 2.77 0.203 0.100 1.60 18.0 1.33 0.650 10.4 0.76 3.00 0.221 0.109 1.73 19.0 1.40 0.686 10.9 1.0 4.00 0.294 0.144 2.31 20.0 1.47 0.722 11.5 1.2 5.0 0.368 0.181 2.89 0.903 14.4 1.5 6.0 0.442 0.217 3.46 25.0 1.84 0.975 15.7 1.7 7.0 0.515 0.253 4.04 27.2 2.00 1.00 16.0 27.7 2.03

locating large LPG storage tanks. The lines also have to be purged of air prior to the startup of the facility.

GLOSSARY

kP 2.0 2.2 2.5 2.7 3.0 3.2 3.37 3.4 3.5 3.7 4.0 4.2 4.5 4.7 5.0 6.2 6.7 6.9

Btu  Abbreviation for British thermal unit, the quantity of heat required to raise the temperature of one pound of water by one degree Fahrenheit. Boiling point  The temperature of a liquid at which the internal vapor pressure is equal to the external pressure exerted on the surface of the liquid. Burner  A device for the final conveyance of gas, or a mixture of gas and air, to the combustion zone. Butane (C4H10)  A saturated aliphatic hydrocarbon existing in two isomeric forms and used as a fuel and a chemical intermediate. Caloric value  See heating value. Chimney  A vertical shaft enclosing one or more flues for conveying flue gases to the outside atmosphere. Condensate  The liquid that separates from a gas (including flue gas) due to a reduction in temperature. Cubic foot (meter) of gas  The amount of gas that would occupy 1 cubic foot (cubic meter) when at a temperature of 60°F (15.6°C), saturated with water vapor, and under a pressure equivalent to that of 30 in. of mercury (101.3 kPa). Demand  The maximum amount of gas per unit time, usually expressed in cubic feet per hour (liters per minute) or Btu (watts) per hour, required for the operation of the appliance(s) supplied. Dilution air  Air that enters a draft hood or draft regulator and mixes with the flue gases. Diversity factor  The ratio of the maximum probable demand to the maximum possible demand. Draft hood  A device built into an appliance, or made a part of the vent connector from an appliance, that is designed to:

JANUARY/FEBRUARY 2008 

Plumbing Systems & Design  15

CONTINUING EDUCATION: Fuel Gas Piping Systems 1. Provide for the ready escape of the flue gases from the Table 14  100% Propane for Interior Piping Simpo PDFinMerge Version - http://www.simpopdf.com appliance the eventand of noSplit draft,Unregistered backdraft, or stoppage Nominal 1 3 Inside ⁄2 ⁄4 1 11⁄4 11⁄2 beyond the draft hood. 2. Prevent a backdraft from entering the appliance. 3. Neutralize the effect of stack action of the chimney or gas vent upon the operation of the appliance. Excess air  Air that passes through the combustion chamber and the appliance flues in excess of that which is theoretically required for complete combustion. Flue gases  The products of combustion plus the excess air in appliance flues or heat exchangers (before the draft hood or draft regulator). Fuel gas  A gaseous compound used as fuel to generate heat. It may be known variously as utility gas, natural gas, liquefied peteroleum gas, propane, butane, methane, or a combination of the above. It has a caloric value that corresponds to the specific compound or combination of compounds. Care must be exercised in determining the caloric value for design purposes. Gas log  An unvented, open-flame-type room heater consisting of a metal frame or base supporting simulated logs designed for installation in a fireplace. Gas train  A series of devices pertaining to a fuel gas appliance located on the upstream side of the unit. Typically, it consists of a combination of devices and may include pipe, fittings, fuel, airsupervisory switches (e.g., pressure regulators), and safety shutoff valves. Gas-train vent  A piped vent to atmosphere from a device on a gas train. Gas vents  Factory-built vent piping and vent fittings listed by a nationally recognized testing agency, assembled and used in accordance with the terms of their listings, used for conveying flue gases to the outside atmosphere. 1. Type B gas vent. A gas vent for venting gas appliances with draft hoods and other gas appliances listed for use with type B gas vents. 2. Type B-W gas vent. A gas vent for venting listed gas-fired vented wall furnaces. 3. Type L vent. A gas vent for venting gas appliances listed for use with type L vents. Heating value (total)  The number of British thermal units produced by the combustion, at constant pressure, of 1 cubic foot (cubic meter) of gas when the products of combustion are cooled to the initial temperature of the gas and air; the water vapor formed during combustion is condensed; and all the necessary corrections have been applied. LPG  Liquefied petroleum gas, a mixture of propane and butane. Loads, connected  The sum of the rated Btu input to individual gas utilization equipment connected to a piping system. May be expressed in cubic feet (cubic meters) per hour. Meter set assembly  The piping and fittings installed by the serving gas supplier to connect the inlet side of the meter to the gas service and the outlet side of the meter to the customer’s building or yard piping. Pipe, equivalent length  The resistance of valves, controls, and fittings to gas flow, expressed as equivalent length of straight pipe. Pressure drop  The loss in static pressure due to friction or obstruction during flow through pipe, valves, fittings, regulators, and burners.

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Actual Lenth (ft) 10 20 30 40 50 60 80 100 125 150 175 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1,000 1,100 1,200 1,300 1,400 1,500 1,600 1,700 1,800 1,900 2,000

2 21⁄2 3 0.622 0.824 1.049 1.380 1.610 2.067 2.469 3.068 Capacity in Thousands of Btu per Hour 291 608 1,150 2,350 3,520 6,790 10,800 19,100 200 418 787 1,620 2,420 4,660 7,430 13,100 160 336 632 1,300 1,940 3,750 5,970 10,600 137 287 541 1,110 1,660 3,210 5,110 9,030 122 255 480 985 1,480 2,840 4,530 8,000 110 231 434 892 1,340 2,570 4,100 7,250 101 212 400 821 1,230 2,370 3,770 6,670 94 197 372 763 1,140 2,200 3,510 6,210 89 185 349 716 1,070 2,070 3,290 5,820 84 175 330 677 1,010 1,950 3,110 5,500 74 155 292 600 899 1,730 2,760 4,880 67 140 265 543 814 1,570 2,500 4,420 62 129 243 500 749 1,440 2,300 4,060 58 120 227 465 697 1,340 2,140 3,780 51 107 201 412 618 1,190 1,900 3,350 46 97 182 373 560 1,080 1,720 3,040 42 89 167 344 515 991 1,580 2,790 40 83 156 320 479 922 1,470 2,600 37 78 146 300 449 865 1,380 2,440 35 73 138 283 424 817 1,300 2,300 33 70 131 269 403 776 1,240 2,190 32 66 125 257 385 741 1,180 2,090 30 64 120 246 368 709 1,130 2,000 29 61 115 236 354 681 1,090 1,920 28 59 111 227 341 656 1,050 1,850 27 57 107 220 329 634 1,010 1,790 26 55 104 213 319 613 978 1,730 25 53 100 206 309 595 948 1,680 25 52 97 200 300 578 921 1,630 24 50 95 195 292 562 895 1,580 23 48 90 185 277 534 850 1,500 22 46 86 176 264 509 811 1,430 21 44 82 169 253 487 777 1,370 20 42 79 162 243 468 746 1,320 19 40 76 156 234 451 719 1,270 19 39 74 151 226 436 694 1,230 18 38 71 146 219 422 672 1,190 18 37 69 142 212 409 652 1,150

4 4.026 39,000 26,800 21,500 18,400 16,300 14,800 13,600 12,700 11,900 11,200 9,950 9,010 8,290 7,710 6,840 6,190 5,700 5,300 4,970 4,700 4,460 4,260 4,080 3,920 3,770 3,640 3,530 3,420 3,320 3,230 3,070 2,930 2,800 2,690 2,590 2,500 2,420 2,350

100% Propane, Pressure 11 in wc, Pressure Drop 0.5 in wc

Propane (C3H8)  A gaseous hydrocarbon of the methane series, found in petroleum. Regulator, gas pressure  A device for controlling and maintaining a uniform gas pressure. This pressure is always lower than the supply pressure at the inlet of the regulator. Safety shutoff device  A device that is designed to shut off the gas supply to the controlled burner(s) or appliance(s) in the event that the source of ignition fails. This device may interrupt the flow of gas to the main burner(s) only or to the pilot(s) and main burner(s) under its supervision. Specific gravity  The ratio of the weight of a given volume of gas to that of the same volume of air, both measured under the same conditions. Vent connector  That portion of the venting system that connects the gas appliance to the gas vent, chimney, or single-wall metal pipe. Vent gases  The products of combustion from a gas appliance plus the excess air and the dilution air in the venting system above the draft hood or draft regulator.

REFERENCES PSDMAGAZINE.ORG

Table 15  100% Propane for Site Mains Simpo PDF Merge and Split Unregistered Nominal 1 3 Inside ⁄2 ⁄4 1 11⁄4 11⁄2 2 21⁄2 Actual 0.622 0.824 1.049 1.380 1.610 2.067 2.469 Lenth (ft) Capacity in Thousands of Btu per Hour 10 5,890 12,300 23,200 47,600 71,300 137,000 219,000 20 4,050 8,460 15,900 32,700 49,000 94,400 150,000 30 3,250 6,790 12,800 26,300 39,400 75,800 121,000 40 2,780 5,810 11,000 22,500 33,700 64,900 103,000 50 2,460 5,150 9,710 19,900 29,900 57,500 91,600 60 2,230 4,670 8,790 18,100 27,100 52,100 83,000 70 2,050 4,300 8,090 16,600 24,900 47,900 76,400 80 1,910 4,000 7,530 15,500 23,200 44,600 71,100 90 1,790 3,750 7,060 14,500 21,700 41,800 66,700 100 1,690 3,540 6,670 13,700 20,500 39,500 63,000 125 1,500 3,140 5,910 12,100 18,200 35,000 55,800 150 1,360 2,840 5,360 11,000 16,500 31,700 50,600 175 1,250 2.620 4,930 10,100 15,200 29,200 46,500 200 1,160 2,430 4,580 9,410 14,100 27,200 43,300 250 1,030 2,160 4,060 8,340 12,500 24,100 38,400 300 935 1,950 3,680 7,560 11,300 21,800 34,800 350 860 1,800 3,390 6,950 10,400 20,100 32,000 400 800 1,670 3,150 6,470 9,690 18,700 29,800 450 751 1,570 2,960 6,070 9,090 17,500 27,900 500 709 1,480 2,790 5,730 8,590 16,500 26,400 550 673 1,410 2,650 5,450 8,160 15,700 25,000 600 642 1,340 2,530 5,200 7,780 15,000 23,900 650 615 1,290 2,420 4,980 7,450 14,400 22,900 700 591 1,240 2,330 4,780 7,160 13,800 22,000 750 569 1,190 2,240 4,600 6,900 13,300 21,200 800 550 1,50 2,170 4,450 6,660 12,800 20,500 850 532 1,110 2,100 4,300 6,450 12,400 19,800 900 516 1,080 2,030 4,170 6,250 12,000 19,200 950 501 1,050 1,970 4,050 6,070 11,700 18,600 1,000 487 1,020 1,920 3,940 5,900 11,400 18,100 1,100 463 968 1,820 3,740 5,610 10,800 17,200 1,200 442 923 1,740 3,570 5,350 10,300 16,400 1,300 423 884 1,670 3,420 5,120 9,870 15,700 1,400 406 849 1,600 3,280 4,920 9,480 15,100 1,500 391 818 1,540 3,160 4,740 9,130 14,600 1,600 378 790 1,490 3,060 4,580 8,820 14,100 1,700 366 765 1,440 2,960 4,430 8,530 13,600 1,800 355 741 1,400 2,870 4,300 8,270 13,200 1,900 344 720 1,360 2,780 4,170 8,040 12,800 2,000 335 700 1,320 2,710 4,060 7,820 12,500

10. National Fire Protection Association. Oxygen-fuel gas

Version - http://www.simpopdf.com systems for weldings and cuttings. NFPA 51. Boston. 3 3.068

4 4.026

387,000 266,000 214,000 183,000 162,000 147,000 135,000 126,000 118,000 111,000 98,700 89,400 82,300 76,500 67,800 61,500 56,500 52,600 49,400 46,600 44,300 42,200 40,500 38,900 37,400 36,200 35,000 33,900 32,900 32,000 30,400 29,000 27,800 26,700 25,700 24,800 24,000 23,300 22,600 22,000

789,000 543,000 436,000 373,000 330,000 299,000 275,000 256,000 240,000 227,000 201,000 182,000 167,800 156,100 138,400 125,400 115,300 107,300 100,700 95,100 90,300 86,200 82,500 79,300 76,400 73,700 71,400 69,200 67,200 65,400 62,100 59,200 56,700 54,500 52,500 50,700 49,000 47,600 46,200 44,900

11. National Fire Protection Association. Powered industrial trucks. NFPA 505. Boston. 12. U.S. Army Corps of Engineers manual. EM-1110-34-166. 13. Frankel, M., Facility Piping Systems Handbook, 2002, McGraw Hill, New York City The material reproduced from the NFPA is not the official and complete position of the NFPA on the referenced subject which is presented only by the standard in its entirety.

100% Propane Pressure 10 PSI (70 kPa) Pressure Loss 3.0 PSI (21 kPa)

1. American Society of Heating, Refrigerating and Air Conditioning Engineers. Handbooks. Fundamentals and Equipment Vols. Latest ed. New York. 2. American Society of Mechanical Engineers (ASME). Fuel gas piping. ASME B31.2. 3. Ingersoll-Rand Company. 1969. Compressed air and gas data. New York. 4. International Association of Plumbing and Mechanical Officials (IAPMO) Code. 5. n.a. 1994. Mechanical engineering reference manual. 9th ed. Professional Publications. 6. Mohinder Nayer ed, . 1998. Piping handbook. New York: McGraw-Hill. 7. National Fire Protection Association. Cutting and welding processes. NFPA 51B. Boston, Mass. 8. National Fire Protection Association (NFPA). LP-gases at utility gas plants. NFPA 59. Boston Mass. 9. National Fire Protection Association. National fuel gas code. NFPA 54. Boston, Mass. JANUARY/FEBRUARY 2008 

Plumbing Systems & Design  17

Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com Continuing Education from Plumbing Systems & Design Diane M. Wingard, CPD

Now Online!

The technical article you must read to complete the exam is located at www.psdmagazine.org. Just click on “Plumbing Systems & Design Continuing Education Article and Exam” at the top of the page. The following exam and application form also may be downloaded from the website. Reading the article and completing the form will allow you to apply to ASPE for CEU credit. If you earn a grade of 90 percent or higher on the test, you will be notified that you have logged 0.1 CEU, which can be applied toward CPD renewal or numerous regulatory-agency CE programs. (Please note that it is your responsibility to determine the acceptance policy of a particular agency.) CEU information will be kept on file at the ASPE office for three years. Note: In determining your answers to the CE questions, use only the material presented in the corresponding continuing education article. Using information from other materials may result in a wrong answer.

About This Issue’s Article The January/February 2008 continuing education article is “Fuel Gas Piping Systems,” Chapter 7 of Plumbing Engineering Design Handbook, Volume 2: Plumbing Systems. This chapter describes fuel gas systems on consumer sites from the property line to the final connection with the most remote gas appliance or piece of equip­ment. The system is intended to provide sufficient pressure and volume for all uses. Since natural gas (NG) is a nonrenewable energy resource, the engineer should design for its efficient use. The direct utilization of NG is preferable to the use of electrical energy when electricity is obtained from the combustion of gas or oil. However, in many areas, the gas supplier and/or governmental agencies may impose regulations that restrict the use of natural gas. You may locate this article at www.psdmagazine.org. Read the article, complete the following exam, and submit your answer sheet to the ASPE office to potentially receive 0.1 CEU.

CE Questions—“Fuel Gas Piping Systems” (PSD 144)

PSD 144

Do you find it difficult to obtain continuing education units (CEUs)? Through this special section in every issue of PS&D, ASPE can help you accumulate the CEUs required for maintaining your Certified in Plumbing Design (CPD) status.

1. The maximum allowable operating pressure for NG piping inside a building is ______. a. 0.5 psig b. determined by the authority having jurisdiction c. 5.0 psig d. no limit

7. LPG ______. a. needs to be alarmed when installed in crawl spaces b. is heavier than air c. vents shall be terminated a minimum of 3 feet horizontally from an opening d. slope on grade at the site

2. Which of the following is true when installing a pressure regulator? a. If located indoors, a relief vent may be required. b. It is provided to reduce the pressure of the incoming service to a safe operating pressure at the appliance. c. It normally is located outside before the meter. d. All of the above are true.

8. The purpose of a gas booster is ______. a. to increase the volumetric supply b. to increase the pressure c. to maintain the pressure delivered by the supplier d. none of the above

3. NG systems should be designed with an allowable pressure drop of ______. a. 0.2–0.5 inch w.c. b. 5.0 inches w.c. c. 10 psi d. none of the above 4. Which of the following is an acceptable material for fuel gas piping? a. black steel b. type L copper c. corrugated stainless steel tubing d. all of the above 5. LP gas can be stored in tanks at a pressure of ______. a.  300 psi, b.  150 psi, c.  250 psi, d.  1,000 psi 6. Which of the following is true for a fuel gas system? a. The flow rate of an appliance is equal to the consumption divided by 1,000. b. Natural gas is stored on site in large tanks. c. Gas systems always should be vented. d. Gas that is vented through regulators can always discharge into occupied space.

18  Plumbing Systems & Design 

JANUARY/FEBRUARY 2008

9. When providing a booster, ______. a. it is important to provide a regulator to protect the appliances from high pressure during times of low demand b. the equipment needs to be shut down during low demand periods c. it needs to be located outside of the building d. it is sized and provided by the gas supplier 10. Which of the following is required to size a system? a. allowable friction loss b. pipe layout c. probable demand d. all of the above 11. Which standard is referenced for fuel gas systems? a. NFPA 99 b. NFPA 101 c. NFPA 54 d. NFPA 13 12. Large LPG tanks must be located ______. a. away from the building in case of leaks b. near the appliances being served c. inside the building in a fire-rated enclosure d. underground

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Fuel Gas Piping Systems (PSD 144)

Appraisal Questions

Questions appear on page 18. Circle the answer to each question.

Q 1. Q 2. Q 3. Q 4. Q 5. Q 6. Q 7. Q 8. Q 9. Q 10. Q 11. Q 12.

A A A A A A A A A A A A

B B B B B B B B B B B B

C C C C C C C C C C C C

D D D D D D D D D D D D

1. 2. 3. 4. 5. 6.

Fuel Gas Piping Systems (PSD 144) Was the material new information for you?  ❏ Yes ❏ No Was the material presented clearly?  ❏ Yes ❏ No Was the material adequately covered?  ❏ Yes ❏ No Did the content help you achieve the stated objectives?  ❏ Yes ❏ No Did the CE questions help you identify specific ways to use ideas presented in the article?  ❏ Yes ❏ No How much time did you need to complete the CE offering (i.e., to read the article and answer the post-test questions)?___________________

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Plumbing Systems & Design  19

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PSD 132

Plumbing Design for Health Care Facilities

Continuing Education from Plumbing Systems & Design Kenneth G.Wentink, PE, CPD, and Robert D. Jackson

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CONTINUING EDUCATION

Plumbing Design for Health Care Facilities

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Introduction Health-care facilities, nursing homes, medical schools, and medical laboratories require plumbing systems that are more complex than those for most other types of building. The plumbing designer should work closely with the architect and facility staff and be involved in meetings and discussions in ­order to fully understand the plumbing requirements for any new or spe­cial medical equipment. The plumbing design must be coordinated with the civil, architectural, structural, mechanical, and electrical designs to en­sure that adequate provisions have been made for util­ity capacities, for the necessary clearances and space requirements of the piping sys­tems and related plumbing equipment, and for compliance with applicable codes. Health-care facilities may have different requirements or be ex­empt from some codes and standards, such as wa­ter and energy conservation codes and regulations regarding the physically challenged. The ­ plumbing engineer should consult with the administrative authority in order to ensure conformance with local ordinances. This chapter discusses the provisions that may be encountered by the plumbing professional in the de­sign of a health-care facility, including the following: plumbing fixtures and related equipment, the sanitary drainage system, the water-supply sys­ tem, laboratory waste and vent systems, pure-wa­ter systems, and medical-gas systems.

Plumbing Fixtures and Related Equipment Selection Process Meetings of the plumbing engineer with the architect and the facility staff to discuss the general and specific requirements regarding the plumbing fixtures and related equipment are usually held after the architect has prepared the preliminary drawings. At these meetings, the plumbing designer should assist in the selection of plumbing fixtures. Following these sessions, the plumbing designer can prepare the preliminary drawings and coordinate with the architect and facility staff the required piping systems and the plumbing fixture space requirements. In detailing the piping system spaces and plumbing fixture locations, the plumbing engineer should refer to the framing drawings. It is common for the architect to locate the piping shafts and the spaces in direct conflict with the framing; it is the plumbing designer’s re­sponsibil­ity to give the architect directions regarding the space requirements, fixture ar­rangement, and pipe-shaft size and locations. Following the meetings held with the archi­tect and hospital staff, and with the preliminary drawings available, the plumbing designer should prepare an outline specification for the plumbing fixtures and related equipment. A guide to the required

plumbing fixtures and equipment for health-care facilities is provided in Table 1 and is discussed later in this section. A review of applicable code requirements regarding the quality and types of plumbing ­fixtures is always required. In addition to the local codes, it is necessary for the plumbing engineer to refer to the special hospital code requirements published by the local hospital ­ authorities, the state hospital or health-­department authorities, the Joint Com­mission for the Accreditation of Hospitals Organi­zation (JCAHO), and the US Department of Health and Human Services. The architect may investigate these special requirements; however, the plumbing designer must be familiar with them since they contain many other applicable require­ments (in addition to the table indicating the plumbing fixtures necessary for a particular installation). General Requirements Plumbing fixtures in health-care facilities should be of dense, impervious materials having smooth sur­faces. Plumbing fixtures of vitreous china, enam­eled cast iron, and stainless steel are commonly used. Fixture brass—including faucets, traps, strain­ ers, escutcheons, stops, and supplies—should be chromium plated in a manner approved by the administrative authority. Die-cast metals should not be used. Faucets should have a laminar flow device (no alternative) of brass, Monel metal, or stainless-steel trim. Each plumbing fixture in health-care fa­cilities should be provided with individual stop valves. Each water-service main, branch main, and riser shall have valves. Access shall be provided at all valves. All submerged inlets, faucets with hose adapters, and flush valves must be equipped with approved vacuum breakers. Backflow-prevention devices shall be installed on hose bibbs, supply nozzles used for the connection of hoses or tubing, and at other locations where the potable water supply must be protected from contamination. All plumbing fixtures, faucets, piping, solder, and fluxes used in potential drinking-water areas should comply with the latest maximum lead con­tent regulations. Facilities for the physically challenged shall be in compliance with the Americans with Disabilities Act (ADA) accessibility guidelines. Fixtures for Specific Health-Care Areas General-use staff and public areas Water closets  Vitreous china, siphon-jet water closet with elongated bowl design with open-front seat, less cover, should be specified. Wall-hung water closets are preferred for easy cleaning; how­ever, floor-set models are also acceptable by most local jurisdictions. All water closets should be op­erated by watersaver flush valves. Lavatories and sinks  Vitreous china, enameled cast iron or stainless-steel lavatories and sinks should be specified. The most commonly specified size is 20 × 18 × 7½ in. deep (508 × 457.2 × 190.5 mm deep). Hands-free controls (foot or knee

Reprinted from American Society of Plumbing Engineers Data Book Volume 3: Special Plumbing Systems, Chapter 2: “Plumbing Design for Health Care Facilities.” ©2000, American Society of Plumbing Engineers. 56  Plumbing Systems & Design 

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controls) are gen­erally employed for staff use and for scrub-up sinks. In public areas, codes should be checked for the requirement of self-closing valves and/or metered valves. Stops should be provided for all supply lines. Aerators are not permitted; use laminar flow devices. Insulated and/or offset p-traps should be used for handicapped fixtures. Faucets  Valves should be operable without hands, i.e., with wrist blades or foot controls or electronically. If wrist blades are used, blade handles used by the medical and nursing staff, patients, and food handlers shall not exceed 4½ in. (11.43 cm) in length. Handles on scrub sinks and clinical sinks shall be at least 6 in. (15.24 cm) long. Water spigots used in lavatories and sinks shall have clearances adequate to avoid contaminating utensils and the contents of carafes, etc.

Infant Bathtub

Glass Washer

Immersion Bath

Arm / Leg Bath

Ice Maker

Waste Grinder

Bedpan Washer

Sitz Bath

Bathtub / Shower

Emergency Eyewash

Emergency Shower

Floor Drain, Flushing Rim

Floor Drain

Cup Sink

Plaster Sink, Plaster Trap

Sink, Triple Compartment

Utility Sink

Scrub-up Sink

Clinic Sink, Flushing Rim

Counter Sink,   Single Compartment Counter Sink,   Double Compartment

Mop Service Basin

Drinking Fountain / Water Cooler

Shower

Handwashing Lavatory

Urinal

Elongated Water Closet, FlushValve

Table 1  Recommended Plumbing Fixtures and Related Equipment Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com Medical-Care Areas l l l l l l l Public/Staff Restrooms l l l l l l Staff Lounge l l l l Patient Rooms l l l l Isolation Rooms l Nurse Stations l l Nursery l l l Formula Room l l l Intensive-Care Room l l l l Outpatient-Services Area l l l l l Emergency Rooms l l l Exam/Treatment Room l l l Labor Room l l l Janitor’s Closet l Clean Linen Holding l l Soiled Linen Holding l l l Nourishment Station l l l l l Patient Bathing Area l l l l l Critical-Care Area l Pharmacy l Surgical Scrub-up l Anesthesia Workroom l Surgical Supply Services l Surgical Cleanup Room l l l l Doctors’ Locker Room l l l Nurses’ Locker Room l l l Recovery Room l l Fracture Room l l l l Cleanup/Utility Room l Sub-Sterilizing Room l l l l l l l l l l l Medical Laboratory l l l l l l l Physical Therapy Room l l l l l l Cystoscopic Room l l l l l l l l Autopsy Room l l l l l l l l l l Dietary Services l l l l Laundry Facility l l l Family Waiting Room

Urinals  Vitreous china wall-hung urinals with flush valves. Flush valves should be equipped with stops and may be of the exposed or concealed de­sign. Showers  The shower enclo­sures and floor ­ specified by the plumbing engi­neer may be constructed of masonry and tile or of prefabricated fiberglass. Showers and tubs shall have nonslip walking surfaces. The shower valve should automatically compensate for variations in the water-supply pressure and temperature to deliver the discharge water at a set temperature that will prevent scaldings. Drinking fountains and water coolers  Drinking fountains are available in vitreous china, steel and stain­less steel. Units for exterior installations are avail­able in suitable materials. Refrigerated water coolers are available in steel or stainless steel. All of these materials are ­acceptable by most local ad­ministrative

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Plumbing Systems & Design  57

CONTINUING EDUCATION: Plumbing Design for Health Care Facilities a­ uthorities. These units may be of the surface-mounted, semiA water closet and lavatory, with a fixed or fold-away water Simpo PDF Merge and Split Unregistered Versioncloset - http://www.simpopdf.com recessed or fully-recessed design. made of stainless steel, may be considered. This concept, Chilled water for drinking purposes should be provided as well as the construc­tion of the unit, must be accepted by the between 45 and 50°F (7.2 and 10.0°C) and obtained by chill- adminis­trative authority. ing water with a refrigeration compressor. The compressor may Ward rooms  Ward rooms are infrequently found in healthbe enclosed in a cabinet with the dispenser (water cooler), care facilities, particularly in the private hospital field. These installed in a wall cavity behind a grill adjacent to the dispenser, rooms require at least 1 lavatory. This lavatory should be a minior remotely located for single or multiple dispensers. A remotely mum 20 × 18 in. (508 × 457.2 mm) and made of vitreous china installed unit for multiple dispensers (central system) should or stainless steel. The faucet should be of the gooseneck-spout have a recirculation ­system. design and provided with wrist-blade handles or hands-free Mop-service basins  Floor-mounted mop-service basins controls. can be obtained in precast or (terazzo) molded-stone units of Nurseries  The hospital’s nursery is usually provided with a various sizes. The plumbing engineer should specify the most minimum size 20 × 18 in. (508 × 457.2 mm) lava­tory with handssuitable model. Rim guards are normally provided to protect the free controls and a high gooseneck spout. An infant’s bathtub, rims from damage and wall guards are provided to pro­tect walls wall- or counter-mounted with an integral large drainboard and from splashing and chemical stains. The water-supply fixture is rinsing basin, is provided. Water-supply fittings are filler spouts usually a two-handle mixing faucet mounted on the wall with a over the basins with separate hand-valve controls. The spout wall brace, vacuum breaker, and hose adapter. and the spray are usually supplied and controlled through a Floor drains  Floor drains in toilet rooms are optional in most thermostatic mixing valve. The ultimate in maintaining a safe cases; however, there are many instances where the floor drains water temperature is a separate supply tank. are required by the applicable codes. The plumbing designer Intensive-care rooms  These rooms usually have utility sinks should give consideration to maintaining a trap seal in the floor with hands-free controls with high gooseneck spouts. A waterdrain through the use of deep-seal p-traps and/or trap prim- supply fitting equipped with a gooseneck spout and provision for ers. Floor drains shall not be installed in operating and delivery bedpan washing (either at an im­mediately adjacent water closet rooms. or at a separate bedpan washing station within an enclosure in Patient rooms  These rooms (private or semiprivate) usually the room) should be provided. Newer designs have in­cluded are provided with a toilet room containing a water closet, a lava- combination lavatory/water closets for pa­tient use, especially in tory, and a shower or bathtub. (Some hospitals use common cardiac-care units. shower and bath facilities for a group of patient rooms.) The Emergency (triage) rooms  The plumbing fixtures provided plumbing fix­tures should conform with the following recom­ in emergency rooms include a utility sink with an integral tray mendations: and a water-supply fitting with a gooseneck spout and wristThe water closet should be vitreous china, wall-hung or floor- blade handles. A vitreous china clinic sink (or a flushing-rim mounted design, with an elongated bowl. All water closets should sink), for the disposal of solids, with the water-supply fitting be operated by a flush valve. Water closets should have open- consisting of a flush valve and a separate combination faucet front seats, less cover. Bedpan lugs and bedpan washers are often with vacuum breaker mounted on the wall above the plumbing required by the local codes. Bedpan-flushing devices shall be fixture, should also be provided. provided in each inpatient toilet room; however, installation is Examination and treatment rooms  These rooms are usuoptional in psychiatric and ­alcohol-abuse units, where patients ally provided with vitreous china or stainless-steel lavatories. are ambulatory. The water-sup­ply fitting should be a hands-free valve equipped The lavatory should be a minimum of 20 × 18 × 7½ in. (508 × with a high, rigid, gooseneck spout. For a particular examina457.2 × 190.5 mm) deep. Lavatories should be installed at least 34 tion room or a group of patient rooms, an adjacent toilet room is in. (863.6 mm) above the floor. Mixing faucets should be of the provided containing a specimen-type water closet for inserting gooseneck-spout design and provided with wrist-blade handles, a specimen-collecting bedpan. The toilet room also requires a electronic, or hands-free controls. lavatory and a water supply with wrist-blade handles or handsThe shower is usually constructed of masonry and tile, acrylics, free controls and with a gooseneck spout. or fiberglass. The shower bases should be nonslip surfaces. The Physical-therapy treatment rooms  The plumbing fixtures shower valve should automatically compensate for ­variations in and related equipment for these rooms usually include hydrothe water-supply pressure and temperature to de­liver the dis- therapy immer­sion baths and leg, hip, and arm baths. These units charge water at a set temperature that will prevent scalding. Grab are generally furnished with electric-motor-driven whirlpool bars, located within the shower enclosure, are usually required by equipment. The water is introduced into the stainless-steel tank the local codes. The plumbing engineer should always check with enclosure by means of a thermostatic control valve to prevent the local administrative author­ity regarding approved designs. scalding, usu­ally wall mounted adjacent to the bath for opera­ Bathtubs can be constructed of cast iron, fiberglass, acryl- tion by a hospital attendant. The water supply should be sized ics, or steel. Faucets should be as they are for showers. Shower to minimize tub fill time. The im­mersion baths are usually proheads may be of the stationary design, but in many locations vided with overhead hoists and canvas slings for facilitating the hand-held showers are required. lifting in and out of the bath of a completely immobile pa­tient. A lavatory intended for use by doctors, nurses, and other hos- A hydrotherapy shower is sometimes re­quired. These showers pital staff is sometimes re­quired by the local ordinances. This usually consist of multiple shower heads, sometimes as many particular lava­tory is usually located on the wall near the door as 12 to 16, ver­tically mounted in order to direct the streams of with a gooseneck spout and hands-free controls. water at a standing patient by means of a so­phisticated control console operated by a hospital attendant. 58  Plumbing Systems & Design 

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Cystoscopic rooms  Among the various plumbing fixtures breaker. A bedpan washer should also be installed next to the Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com required in cystoscopic rooms are the following: wall-mounted clinical sink. The type of bedpan washer will depend upon the clinic sinks equipped with flush valves and bedpan washer and hospital’s method of washing and sterilizing bedpans. combination faucets; lavatories pro­vided with water-supply fitBirthing rooms  Each birthing room should include a vitreous tings and gooseneck spouts; and, in a separate adjacent room, china lavatory provided with a gooseneck spout and wrist-blade specimen water closet and a lavatory. If a floor drain is installed handles or hands-free controls. Each la­bor room should have in cystoscopy, it shall contain a nonsplash, horizontal-flow access to a water closet and a lavatory. A shower should be proflushing bowl beneath the drain plate. vided for the la­bor-room patients. The shower controls, includAutopsy room  The autopsy room table is usually provided ing pressure/thermostatic mixing valve, should be lo­cated outwith cold and hot-water supplies, with a vacuum breaker or side the wet area for use by the hospital’s nursing staff. A water backflow preventer, and a waste line. It is nec­essary that the closet should be accessible to the shower facility. plumbing designer consult with the table manufacturer and Anesthesia workrooms  This area is designed for the cleanthe administrative au­thority regarding the requirements of the ing, testing, and storing of the anesthesia equipment and should autopsy room table. Drain systems for autopsy tables shall be contain a work counter-mounted sink. The sink is usually made designed to positively avoid splatter or overflow onto floors or of stainless steel. The faucet should be of the gooseneck spout back siphonage and for easy cleaning and trap flushing. The design with wrist-blade handles and/or hands-free ­controls. autopsy room is also usually equipped with a stainless steel or Fracture rooms  A large-size, vitreous china plaster, work vitreous china sink with hands-free fittings, a clinic sink and a sink equipped with a combination water-supply fitting and “blood” type floor drain. Adjacent to the autopsy room a water wrist-blade handles, gooseneck spout, and plas­ter trap on the closet and a shower room are usu­ally provided. Many autopsy waste line (located for convenient access) should be provided. rooms are equipped with waste-disposal units integral with the Kitchens and Laundries sink. The plumbing designer should consult with the ar­chitect and the Nourishment stations  These stations are usually provided on food-service consultant for kitchen equipment utility requireeach patient room floor near the nurse station for serving nour­ ments. Typically, one of these people should provide location ishment between regularly scheduled meals. A sink, equipped and rough-in drawings for all kitchen equipment. Normally for hand washing with hands-free controls, an icemaker, and a required are toilet fixtures for kitchen staff, food preparation hot-water dispenser (optional) to provide for the patient’s ser- sinks, hand-wash sinks, pot and pan-wash sinks, dishwashers, vice and treatment should be provided. glassware washers, floor drains, hose bibbs, mixing stations, Pharmacy and drug rooms  The plumbing fixtures for these and grease in­terceptors. Kitchen grease traps shall be located rooms include medicine and solution sinks. These units can be and arranged to permit easy access without the necessity of counter-type or made of stainless steel or vitreous china with a entering food preparation or storage areas. Grease traps shall be mixing faucet and a swing spout. A solids interceptor should be of the capacity required and shall be accessible from outside the considered for com­pounding areas. building without the necessity of interrupting any services. In Operating-room areas  No plumbing fixtures or floor drains dietary areas, floor drains and/or floor sinks shall be of a type are required in the hospital’s operating room. However, the that can be easily cleaned by the removal of a cover. Provide scrubbing station located adjacent to the operating room should floor drains or floor sinks at all “wet” equipment (such as ice have at least two scrub sinks, usually made of vitreous china or machines) and as required for the wet cleaning of floors. The stainless steel, fur­nished with hands-free water-supply fittings, location of floor drains and floor sinks shall be coordinated to and equipped with gooseneck spouts. These sinks should be avoid conditions where the location of equipment makes the large and deep enough to allow scrub­bing of hands and arms to removal of covers for cleaning difficult. Also, the kitchen equipthe elbow. A soiled workroom, designed for the exclusive use of ment may re­quire other utility services, such as fuel gas, steam, the hospital’s surgical staff, should be located near the operat- and condensate. ing room area. This workroom should con­tain a vitreous china, When considering laundry facilities, the plumb­ing designer flushing-rim clinical sink, for the disposal of solids, with the should consult with the ­architect and the laundry consultant for water-supply fittings consisting of a flush-valve bedpan washer equipment utility requirements. These facilities require largeand a separate faucet mounted on the wall above the fixture and capacity washers/extractors and dryers, presses, and folding hand-washing ­facilities consisting of a vit­reous china or stain- machines. Waste-water drainage may require lint intercepters. less-steel lavatory with a goose­neck spout and equipped with These facilities are prime candidates for heat and water-recovwrist-blade handles. Substerile rooms should be equipped with ery sys­tems. Also, the laundry equipment may require other an in­strument sterilizer and general-­purpose sink. The plumbing utility services, such as fuel gas, steam, and condensate. designer should consult with the instru­ment sterilizer manufacThe hot-water temperatures required for these areas (100, turer for any special ­requirements for the equipment. The gen- 140, and 180°F [38, 60, and 82°C]) are discussed in Data Book, eral-purpose sink can be countertop-mounted and equipped Volume 2, Chapter 6, “Domestic Water-Heating Systems.” with a hands-free water-supply fitting with a goose­neck spout. Recovery rooms  The rooms for the post-anesthesia recovery Laboratory Rooms of surgical patients should include a hand-washing fa­cility, such Laboratory sinks  Most of the time architects provide the counas a vitreous china or stainless-steel lavatory equipped with a tertops and sinks, usually made of epoxy or other acid-resistant gooseneck spout and wrist-blade handles; and a vitreous china, materials, in their specifications. However, occasionally the flushing-rim, clini­cal sink for the disposal of solids, with the plumbing designer is responsible for selecting the laboratory water-supply fitting consisting of a flush valve and a separate sinks. Laboratory sinks should be acid resistant and can be of faucet mounted on the wall above the fix­ture with a vacuum stainless steel, stone, or plastic. Laboratory and cup sinks are MARCH/APRIL 2006 

Plumbing Systems & Design  59

CONTINUING EDUCATION: Plumbing Design for Health Care Facilities currently available in epoxy resin, composition stone, natural face and body-spray units. The latest edition of the ANSI stanSimpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com stone, ceramic or vitreous china, polyester fiberglass, plastic, dard for emergency eyewash and shower equipment and local stainless steel, and lead. The lead type is not recommended codes should be consulted. A tempered water supply should be where mercury, nitric, hydrochloric or acetic acids are used. considered. Often these laboratory sinks are furnished with the labora­tory Laboratory service outlets for gas, air, nitrogen, vacuum, and equipment as rectangular sinks or cup sinks mounted in, or other required gas services may be furnished as part of the related as part of, counter tops and as cup sinks in fume hoods. Rules equipment under another contract or may be included in the of thumb that can be used when the sink sizes are not recom- plumb­ing work. In either case, the plumbing designer should mended by the laboratory staff are as follows: be knowledgeable about the various types of service outlet cur­ rently available, the materials (or construction), and the usage 1. Sinks with a compartment size of 12 × 16 × 7.5 in. (304.8 × (diversity). It is desirable to have bodies of cast red brass, brass 406.4 × 190.5 mm) for general laboratory work areas. forgings, or brass bar stock that are specially designed for labo­ 2. Sinks with a compartment size of 18 × 24 × 10 in. (457.2 × ratory use and, where possible, made by one manufac­turer. 609.6 × 254 mm) for classroom work and tests. Handles should be made of forged brass and provided with 3. Sinks with a compartment size of 24 × 36 × 12 in. (609 × screw-in-type, color-coded index discs. All outlets should be 914.4 × 304.8 mm) for washing large equipment. properly labeled. Ser­rated tips should be machined from solid The sink itself and sink outlet should be chemically resistant, stock or forgings. The service fittings should be chrome plated a minimum of 316 stainless steel, and so designed that a stopper over nickel plating or copper plating. The outlets in fume hoods or an overflow can be inserted and removed easily. The outlet should have an acid and solvent-resistant, plastic coating over should be removable and have a strainer to intercept any mate- the chrome-plated surface or be made of acid-resistant materirials that might cause a stoppage in the line. Unless an indus- als. Nonmetallic fittings are also available. trial water system is employed that isolates the laboratory water systems from the potable water system, via a central backflow- Special Equipment prevention device, all faucets should be provided with vacuum Dialysis machines  Dialysis machines require a funnel drain or breakers. Supply fittings for distilled or deionized water are usu- floor sink and cold-water hose bibb with vacuum breaker. Heart-and-lung machines  Heart-and-lung machines also ally either virgin plastic or tin lined and, where central systems require a funnel-type drain. If the apparatus is located in the are used, should be able to withstand higher pressures. Many oper­ating room, an indirect waste is required. fitting types, especially PVC, can handle pressures up to but not Electron microscopes  Electron microscopes require filtered, exceeding 50 psig (344.74 kPa). In these cases, pressure regulabackflow-protected, cold water or circulated chilled water. tion is required. Stills  Stills for producing distilled water require cold water Cup sinks  These are small, 3 × 6 in., 3 × 9 in., or 3 × 11 in. (76.2 with a vacuum breaker and floor sinks or funnel drains. × 152.4 mm, 76.2 × 228.6 mm, or 76.6 × 279.4 mm) oval sinks Sterilizers  Sterilizers require an acid-resistant floor sink or for receiving chemicals, nor­mally from a condensate or a supply fun­nel drains, a backflow-protected water supply and someline. They are designed to fit into the center section be­tween the times steam and condensate connections. table tops; against a wall; or on raised, back ledges. These sinks Film-processing equipment  Film-processing (x-ray) areas are also common in fume hoods. require an acid-resistant floor sink or funnel drains for indirect Laboratory glass washers are usually included, either furwaste; and a hot, cold and/or tempered water supply operatnished by the laboratory equipment sup­plier or selected by the plumbing designer. Automatic washers are available. In addi- ing be­tween 40 and 90°F (4.4 and 32.2°C). Drain piping for any tion to waste or indirect waste ser­vices, these units re­quire hot photo-developing equipment should not be brass or copper. water­ (usually 140°F [60°C] boosted to 180°F [82°C]) internal Polypropylene, high-silica, cast-iron, corrosion-resistant piping to the unit, distilled or deion­ized water, and compressed air. and drains should be used. Silver recovery and neutral­ization Manual-type glass bottle and tube washers may also be required may be required; consult with the local authority. Dental equipment  Dental areas should include console serin these rooms. Tube washers may have manifold-type supply vices (wa­ter, air, medical gas, nitrous oxide and waste); and for fittings using cold water only. The mani­folds can be fitted with a oral surgery a separate surgical vacuum system should be pronumber of individually serrated tip outlets provided with sepavided. rate controls and vacuum breakers. The plumbing engineer should always consult with the equipEmergency showers should be included through­out and ment manufacturer’s authorized rep­resentative and the local located in the adjacent corridors or at the door exits. The showadministrative authority, in order to determine the equipment ers must be accessible, re­quire no more than 10 s to reach, and requirements and the acceptability under the jurisdiction’s be within a travel distance of no greater than 100 ft (30.5 m) from appli­cable codes, during the preliminary design. the hazard rooms. The shower head is a del­uge-type shower with a 1-in. (25.4 mm) nominal cold water, stay-open design, supply valve operated by a hanging pull rod, or a chain and pull ring, or a pull chain secured to the wall. A floor drain may be provided, if required. If floor drains are provided, trap primers should be incorporated. Eye and face-wash fountains are also required. These are wall or counter-mounted units with a foot-pedal or wrist-bladehandle-operated, water-supply fixture; double side-mounted, full face-wash outlets; or deck-mounted, hand-held (with hose) 60  Plumbing Systems & Design 

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Drainage Systems for Laboratories In addition to the conventional sanitary drainage systems (those found in most buildings), special sani­tary drainage systems may be required in health-care facilities. Insofar as possible, drainage piping shall not be installed within the ceiling or exposed in ­ operating or delivery rooms, nurseries, food-preparation cen­ters, food-serving facilities, food-storage areas, cen­tral services, electronic data-processing areas, electric closets, and other sensitive areas. Where exposed, PSDMAGAZINE.ORG

overhead drain piping in these areas is unavoidable, special pro- sensors can be installed be­tween the pipe walls that can pinpoint Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com visions shall be made to protect the space below from leakage, the original leak location. The latter could reduce the amount of condensa­tion, or dust ­particles. excavation or exploration required to find the leak. Acid-Waste Drainage Systems Acid-waste drainage systems require special de­sign criteria because the corrosive solutions de­mand special handling from the actual work area to an approved point at which such acid waste (and fumes) can be safely neutralized and discharged. The plumbing engineer must exercise extreme care in this regard. Acid-resistant waste and vent systems are neces­sary where acids with a pH lower than 6.5 or alkalis with a pH greater than 8.5 are present. These special conditions are commonly encountered in hospitals, research facilities, and laboratories. Since acid fumes are often more corrosive than the liquid ac­ids themselves, proper drainage and venting is imperative. Nationally recognized standards for sanitary sys­tems that handle acid wastes and other re­agents are set forth in model plumbing codes; such systems are often further regulated by local building and safety or health department requirements. For these reasons, the plumbing engineer should check for all special design conditions that may affect the project. Strong acids and caustics may enter the sanitary-waste system in large quantities and at elevated temperatures. These substances can mix to form highly corrosive and even ­ dangerous compounds. Common laboratory procedures encourage neutral­ ization or flushing with copious amounts of water in order to dilute and cool these chemicals to more acceptable levels. However, the plumbing engineer must protect the acid-waste system by designing for the maximum hazard conditions that might be brought about by any human error, poor housekeeping, or acci­ dental spillage. Corrosive-Waste Systems Materials Borosilicate glass pipe  Sizes range from 1½ to 6-in. (40 to 150mm) pipe. Mechanical joint, flame resistance, and clear pipe allow for easy visual inspection and high corrosion resistance. High-silicon cast iron  Sizes range from 1½ to 4-in. (40 to 100-mm) pipe. Mechanical joint, flame resistance, high corrosion resistance, fire stop at floor penetration equal to cast iron. More fragile and heavier than standard-weight cast iron and easier to break in the field. Excellent application for moderate to high-budget project. Polypropylene  Sizes range from 1½ to 6-in. (40 to 150-mm) pipe. Mechanical or heat-fusion joints. Mechanical joints are not recommended for straight runs or sizes over 2 in. (50 mm); they should be used to access p-traps or other maintenance areas. Flame resistant and acceptable within most jurisdictions (meets 25/50 flame/smoke criteria), newer UL listed methods are close to glass in cost. Consult local authority for approval. Light weight and easy to install. Good application for moderate acids at low temperatures. Must be installed by qualified technicians. Inexpensive com­pared to borosilicate glass or high-silicone cast iron. Double-containment waste piping  With ever-in­creasing pressure to protect our environment, double-containment (pipe within a pipe) systems have become a consideration. Usually made of polypro­pylene inside and PVC or fiberglass outside. Sys­tems should be pitched toward a containment vault for collection of leaking fluid. Alarm systems can be employed to detect leaks at the collection basin or, if the budget and the nature of the liquid allow,

Discharge to Sewers Many local jurisdictions require that the building’s sanitarysewer discharge be at an acceptable pH level before it can be admitted into a sanitary-sewage system. In such cases, it is recommended that a clarifying (or neutralizing) tank be added to the sanitary system. Small ceramic or polypro­pylene clarifiers with limestone can be located under casework for low flow rates; however, suffi­cient space must be allowed above the unit for ser­vicing. Unless properly maintained and monitored, this type of system can be rendered ineffective. Large clarifiers and neutralizers may be regu­lated by the requirements of a local industrial-waste department. Acidic-Waste Neutralization The lower the pH number, the Table 2 Acidic-Waste Neutralization higher the concen­tration of acid. Tank Sizing Table Discharging high concentrations Number of gal (L) Lab Sinks of acid into a public sewer may 2 5 (18.9) cause considerable corrosion to 4 15 (56.8) piping systems and eventual fail8 30 (113.6) ure. Most local authorities do not 16 55 (208.2) allow acid wastes to be discharged 22 75 (283.9) to a public sewer without some 27 90 (340.7) form of treatment. 30 108 (408.8) 40 150 (567.8) The neutralization of acidic 50 175 (662.4) wastes is generally and most eco60 200 (757.0) nomically dealt with through an 75 275 (1,040.9) acid-neu­tralization tank. An acid110 360 (1,362.6) neutralization tank may be con150 500 (1,898.5) structed of polyethylene, molded 175 550 (2,081.8) stone, stain­less steel, or another 200 650 (2,460.3) 300 1200 (4,542) acid-resistant material. Tanks are 500 2000 (7,570) sized to provide a dwell time of 2 to 600 3000 (11,355) 3 h (re­fer to Table 2). Limestone or Note: For commercial and industrial marble chips fill the interior of the laboratories, the number of lab sinks should be tank, helping to neutralize incom- multiplied by a 0.5 use factor. ing acid wastes. Chips may be 1 to 3 in. (25.4 to 76.2 mm) in diameter and should have a calcium carbonate con­tent in excess of 90%. A discharge pH sensor and routine maintenance schedule must be provided to ensure that the system operates properly. Acid-Waste Solids Interceptor As with many sewer systems, it is impossible to control all materials discarded to the drain system. Unless building effluent is controlled, many un­wanted items, such as glass fragments and needles, will find their way to the neutralization tank, thereby clogging the limestone or marble chips. When this happens, replacement of the chips is re­quired. One way to prolong chip life is to install an acid-waste solids interceptor immediately upstream of the neutralization tank, although maintenance of the interceptor may have to be done quite ­frequently. Acid-Waste Metering Detail Many local authorities require some means of sampling effluent from industrial, institutional, and laboratory buildings. An example of a device used for this purpose is a sampling manhole. This unit is installed as the last component be­fore neutralMARCH/APRIL 2006 

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CONTINUING EDUCATION: Plumbing Design for Health Care Facilities ized acidic wastes or treated industrial wastes are discharged Water-Supply Systems Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com to a public sewer. There are as many types of sampling point A domestic-water supply of adequate flow volume and presrequirements as there are municipal sewer authorities. Consult sure must be provided for all the plumb­ing fixtures and related local code authorities for individual requirements. equipment. Systems typi­cally encountered in these types of facility are as follows: Traps for Laboratory Sinks The trap is recognized by most plumbing engineers as the weak- 1. Potable-water systems. A. Cold water. est link in the acid-waste system. The trap must be acid resisB. Hot water (at various temperatures). tant. If strong acids and solvents collect in an ordinary trap, failC. Chilled water. ure of the system will occur. Three types of acid-waste traps are D. Controlled-temperature (tempered) ­water. currently in common use: p-traps, drum traps, and centrifugal E. Hot water recirculation. drum traps. (Running and s-traps are not allowed by many local 2. Non-potable water systems. plumbing codes because of the po­tential for trap siphoning.) 1. P-traps maintain a water seal to keep the acid fumes from 3. Pure-water systems. reentering the work area. A. Distilled water. 2. Drum traps provide a greater water seal and are fre­quently B. Deionized (or demineralized) water. used to separate either precious metals or other matter C. Reverse osmosis. before they enter the drainage system to become lost or Health-care facilities should have dual domestic-water sercause a stoppage in the sink. Drum traps with removable vices installed to ensure provision of an uninterrupted supply bottoms should be installed high enough above the floor of water. The design should consider water-conservation profor servicing. P-traps, including some of the simple drum visions. Many lo­cal jurisdictions have strict water-conservatraps, can easily be back-siphoned if the head pressures are tion laws in effect. Water recycling may be a consideration for extreme. use in landscaping, etc., depending on local code and health3. Centrifugal drum traps are designed to prevent backdepartment regulations. (For more information, see Data Book, siphonage conditions. Volume 2, Chapter 2, “Gray-Water Systems.”) Water supply through a tank (suction or gravity type) should Laboratory Waste and Vent Piping be considered by the plumbing engi­neer when the water-supply Sizing for under-table waste and vent piping, as de­termined by source may be subjected to some unusual demands, pressure the local plumbing codes, should be suitable for the installation fluctuations, and/or interruptions that will cause a sudden excesand allow for future ex­pansion. Approved corrosion-resistant sive draw and pressure loss on the main sys­tem. The tank will act piping should be used for vent piping as well, since acid fumes as a buffer. Inadequate flow and pressure require the de­sign of a are also highly corrosive. Space is often lim­ited under tables water-storage tank and/or a booster pump for the water-supply and in vent areas. The space-saving features of mechanical joint system. Excessive pressure fluctuations are highly unde­sirable in ­piping have proven to be useful in many installations. medical-research laboratories. When such facilities are supplied Note: When fusion-joint, plastic piping systems are used, from street pressure systems, the engineer may provide pressuremechanical joints should be installed at traps and trap arms for reducing valves on the branch lines, or a gravity tank system. maintenance ­reasons. Use of diversity factors for sizing the water sys­tems must be Special island (or loop) venting is frequently used when cabicarefully analyzed by the designer. Medical-school laboratory nets or work tables are located in the cen­ter of the laboratory classrooms have higher rates of simultaneous use than most area. ­research laboratories. Emergency rooms, out-patient treatment The transportating of acid waste, above and below the ground, rooms, and operating-room wash-up areas also have high rates must be done in approved, corrosion-resistant piping (acceptof simultaneous use. able to the local administrative au­thority) and continued to a Extreme care must be taken in order to ­protect the potablesuitable point where neutralization can occur or where suffiwater supply from contamination (cross connection). When cient water or chemicals can be introduced to bring the pH level an industrial (non-potable) system is not present, the engineer of the so­lution to an acceptable level. ­Acids below a pH of 6.5 should specify the appropriate type of vacuum breakers (neces­ normally may not be admitted into the sanitary-sewage system sary for each fixture below the rim connection), hose-end outlet, or emitted into surrounding soil, polluting (or degenerating) and an aspirator or other serrated-tip labo­ratory outlet, whether local ground water. High-silicon cast iron with hub-and-spigot they are required by the lo­cal plumbing regulations or not. The joints may be caulked with teflon, or neoprene gaskets may be vacuum breakers provided for fume-hood outlets should be used for sealing. This type of joint will allow flexibility and, when located outside the hood. Built-in (or integral) vacuum breakers properly supported, is par­ticularly recommended on the horiare preferred to the hose-end type units. zontal runs where the expansion and contraction of pipe from heated chemicals can cause leaking. Plumbing codes require Potable-Water Systems proper bed preparation and careful backfilling on all below- Cold water should be provided at all required lo­cations. The hot water should be generated with the most economical heating ground piping, particularly plastic piping. The plumbing engineer should check the manu­facturer’s rec- medium ­available. With today’s technology, several reliable methods can be ommendations in order to evaluate the severity of the chemicals to be used. A listing of the common chemicals and how these applied to produce and store domestic hot water. Refer to substances react with the various materials must be considered ASPE’s Domestic Water Heating De­sign Manual and ASPE Data Book Volume 2, Chapter 6, “Domestic Water-Heating Systems,” by the designer. 62  Plumbing Systems & Design 

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for in-depth explanations of design methods for hot-water sys- are usually required in the hospital’s pharmacy, central-supply Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com tems and a discussion of the various hot-water systems avail- room, laboratories, and laboratory-glassware washing facilities. able. When large “dump” loads are anticipated (kitchens and There are two basic types of pure water available in hospital laundries), storage of hot water is recommended. Hot-water facilities: bio-pure water (water containing no bugs or other usage in patient-care areas requires consideration of water tem- life forms) and high-pu­rity water (pure water that is free from perature and bacterial growth. The most com­mon water-borne minerals, dissolved gases, and most particulate matters). Refer bacterium of concern is Legionella pneumophila. to ASPE Data Book, Volume 2, Chapter 11, “Water Treatment, Recommended water temperatures for specific applications Conditioning, and Purification,” for additional information on are as follows: water purity. Water purity is most easily measured as specific resistance (in 1. Patient-care and hospital general usage ­requires water temohm-centimeter [Ω-cm] units) or expressed as parts per milperatures between 105 and 120°F (40.5 and 49°C), except where the ­local plumbing codes or other regulations require lion (ppm) of an ionized salt (NaCl). The theoretical maximum specific resis­tance of the pure water is given as 18.3 MΩ-cm at other maxi­mum temperatures. Hot‑water distribution 77°F (25°C). This water purity is difficult to produce, store, and systems serving patient-care areas shall be under constant distribute. This water is “starved” for impurities and constantly recirculation to provide continuous hot water at each attempts to absorb contaminants. It is important to note that hot-water outlet. The temperature of hot water for bathing the specific resistance of the pure water is indica­tive only of its fixtures and hand-wash lavatories shall be appropriate for mineral contents and in no way shows the level of bacterial, comfortable use but shall not exceed 120°F (49°C). pyrogenic, or organic contamination. An independent labora2. Kitchen general usage requires 140°F (60°C) to fix­tures, tory analysis should be made, whenever possible. except the dishwasher’s sanitizing cycle. The sanitizing The five basic methods of producing pure water are as follows: cycle requires 180 to 190°F (82 to 88°C) to the dishwasher, distillation, demineral­ization, re­verse osmosis, filtration, and with 180°F (82°C) minimum required at the dish rack. recirculation. Depend­ing upon the type of pure water required (Consult lo­cal health-department regulations.) Also, some in the facility, one (or more) of these methods will be needed. health departments set a maximum temperature of 105 to Under certain conditions, a combination of several methods 120°F (40.5 to 49°C) for hand-washing lavatories. may be necessary. 3. Laundry facilities should be supplied with two water tem1. Distillation produces bio-pure water, which is completely peratures, 140°F (60°C) for general usage and 160°F (71°C) free from particulate matters, minerals, organics, bacteminimum to washers/extractors for laundry sterilizations. ria, pyrogens, and most of the dis­solved gases and has a Providing a point-of-use booster heater for high-temperature minimum specific resistance of 300,000 Ω. An important applications instead of a ­central wa­ter-heater system is often more consideration in this case is that the water is free from baceconomical. teria and pyrogen contamination, which is dangerous to A closed system of chilled water may be required for the coolthe patients, particularly where intravenous solu­tions are ing of electron microscopes and x-ray tubes and should be of a concerned. Bio-pure water is needed in the hospital’s pharrecirculating design. macy, central-supply room, and other areas where there Film processors operate at a normal range of 40 to 30°F (4.4 may be patient contact. Bio-pure water may also be desired to –1.1°C). Some models do require controlled water temperain cer­tain specific laboratories at the owner’s request and as ture for film processing. Depending on the quality of the water a final rinse in the laboratory’s glassware washer. supply, a 5 to 75-µ filter may be required. The typical water-distillation apparatus consists of an A thermometer should also be provided on the outlets of evaporator section, an internal baffle system, a waterwater heaters and thermostatically con­trolled valves. A pressure cooled condenser, and a storage tank. The best material for regulator, gauge, and flow meter may also be desired on the inlet its construction is a pure block-tin coating for both the still side of pressure-sensitive equipment. and the tank. The heat sources, in order of preference based Non-Potable Water Systems on economy and maintenance, are as follows: steam, gas, Non-potable water systems are usually ­ employed in areas and electricity. The still may be operated manually or autohaving multiple water ­requirements that could contaminate the matically. The distilled water may be distributed from the potable-water ­supply. Areas in this category include: flushingstorage tank by gravity or by a pump. A drain is required for rim floor drains in animal rooms, all outlets in au­topsy rooms, system drainage and flushing. On stills larger than 50 gph outlets in isolation rooms, and all out­lets in infectious-disease (189.3 L/h), a cooling tower should be considered for the and tissue-culture rooms. These systems normally use reducedcondenser water. pressure-type backflow preventers as the means to protect the 2. Demineralization, sometimes called “deionization,” propotable-water ­ system. Hot water, when required, may be produces high-purity water that is completely free from minervided by a separate generator supplied from the non-potable als, most particulate matters, and dissolved gases. Dependwater system. ing upon the equipment used, it can have a specific resisPure-Water Systems tance ranging from 50,000 Ω to nearly 18 MΩ. However, it “Pure water” is the term generally used to ­describe water that could be contaminated with bacteria, pyrogens, and organis free from particulate matters, miner­als (soluble ions), bacteics (these ­contaminants may be produced inside the deminria, pyrogens, ­organic mat­ters, and dissolved gases, which freeralizer itself ). Demineralized water can be employed in quently exist in the potable water supply. Pure-water sys­tems MARCH/APRIL 2006 

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CONTINUING EDUCATION: Plumbing Design for Health Care Facilities most laboratories, the laboratory’s glass-washing facilities 2. Clean joining methods—avoid solvents, lubri­cants, and Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com (as a final rinse) and as the pre-treatment for still feedwater. crevices. The typical demineralizer apparatus consists of either 3. No material erosion—must not flake off particles. a two-bed deionizing unit (with a resistivity range of 4. Material should not enhance microorganism growth. 50,000 Ω to 1 MΩ) or a mixed-bed deionizing unit (with a 5. Material should be smooth, crack and crevice-free, and resistivity range of 1 to 18 MΩ). The columns are of an inert nonporous. material filled with a synthetic resin, which re­moves the 6. Avoid dead legs—system should have continuous flow minerals by an ionization process. Since the unit operates through piping. on pressure, a storage tank is not required or recommended 7. Provide chemical cleaning connections. (as bacteria will grow in it). A demineralizer must be chemically re­generated periodically, and during that regeneration 8. Install (slope) with future cleaning and disinfec­tion in mind. time no pure water is produced. If a continuous supply of pure water is needed, a backup unit should be considered A wide variety of piping materials are available on the market by the engineer, as the regeneration pro­cess takes several today. Their properties and cost cover a wide range. hours. The regeneration process can be done manually or Common pure-water materials automatically. An atmospheric, chemical-resistant drain is 1. Stainless steel—various grades (304L & 316L). required. High-flow water is required for backwash during 2. Aluminum. the regen­eration. 3. Tin-lined copper. 3. Reverse osmosis (RO) produces a high-­purity water that does 4. Glass or glass-lined pipe. not have the high resistivity of dem­ineralized water and is 5. PVC/CPVC—Polyvinyl chloride/chlorinated polyvinyl chlonot bio-pure. Under certain conditions an RO process can ride. offer economic ad­vantages over demineralized water. In areas that have high mineral contents, an RO process can be 6. Polypropylene. used as a pre-treatment for a demineralizer or still. 7. Polyethylene. There are several types of reverse osmosis units currently 8. ABS—Acrylonitrile butadiene styrene. available. Units consist of a semiperme­able membrane, in 9. PVDF—Polyvinylidene fluoride. either a roll form or a tube con­taining numerous hollow Metal pipe  Aluminum, tin-lined copper, and stainless-steel fibers. The water is then forced through the semipermeable pipe have all been used in pure-water treatment sys­tems. Tinmembrane un­der high pressure. A drain is required with lined pipe was once the material of choice in ultra-pure water these systems. systems. However, it does leach tin and eventually copper into Note: Chlorine must be removed from the water, otherwise the pro­cess fluid. Methods of joining tin-lined pipe can also it will destroy the RO membrane. leave non-smooth joints with crevices. Aluminum pipe has also been used in pure-wa­ter systems. 4. Filtration   Various types of filter are currently available Pure water creates an oxide layer inside the pipe that continuto remove the particulate matters from the water as a preally erodes, producing particles and aluminum in the water. treatment. Depending upon the type of filter, a drain may Stainless steel has been used extensively in high-purity water be required. Bacteria may be eliminated through ultraviolet systems. It can be joined with threads, butt welded, flanged, or sterilization. manufactured with sanitary-type connection ends. Because 5. Recirculation   High-purity systems should be pro­vided it can use sanitary joints and can handle steam sterilizing, the with a circulation loop. Dead-end legs should be avoided sanitary-type connection method has been used in many pharwhenever possible or limited to 50 in. (1.52 m). System design velocity should be between 4 and 7 fps (1.22 and 2.13 maceutical applications. However, experience has shown that even the best grades of stainless steel, with the best joints, still m/s) so as to discourage bacteria accum­ulation and provide leach material from the metal that can cause problems in crititransport back to an ultraviolet sterilizer and fil­tration for cal water ­systems. ­removal. Glass or glass-lined pipe  Glass piping has been used in some Pure-water piping system materials  Water-treatment special labora­tory applications but, because it is fragile and system components are selected to remove various impurities does leach material into the water, it is not generally considered from the influent water. Connecting various system ­components applicable for high-purity water sys­tems. together involves the use of interconnecting piping. The use of PVC  PVC pipe has been used on equipment and in pip­ing this piping should not contribute to adding any such impurity systems successfully for many years. Advances in technology, back into the treated water. especially in electronics, have now raised questions about the Selection of piping-system materials is de­ter­mined by the “true purity” or inert­ness of PVC. application intended, the availability of the material, and the PVC pipe contains color pigments, plasticizers, stabilizers, cost of the material. Pure-water applications, such as ­exist in the and antioxidants that can all leach out of the plastic and into health-care industry, can be very sensitive to the piping meth- ultra-pure water. Remember that 18,000,000-Ω quality water is ods selected. highly aggres­sive. When PVC pipe is made (extruded), bubbles General pure-water piping requirements include: of air exist, some of which are covered over with a thin film of 1. Inert materials—must not leach contamination into water. PVC on the interior walls of the pipe. As the pipe ages, these thin coverings wear away, exposing small holes which then serve as 64  Plumbing Systems & Design 

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debris-collecting or microorganism-breeding sites, not to menABS has some of the same contamination leach problems as Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com tion the contribution of PVC particles and the potential release PVC. In its manufacture, pigment dis­persants, surfactants, styof organic dispersants, stabilizers, etc., originally trapped in rene, and other additives are used that can leach into water over these bubbles (holes). time. Hydrogen peroxide (used for system cleaning) will also Joints, either solvent welded or threaded, can leave crevices attack ABS plastic. for the accumulation of particles and bacteria. Solvents from the PVDF  There are numerous types of high-molecular-weight weld can also leach into the water. fluorocarbon pipes on the market, SYGEF, KYNAR, and HALAR, Premium grades of PVC, which re­portedly have fewer leach- to name a few. Polyvinylidene fluoride (PVDF) plastic can be ables than standard PVC, are now being marketed. extruded without the use of additives that can leach out later. CPVC is a special high-temperature PVC that has similar ero- The different polymerization tech­niques used by each manusion and leachable characteristics. facturer can produce slightly different properties. Polypropylene  Polypropylene is a very inert, strong piping PVDF pipe is currently considered to be the state of the art mate­rial. However, in the manufacture of the pipe anti­oxidants in pure-water piping systems. It has ex­ceptional chemical resisand other additives are used to control embrittlement. These tance; temperature range, –40 to 320°F (–40 to 160°C); impact additives are potential sources of contaminants that can leach strength; resis­tance to UV degradation; abrasion resistance; and into the water. However, a virgin material with no leachable smooth, clean, inside surfaces that discourage the collection of prod­ucts is now available. bacteria and particles. Most laboratory test reports show virtuPolypropylene pipe shows good ability to with­stand both cor- ally zero leachables from PVDF piping systems. rosive chemicals and high tempera­tures, up to 220°F (104°C). PVDF pipe is joined by the butt-fusion method, resulting in The natural toughness of the material minimizes damage to clean, smooth joints. pipe during in­stallation and service. When system pressures exceed 70 psig (482.6 kPa) or temPolypropylene is generally joined by the butt-fusion method, peratures exceed 75°F (24°C), plastic piping system manufacresulting in smooth joints. turers should be consulted for compatibility. Polypropylene ABS  Acrylonitrile butadiene styrene (ABS) plastic pipe has or PVDF-lined metal piping systems may be incorporated to been used in the primary stages of water-treat­ment systems meet pressures up to 150 psig (1034.2 kPa). ✺ because of relatively low cost and ease of installation.

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CONTINUING EDUCATION Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com Continuing Education from Plumbing Systems & Design Kenneth G.Wentink, PE, CPD, and Robert D. Jackson

Do you find it difficult to obtain continuing education units (CEUs)? Is it hard for you to attend technical seminars? Through Plumbing Systems & Design (PS&D), ASPE can help you accumulate the CEUs required for maintaining your Certified in Plumbing Design (CPD) status. ASPE features a technical article in every issue of PS&D, excerpted from its own publications. Each article is followed by a multiplechoice test and a simple reporting form. Reading the article and completing the form will allow you to apply to ASPE for CEU credit. For most people, this process will require approximately 1 hour. A nominal processing fee is charged—$25 for ASPE members and $35 for nonmembers (until further notice, the member fee is waived). If you earn a grade of 90% or higher on the test, you will be notified that you have logged 0.1 CEU, which can be

applied toward the CPD renewal requirement or numerous regulatory-agency CE programs. (Please note that it is your responsibility to determine the acceptance policy of a particular agency.) CEU information will be kept on file at the ASPE office for 3 years. No certificates will be issued in addition to the notification letter. You can apply for CEU credit on any technical article that has appeared in PS&D within the past 12 months. However, CEU credit only can be obtained on a total of eight PS&D articles in a 12-month period. Note: In determining your answers to the CE questions, use only the material presented in the continuing education article. Using other information may result in a wrong answer.

CE Questions—“Plumbing Design for Health Care Facilities” (PSD 132) 1. High-silicon cast iron pipe is _________ than standard weight cast iron pipe. a. lighter b. heavier c. more costly d. less costly 2. Fixture-unit values for unique fixtures found in health-care facilities can be _________. a. estimated b. assigned by the authority having jurisdiction c. higher then anticipated d. found in Table 2-2 3. The theoretical maximum specific resistance of pure water is _________ ohm-centimeter units at 77oF. a. 12.6 b. 16.8 c. 18.3 d. 20.2 4. Hand washing lavatories are not required in _______. a. family waiting rooms b. janitor’s closets c. outpatient services areas d. nurses’ stations 5. A review of applicable code requirements is ________. a. always required b. is under the jurisdiction of the Joint Commission of the Accreditation of Hospital Organization (JCAHO) c. restricted to local codes only d. is not necessary for the experienced plumbing engineer 6. When referring to acid waste, the lower the pH number, the _________ the concentration of acid. a. lower b. higher c. more neutral d. none of the above

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MARCH/APRIL 2006

7. It is common for architects to locate the piping shafts and the spaces in direct conflict with the structural framing because _________. a. they do not know any better b. it serves their purpose c. the plumbing designer has not given the architect direction regarding space requirements d. none of the above 8. What type of vent system is used on laboratory sinks that are located in the center of laboratory areas? a. end vent b. stack vents c. loop vents d. crown vents 9. What is the size, in liters, of an acid waste neutralization tank that serves 75 laboratory sinks? a. 1,020.9 b. 1,040.9 c. 1,050.9 d. 1,060.9 10. This chapter discusses _________. a. the requirements of health care facilities b. the provisions that may be encountered by the plumbing professional in the design of a health care facility c. nursing homes, medical schools, and medical laboratories d. energy codes as they apply to medical facilities 11. X-ray areas require _________. a. tempered water b. corrosion-resistant piping and drains c. silver recovery d. a and b 12. Which of the following piping materials is not commonly used for the distribution of pure water? a. aluminum b. CPVC c. copper d. PVDF

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Plumbing Systems & Design

Continuing Education Application Form 1. Make a photocopy of this form. Leaving this page in PS&D allows others to use it to obtain continuing education units (CEUs). 2. PRINT your name and address. Be sure to place your membership number in the appropriate space. This form is valid up to 1 year from date of publication. The PS&D continuing education unit program is approved by ASPE for up to 1 contact hour (0.1 CEU) of credit per article studied. 3. Answer the multiple-choice continuing education (CE) questions (found after each CE article) and the appraisal questions on this page. 4. Submit this form and the answer sheet below, with the payment of the appropriate fee by check or money order made payable to ASPE, or submit the credit card information to ASPE Education Credit, 8614 W. Catalpa Avenue, Suite 1007, Chicago, IL 60656–1116. 5. Participants who earn a passing score (90%) on the CE questions will receive a letter of certification within 30 days of PS&D’s receipt of the application (no special certificates will be issued). (CEU information will be retained on the ASPE Database.) Participants who wish to retake the test should submit their retest along with an additional fee—$25 for an ASPE member (currently waived) or $35 for a nonmember. Please print or type; this information will be used to process your credits. Name _ __________________________________________________________________________________________________ Title _______________________________________________ ASPE Membership No.____________________________________ Organization _ ____________________________________________________________________________________________ Billing Address ____________________________________________________________________________________________ City_ _______________________________________ State/Province________________________ Zip _ ____________________ Country____________________________________________ E-mail_________________________________________________ Daytime telephone_ _________________________________ Fax___________________________________________________ I am applying for the following continuing education credits:

❏ ASPE Member Each examination: $25

I certify that I have read the article indicated above.

Limited Time: No Cost to ASPE Member

Signature Expiration date: Continuing education credit will be given for this examination through March 31, 2007. Applications received after that date will not be processed.

PS&D Continuing Education Answer Sheet

Payment: ❏ Personal Check (payable to ASPE) $____________ ❏ Business or government check $____________ ❏ DiscoverCard ❏ VISA ❏ MasterCard ❏ AMEX $____________ If rebilling of a credit card charge is necessary, a $25 processing fee will be charged. ASPE is hereby authorized to charge my CE examination fee to my credit card. Account Number

Expiration date

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Plumbing Design for Health Care Facilities (PSD 132)

Questions appear on page 66. Circle the answer to each question. Q 1. A B C D Q 2. A B C D Q 3. A B C D Q 4. A B C D Q 5. A B C D Q 6. A B C D Q 7. A B C D Q 8. A B C D Q 9. A B C D Q 10. A B C D Q 11. A B C D Q 12. A B C D

❏ Nonmember Each examination: $35

Cardholder’s name (Please print)

Appraisal Questions 1. 2. 3. 4. 5. 6.

Plumbing Design for Health Care Facilities (PSD 132) Was the material new information for you? ❏ Yes ❏ No Was the material presented clearly? ❏ Yes ❏ No Was the material adequately covered? ❏ Yes ❏ No Did the content help you achieve the stated objectives? ❏ Yes ❏ No Did the CE questions help you identify specific ways to use ideas presented in the article? ❏ Yes ❏ No How much time did you need to complete the CE offering (i.e., to read the article and answer the post-test questions)?___________________

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Plumbing Systems & Design  67

Irrigation Systems

PSD 141

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Continuing Education from Plumbing Systems & Design Kenneth G.Wentink, PE, CPD, and Robert D. Jackson

SEPTEMBER 2007

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CONTINUING EDUCATION

Irrigation Systems

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Introduction The function of an automatic irrigation system is to provide and distribute a predetermined amount of water to economically produce and maintain ornamental shrubs, cultivated lawns, and other large turf areas. Other benefits of an automatic irrigation system include convenience, full landscape coverage, easy control for overnight and early morning watering, and minimized plant loss during drought. This chapter discusses the basic design criteria and components of irrigation systems for ornamental lawns and turf. Among the factors considered are water quality and requirements, soil considerations, system concepts, and system components. A design information sheet is also provided, as Appendix A, to assist the plumbing engineer in the orderly collection of the required field information and other pertinent data.

Water Quality and Requirements In urban areas, where the source of the water supply is often the municipal water system, the plumbing engineer does not need to be concerned with the quality of the water. In cases where private sources are used and the water quality is unknown, the water should be analyzed by the appropriate local health authority having jurisdiction prior to use. The three main areas of concern are as follows: 1. Any silt content that, if high, may result in the baking and sealing of soils 2. Any industrial waste that may be harmful to good growth 3. Any soluble salts that may build up in the root area The most common solution currently available for handling excessive amounts of silt is the construction of a settling basin, usually in the form of a decorative lake or pond. In those areas where the salt

Table 1  Net Amount of Water to Apply per Irrigation Cycle Soil Profile Amount, in. (mm) Coarse, sandy soils 0.45 (11.43) Fine, sandy loams 0.85 (21.59) Silt loams 1.10 (27.94) Heavy clay or clay loams 0.90 (22.86) Note: Net amount of moisture required based on 12 in. (304.8 mm) root depth.

content is excessive, 1,000 parts per million (ppm) and above, the inability of the soil to cope with the problem may require the use of special highly salt-tolerant grasses. The quantity of water required for an effective irrigation system is a function of the type of grass, the soil, and local weather conditions. The quantity of water is usually expressed as the depth of the water applied during a given period over the area to be covered. The amount of water applied to a given area can be controlled easily by adjusting the irrigation system’s length and frequency of opera-

Figure 1  Examples of a Block System

Reprinted from ASPE Data Book Volume 3: Special Plumbing Systems, Chapter 4: “Irrigation Systems.” © American Society of Plumbing Engineers. 2  Plumbing Systems & Design 

SEPTEMBER 2007

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tion. An efficient irrigation system takes to be operated at any given time. Figure 3 Figure 2  Quick-Coupling Valve Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com into consideration the rate of the appliillustrates this design. cation of the water, usually expressed in System Components inches per hour, and the attempt to match Sprinklers the application rate with the absorption One of the most important considerations rate of the soil. Often, this condition is for the plumbing engineer when designachieved through frequent short watering an irrigation system is the selection of ing cycles. the sprinklers. Sprinklers are mechanical Soil Considerations devices with nozzles used to distribute Sandy, porous soils have relatively high water by converting water pressure to a absorption rates and can handle the high high-velocity discharge stream. Many output of the sprinklers. Steep slopes different types of sprinklers are manufacand very tight, nonporous soils require tured for a variety of system applications. low precipitation rates to avoid erosion The plumbing engineer should become damage and wasteful runoff. knowledgeable of the various types before A sufficient amount of water must be selecting the sprinklers, as the flow rates applied during each irrigation period to and operating pressures must be nearly ensure penetration to the root zone. Table the same in each of the irrigation system’s 1 suggests guidelines for several soil procircuits. files (net amount of water to apply per Spray Sprinklers Surface-type spray irrigation cycle). In the absence of any and pop-up spray sprinklers (see Figure specific information on the soil and local 4) produce a single sheet of water and weather conditions, the irrigation system cover a relatively small area, about 10 to 20 may be designed for 1½ inches (38.1 milfeet (3.05 to 6.10 meters) in radius. These limeters) of water per week. The plumbsprinklers can operate on a low-pressure ing engineer should consult with the local range of 15 to 35 pounds per square inch administrative authority to determine (psi) (103.4 to 241.3 kPa). They apply the compliance with the applicable codes in water at a high rate of application—1 to the jurisdiction. The engineer can obtain 2 inches/hour (25.4 to 50.8 mm/hour)— specific information on the soil and local and are most economical in small turf weather conditions by contacting a local or shrub areas and in irregularly shaped weather bureau, university, or state engiareas. neer. Due to the fine spray design, the pattern be considered by the engineer. An examSystem Concepts can be easily distorted by the wind; thereple of a quick-coupling valve is illustrated The three basic system concepts that can in Figure 2. be used by the engineer in the design The last concept in of an irrigation network are the block sprinkler system design Figure 3  Valve-in-Head System method, the quick-coupling method, and is the valve-per-sprinkler the valve-per-sprinkler method. method. Small actuator The block system is an approach in valves, operated at low voltwhich a single valve controls the flow of age, provide great flexibilwater to several sprinklers. It is ideal for ity and control. Sprinklers residential and other small turf areas. in diverse areas having the Either manual or automatic valves may same (or similar) water be used in the block system. As the irriga- requirements may be tion area increases or where high-volume operated concurrently. In sprinklers are employed, the block system other applications, such as becomes less attractive to the engineer quarter applications covbecause of the large valves and pipelines ering quarter circles or half required. Examples of the block system circles, the irrigation sprinare shown in Figure 1. klers may be piped, wired, The quick-coupling irrigation system and operated together is an answer to the high cost incurred on through system programlarge block system projects. Development mers. The valve-per-sprinof the quick-coupling valve provided a kler system provides the more flexible irrigation system. The valve opportunity to standardize is located underground but can be acti- the pipe sizes by selecting vated from the surface. Where manpower the appropriate sprinklers is not critical and security is reasonable, the quick-coupling irrigation system may SEPTEMBER 2007 

Plumbing Systems & Design  3

CONTINUING EDUCATION: Irrigation Systems in both single-nozzle and

Figure 4  Pop-Up Spray Heads

Figure 6  Rotor Sprinkler—Arcs and Full Circles

Photo courtesy of Rain Bird Corporation

These devices can operate at a higher pressure (25 to 100 psi [172.3 to 689.5 kPa]) and cover larger areas (40 to 100 feet [12.2 to 30.5 meters] in radius). The water is applied at a lower rate (0.20 to 0.5 inches/hour [5.08 to 12.7 mm/hour]). Because of its larger, more compact stream of water, this sprinkler is not easily distorted by the wind and is most economical in large, open turf areas. Freestanding sprinklers are not desirable where they are exposed. In such cases, the pop-up, rotary-type sprinklers shown in Figure 6 may be used. These nozzles rise above the ground level only when the water is being delivered to the unit. Half-circle, rotary sprinklers can discharge the same volume of water as full-circle units. A half-circle, rotary sprinkler can provide the same amount of water as a full-circle unit over half the area, doubling the application rate. Quarter-circle sprinklers will quadruple the application rate. Some equipment manufacturers use different nozzles to compensate for the reduced area and to provide a uniform application rate. If compensating nozzles are not used in halfcircle sprinklers, these units must be valved and operated separately for a balanced application of the water. Shrub Sprinklers Several types of shrub sprinklers are available, including bubblers (see Figure 7), flat-spray sprinklers, and stream-spray sprinklers. Shrub sprinklers can be mounted on risers to spray over plants. If the plants are tall and not dense near the ground, shrub Photo courtesy of Rain Bird Corporation

Figure 5  Impact Sprinkler

fore, these sprinklers should be installed in protected areas. Impact Sprinklers Impact sprinklers (see Figure 5) can be permanent or movable and either the riser-mounted type (see Figure 2) or the pop-up rotary type (see Figure 6). Impact sprinklers have an adjustable, revolving water stream and are available 4  Plumbing Systems & Design 

SEPTEMBER 2007

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sprinklers can be used on short risers, and the spray can be directed under the plants. The spray can also be kept below the plant. Flat-spray shrub heads are best employed for these applications. Trickle Irrigation Trickle irrigation is commonly used in vineyards and orchards and routed through tubing with special emitters installed at each planting. Most emitters have flexible orifices and may have provisions for adding fertilizer. These irrigation systems have a low-volume usage and usually are not installed in conjunction with conventional lawn sprinkler systems. Valves Remote-control valves are generally classified into three basic categories: electric, hydraulic, and thermal-hydraulic. The electrically operated valve receives an electric signal from the controller and actuates a solenoid in the valve. This solenoid opens and closes the control valve. The hydraulic control valve is operated with the water pressure and has control tubing from the controller to the valve. The thermal-hydraulic control valve uses an electric signal from the controller to heat up the components of the valve to open the unit. The most common use of this valve is to control the water usage to the different zones. These devices should be installed with access for maintenance. Most control valves have some provisions for manual operation. In some systems, manual control valves are installed in pits or vaults

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surface mounted, recessed mounted, or

Figure 7  Nozzles—Adjustable Arcs and Patterns

Photo courtesy of Rain Bird Corporation

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with a long T-handle wrench used for the activation of each circuit. An irrigation system may be installed with an automatic check valve on the sprinkler heads. When a zone is installed on sloping terrain, these valves will close when they sense a low pressure at turnoff, preventing the drainage of the supply pipe through a sprinkler head installed in a lower area. Atmospheric vacuum breakers (see Figure 8) must be installed on every sprinkler circuit downstream of the control valve to eliminate the possibility of back-siphonage into the potable water system. Many (if not all) local jurisdictions have codes that require this type of valve. The plumbing designer should consult with the local administrative authority and check all applicable codes for their requirements. Pressure-reducing valves are installed where higher street pressures are involved and also are commonly used to maintain a constant pressure where the inlet pressures may vary. Some manufacturers offer remote-control valves with pressure regulation. Low-flow control valves may be installed to avoid damage to the piping or tubing from pressure surges during the filling of a (dry) system. This control valve allows a slow filling of the piping or tubing until the pressure is established. In climates where freezing conditions may occur, automatic-type drain valves should be installed at the low points of the system to allow for drainage of the system. This control valve will open automatically when the water pressure drops below a set point. In heavy or dense soils, a pit of gravel should be provided for quick drainage.

ing drainage of the supply pipe through a sprinkler head installed in a low area. The use of pressure vacuum breakers to eliminate the possibility of backsiphonage into the potable water system is the minimum level of backflow prevention accepted by most jurisdictions. The plumbing engineer should consult with the local administrative authority and check all applicable codes for their requirements. Controllers Presently, many types of controllers for irrigation systems are available. Selection of this device is based on the specific application involved. Controllers are programmed to activate each irrigation zone at a specific time and also will control the length of time that each zone is activated. Some controllers have a calendar that allows the irrigation system to be used only on certain days. Other types of controllers have manual (or automatic) overrides to shut down all systems during rain or to turn on specific zones for extra water. Some controllers have soil moisture monitors, which turn on zones only when needed. Controller panels can be

cal illustration of a surface-mounted and a pedestal-mounted irrigation system programmer.

Design Information When designing an underground sprinkler system, the plumbing engineer should consider the following factors: the site plan, type of plants, type of soil, type and source of water, and system location. Site Plan An accurate site plan, preferably laid out to scale and showing all buildings, shrubs, trees, hedges, walks, drives, and parking, should be drawn as accurately as possible. Areas where overspray is undesirable, such as walkways and buildings, should be clearly noted. Property lines also should be shown on the site plan. The heights and diameters of shrubs and hedges should be indicated. Types of Plantings The engineer should show the areas that will be irrigated on the site plan as well as the areas that will be omitted. Those areas that require a different style of sprinkler and separate zoning also should be indicated. Some plantings require more frequent watering than others; therefore, they will require a separate zone and control valve. The engineer should determine whether the plantings allow spray on their leaves (or any other special type of spray) and should select the sprinklers accordingly.

Figure 8  Installation of Atmospheric-Type Vacuum Breakers

Backflow Devices An irrigation system may be installed with an automatic check valve on the sprinklers. When a zone is installed on sloping terrain, these valves will close when they sense a low pressure at turnoff, preventSEPTEMBER 2007 

Plumbing Systems & Design  5

CONTINUING EDUCATION: Irrigation Systems System Location

Figure 9  Irrigation Sprinkler Programmers

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Type of Soil The type of soil determines the proper rate of application of water to the soil. The length and frequency of the applications can be determined by considering the soil and the types of plants. A sufficient amount of water must be applied during each irrigation period to ensure penetration to the root zone. Table 1 recommends acceptable guidelines for several types of soil profiles. Where available, the engineer should secure local soil and weather conditions by contacting the local state extension engineer, a university, or the weather bureau. The local weather bureau usually publishes an evapotranspiration guide, which shows the deficit water required to maintain turf grass. This value is compiled by measuring the rainfall minus the evaporation taking place during a particular period. The balance is the amount of water required. In the absence of any specific information on local soil and weather conditions, the irrigation system should be designed for

6  Plumbing Systems & Design 

SEPTEMBER 2007

a minimum of 1½ inches (38.1 mm) of water per week. Sandy, porous soils (as previously indicated) have relatively high absorption rates and can handle the high output of sprinklers. Steep slopes and very tight, nonporous soils require low precipitation rates to avoid erosion damage and runoffs. Type and Source of Water The source of the water should be located on the site plan. If the water source is a well, the pump capacity, well depth, pump discharge pressure, and other pertinent data should also be recorded. If the water source is a city water main, the locations, size, service-line material, and length of piping from the service line to the meter should be researched by the plumbing engineer. The water meter size and the static water pressure of the city main are also needed. The engineer should determine whether special meter pits or piping arrangements are required by the utility company.

local climatic conditions, the general area may require specific design considerations, such as drain valves on systems subjected to freezing temperatures. Windy areas require closer spacing of sprinklers, and the wind velocity and direction must be considered. For areas on sloping terrain, there will be a difference in the outlet pressure, and consideration must be made for system drainage. The engineer must review local codes to determine acceptable piping materials, installation, requirements, and the approved connection to municipal water works. ✺

References The ABCs of Lawn Sprinkler Systems. Irrigation Association, Fairfax, Virginia. Pair, Claude H., ed. Sprinkler Irrigation, 4th edition. Sprinkler Irrigation Association, Silver Spring, Maryland. Architect-engineers Turf Sprinkler Manual. The Rainbird Company, Glendora, California. Design Information for Large Turf Irrigation Systems. The Toro Company, Riverside, California. Young, Virgil E. Sprinkler Irrigation Systems. Mister Rain, Inc., Auburn, Washington.

Resources The Irrigation Association, www.irrigation.org

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Appendix A

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Suggested Information Sheet for Sprinkler System Design

All available information should be contained on this sheet, plot plan, or both. 1. Project name_______________________________ Address_______________________________________ 2. Water supply: a. Location and size of existing tap, meter, pump, or other __________________________________

3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14.



b. Existing meter, pump, or tap capacity: Residual pressure _______________GPM _____________



c. Power supply: Location _________________________________________ Voltage _________________

d. Length, type, location, and size of existing supply line (identify on plan) Area to be watered. Identify all planted areas whether shrubbery or trees; indicate clearance under trees. (Identify on plan.) Soil type: Light _______________________ Medium _____________________ Heavy __________________ Hours per day and night allowed for irrigation __________________________________________________ Amount of precipitation required per week __________________________________________________ Area to be bordered or not watered (identify on plan) Elevations and prevailing wind conditions (identify on plan) Type of system: (a) Automatic electric _________________ (b) Automatic hydraulic _______________ (c) Manual pop-up ______________ (d) Manual quick-coupling _____________ (e) Other____________ Indicate equipment preference _____________________________________________________________ Indicate preferred location for valves and controllers _________________________________________________________________ ______________________________________________________________ Indicate vacuum breaker and/or drain valve requirement ____________________________________________________________ _________________________________________________________________ Indicate pipe material preference: 2½” and larger ______________ 2” and smaller _______________ Indicate any preference for sprinkler riser types ____________________________________________

Special Notes (use additional sheet if necessary)______________________________________________________________________ ____________________________________________________________________________________________________________________ ____________________________________________________________________________________________________________________ ____________________________________________________________________________________________________________________

SEPTEMBER 2007 

Plumbing Systems & Design  7

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Now Online!

The technical article you must read to complete the exam is located at www.psdmagazine.org. The following exam and application form also may be downloaded from the website. Reading the article and completing the form will allow you to apply to ASPE for CEU credit. For most people, this process will require approximately one hour. If you earn a grade of 90 percent or higher on the test, you will be notified that you have logged 0.1 CEU, which can be applied toward the CPD renewal requirement or numerous regulatory-agency CE programs. (Please note that it is your responsibility to determine the acceptance policy of a particular agency.) CEU information will be kept on file at the ASPE office for three years. Note: In determining your answers to the CE questions, use only the material presented in the corresponding continuing education article. Using information from other materials may result in a wrong answer.

About This Issue’s Article The September 2007 continuing education article is “Irrigation Systems,” Chapter 4 of ASPE Data Book 3: Special Plumbing Systems. This chapter discusses the basic design criteria and components of irrigation systems for ornamental lawns and turf. Among the factors considered are water quality and requirements, soil considerations, systems concepts, and components. A design information sheet is also provided, as Appendix A, to assist the plumbing engineer in the orderly collection of the required field information and other pertinent data. You may locate this article at www.psdmagazine.org. Read the article, complete the following exam, and submit your answer sheet to the ASPE office to potentially receive 0.1 CEU.

CE Questions—“Irrigation Systems” (PSD 141) 1. The function of an irrigation system is _________. a. to conserve water b. as a labor-saving device for yard maintenance c. to provide and distribute a predetermined amount of water to economically produce and/or maintain shrubs, lawns, and turf d. none of the above 2. When designing an underground sprinkler system, the plumbing engineer should consider which of the following factors? a.  site plan, b.  types of plants, c.  type of soil, d.  all of the above 3. The amount of water to apply per irrigation cycle in coarse, sandy soil, assuming a 14-inch root depth, is ____. a.  0.45 inch, b.  0.85 inch, c.  1.10 inches, d.  none of the above 4. The three basic concepts that can be used by the engineer in the design of the irrigation network are _________. a. block method, quick-coupling method, and valve-persprinkler method b. uniform water coverage, controlled depth of water per square foot, and zone control method c. both a and b d. none of the above 5. Water for irrigation systems _________. a. may be from an urban source b. may be from a private source c. may be from a storage reservoir, tank, or surface pond d. any of the above 6. Soil conditions _________. a. need not be considered when urban sources of water are used b. affect the amount of water needed c. are not important because the landscaper will supply the proper soil for the plants used d. should have high absorption rates

8  Plumbing Systems & Design 

SEPTEMBER 2007

PSD 141

Do you find it difficult to obtain continuing education units (CEUs)? Through this special section in every issue of PS&D, ASPE can help you accumulate the CEUs required for maintaining your Certified in Plumbing Design (CPD) status.

7. The last concept in sprinkler system design is _________. a.  plant type, b.  soil type, c.  the valve-in-head method, d.  slope of grade at the site 8. One of the most important considerations for the plumbing engineer when designing an underground sprinkler system is _________. a. the selection of the sprinkler heads b. the system controller c. using a sufficient quantity of water d. using the least amount of water 9. Windy areas require _________. a. more water due to evaporation b. closer spacing of sprinklers c. increased outlet pressure d. both a and c

10. Atmospheric vacuum breakers must be installed _________. a. only if required by code b. on every sprinkler circuit downstream of the control valve c. when the designer does not want to use a backflow preventer d. below grade 11. Trickle irrigation is commonly used in _________. a. vineyards and orchards b. where water is scarce c. foreign countries d. less affluent areas

12. In climates where freezing conditions may occur, _________. a. manual drain valves should be installed b. reduced-pressure backflow preventers should not be installed c. automatic-type drain valves should be installed d. the piping system must be heat traced

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Simpo PDFSystems Merge and Unregistered Version - http://www.simpopdf.com Plumbing &Split Design Continuing Education Application Form This form is valid up to one year from date of publication. The PS&D Continuing Education program is approved by ASPE for up to one contact hour (0.1 CEU) of credit per article. Participants who earn a passing score (90 percent) on the CE questions will receive a letter or certification within 30 days of ASPE’s receipt of the application form. (No special certificates will be issued.) Participants who fail and wish to retake the test should resubmit the form along with an additional fee (if required). 1.  Photocopy this form or download it from www.psdmagazine.org. 2.  Print or type your name and address. Be sure to place your ASPE membership number in the appropriate space. 3.  Answer the multiple-choice continuing education (CE) questions based on the corresponding article found on www.psdmagazine.org and the appraisal questions on this form. 4.  Submit this form with payment ($35 for nonmembers of ASPE) if required by check or money order made payable to ASPE or credit card via mail (ASPE Education Credit, 8614 W. Catalpa Avenue, Suite 1007, Chicago, IL 60656) or fax (773-695-9007). Please print or type; this information will be used to process your credits. Name _ __________________________________________________________________________________________________ Title _______________________________________________ ASPE Membership No.____________________________________ Organization _ ____________________________________________________________________________________________ Billing Address ____________________________________________________________________________________________ City_ _______________________________________ State/Province________________________ Zip _ ____________________ Country____________________________________________ E-mail_________________________________________________ Daytime telephone_ _________________________________ Fax___________________________________________________

I am applying for the following continuing education credits:

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I certify that I have read the article indicated above.

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Signature Expiration date: Continuing education credit will be given for this examination through September 30, 2008. Applications received after that date will not be processed.

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Irrigation Systems (PSD 141)

Questions appear on page 8. Circle the answer to each question. Q 1. A B C D Q 2. A B C D Q 3. A B C D Q 4. A B C D Q 5. A B C D Q 6. A B C D Q 7. A B C D Q 8. A B C D Q 9. A B C D Q 10. A B C D Q 11. A B C D Q 12. A B C D

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Appraisal Questions

Irrigation Systems (PSD 141) Was the material new information for you?  ❏ Yes ❏ No Was the material presented clearly?  ❏ Yes ❏ No Was the material adequately covered?  ❏ Yes ❏ No Did the content help you achieve the stated objectives?  ❏ Yes ❏ No Did the CE questions help you identify specific ways to use ideas presented in the article?  ❏ Yes ❏ No 6. How much time did you need to complete the CE offering (i.e., to read the article and answer the post-test questions)?___________________ 1. 2. 3. 4. 5.

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PSD 129

Jail and Prison Housing Units

Continuing Education from Plumbing Systems & Design Kenneth G.Wentink, PE, CPD, and Robert D. Jackson

SEPTEMBER/OCTOBER 2005

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Jail and Prison Housing Units INTRODUCTION The objective of this chapter is to help the designer understand and deal with the problems of designing water heating systems for jail and prison housing units. It is important that the designer recognize that each building is unique and work closely with the owner, architect, and government authorities to determine how a building will oper­ate. A building’s operation will affect when and for how long the peak hot water demand will occur. The first part of this chapter discusses generally some of the design criteria and areas of special concern involved in designing for jail and prison housing units. The second part gives two practical examples of sizing methodol­ogy, one for jails and one for prisons. GENERAL The design criteria used to design hot water systems for jail housing units differ from those used for prison housing units. This difference is due to the fact that the facilities are used for different purposes. Jails are used primari­ly to house people awaiting trial or serving short sentenc­es. Prisons are used to house convicted criminals serving long prison terms. This difference affects the prisoners’ daily routines, which, in turn, determine when the facilities’ peak hot water demands occur. It is required that hot water temperature for the showers and lavatories in jails and prisons be limited to between 100 and 110°F (38 and 43°C). This temperature range has been estab­ lished to prevent inmates from using hot water as a weapon.1 The generally used standard temperature is 105°F (41°C). Push-button type self-closing or timed-control valves are used to deliver hot water of this temperature to the showers and lavatories. Occasionally an owner will require that a shower control valve that allows some inmate control of shower water temperature be provided. New security type valves provide this feature. Hot water at the design tempera­ture must be furnished at the fixture beca­use of the lower-than-usual water temperature and the self-closing features of inmate control valves. The designer should take into consideration that the typical life of a jail or prison is 50 to 100 years and that any system installed must be accessible for replacement or repair. Large jail facilities and all prisons have central laundry facilities and central kitchens. The hot water systems for the laundry and kitchen areas should be separate from those for housing because these areas have very different hot water demands. For instance, the temperature of the hot water delivered will be higher, between 140 and 180°F (60 and 82°C). If a centralized water heating system is used for the general purpose and kitchen/laundry water, then a fail-safe water tempering system must be installed for the general purpose water.

Note: All decimal equivalencies in the metric calculations are rounded. Therefore, the metric conversions shown in the text may vary slightly from the answers shown in the metric equations.



Hot Water Demand The usual fixtures requiring hot water found in housing units are showers and lavatories. Some units also have small kitchens or serving areas, which may have additional sinks and small dishwashers. Such serving areas are project specific. In jails, very often one or two residential type washing machines are require­d for each housing unit pod (a group of 10 to 20 cells).­ The typical housing unit is composed of multiple pods, with each cell opening onto a day room. Currently it is recom­ mended that there be one shower for every eight inmates and a lavatory in each cell.2 The number and location of the showers are decided by the archi­tect in coordina­tion with the owner and according to specific code require­ments. The shower operation is the factor that determines the required sizes of the water heater and storage tank. Primary considerations 1. The standard recommendation of eight inmates per shower was made so that all inmates could shower during a 1-h period. This arrangement allows an average of 7 min for each inmate to shower. About half that time is taken up by drying and switching inmates, leaving only about 3.5 min of actual water usage per inmate. 2. Showers are the main factor affecting water heater size. Allowance should be made for the many lavatories in housing units when sizing the storage tank. 3. The efficiency of storage systems varies from manu­ factur­er to manufacturer, but 65 to 80% is a good efficien­cy range to use until you have actual data on the tank and system ­speci­fied. JAIL EXAMPLE This is an example of a jail housing unit with six pods of 24 cells each (one inmate per cell) and three showers per pod. Assume that the hot water generated is 140°F (60°C) and the incoming water temperature is 50°F (10°C). Questions 1. Will the inmates be required to shower at a specific time? •  No 2. Will all the cell pods release their inmates for showering within the same hour? •  Yes. (This means that the design must accommodate a 1-h recovery period.) 3. Will the shower duration per inmate be limited? •  Yes, to 7 min per inmate, with 3.5 min of water usage 4. Does the facility anticipate double bunking inmates, either now or in the future? •  No Calculations for Jail Housing Units The ratio of 140 to 50°F (60 to 10°C) water flowing at the shower can be calculated using the mixed-water formula, Equation 1.7, from Chapter 1: American Corrections Association, Adult Corrections Institutions, 3d ed. Ibid.

1 2

Sept/Oct 2005 • Plumbing Systems & Design

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Continuing Education: Jail and Prison Housing Units Simpo PDF Merge and - http://www.simpopdf.com (T –Split Tc) Unregistered Versionsized to handle approximately 50% of the shower demand P= m where P = Tm = Th = Tc =

(Th – Tc)

Percentage of mixture that is hot water Temperature of mixed water = 105°F (41°C) Temperature of hot water = 140°F (60°C) Temperature of cold water = 50°F (10°C) – 50 55 P = 105 140 – 50 = 90 = 0.61 – 10 31 P = 41 60 – 10 = 50 = 0.61

[

]

With each shower flowing 2.5 gpm (0.13 L/sec), 2.5 gpm × 0.61 = 1.53 gpm will be 140°F hot water (0.13 L/sec • 0.61 = 0.08 L/sec will be 60°C hot water) 8 inmates × 3.5 min = 28 min of water flowing per shower during the peak hour 6 pods × 3 showers per pod = 18 showers total 18 showers × 28 min = 504 min 504 min × 1.53 gpm = 771.12 gal 140°F hot water per peak hour demand (504 min • 0.10 L/sec • 60 sec/min = 3024 L 60°C hot water per peak hour demand) At this time a judgment will have to be made by the designer as to whether or not the auxiliary equipment will be operating during the peak hour. For this example, we will assume it will not.

Auxiliary Equipment Demand Door type dishwasher with internal heater = 69 gph (261.17 L/h) Single compartment sink = 30 gph (113.55 L/h) Clothes washing machines, 1 per pod × 6 pods = 6 6 × 2 loads @ 20 gal/load = 240 gph (6 • 2 loads @ 75.7 L/load = 908.40 L/h) Auxiliary equipment demand for 140°F water = 339 gph (Auxiliary equipment demand for 60°C water = 1283.12 L/h) Assuming that operation of the auxiliary equipment does not coincide with the peak hour demand, sizing the heater and storage tank to handle the additional load will not be necessary. The heater size required for inmate showering is more than twice the size needed for the auxiliary equip­ment demand. Recommendation Heater sizing Two heaters should be selected, each sized to serve between 60 and 100% of the total demand. In prison housing units some redundan­cy in the water heating system is necessary. The level of redundancy should be discussed with the facility’s owners. Storage tank sizing If the water heater is sized to meet the recovery required to handle the peak shower demand, the storage tank may be

during the period of peak use. The storage tank should be large enough to prevent the heater from cycling on and off more than four times per hour during off-peak hours. This requirement necessitates finding a balance between exces­sive tank size and short cycling. Calculation 771.12 gph × 0.50 = 385.6 gal (2.93 m3/h • 0.50 = 1.47 m3/h) 385.6 = 481.6 gal storage tank size 0.80 1470 L = 1837.5 L storage tank size 0.80

[

]

The auxiliary equipment demand of 339 gph (1283.12 L/h) will have the greatest influ­ence on the amount of cycling done by the heater during off-peak hours. 339 gph = 5.56 gpm average flow of 140°F water 60 1283.12 L/h = 0.36 L/sec average flow of 60°C water 60 • 60 5.56 gpm × 15 min = 83.4 gal

[

]

(0.36 L/sec • 60 sec/min • 15 min = 324 L) 83.4 = 104.25 gal storage 0.80 324 L = 405 L storage 0.80

[

]

The selected size of a 481.6-gal (1837.5-L) storage tank is more than ade­quate to meet this demand. PRISON EXAMPLE This is an example of a housing facility for 384 inmates. It has four wings (96 inmates per wing) and each wing has four stories (24 inmates per wing per sto­ry). A central kitchen and laundry are located in a separate building. Shower areas are provided on every floor of every wing, and each of these areas has three shower heads. Design Criteria and Assumptions 1. Inmate lavatories and showers will be supplied with 105°F (41°C) circulat­ed hot water. Showers are to have 2.5 gpm (0.16 L/sec) flow restrictors and lavatories 2.0 gpm (0.13 L/sec) flow restrictors. 2. There will be separate systems for the kitchen and laundry areas. 3. The water temperature for the laundry area will be 180°F (82°C) and for the kitchen area 140°F (60°C), plus there will be a separate loop of 105°F (41°C) water for the hand washing lavatories and toilets located in the kitchen area . 4. Water at 140°F (60°C) will be supplied to the dishwasher. The dish­washer will have a separate booster heater to raise water temperature to the 180°F (82°C) required for the final rinse cycle. 5. The storage tank capacity varies considerably—from 0% for instantaneous heaters to more than100%. Check

Reprinted from Domestic Water Heating Design Manual, 2nd ed. 2003. Chicago: American Society of Plumbing Engineers. Chapter 9, “Jail and Prison Housing Units” (pp. 179-188). © 2003, American Society of Plumbing Engineers.

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to determine if the owner has a prefer­ence. Remember, most owners already operate existing jails or prisons; they may have established design parameters. The initial cost of equipment, the unit perfor­mance, and operating costs are also factors to be consid­ered when sizing the storage tank. 6. Look for additional support facilities, such as the barber shop, pantries, or an emergency medical clinic. 7. Although operating hours for the laundry area are generally from 8:00 A.M. to 5:00 P.M., review operational times and schedules with the owner. 8. Sources of heat: The selection of steam, natural gas, or electricity will have an enormous impact on the type of heater and on energy consumption. Note: A central steam generation plant may favor an instan-t­aneous­ type steam-to-hot-water converter with minimum hot water storage for surges. Remember, redun­ dancy in heaters is always required for jails and prisons to allow for problems created by in­mates. The cost of generating and distributing steam is also a fac­tor to be con­sid­ ered. 9. The method to use for sizing the water heater and storage tank may be determined by the owner/operator of the facility. 10. One inmate per cell equals 384 inmates. A question that should be asked is whether the owner plans to expand in the future by putting more than one inmate in each cell. Questions 1. Will the inmates be required to shower at a specific time? •  No 2. Will the shower duration per inmate be limited or do inmates have control over when they shower? •  Showers are limited to 7 min per inmate, with 3.5 min of water usage per shower. 3. Will all of the cell pods release their inmates for showering within the same hour? •  Yes. (This means that the design must accommodate a 1-h recovery period.) 4. Does the facility anticipate double bunking the inmates now or in the future? •  No 5. Does the facility have a work-release program? •  Yes 6. What is the time allocated for the work-release inmates to shower prior to leaving for their duties in the work– release program? •  One hour, at the same approximate time as the other inmates. Calculations for Inmate Housing Units Refer to the calculations done for the jail example for the methodology for determin­ing the 1.53 gpm (0.1 L/sec) flow per shower head and the operation time of 28 min per shower. 48 showers × 28 min = 1344 min



1344 min × 1.53 gpm = 2056 gal of 140°F hot water for peak hour demand (1344 min • 0.096 L/sec • 60 sec/min = 7741.44 L/h of 60°C hot water for peak hour demand)

Storage Tank Sizing In this example, inmate lavatories will have the only impact on tank sizing because the kitchen and laundry will have sepa­rate systems. If the water heater is sized to meet the recovery required to handle the peak shower demand, the storage tank may be sized to handle approximately 50% of the shower demand during the period of peak use. The storage tank should be large enough to prevent the heater from cycling on and off more than four times per hour during off-peak hours. This requirement necessitates finding a balance between exces­sive tank size and short cycling. Calculation 2056 gph × 0.50 = 1028 gal 140°F hot water (7.74 m3/h • 0.50 = 3.87 m3 60°C hot water) 1028 gal = 1285 gal storage tank size 0.80 eff. 3870 L = 4837.5 L storage tank size [ 0.80 ] eff. Kitchen Considerations 1. The item that has the greatest effect on hot water demand is the dishwasher. Some central kitchens do not have dining areas, in which case all meals are shipped to the housing units in bulk for distribution and the dishwashers are in the housing units. 2. The temperature of the hot water going to kitchen lavatories should not exceed 110°F (43°C) for safety reasons. 3. Check to see if the dishwasher has a booster heater and determine the type of energy used (steam or electricity). This information will help you decide whether or not to generate 180°F (82°C) water. Note: Some dishwashers on the market use chemicals for disinfecting, thus the higher water tempera­ture is not re­quired. 4. After dishwashers, compartment sinks are the next largest user of 140°F (60°C) hot water. The higher temperature is required to cut through grease on pots and pans. Some three-compartment sinks have booster heaters in the rinse tank to maintain the higher temperature. 5. Other kitchen items that use hot water are the prerinse for the dishwash­er, the vegetable sinks, and the cart washdown hose bibs. 6. Always check the kitchen consultant’s plans for hot water requirements. 7. Refer to the “Hospitals” chapter for additional information on kitchens. Laundry Considerations 1. Review the laundry consultant’s plans and determine the type of washing machine/extractor used. Prison laundries are similar to hospital laundries in that they process sheets, pillow cases, and uniforms. The size and number Sept/Oct 2005 • Plumbing Systems & Design

59

Continuing Education: Jail and Prison Housing Units Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com of ma­chines are normally decided by the owner or the consultant. 2. Inmates each generate about 30 lb (13.61 kg) of laundry a week. This consists of 1 pillowcase, 2 sheets, 1 towel, and uni­forms. 3. Additionally, prison laundries usually handle the uniforms of the correctional officers. 4. Sometimes prison laundries do laundry for outside hospitals as a prison industry. 5. Consider the feasibility of a heat recovery system that uses the wash-water discharge. The laundry consultant can probably advise you about this. 6. Laundry equipment suppliers are the only reliable source of information on the hot water demands and required temperaures of their wash­ers. They can tell you how many gallons (liters) of water the machines require and the maximum number of cycles per hour they will operate. 7. Washers demand their hot water fast. It is not unusual for a 2-in. (DN50) hot water line to be connected to the larger

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Plumbing Systems & Design • Sept/Oct 2005

washers. Therefore, larger than normal storage capacity is needed to handle the surges in hot water demand. One rule of thumb is to provide 75% of the maximum hourly demand in storage; don’t provide less than 50% of that amount. 8. In 1992 a new federal law (“Bloodborne Pathogen”) was passed to protect workers against the human immunodeficiency virus (HIV) and hepatitis B virus (HBV). All detention facilities are now under this new federal regulation. A ma­jor/critical new standard was created by the law: “When an officer’s uniform becomes contaminated with blood products, the officer cannot leave his workplace with the uniform on. The facility must clean that uniform and reissue it to the officer.” The law states further that “inmate labor cannot be used when handling blood contaminated items.” A washer and dryer for the aforementioned are required to achieve compliance with the law. They should be located in a space that is under the direct supervision of an officer so the security of the officers’ uniforms will not be jeopardized. n

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Continuing Education from Plumbing Systems & Design Kenneth G.Wentink, PE, CPD, and Robert D. Jackson, Chicago Chapter President Do you find it difficult to obtain continuing education units (CEUs)? Is it hard for you to attend technical seminars? Through Plumbing Systems & Design (PSD), ASPE can help you accumulate the CEUs required for maintaining your Certified in Plumbing Design (CPD) status. ASPE features a technical article in every issue of PSD, excerpted from its own publications. Each article is followed by a multiplechoice test and a simple reporting form. Reading the article and completing the form will allow you to apply to ASPE for CEU credit. For most people, this process will require approximately 1 hour. A nominal processing fee is charged—$25 for ASPE members and $35 for nonmembers (until further notice, the member fee is waived). If you earn a grade of

90% or higher on the test, you will be notified that you have logged 0.1 CEU, which can be applied toward the CPD renewal requirement or numerous regulatory-agency CE programs. (Please note that it is your responsibility to determine the acceptance policy of a particular agency.) CEU information will be kept on file at the ASPE office for 3 years. No certificates will be issued in addition to the notification letter. You can apply for CEU credit on any technical article that has appeared in PSD within the past 12 months. However, CEU credit only can be obtained on a total of eight PSD articles in a 12-month period. Note: In determining your answers to the CE questions, use only the material presented in the continuing education article. Using other information may result in a wrong answer.

CE Questions—“Jail and Prison Housing Units” (PSD 129) 1. The sizing of a domestic water storage tank shall be large enough to prevent the water heaters from cycling no more than ____________ times per hour during off-peak hours. a. two b. four c. six d. eight 2. What are some of the most important factors to consider when sizing a domestic hot water storage tank? a. operating costs b. initial costs c. unit performance d. all of the above 3. The American Corrections Association ____________. a. has established the hot water requirements for jails and prisons b. requires the temperature of the hot water at inmate showers be between 100oF and 110oF c. has established the generally used standard of 105oF for inmate showers d. requires the use of push button type showers

7. Each inmate generates approximately ____________ pounds of laundry per week. a. 10 b. 20 c. 30 d. 40 8. In what year was the Bloodborne Pathogen law passed that was intended to protect workers against human immunodeficiency virus (HIV) and the hepatitis B virus (HBV)? a. 1986 b. 1992 c. 1998 d. 2004 9. Auxiliary equipment demand ____________. a. must be included in the water heating sizing b. must be assumed to not be in operation during the shower period c. should be determined whether or not it will be operating during the peak hour d. is equal to 69 gallons per hour

4. A typical hot water delivered temperature for inmate lavatories is ____________oF. a. 95 b. 100 c. 105 d. 110

10. The item of kitchen equipment that has the greatest effect on the hot water demand is the ____________. a. vegetable prep sink b. triple pot sink c. dishwasher d. exhaust hood washdown system

5. If the water heater is sized to meet the recovery required to handle the peak shower demand of a jail housing unit, ____________. a. the storage tank may be sized to handle approximately 50% of the shower demand b. the storage tank should be large enough to prevent the heater from cycling on and off more than four times per hour during off-peak hours c. the storage tank should be 481.6 gallons d. both a and b

11. A jail housing pod of 20 cells, each with one inmate, would require how many showers? a. one per cell b. three c. four d. the number is determined by the architect

6. The main factor to consider in sizing a water heating system for a jail is ____________. a. showers b. the many lavatories in housing units c. the temperature of the hot water to be provided and the duration of the peak flow d. the efficiency of the storage system



12. The objective of this chapter is ____________. a. to help government authorities determine how the building will operate b. to help the designer understand and deal with the problems of designing water heating systems for jail and prison housing units c. to help the designer understand and deal with the problems of designing water heating equipment for jail and prison housing units

d. all of the above

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Continuing Education Application Form 1. Make a photocopy of this form. Leaving this page in PSD allows others to use it to obtain continuing education units (CEUs). 2. PRINT your name and address. Be sure to place your membership number in the appropriate space. This form is valid up to 1 year from date of publication. The PSD continuing education unit program is approved by ASPE for up to 1 contact hour (0.1 CEU) of credit per article studied. 3. Answer the multiple-choice continuing education (CE) questions (found after each CE article) and the appraisal questions on this page. 4. Submit this form and the answer sheet below, with the payment of the appropriate fee by check or money order made payable to ASPE, or submit the credit card information to ASPE Education Credit, 8614 W. Catalpa Avenue, Suite 1007, Chicago, IL 60656–1116. 5. Participants who earn a passing score (90%) on the CE questions will receive a letter of certification within 30 days of PSD’s receipt of the application (no special certificates will be issued). (CEU information will be retained on the ASPE Database.) Participants who wish to retake the test should submit their retest along with an additional fee—$25 for an ASPE member (currently waived) or $35 for a nonmember. Please print or type; this information will be used to process your credits. Name _ __________________________________________________________________________________________________ Title _______________________________________________ ASPE Membership No.____________________________________ Organization _ ____________________________________________________________________________________________ Billing Address ____________________________________________________________________________________________ City_ _______________________________________ State/Province________________________ Zip _ ____________________ Country____________________________________________ E-mail_________________________________________________ Daytime telephone_ _________________________________ Fax___________________________________________________ I am applying for the following continuing education credits:

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Jail and Prison Housing Units (PSD 129)

Questions appear on page 61. Circle the answer to each question. Q 1. A B C D Q 2. A B C D Q 3. A B C D Q 4. A B C D Q 5. A B C D Q 6. A B C D Q 7. A B C D Q 8. A B C D Q 9. A B C D Q 10. A B C D Q 11. A B C D Q 12. A B C D 62

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Appraisal Questions 1. 2. 3. 4. 5. 6.

Jail and Prison Housing Units (PSD 129) Was the material new information for you? ❏ Yes ❏ No Was the material presented clearly? ❏ Yes ❏ No Was the material adequately covered? ❏ Yes ❏ No Did the content help you achieve the stated objectives? ❏ Yes ❏ No Did the CE questions help you identify specific ways to use ideas presented in the article? ❏ Yes ❏ No How much time did you need to complete the CE offering (i.e., to read the article and answer the post-test questions)?___________________

Life-Safety Systems

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Continuing Education from Plumbing Systems & Design Kenneth G.Wentink, PE, CPD, and Robert D. Jackson

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Life-Safety Systems

Introduction A threat to personnel safety often present in pharmaceutical facilities is accidental exposure and possible contact with toxic gases, liquids, and solids. This chapter describes water-based emergency drench equipment and systems commonly used as a first-aid measure to mitigate the effects of such an accident, Also described are the breathing-air systems that supply air to personnel for escape and protection when they are exposed to either a toxic environment resulting from an accident or normal working conditions that make breathing the ambient air hazardous.

Emergency Drench-Equipment Systems General When toxic or corrosive chemicals come in contact with the eyes, face, and body, flushing with water for 15 min with the clothing removed is the most recommended first-aid action that can be taken by nonmedical personnel prior to medical treatment. Emergency drench equipment is intended to provide a sufficient volume of water to effectively reach any area of the body exposed to or has come into direct contact with any injurious material. Within facilities, specially designed emergency drench equipment, such as showers, drench hoses, and eye and face washes, are located adjacent to all such hazards. Although the need to protect personnel is the same for any facility, specific requirements differ widely because of architectural, aesthetic, location, and space constraints necessary for various industrial and laboratory installations. System Classifications Drench equipment is classified into two general types of system based on the source of water. These are plumbed systems, which are connected to a permanent water supply, and self-contained or portable equipment, which contains its own water supply. Self-contained systems can be either gravity feed or pressurized. One type of self-contained eyewash unit is available that does not meet code requirements for storage or delivery flow rate. This is called the personnel eyewash station and is selected only to supplement, not replace, a standard eyewash unit. It consists of a solution-filled bottle(s) in a small cabinet. This cabinet is small enough to be installed immediately adjacent to a high hazard. If an accident occurs, the bottle containing the solution is removed and used without delay to flush the eyes while waiting for the arrival of trained personnel and during travel to a code-approved eyewash or first-aid station. Codes and Standards 1. ANSI Z-358.1, Emergency Shower and Eyewash Equipment. 2. OSHA has various regulations for specific industries pertaining to the location and other criteria for emergency eyewashes and showers.

3. The Safety Equipment Institute (SEI) certifies that equipment meets ANSI standards. 4. Applicable plumbing codes. For the purposes of the discussion in this section on drench equipment, the word “code” shall refer to ANSI Z-358.1. Types of Drench Equipment Emergency drench equipment consists of showers, eyewash units, face-wash units, and drench hoses, along with interconnecting piping and alarms if required. All of these units are available either singly or in combination with each other. Ancillary components include thermostatic mixing systems, freeze protection systems and enclosures. Each piece of equipment is designed to perform a specific function. One piece is not intended to be a substitute for another, but rather, to complement the others by providing additional availability of water to specific areas of the body as required. Emergency Showers Plumbed Showers  Plumbed emergency showers are permanently connected to the potable water piping and designed to continuously supply enough water to drench the entire body. A unit consists of a large-diameter shower head intended to distribute water over a large area. The most commonly used type has a control valve with a handle extending down from the valve on a chain or rod that is used to turn the water on and off manually. Code requires the shower be capable of delivering a minimum of 30 gpm (113.6 L/min) of evenly dispersed water at a velocity low enough so as not to be injurious to the user. Where this flow rate is not available, 20 gpm (75.7 L/min) is acceptable if the shower-head manufacturer can show the same spray pattern required for 30 gpm can be achieved at the lower flow rate. The minimum spray pattern shall have a diameter of 20 in. (58.8 cm), measured at 60 in. (152.4 cm) above the surface on which the user stands. This requires a minimum pressure of approximately 30 psi (4.47 kPa). Emergency showers can be ceiling mounted, wall mounted or floor mounted on a pipe stand, with the center of the spray at least 16 in. (40.6 cm) from any obstruction. Showers should be chosen for the following reasons: 1. When large volumes of potentially dangerous materials are present. 2. Where a small volume of material could result in large affected areas, such as in laboratories and schools. A typical emergency shower head mounted in a hung ceiling is illustrated in Figure 1. Self-Contained Showers  Self-contained emergency showers have a storage tank for water. Often this water is heated. The shower shall be capable of delivering a minimum of 20 gpm (75.5 L/min) for 15 min. The requirements for mounting height and spray pattern are the same as they are for plumbed showers.

Reprinted from Pharmaceutical Facilities Plumbing Systems, Chapter 8: “Life-Safety Systems,” by Michael Frankel. © American Society of Plumbing Engineers.   Plumbing Systems & Design 

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Emergency Face Wash

Split Unregistered Version - http://www.simpopdf.com The face wash is an enhanced version of the eyewash. It has the same design requirements and configuration, except the spray heads are specifically designed to deliver a larger water pattern and volume will flush the whole face and not just the eyes. The face wash should deliver approximately 8 gpm (55 L/min). The stream configuration is illustrated in Figure 2. Very often, the face wash is chosen for combination units. In general, the face wash is more desirable than the eyewash because it is very likely an accident will affect more than just the eyes. All dimensions and requirements of the free-standing face wash are similar to those for the eyewash. Drench Hoses A drench hose is a single-head unit connected to a water supply with a flexible hose. The head is generally the same size as a single head found on an eye/ face wash. Code requires the drench hose be capable of delivering a minimum of 0.4 gpm (1.5 L/min). It is controlled either by a squeeze handle near the head or a push-plate ball valve located at the connection to the water source. It is used as a supplement to showers and eye/face washes to irrigate specific areas of the body. Drench hoses are selected for the following reasons: 1. To spot drench a specific area of the body when the large volume of water delivered by a shower is not called for. 2. To allow irrigation of an unconscious person or a victim who is unable to stand. 3. To irrigate under clothing prior to the clothing’s removal.

Emergency Eyewash Plumbed Eyewash  Emergency eyewashes are specifically designed to irrigate and flush both eyes simultaneously with dual streams of water. The unit consists of dual heads in the shape of a “U,” each specifically designed to deliver a narrow stream of water, and a valve usually controlled by a large push plate. Code requires the eyewash to be capable of delivering a minimum of 0.4 gpm (1.5 L/min). Many eyewashes of recent manufacture deliver approximately 3 gpm (11.4 L/min). Once started, the flow must be continuous and designed to operate without the use of the hands, which shall be free to hold open the eyelids. The flow of water must be soft to avoid additional injury to sensitive tissue. To protect against airborne contaminants, each dual stream head must be pro- Figure 2  Combination Emergency Shower, Eye/Face Wash, and Drench Hose Unit tected with a cover that is automatically discarded when the unit is activated. The head covers shall be attached to the heads by a chain to keep them from being lost. The eyewash can be mounted on a counter or wall, or as a free stranding unit attached to the floor. The eyewash could be provided with a bowl. The bowl does not increase the efficiency or usefulness of the unit but aids in identification by personnel. It is common practice to mount a swivel type eyewash on a laboratory sink faucet, installed so it can be swung out of the way during normal use of the sink but can be swung over the sink bowl in order to be operated in an emergency. The code recommends (but does not require) the use of a buffered saline solution to wash the eyes. This could be accomplished with a separate dispenser filled with concentrate that will introduce the proper solution into the water supply prior to reaching the device head. A commonly used device is a wallmounted, 5 to 6-gal (20 to 24-L) capacity solution tank connected to the water inlet dispenses a measured amount of solution when flow to the eyewash is activated. A backflow device shall be installed on the water supply. Self-Contained Eyewash  A typical self-contained eyewash has a storage tank with a minimum 15-min water supply. The mounting height and spray pattern requirements are the same as those for a plumbed eyewash. JULY/AUGUST 2006 

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CONTINUING EDUCATION: Life-Safety Systems shower and eyewash that is handicapped accessible using handles Combination Equipment Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com Combination equipment consists of multiple-use units with a hung from the ceiling is illustrated in Figure 3. The handle must common water supply and supporting frame. Combinations are be located close enough to the center of the shower to be easily available that consist of a shower, eye/face wash, and drench reached, which is about 2 ft 0 in. from the center of the shower. hose in any configuration. The reason for the use of combina- Alarms tion equipment is usually economy, but the selection should Alarms are often installed to alert security or other rescue perbe made considering the type of irrigation appropriate for the sonnel that emergency drench equipment has been operated potential injuries at a specific location. For combination units, and to guide them rapidly to the scene of the accident. Comthe water supply must be larger, capable of delivering the flow monly used alarms are audible and visual devices—such as rate of water required to satisfy two devices concurrently rather flashing or rotating lights on top of, or adjacent to, a shower than only a single device. or eyewash—and electronic alarms wired to a remote security The most often-used combination is the drench shower and panel. Remote areas of a plant are particularly at risk if personface wash. Figure 2 illustrates a combination shower, eye/face nel often work alone. Alarms are most often operated by a flow wash and drench hose complete with mounting heights. switch activated by the flow of water when a piece of equipment Drench Equipment Components Controls Often referred to as “activation devices,” controls cause water to flow at an individual device. Stay-open valves are required by code in order to leave the hands free for the removal of clothing or for holding eyelids open. The valves most often used are ball valves with handles modified to provide for the attachment of chains, rods, and push plates. In very limited situations, such as in schools, valves that automatically close (quick-closing) are permitted if they are acceptable to the facility and authorities having jurisdiction. Valves are operated by different means to suit the specific hazard, location, durability, and visibility requirements. The operators on valves are handles attached to pull rods, push plates, foot-operated treadle plates and triangles. A solid pull rod is often installed on concealed showers in order to push the valve closed after operation. Another method is to have two handles attached to chains that extend below the hung ceiling, one to turn on the valve and another handle to turn it off. Chains are used if the handle might be accidentally struck, they enable the handle to move freely and not injure the individual who might accidentally strike the hanging operator. Operating handles for the physically challenged are mounted lower than those for a standard unit. In many cases, this requires that operating handles be placed near walls to keep them out of traffic patterns where they would be an obstruction to ablebodied people passing under them. A free-standing combination Figure 3  Clearance Dimensions Around Shower and Eye/Face Wash

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is used. When tempered water systems are used to supply drench equipment, a low water temperature of 60°F shall cause an alarm annunciation. Flow-Control Device Where water pressure exceeds 80 psig (550 kPa) or if the difference in water pressure between the first and last shower head is more than 20 psig (140 kPa), it is recommended that a selfadjusting flow-control device be installed in the water-supply pipe. Its purpose is to limit the flow to just above the minimum required by the specific manufacturer for proper functioning of equipment. Such devices are considered important because a shower installed at the beginning of a long run has a much greater flow than the device at the end. During operation, the higher pressure could cause the flow rate to be as much as 50 gpm (L/min). If no floor drain is provided, the higher flow for 15 min at the higher pressure could produce a much greater amount of water that must be cleaned up and disposed of afterwards. Drench hoses and eye and face washes are not affected because of their lower flow rates and their flow head designs. Where pressure-reducing devices are required for an entire system, they should be set to provide approximately 50 psig (345 kPa). System Design General It is a requirement that a plumbed system be connected to a potable water supply as the sole source of water. This system is therefore subject to filing with a plumbing or other code official for approval and inspection of the completed facility, as are standard plumbing systems. An adequately sized pipe with sufficient pressure must be provided from the water supply to meet system and device operating-pressure requirements for satisfactory functioning. One maintenance requirement is that the water in the piping system be flushed to avoid bacterial growth. It is common practice to add antibacterial and saline products to a self-contained eyewash unit and an antibacterial additive to an emergency shower. Water is also commonly used if it can be changed every week. It is well established that no preservative will inhibit bacterial growth for an extended period of time. Selfcontained equipment must be checked regularly to determine if the quality of the stored water has deteriorated to a point where it is not effective or safe to use. If valves are placed in the piping network for maintenance purposes, they should be made for unauthorized shut-off. PSDMAGAZINE.ORG

Appropriate pressure loss calculations should be made to ensure Water-Supply Pressure and Flow Rates Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com Emergency showers require between 20 and 30 gpm (76 to 111 the hydraulically most remote unit is supplied with adequate L/min), with 30 gpm recommended. The minimum pressure pressure with the size selected. Adjust sizes accordingly to meet required is 30 psig (4.5 kPa) at the farthest unit, with a generally friction loss requirements. The pipe material should be copper to minimize clogging the accepted maximum pressure of 70 psi (485 kPa). Code mentions a high pressure of 90 psig (612 kPa), which is generally consid- heads of the units in time with the inevitable corrosion products ered to be excessive. Most plumbing codes do not permit water released by steel pipe. Plastic pipe (PVC) should be considered pressures as high as 90 psig. Generally accepted practice limits where excessive heat and the use of closely located supports will the high water pressure to between 70 and 80 psig (480 and 620 not permit the pipe to creep in time. Emergency drench equipment shall be sized based on the kPa). Most eyewash units require a minimum operating pressure single highest flow rate, usually 30 gpm (115 L/min) for an of 15 psig (105 kPa) with a flow rate minimum of 3 gpm (12 L/ emergency shower. Piping is usually a 1¼-in. header of copper min) at the farthest unit. Maximum pressure is similar to that pipe for the entire length of a plumbed system. for showers. Face washes and drench hoses require a minimum Flushing Water Disposal operating pressure of 15 psig (105 kPa) with a minimum flow Water from emergency drench equipment is mainly discharged rate of 8 gpm (30 L/min) at the farthest unit. onto the floor. Individual eye/face washes mounted on sinks System Selection

Plumbed System

The advantages of a plumbed system include:

1. Permanent connection to a fresh supply of water, requiring no maintenance and only minimum testing of the devices to ensure proper operation. 2. It provides an unlimited supply of water often at larger volumes than self-contained units. Disadvantages include: 1. Higher first cost than a self-contained system. 2. Maintenance is intensive. Such systems require weekly flushing, often into a bucket, to remove stagnant water in the piping system and replace it with fresh water. Self-Contained System

Advantages of the self-contained system include:

1. Lower first cost compared to a plumbed system. 2. Can be filled with a buffered, saline solution, which is recommended for washing eyes. 3. Available with a container to catch waste water. 4. Portable units can be moved to areas of greatest hazard with little difficulty. 5. A gravity eyewash is more reliable. The water supply can be installed where there is room above the unit. If not, a pressurized unit mounted remotely should be selected. Disadvantages include: 1. Only a limited supply of water at a lesser flow rate is available. 2. The stored liquid must be changed on a regular basis to maintain purity. The plumbed system is the type of system selected most often because of the unlimited water supply. Pipe Sizing and Material In order to supply the required flow rate to a shower, a minimum pipe size of 1 in. (25 mm) is required by code, with 1¼ in. (30 mm) recommended. If the device is a combination unit, a 1¼-in. size should be considered as minimum. An emergency eye/face wash requires a minimum ½ in. (13 mm) pipe size. Except in rare cases where multiple units are intended to be used at once, the piping system size should be based on only one unit operating. The entire piping system is usually a single size pipe based on the requirements of the most remote fixture.

discharge most of the water into the adjacent sink. Combination units have an attached eye/face wash also discharge water on the floor. There are different methods of disposing of the water resulting from an emergency device depending on the facility. The basic consideration is whether to provide a floor drain adjacent to a device to route that water from the floor to a drainage system. It is accepted practice not to provide a floor drain at an emergency shower. Experience has shown in most cases, particularly in schools and laboratories, it is easier to mop up water from the floor in the rare instances emergency devices are used rather than add the extra cost of a floor drain, piping and a trap primer. Considerations include: 1. If the drain is not in an area where frequent cleaning is done, the trap may dry out, allowing odors to be emitted. 2. Is there an available drainage line in the area of the device? 3. Can the chemical, even in a diluted state, be released into the sanitary sewer system or must it be routed to a chemical waste system for treatment? 4. Must purification equipment be specially purchased for this purpose? Installation Requirements for Drench Equipment The need to provide emergency drench equipment is determined by an analysis of the hazard by design professionals or health or safety personnel and by the use of common sense in conformance with OSHA, CFR, and other regulations for specific occupations. Judgment is necessary in the selection and location of equipment. Very often, facility owners have specific regulations for its need and location. Dimensional Requirements The mounting height of all equipment, as illustrated in ANSI Z358.1, is shown in Figure 2. If the shower head is free-standing, the generally accepted dimension for the mounting height is 7 ft 0 in. (2.17 m) above the floor. Generally accepted clearance around showers and eye/face washes is illustrated in ­Figure 3. A wheelchair-accessible, free-standing, combination unit is illustrated in Figure 4. Equipment Location The location of the emergency drench equipment is crucial to the immediate and successful first-aid treatment of an accident victim. It should be located as close to the potential hazard as is practical without being affected by the hazard itself or potential accidental conditions, such as a large release or spray of chemiJULY/AUGUST 2006 

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CONTINUING EDUCATION: Life-Safety Systems Figure 4  Wheelchair-Accessible Shower Eyewash Equipment Simpo PDF Merge andandSplit Unregistered

Traveling through rooms that may have locked doors to

Version - http://www.simpopdf.com reach equipment shall be avoided, except placing emergency showers in a common corridor, such as outside individual laboratory rooms, is accepted practice. Care should be taken to avoid locating the shower in the path of the swinging door to the protected room to prevent personnel coming to the aid of the victims from knocking them over. Emergency eye/face washes should be located close to the potential source of hazard. In laboratories, accepted practice is to have 1 sink in a room fitted with an eyewash on the counter adjacent to the sink. The sink cold-water supply provides water to the unit. The eyewash could be designed to swing out of the way of the sink if desired. Visibility of Devices High visibility must be considered in the selection of any device. The recognition methods usually selected are high-visibility signs mounted at or on the device; having the surrounding floors and walls painted a contrasting, bright color; and having the device in a bright, well lit area on the plant floor to help a victim identify the area and help in first-aid activities.

cals resulting from an explosion or a pipe and tank rupture. Another location problem is placement adjacent to electrical equipment. Location on normal access and egress paths in the work area will reinforce the location to personnel, who will see it each time they pass. There are no requirements in any code pertaining to the location of any drench equipment in terms of specific, definitive dimensions. ANSI code Z-358.1 requires emergency showers be located a maximum distance of either 10 seconds travel time by an individual or no more than 75 ft (22.5 m) from the potential protected hazard, whichever is shorter. If strong acid or caustic is used, the equipment should be located within 10 ft (3 m) of the potential source of the hazard. The path to the unit from the hazard shall be clear and unobstructed, so impaired sight or panic will not prevent clear identification and access. There is no regulation as to what distance could be covered by an individual in 10 seconds. There are also no specific provisions for the physically challenged. Since there are no specific code requirements for locating drench equipment, good judgment is required. Accepted practice is to have the equipment accessible from three sides. Anything less generally creates a “tunnel” effect that makes it more difficult for the victim to reach the equipment. It should be located on the same level as the potential hazard when possible.   Plumbing Systems & Design 

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Number of Stations The number of drench-equipment devices provided in a facility is a function of the number of people in rooms and areas with potential exposure to any particular hazard at any one time, based on a worst-case scenario. It is rare for more than one combination unit to be installed. It is important to consider if a group of individuals has potential exposure to a specific hazard, more than one drench unit may be required. Consulting with the end user and the safety officer will provide a good basis for the selection of the type and number of equipment. Generally, one shower can be provided between an adjacent pair of laboratories, with emergency eye/face washes located inside each individual laboratory. In open areas, it is common practice to locate emergency equipment adjacent to columns for support. Water Temperature Code now requires tempered water of approximately 85°F be supplied to equipment. A comfortable range of 60 to 95°F (15 to 35°C) is mentioned in the code. For most indoor applications, this temperature range is achieved because the interior of a facility is heated in the winter and cooled in the summer to approximately 70°F (20° C). Since the water in the emergency drench system is stagnant, it assumes the temperature of the ambient air. A generally accepted temperature of between 80 and 85°F (27 and 30°C) has been established as a “comfort zone” and is now the recommended water temperature. The body will attempt to generate body heat lost if the drenching fluid is at a temperature below the comfort zone. The common effect is shivering and increased heart rate. In fact, most individuals are uncomfortable taking a shower with water at about 60°F (15°C). With the trauma induced by an accident, the effect is escalated. Another consideration is the potential chemical reaction and/or acceleration of reaction with flushing water or water at PSDMAGAZINE.ORG

a particular temperature. Where the hazard is a solid, such as the respirator. The most common operating range for systems is Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com radioactive particles, that can enter the body through the pores, between 90 and 110 psig (620 and 760 kPa). a cold-water shower shall be used in spite of its being uncomMuch of the equipment used in the generation, treatment, fortable. It is necessary to obtain the opinions of medical and and distribution of compressed air for breathing-air systems is hygiene personnel where any doubt exists about the correct use common to that for medical/surgical air discussed in the “Comof water or water temperature in specific facilities. pressed-Gas Systems” chapter. Where showers are installed outdoors, or indoors where heatCodes and Standards ing is not provided, the water supplying the showers must be 1. OSHA: 29 CFR 1910. tempered if the air temperature is low. Manufacturers offer a 2. CGA: commodity specifications G-7 and G-7.1. variety of tempering methods, including water-temperature 3. Canadian Standards Association (CSA). maintenance cable similar to that used for domestic hot-water 4. National Institute of Occupational Safety and Health systems for this purpose and mixing valves with hot and cold(NIOSH). water connections. In remote locations, complete self-contained 5. Mine Safety and Health Act (MSHA). units are available with storage tanks holding and maintaining 6. NFPA: NFPA-99, Medical Compressed Air. heated water. 7. DOD (Department of Defense): Where applicable. Protection Against Temperature Extremes 8. ANSI: Z-88.2, Standard for Respiratory Protection. In areas where freezing is possible and water drench equipment 9. Code of Federal Regulations (CFR). is connected to an above-ground, plumbed water supply, freeze protection is required. This is most often accomplished by using Breathing-Air Purity electric heating cable and providing insulation around the Air for breathing purposes supplied from a compressor or a entire water-supply pipe and the unit itself. It is recommended pressurized tank must comply, as a minimum, with quality the water temperature be maintained at 85°F (20°C). verification level grade D in CGA G-7.1 (ANSI Z-86.1). Table 1, For exterior showers located where freezing is possible, the from ANSI/CGA G-7.1, lists the maximum contaminant levels water supply shall be installed below the frost line and a freeze- for various grades of air. proof shower shall be installed. This type of shower has a method For grade D quality air, individual limits exist for condensed of draining the water above the frost line when the water to the hydrocarbons, carbon monoxide, and carbon dioxide. Particudrench equipment is turned off. When a number of drench-equipment Table 1 Maximum Contaminant Levels for Various Grades of Air (in ppm [mole / mole] unless shown otherwise) devices are located where low temperature is common, a circulating tempered-water supply Limiting Characteristics A K L D E G J M N should be considered. This uses a water heater atm / atm / atm / atm / atm / atm / atm / atm / atm / and a circulating pump to supply the drench Percent O2 balancea 19.5 - 19.5 - 19.5 - 19.5 - 20 - 19.5 - 19.5 - 19.5 - 19.5 23.5 23.5 23.5 23.5 22 23.5 23.5 23.5 23.5 equipment. The heater shall be capable of gen- predominantly N2b Water, ppm (v / v) 200 50 1 3 erating water from 40 to 80°F at a rate of 30 gpm Dew point, °F b -33 -54 -104 -92 (or more if more than one shower could oper- Oil (condensed) (mg / m3 ate simultaneously). at NTP) 5c 5c Noned e,f Carbon monoxid 10 10 5 1 1 10 In areas where the temperature may get too None high, it is accepted practice to insulate the Odor f Carbon dioxide 1000 500 500 0.5 1 500 water-supply piping. Total hydrocarbon content (as methane) 25 25 15 0.5 1 Breathing-Air Systems Nitrogen dioxide Nitric 2.5 0.1 0.5 2.5 oxide General Sulfur dioxide 2.5 0.1 5 Breathing-air systems supply air of a specific Halogenated Solvents 10 0.1 minimum purity to personnel for purposes Acetylene 0.05 of escape and protection after exposure to Nitrous oxide 0.1 a toxic environment resulting from an acci- USP Yes dent or during normal work where conditions Source:  ANSI / CGA G-7.1.ANSI 2-86.1, Table 1. make breathing the ambient air dangerous. Note:  The 1973 edition of CGA G-7.1 listed nine quality verification levels of gaseous air, lettered A to J, and two quality verification levels As defined by 30 CFR 10, a toxic environment of liquid air, lettered A and B. Some of those letter designations were dropped from the 1989 edition, since they no longer represent major has air that “may produce physical discomfort volume usage by industry. Four new letter designations, K, L, M, and N, have been added to reflect current specifications. To get a listing of immediately, chronic poisoning after repeated quality verification levels dropped, see CGA-7-1-1973 or contact the Compressed Gas Association. a The term atmospheric (atm) denotes the oxygen content normally present in atmospheric air; the numerical values denote the oxygen exposure, or acute adverse physiological symplimits for synthesized air. toms after prolonged exposure.” b The water content of compressed air required for any particular quality verification level may vary with the intended use from saturated to very dry. For breathing air used in conjunction with a self-contained breathing apparatus in extreme cold where moisture can This section discusses the production, puricondense and freeze, causing the breathing apparatus to malfunction, a dew point not to exceen -50°F (63 ppm v / v), or 10° lower fication, and distribution of a low-pressure than the coldest temperature expected in the area, is required. If a specific water limit is required, it should be specified as a limiting breathing air and individual breathing devices concentration in ppm (v / v) or dew point. Dew point is expressed in °F at 1 atmosphere pressure absolute, 101 kPa abs. (760 mm Hg). used to provide personnel protection only c Not required for synthesized air whose oxygen and nitrogen components are produced by air liquefaction. when used with supplied air systems. Low pres- d Includes water. sure for breathing air refers to compressed air e Not required for synthesized air when the nitrogen component was previously analyzed and meets National Formulary (NF) specification. pressures up to 250 psig (1725 kPa) delivered to f Not required for synthesized air when the oxygen component was produced by air liquefaction and meets United States Pharmacopeia

}

(USP) specification.

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CONTINUING EDUCATION: Life-Safety Systems lates and water vapor, whose allowable quantities have not been Constant-Flow System Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com established, must also be controlled because of the effects they Also known as a “continuous-flow system,” the constant-flow may have on different devices of the purification system, on the system provides a continuous flow of purified air through perpiping system, and on the end user of the equipment. sonnel respirators to minimize the leakage of contaminants into the respirator and to ventilate the respirator with cool or warm Contaminants Condensed Hydrocarbons  Oil is a major contaminant in air depending on conditions. This system could be used in a wide variety of areas, ranging breathing air. It causes breathing discomfort, nausea, and, in from least harmful to most toxic, depending on the type of resextreme cases, pneumonia. It can also create an unpleasant pirator selected. taste and odor and interfere with an individual’s desire to work. In addition, the oxidation of oil in overheated compressors can produce carbon monoxide. A limit of 5 ppm has been established. Some types of reciprocating and rotary-screw compressors put oil into the airstream as a result of their operating characteristics. Accepted practice is to use only oil-free air compressors in order to eliminate the possibility of introducing oil into the airstream. Carbon Monoxide  Carbon monoxide is the most toxic of the common contaminants. It enters the breathing-air system through the compressor intake or is produced by the oxidation of heated oil in the compressor. Carbon monoxide easily combines with the hemoglobin in red blood cells, replacing oxygen. The lack of oxygen causes dizziness, loss of motor control, and loss of consciousness. A limit of 10 ppm in the airstream has been established based on NIOSH standards. Carbon Dioxide  Carbon dioxide is not considered one of the more dangerous contaminants. Although the lungs have a concentration of approximately 50,000 ppm, a limit of 1,000 ppm has been established for the breathing airstream. Water and Water Vapor  Water vapor enters the piping system through the air compressor intake. Since no upper or lower limits have been established by code, the allowable concentration is governed by specific operating requirements of the most demanding device in the system, which is usually the CO converter, or the requirement of being 10°F lower than the lowest possible temperature the piping may experience. After compression, water vapor is detrimental to the media used to remove CO. The dew point of the airstream must be greatly lowered at this point in order to provide the highest efficiency possible for this device. Water vapor is removed to such a low level that breathing air with this level of humidity will prove uncomfortable to users. After purification, too much humidity will fog the faceplate of a full face mask. It will also cause freeze-up in the pipeline if the moisture content of the airstream in the pipe has a dew point that is higher than the ambient temperature of the area where the compressed-air line is installed. Solid Particles  Solid particles known as “particulates” can enter the system through the intake. They are released from non-lubricated compressors as a result of friction from carbon and Teflon material used in place of lube oils. No limits on particulates have been established by code. Odor  There is no standard for odor measurement. A generally accepted requirement is that there be no detectable odor in the breathing air delivered to the user. This requirement is subjective and will vary with individual users. Types of System There are three basic types of breathing-air system: constant flow, demand flow, and pressure demand.   Plumbing Systems & Design 

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Demand-Flow System The demand-flow system delivers purified air to personnel respirators only as the individual inhales. Upon exhalation, the flow of air is shut off until the next breath. Demand-flow systems automatically adjust to an individual’s breathing rate. This system requires tight-fitting respirators. Its application is generally limited to less harmful areas because the negative pressure in the respirator during inhalation may permit leakage of external contaminants. This system is designed for economy of air use during relatively short-duration tasks and is usually supplied from cylinders. Pressure-Demand System A pressure-demand system delivers purified air continuously through personnel respirators with increased air flow during inhalation. By continuously providing a flow of air above atmospheric pressure, leakage of external contaminants is minimized. This system also uses tight-fitting respirators, but the positive pressure aspect allows them to be used in more toxic applications. System Components The breathing-air system consists of a compressed-air source, purification devices and filters to remove unwanted contaminants from the source airstream, humidifiers to introduce water vapor into the breathing air, the piping distribution network, respirator outlet manifolds, respirator hose, and the individual respirators used by personnel. Alarms are needed to monitor the quantity of contaminants and other parameters of the system as a whole and to notify personnel if necessary. Compressed-Air Source The source of air for the breathing-air system is an air compressor and/or high-pressure air stored in cylinders. Cylinders use ambient air, which is purified to reduce or eliminate impurities to the required level, and compress it to the desired pressure. A typical schematic detail is shown in Figure 5. Air Compressor  The standard for air compressors used to supply breathing air shall comply with the requirement for oilfree medical gas discussed in the “Compressed-Gas Systems” chapter. Medical-gas type compressors are used because these systems as a whole generate far fewer contaminants than other types of system. When a liquid-ring compressor is used, it has the advantage of keeping the temperature of the air leaving the unit low. It is also possible to use any type of compressor for this service, provided the purification system is capable of producing air meeting all the requirements of code. The air-compressor assembly consists of the intake assembly (including the inlet filter), the compressor and receiver, the aftercooler, and the interconnecting water-seal supply and the other ancillary piping. All of these components are discussed in the “Specialty Gases for Laboratories” section. PSDMAGAZINE.ORG

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Source: Courtesy of Nomonox.

Figure 5  System with Standby High-Pressure Breathing Air Reserve Simpo PDF Merge and Split Unregistered

Air compressors have a high first cost and are selected if the use of air for breathing is constant and continuous, making the use of cylinders either too costly or too maintenance intensive because of the frequent changing of cylinders. Storage Cylinder  When high-pressure cylinders are used either as a source or as an emergency supply of breathing air, they shall be filled with air conforming to breathing-air standards. The regulator should be set to about 50 psi (340 kPa) depending on the pressure required to meet system demands and losses. The cylinders have a low initial cost and are not practical to use if there is continuous demand. Cylinders are best suited to intermittent use for short periods of time or as an emergency escape backup for a compressor. Aftercooler Some components of the purification system require a specific temperature in order to function properly. Depending on the type of compressor selected and the type of purification necessary, the temperature of the air leaving the compressor may have to be reduced. This is done with an aftercooler. Aftercoolers can be supplied with cooling water or use air as the cooling medium. Water, if recirculated, is the preferred method. The manufacturer of both the compressor and purification system should be consulted as to the criteria used and the recommended size of the unit. Purification Devices The contaminants that are problematic for breathing-air systems must be removed. This can be done with separate devices used to remove individual contaminants or with a prepiped assembly of all the necessary purification devices, commonly referred to as a “purification system,” which requires only an inlet and

outlet air connection. For breathing-air systems it is commonly done with a purification system. The individual purification methods used to remove specific contaminants are the same as those discussed in the “Compressed-Gas Systems” chapter. For breathing air, oil and particulates are removed by coalescing and other filters, water is removed by desiccant or refrigerated dryers, and carbon monoxide is removed by chemical conversion to carbon dioxide using a catalytic converter. Carbon Monoxide Converter  The purpose of the converter is to oxidize carbon monoxide and convert it into carbon dioxide, which is tolerable in much greater quantities. This is typically accomplished by the use of a catalyst usually consisting of manganese dioxide, copper oxide, cobalt, and silver oxide in various combinations and placed inside a single cartridge. The material is not consumed but does become contaminated. The conversion rate greatly decreases if any oil or moisture is present in the airstream. Therefore, moisture must be removed before air enters the converter. Catalyst replacement is recommended generally once a year since it is not possible to completely control all contaminants that contribute to decreased conversion. Moisture Separator  Water and water vapor are removed by two methods, desiccant and refrigerated dryers. The most common desiccant drying medium is activated alumina. For a discussion of air-drying methods, refer to the “Compressed-Gas Systems” systems. Odor Remover  Activated, granular charcoal in cartridges is used for the removal of odors. Particulates Remover  Particulates are removed by means of in-line filters. Generally accepted practice eliminates particulates 1 µ and larger from the piping system .

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CONTINUING EDUCATION: Life-Safety Systems 4. Level D protection is used where special respiratory or skin Humidifier Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com protection is not required but a rapid increase of contamiWhen water is removed from the compressed airstream prior nant level or degradation of ambient oxygen content is posto catalytic conversion, the dryer produces very dry air. If the sible. breathing-air system is intended to be used for long periods of time, very low humidity will dry the mucous membranes of If the hazard cannot be identified, it must be considered an the eyes and mouth. Therefore, moisture must be added to the immediate danger to life and health (IDLH). This is a condition airstream to maintain recommended levels. Humidifiers, often that exists when the oxygen content falls below 12.5% (95 ppm called “moisturizers,” are devices that inject the proper level of O2) or where the air pressure is less than 8.6 psi (450 mm/Hg), water vapor into an airstream. Some require a water connec- which is the equivalent of 14,000 ft (4270 m). tion. There are five general types of respirator available, as follows: A recommended level of moisture is 50% relative humidity Mouthpiece Respirators  Used only with demand type in the compressed airstream. Care must be taken not to route systems, mouthpiece respirators are designed only to deliver the air-distribution piping through areas capable of having tem- breathable air. They offer no protection to the skin, eyes, or face. peratures low enough to cause condensation. If the routing is Their use is limited to areas where there is insufficient oxygen impossible to change, a worker will have shorter periods of time and no other contaminants could affect the eyes and skin. on the respirator. Half-Face-Piece Respirators  Half-face-piece respirators cover the nose and mouth and are designed primarily for Combination Respirator Manifold and Pressure Reducer demand and pressure type systems. They are usually tightfitting This is a single component with multiple quick-disconnect outlets providing a convenient place both to reduce the pressure of and provide protection for extended periods of time in atmothe distribution network and to serve as a connection point for spheres that are not harmful to the eyes and skin. Often worn several hoses. A pressure gauge should be installed on the man- with goggles, these respirators are limited to areas of relatively ifold to ensure the outlet pressure is within the limits required low toxicity. Full-Face-Piece Respirators  Full-face-piece respirators by the respirator. cover the entire face and are designed for use with constant-flow Respirator Hose and pressure-demand systems. They are tightfitting and suitable The respirator hose is flexible and is used to connect the resfor atmospheres of moderate and high toxicity. They are usually pirator worn by an individual to the central-distribution piping used in conjunction with full protective clothing for such tasks system. Code allows a maximum hose length of 300 ft (93 m) as chemical-tank cleaning where corrosive and toxic gas, mist, Personnel Respirators and liquids may be present. Since the face masks provide proThere are two general categories of respirator used for individual tection to the face and eyes, they are also suitable for other tasks, protection: air purifying and supplied air. such as welding and the inspection of tanks and vessels where The air-purifying type of respirator is portable and has self- there is an oxygen-deficient atmosphere. contained filters that purify the ambient air on a demand basis. Hood-and-Helmet Respirators  Hood-and-helmet respiraThe advantages to its use are that it is less restrictive to move- tors cover the entire head and are normally used with a conments and is light in weight. Disadvantages are that it must not stant-flow system. They are loose fitting and suitable only for be used where gas or vapor contamination cannot be detected protection against contaminants such as dust, sand, powders, by odor or taste and in an oxygen-deficient atmosphere. This and grit. Constant flow is necessary to ventilate the headpiece type of respirator is outside the scope of this book, it is men- and to provide sufficient air pressure to prevent contaminants tioned only because of its availability. from entering the headpiece. The type of respirator selected depends on the expected Full-Pressure Suits  Full-pressure suits range in design from breathing hazards. In the choice of a respirator, the highest loose-fitting, body-protective clothing to completely sealed, expected degree of hazard, applicable codes and standards, astronaut-like suits that provide total environmental life supmanufacturer recommendations, suitability for the intended port. They are designed to be used only with constant-flow systask and the comfort of the user are all important consider- tems and are suitable for the most toxic and dangerous environations. ments and atmospheres. The EPA Office of Emergency and Remedial Response has Component Selection and Sizing identified four levels of hazard at cleanup sites involving hazardous materials and lists guidelines for the selection of protec- Breathing-Air Source Air Compressor  The air-compressor size is based on the hightive equipment for each: 1. Level A calls for maximum available protection, requiring a est flow rate, in cfm (L/min), required by the number and type of respirators intended to be used simultaneously and the minipositive-pressure, self-contained suit, generally with a selfcontained breathing apparatus worn inside the protective mum pressure required by the purification system. suit. The following general flow rates are provided as a prelimi2. Level B protection is required when the highest level of nary estimate for various types of respirator. Since there is a respiratory protection is needed but a lower level of skin wide variation in the pressure and flow rates required for variprotection is acceptable. ous types of respirator, the actual figures used to size the system 3. Level C protection uses a full face piece and air-purifying must be based on the manufacturer’s recommendations for the respiratory protection with chemical resistant, disposal specific respirators selected. garments. This is required when the contaminant is known 1. 4 scfm (113 L/min) for pressure-demand respirators. and the level is relatively constant. Typical of its uses is for 2. 6 scfm (170 L/min) for constant-flow respirators. asbestos removal. 10  Plumbing Systems & Design 

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3. Up to 16 scfm (453 L/min) for flooded-hood respirators. The converter is sized based on the flow rate of the system. Simpo PDF Merge and Split Unregistered Version -Coalescing http://www.simpopdf.com Filter/Separator  The coalescing filter/separa4. Up to 35 scfm (990 L/min) for flooded suits. tor is a single unit that removes large oil and water drops and 5. Add 15 scfm (425 L/min) of air for suit cooling if used. particulates from the airstream before the air enters the rest of High-Pressure Storage Cylinder  High pressure cylinders the system. It is selected on the basis of maximum system presare used either to supply air for normal operation to a limited sure, flow rate, and the expected level of contaminants leaving number of personnel for short periods of time or as an emerthe air compressor, using manufacturer’s recommendations. If gency supply to provide a means of escape from a hazardous an oil-free compressor is used, a simple particulate filter could area if the air compressor fails. The main advantage to using be substituted for the coalescing filter. cylinders is the air in the cylinders is prepurified, and no further Dryers (Moisture Separators) purification of the air is necessary. The number of cylinders is based on the simultaneous use of Desiccant Dryers — The two types of desiccant media dryer most respirators, the cfm (L/min) of each and the duration, in min, commonly used are the single-bed dryer, which is a disposable the respirators are expected to be used, plus a 10% safety factor. cartridge, and the continuous-duty, two-bed dryer. When two-bed dryers are used, a portion of the air from the The total amount of compressed air in the cylinders should not be allowed to decrease too low. A low-pressure alarm should compressor is used for drying one bed while the other is in sersound when pressure falls to 500 psig (3450 kPa) in a cylinder vice. The compressor must be capable of producing enough air normally pressurized to 2400 psig (16 500 kPa) when filled to for both the system and dryer use. The single-bed dryer has a lower first cost but a higher operatcapacity. ing cost. The disposable cartridge often is combined with other Example 9-1 purification devices into a single, prepiped unit. An indicator is Establish the number of cylinders required for an emergency often added to the media so the need for replacement is indisupply of air for 8 people using constant-flow respirators require cated by a color change. 15 min to escape the area. Disposable units are best suited for short durations or occa1. 8 × 6 × 15 = 720 scfm + 72 (10%) = 792 scfm total required sional use, such as for replacement of a main unit during peri2. Next, find the actual capacity of a single cylinder at the ods of routine service. Because of their generally small size, only selected high pressure, generally 2400 psi (16 500 kPa), a limited number of respirators can be supplied from a single and divide the capacity of each cylinder into the total scfm unit. Other considerations are that these disposable units have required to find the number of cylinders required. a limited capacity, in total cfh, they can process. Manufacturers’ 3. If 1 cylinder has 225 scf, 792 ÷ 225 = 3.5. Use 4 cylinders. recommendations must be used in the selection of the size and number of replacement cartridges required for any application. Purification Components The two-bed unit, commonly called a “heatless dryer,” is simiThe air used to fill breathing-air cylinders is purified before being compressed. Breathing air produced by air compressors lar in principle to that discussed in the “Compressed-Gas Sysrequires purification to meet minimum code standards for tems” chapter. Such units are used for continuous duty. The two factors contributing to the breakdown of media are breathing air. Prior to the selection of the purification equipment, several fast-drying cycles and high air velocity. If a desiccant dryer is samples of the air where the compressor intake is to be located selected, the velocity of air through the unit shall conform to should be taken so specific contaminants and their amounts manufacturer’s recommendations. Velocity should be as low can be identified. The ideal situation is to have the tests taken at as is practical to avoid fluidizing the bed. High velocity requires different times of the year and different times of the day. These more cycles for drying, which means wasting more air. If the tests quantify the type and amount of contaminants present at size of the dryer is a concern, more drying cycles means smaller the intake. With this information known, the purification sys- dryer beds. Longer drying cycles reduce component wear. Refrigerated Dryers — Refrigerated dryers are used if there is tems needed to meet code criteria can be chosen. The other no requirement for a nitrous oxide converter and if the 35–39°F requirement is the highest flow rate that can be expected. With dew point produced is 10°F below the lowest ambient air temthese criteria, the appropriate size and types of purifier can be perature where any pipe will be installed. The refrigerated dryer selected. is less efficient than the desiccant dryer. Its advantages are that The most commonly used method of purification is an assemall the air produced by the compressor is available to the system bly of devices called a “purification system” specifically chosen and it has a lower pressure loss. and based on the previously selected criteria. Manufacturers’ When refrigerated dryers are preferred, several purification recommendations are commonly followed in the selection and devices are often combined into a single unit, including the sizing of the assembly. Carbon-Monoxide Converter  The requirement for installa- refrigeration unit, filter/separator for oil and water, and a chartion of a carbon-monoxide converter is rare. The need for a con- coal filter for odor removal. This unit produces air that is lower verter is based on tests of the air at the proposed location of the in temperature than the inlet air. If the breathing-air distribution piping is to be routed through compressor intake. Another source of information is the EPA, which has conducted tests in many urban areas throughout the an area of lower temperature, the pressure dew point of the air country. Another indication that installation may be necessary must be reduced to 10°F lower than the lowest temperature is the use of a non-oil-free compressor. Good practice requires expected. Odor Remover  Odors are not usually a problem, but their the installation of a converter if there is an outside chance the level of carbon monoxide may rise above the 10 ppm limit set removal is provided for as a safeguard. The activated charcoal cartridges remove odors are selected using manufacturers’ recby code. JULY/AUGUST 2006 

Plumbing Systems & Design  11

CONTINUING EDUCATION: Life-Safety Systems Low-Air-Pressure Monitor  The low-air-pressure monitor ommendations based on the maximum calculated flow rate of Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com the breathing-air system. The cartridges must be replaced peri- must sound an alarm when the pressure in the system reaches odically. a predetermined low point. This set point allows the users of the breathing-air system to leave the area immediately while Humidifiers Often called a “moisturizer,” a humidifier is required to increase still being able to breathe from the system. For cylinder storage, the relative humidity of the breathing air to approximately 50% this set point is about 500 psig in the cylinders. For a compresif required. The unit is selected using the increase in moisture sor system, the alarm should sound when the pressure falls to required for the airstream and the flow rate of air. Caution must a point 10 psig below the pressure set to start the compressor. be used so as not to increase the dew point of the compressed This should also switch over to the emergency backup supply air above a temperature 10°F lower than the lowest temperature if one is used. If no backup is used, the pressure set point shall be 5 psig higher than the minimum required by the respirators in any part of the facility the pipe is routed through. being used. Respirator Hose Dew-Point Monitor  A dew-point monitor is used to meaThe respirator hose most often used to connect the respirator sure the dew point and sound an alarm if it falls to a low point, worn by an individual to the central-distribution piping system set by a health officer, that might prove harmful to the users. It is is 3⁄8 in. (10 mm) in size. Code allows a maximum hose length of required to alarm if the dew point reaches a point high enough 300 ft (93 m). The most common lengths are between 25 and 50 to freeze in some parts of the system. ft (7.75 and 15.5 m). High-Temperature Air Monitor  Some purifiers or purifier components will not function properly if the inlet air temperaSystem Sizing Criteria ture is too high. The set point is commonly 120° F but will vary System Pressure  The outlet pressure of the compressor shall among different manufacturers and components. be within the range required by the purification system. TypiFailure-to-Shift Monitor  This monitor is placed on descally, the pressure is approximately 100 psi (70.3 kg/cm2). The iccant dryers to initiate an alarm if the unit fails to shift from precise range of pressure and flow rate shall be obtained from the saturated dryer bed to the dry bed when regeneration is the purification system manufacturer selected for the project. required. The pressure in the distribution system should be as high as possible to reduce the size of the distribution-piping network. Code requires the pressure be kept below 125 psi (88 kg/cm2). The distribution-piping pressure range is usually 90 to 110 psig (620 to 760 kPa) available in the system after the purifier. The pressure required at the respirator ranges from approximately 15 psig for pressure-demand respirators to 80 psig for full-flooded suits that require cooling. The actual requirements can be obtained only from the manufacturer of the proposed equipment because of the wide variations possible. Pressureregulating valves shall be installed to reduce the pressure to the range acceptable to the respirator used. Often, this reduction is done at the respirator manifold, if one is used, or, if a single respirator type with a single pressure is used throughout the facility, a single regulator can be installed to reduce the pressure centrally. Pipe Sizing and Materials  The most commonly used pipe is type L copper tubing, with wrought copper fittings and brazed joints. For pipe sizing, follow the sizing procedure discussed in the “Compressed-Gas Systems” chapter. The number of simultaneous users must be obtained from the facility. No diversity factor should be used. Alarms and Monitors The following alarms and monitors are often provided: CO Monitor  Usually included as a built-in component, this monitor measures the CO content of the airstream and sounds an alarm when the level reaches a predetermined high set point. Oxygen-Deficiency Monitor  Used as a precautionary measure in an area where respirators are not normally required, the oxygen monitor measures the oxygen content of the air in a room or other enclosed area and sounds an alarm to alert personnel when the level falls below a predetermined level. Usually, several alarm points are annunciated prior to reaching a level low enough to require the use of respirators. 12  Plumbing Systems & Design 

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Plumbing Systems & Design  13

CONTINUING EDUCATION Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com Continuing Education from Plumbing Systems & Design Kenneth G.Wentink, PE, CPD, and Robert D. Jackson

Now Online! Starting with this issue, the technical article you must read to complete the exam will be located at www.psdmagazine.org. The following exam and application form also may be downloaded from the Web site. Reading the article and completing the form will allow you to apply to ASPE for CEU credit. For most people, this process will require approximately one hour. If you earn a grade of 90 percent or higher on the test, you will be notified that you have logged 0.1 CEU, which can be applied toward the CPD renewal requirement or numerous regulatory-agency CE programs. (Please note that it is your responsibility to determine the acceptance policy of a particular agency.) CEU information will be kept on file at the ASPE office for three years. Note: In determining your answers to the CE questions, use only the material presented in the corresponding continuing education article. Using information from other materials may result in a wrong answer.

About This Issue’s Article The July/August 2006 continuing education article is “Life-Safety Systems,” Chapter 8 of Pharmaceutical Facilities Plumbing Systems by Michael Frankel. This chapter describes water-based emergency drench equipment and systems commonly used as a first-aid measure to mitigate the effects of such an accident. Also described are the breathing-air systems that supply air to personnel for escape and protection when they are exposed to either a toxic environment resulting from an accident or normal working conditions that make breathing the ambient air hazardous. You may locate this article at www.psdmagazine.org. Read it, take the following exam, and submit it to the ASPE office to potentially receive 0.1 CEU (comparable to 1.0 PDH).

CE Questions—“Life-Safety Systems” (PSD 134)

PSD 134

Do you find it difficult to obtain continuing education units (CEUs)? Through this special section in every issue of PS&D, ASPE can help you accumulate the CEUs required for maintaining your Certified in Plumbing Design (CPD) status.

1. The recommended supply pipe size to an emergency shower is ________. a. ¾ inch,  b. 1 inch,  c. 1¼ inches,  d. 1½ inches

8. The code-required flow rate from an emergency shower is ___________ gpm. a. 25,  b. 30,  c. 35,  d. 40

2. Since oil is a major contaminant in breathing air systems,  the maximum allowed is ___________. a. 5 ppm,  b. 5 ppb,  c. 10 ppm,  d. 10 ppb

9. How many cylinders of air are required for an emergency supply of air for eight people using pressure demand respirators needing 15 minutes to escape the area? a. 2.3 use 3 cylinders b. 3.5 use 4 cylinders c. 4.7 use 5 cylinders d. cannot be determined

3. An emergency shower drench hose is used to _________. a. wash the floor after a chemical spill b. irrigate the body under the clothing prior to removal of the clothing c. provide a means to fill mop bucket d. none of the above 4. A failure-to-shift monitor is ___________. a. used to control multi-stage compressors b. used to initiate an alarm if a desiccant dryer fails to shift from the saturated bed to the dry bed when regeneration is required c. used to coordinate the output signal of the low air pressure monitor and the refrigerated dryer d. not required on modern systems 5. In areas where strong acid or caustic is used, the emergency shower and eyewash equipment should be located within ___________ feet of the potential source of the hazard per ANSI code Z-358.1. a. 5,  b. 10,  c. 15,  d. 20 6. What is the established comfort zone water temperature for emergency drench equipment? a. 70–75°F,  b. 75–80°F,  c. 80–85°F,  d. 85–90°F 7. As defined by “30 CFR 10,” a toxic environment has air that ___________. a. may produce physical discomfort immediately b. may cause chronic poisoning after repeated exposure c. may cause acute adverse physiological symptoms after prolonged exposure d. all of the above 14  Plumbing Systems & Design 

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10. Refrigerated dryers are used ___________. a. when money is of no concern b. when order removal is not required c. when system pressure is high enough to accommodate them d. none of the above 11. The minimum diameter of the spray pattern from an emergency shower,  measured at 60 inches above the surface on which the user stands,  is ___________ inches. a. 18,  b. 20,  c. 22,  d. 24

12. An oxygen content below 12.5 percent and/or a pressure of 8.6 psi should be considered ___________. a. as a Level A hazard as established by the EPA b. as a Level C hazard as established by the EPA c. as a Level E hazard as established by the EPA d. as an immediate danger to life and health

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Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com Plumbing Systems & Design Continuing Education Application Form This form is valid up to one year from date of publication. The PS&D Continuing Education program is approved by ASPE for up to one contact hour (0.1 CEU) of credit per article. Participants who ear a passing score (90 percent) on the CE questions will receive a letter or certification within 30 days of ASPE’s receipt of the application form. (No special certificates will be issued.) Participants who fail and wish to retake the test should resubmit the form along with an additional fee (if required). 1.  Photocopy this form or download it from www.psdmagazine.org. 2.  Print or type your name and address. Be sure to place your ASPE membership number in the appropriate space. 3.  Answer the multiple-choice continuing education (CE) questions based on the corresponding article found on www.psdmagazine.org and the appraisal questions on this form. 4.  Submit this form with payment ($35 for nonmembers of ASPE) if required by check or money order made payable to ASPE or credit card via mail (ASPE Education Credit, 8614 W. Catalpa Avenue, Suite 1007, Chicago, IL 60656) or fax (773-695-9007). Please print or type; this information will be used to process your credits. Name _ __________________________________________________________________________________________________ Title _______________________________________________ ASPE Membership No.____________________________________ Organization _ ____________________________________________________________________________________________ Billing Address ____________________________________________________________________________________________ City_ _______________________________________ State/Province________________________ Zip _ ____________________ Country____________________________________________ E-mail_________________________________________________ Daytime telephone_ _________________________________ Fax___________________________________________________ I am applying for the following continuing education credits:

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Life-Safety Systems (PSD 134)

Questions appear on page 14. Circle the answer to each question. Q 1. A B C D Q 2. A B C D Q 3. A B C D Q 4. A B C D Q 5. A B C D Q 6. A B C D Q 7. A B C D Q 8. A B C D Q 9. A B C D Q 10. A B C D Q 11. A B C D Q 12. A B C D

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Appraisal Questions 1. 2. 3. 4. 5. 6.

Life-Safety Systems (PSD 134) Was the material new information for you? ❏ Yes ❏ No Was the material presented clearly? ❏ Yes ❏ No Was the material adequately covered? ❏ Yes ❏ No Did the content help you achieve the stated objectives? ❏ Yes ❏ No Did the CE questions help you identify specific ways to use ideas presented in the article? ❏ Yes ❏ No How much time did you need to complete the CE offering (i.e., to read the article and answer the post-test questions)?___________________

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PSD 131

Medical Gas and Vacuum Systems

Continuing Education from Plumbing Systems & Design Kenneth G.Wentink, PE, CPD, and Robert D. Jackson

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CONTINUING EDUCATION

Medical Gas and Vacuum Systems

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General Health care is in a constant state of change, which forces the plumbing engineer to keep up with new technology to provide innovative ­ approaches to the design of medical-gas systems. In designing medi­cal-gas and vacuum systems, the goal is to provide a safe and sufficient flow at required pres­sures to the medical-gas outlet or inlet terminals served. System design and ­layout should allow convenient access by the medical staff to outlet/inlet terminals, valves, and equipment during pa­tient care or ­emergencies. This section focuses on design parameters and current standards required for the design of nonflam­mable medical-gas and vacuum systems used in therapeutic and anesthetic care. The plumbing en­gineer must determine the needs of the health-care staff. Try to work closely with the medical staff to seek answers to the following fundamental design questions at the start of a project: 1. How many outlet/inlets are requested by staff? 2. How many outlet/inlets are required? 3. Based on current conditions, how often is the outlet/inlet used? 4. Based on current conditions, what is the average duration of use for each outlet/inlet? 5. What is the proper usage (diversity) factor to be used?

Medical-Gas System Design Checklist As any hospital facility must be specially designed to meet the applicable local code require­ments and the health-care needs of the community it serves, the medical-gas and vacuum piping sys­ tems must also be designed to meet the specific requirements of each ­hospital. Following are the essential steps to a well-designed and functional medical-gas piped system, which are recommended to the plumbing engineer: 1. Analyze each specific area of the health-care fa­cility to determine the following items: A. Which piped medical-gas systems are re­quired? B. How many of each different type of medical-gas outlet/inlet terminal are required? C. Where should the outlet/inlet terminals be located for maximum efficiency and conve­nience? D. Which type and style of outlet/inlet terminal best meet the needs of the medical staff? 2. Anticipate any building expansion and plan in which direction the expansion will take place (vertically or horizontally). Determine how the medical-gas system should be sized and valved in order to accommodate the future expansion. 3. Determine locations for the various medical-gas supply sources.

A. Bulk oxygen (O2). B. High-pressure cylinder manifolds (O2, N2O or N2). C. Vacuum pumps (VAC). D. Medical-air compressors (MA). 4. Prepare the schematic piping layout locating the following: A. Zone valves. B. Isolation valves. C. Master alarms. D. Area alarms. 5. Calculate the anticipated peak demands for each medical-gas system. Appropriately size each par­ticular section so as to avoid exceeding the maximum pres­sure drops allowed. 6. Size and select the various medical-gas and vacuum supply equipment that will handle the peak demands for each system, including future expansions. If this project is an addition to an ex­isting facility, determine the following: A. What medical gases are currently provided and what are the locations and number of the stations? B. Can the current gas supplier (or the hospital’s purchasing department) furnish the consump­tion records? C. Are the capacities of the existing medical-gas supply systems adequate to handle the addi­tional demand? D. Are any existing systems valved that could be used for an extension? Are the existing pipe sizes adequate to handle the anticipated ad­ditional loads? E. What type of equipment is in use and who is the manufacturer? Is this equipment state-of-the-art? F. Is it feasible to manifold the new and existing equipment? G. What is the physical condition of the existing equipment? H. Is there adequate space available for the new medical-gas supply systems and related equip­ment at the existing location? I. Is existing equipment scheduled to be replaced? (A maintenance history of the existing equip­ment may help in this determination.)

Number of Stations The first step is to locate and count the outlet/inlets, often called “stations,” for each respective medical-gas system. This is usually done by con­sulting a program prepared by the facility plan­ner or architect. This program is a list of all the rooms and areas in the facility and the services that are re­quired in each. If a program has not been prepared, the floor plans for the proposed fa­cility shall be used. There is no code that specifically mandates the exact number of stations that must be ­provided in various areas or rooms for all health-care facilities. In fact, there is no clear consensus of opinion among medical authorities or design professionals as to how many stations are actually required in the fa­cility areas. Guidelines are

Reprinted from American Society of Plumbing Engineers Data Book Volume 3: Special Plumbing Systems, Chapter 2: “Medical Gas and Vacuum Systems.” ©2000, American Society of Plumbing Engineers. 44  Plumbing Systems & Design 

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published by the American Institute of Architects Table 1  Outlet Rating Chart for Medical-Vacuum Piping Systems Merge and Split Unregistered Version - http://www.simpopdf.com (AIA), Simpo NationalPDF Fire Protection Association (NFPA), Zone Allowances— Corridors, Free-Air Allowance, cfm Risers, Main Supply Line, and ASPE that recommend the minimum number (L/min) at 1 atmosphere Valves of stations for various services in specific areas. Simultaneous Air to Be The most often-used recommendations in deter­ Location of Medical-Surgical Vacuum Usage Factor Transported,a Per Room Per Outlet (%) cfm (L/min) mining the number of stations for hospitals are those Outlets Operating rooms: necessary to be accredited by the Joint Com­mission  Major “A” (Radical, open heart; organ for the Accreditation of Hospitals Orga­nization transplant; radical thoracic) 3.5  (100) — 100 3.5  (100) 2.0   (60) — 100 2.0   (60) (JCAHO). Accreditation is required for Medicare and   Major “B” (All other major ORs) 1.0   (30) — 100 1.0   (30) Medicaid compensation. The JCAHO publishes a   Minor 1.0   (30) — 100 1.0   (30) manual that refers to the AIA guide­lines for the mini- Delivery rooms Recovery room (post anesthesia) and mum number of stations for oxy­gen, medical air, intensive-care units (a minimum of 2 and vacuum that must be installed in order to obtain outlets per bed in each such department): — 3   (85) 50 1.5   (40) accreditation. If this is a factor for the facility, these   1st outlet at each bed   2nd outlet at each bed — 1.0  (30) 50 0.5   (15) requirements are mandatory. Other jurisdictions,   3rd outlet at each bed — 1.0  (30) 10 0.1    (3) such as state or local authori­ties, may require plans   All others at each bed — 1.0  (30) 10 0.1    (3) to be approved by local health or building officials. Emergency rooms — 1.0  (30) 100 1.0   (30) These approvals may require adhering to the state Patient rooms: — 1.0  (30) 50 0.5   (15) or local requirements and/or NFPA 99, Health-Care   Surgical   Medical — 1.0  (30) 10 0.1    (3) Facilities. — 1.0  (30) 10 0.1    (3) If accreditation or the approval of authorities is   Nurseries Treatment & examining rooms — 0.5  (15) 10 0.05   (1) not a factor, the number and area locations of sta- Autopsy — 2.0  (60) 20 0.04   (1) tions are not mandated. The actual count then will Inhalation therapy, central supply & — 1.0  (30) 10 0.1    (3) depend upon requirements determined by each instructional areas individual facil­ity or another member of the design a Free air at 1 atmosphere. team using both past experience and anticipated Table 2  Color Coding for Piped Medical Gases future use, often using the guideline recommendaGas Intended for Medical Use United States Color Canada Color tions as a starting point. Oxygen Green Green on whitea Medical-Gas Flow Rates Carbon dioxide Gray Black on gray Each station must provide a minimum flow rate for the Nitrous oxide Blue Silver on blue proper functioning of connected equipment under Cyclopropane Orange Silver on orange design and emergency conditions. The flow rates and Helium Brown Silver on brown diversity factors vary for individual stations in each Nitrogen Black Silver on black system depending on the total number of out­lets and Air Yellow* White and black on black and white the type of care provided. Vacuum White Silver on yellowa The flow rate from the total number of outlets, withGas mixtures (other than Color marking of mixtures shall be a combination of color out regard for any diversity, is called the “total conmixtures of oxygen and nitrogen) corresponding to each component gas. nected load.” If the total connected load were used for Gas mixtures of oxygen and sizing purposes, the result would be a vastly oversized nitrogen system, since not all of the stations in the facility will 19.5 to 23.5% oxygen Yellowa Black and white All other oxygen concentrations Black and green Pink be used at the same time. A di­versity, or simultane-

Source:  Compressed Gas Association, Inc. ous-use factor, is used to allow for the fact that not all a Historically, white has been used in the United States and yellow has been used in Canada to identify vacuum systems. of the stations will be used at once. It is used to reduce Therefore, it is recommended that white not be used in the United States and yellow not be used in Canada as a marking the system flow rate in conjunction with the total conto identify containers for use with any medical gas. Other countries may have differing specific requirements. nected load for siz­ing mains and branch piping to all parts of the distribution system. This factor varies for Medical-Gas System Dispensing Equipment different areas throughout any facility. Medical-gas outlet/inlet terminals  Most manufacturers of The estimated flow rate and diversity factors for various systems, medical-gas system equip­ment offer various types of medicalarea stations, and pieces of equip­ment are found in Table 1. gas outlets. These medical-gas outlets are available in various gas Total demand for medical-gas systems varies as a function of orders (e.g., O2-N2O-Air), center-line spacing, and for exposed and time of day, month, patient-care re­quirements, and facility type. ­concealed mountings. Outlet types and configurations must meet The number of stations needed for patient care is subjective and the re­quirements of the local jurisdictional authority and NFPA cannot be qualified based on physical measurements. Know­ing 99. All outlets must be properly identified and confirmed. Care the types of patient care and/or authority re­quirements will allow should also be taken to accu­rately coordinate the various pieces of placement of stations in usage groups. These groups can establish medical-gas dispensing equipment with the architect and medi­cal demand and simultaneous-use factors (diversities), which are staff involved in the given project. If the project is a renova­tion, the used in the calculation for sizing a particular system. All medical- outlet types should match existing equipment. With prefabricated gas piping systems must be clearly identi­fied using an approved patient headwall units, the medical-gas outlets are generally furcolor-coding system simi­lar to that shown in Table 2. nished by the equipment manufacturer, and it is very impor­tant that coordination be maintained by the engi­neer so that unnecesJANUARY/FEBRUARY 2006 

Plumbing Systems & Design  45

CONTINUING EDUCATION: Medical Gas and Vacuum Systems sary duplication of work is avoided. Also, with regard to the over- lets  In critical-care areas, which are generally consid­ered by Simpo PDF Merge and Splitthese Unregistered - http://www.simpopdf.com the-bed medical-gas service consoles, consoles areVersion often most individuals to be those locations of the hospital providing a specified in the electrical or equipment section of the specifica- special treatment or ser­vice for the patient (such as surgery, recovtion and medical-gas service outlets are specified, furnished, and ery, coronary, or intensive-care units), the designer’s se­lection and installed under the me­chanical contract. placement of the medical-gas service equipment must be done Gas-outlet sequence, center-line spacing, and mul­tiple-gang- very carefully in order to provide efficient work centers around the service outlets are some of the consider­ations to be taken into patient for the medical staff. account when requesting information from the various equip­ment Manufacturers of medical-gas service ­ equipment usually promanufacturers. It is more practical, in terms of both the cost of the vide a wide range of equipment that is avail­able for use in these equipment and the installa­tion, to specify and select the manufac- areas. Depending upon the customer’s preference and the availturer’s stan­dard outlet(s). Details and specifications regarding the able budget, the equipment is selected to provide the necessary individual standard outlets are usually avail­able from all manufac- in­dividual gas services and ­accessories. turers upon request. Table 3 provides a quick ­refer­ence guide for the engineer to use The existing outlets are compatible with the adapters found on as a basis for selecting the commonly used types of outlet dispensthe hospital’s anesthesia ma­chines, flow meters, vacuum regula- ing ­equipment. tors, etc. Care should be taken to make sure all future expan­sions Example 1 in the same facility have compatible equipment. The following illustrative example presents some of the most Patient head-wall systems  A recent and growing trend in important critical-care area equipment and options for the selechospital construction is the requirement for patient head-wall tion of the equipment. systems, which incorporate many services for the patient’s care. Surgery medical-gas services to be piped include: These units may include the following: 1. Oxygen. 1. Medical-gas outlets. 2. Nitrous oxide. 2. Electrical-service outlets (including emergency power). 3. Nitrogen. 3. Direct and indirect lighting. 4. Medical compressed air. 4. Nurse-call system. 5. Vacuum. 5. Isolation transformers. 6. Waste anesthetic-gas disposal. 6. Grounding outlets. Providing medical-gas service outlets in the sur­gery room may 7. Patient-monitoring receptacles. be accomplished in several ways, such as the following: 1. Ceiling outlets Individual medical-gas outlets mounted in the 8. Vacuum slide and IV brackets. ceiling with hose assemblies providing the medi­cal staff with 9. Night lights. connections from the outlets to the administering apparatus. 10. Electrical switches. This method is considered by most to be the most economiBed locator units are also available, which serve to provide cal means of providing an adequate gas service to the surgery power for the more advanced patient beds, telephone, night lights, and standard power. These units Table 3  Types of Dispensing Equipment for Specific Areas also function to protect the walls Medical Gas Outlet Dispensing Equipment from damage as beds are moved Ceilingand adjusted. WallPatient Mounted Rigid Retractable Ceiling Nitrogen Mounted Care Head Outlets with Ceiling Ceiling with Gas Control Head walls currently vary in Hospital Areas Outlets Wall Hose Stops Columns Columns Stacks Cabinets shape, size, type, and cost from a Autopsy rooms • • simple over-the-patient-bed stan­ Delivery rooms • • dard configuration to elaborate Emergency examination and treatment • • total-wall units. Most manufactur- rooms • • ers of medical-gas equipment of­fer Emergency operating rooms Induction rooms • medical-gas outlets for all types • • of patient con­soles available in Labor rooms Major surgery rooms • • • • • • today’s market. When specifying Minor surgery, cystoscopy • • • head-walls outlets, the plumbing Neonatal intensive care units • • engineer should consider the folNormal nursery rooms • • lowing: Nursery workrooms • 1. Is the service outlet selected O.B. recovery rooms • • compatible with the existing Patient rooms • • outlet component? Pediatric and youth intensive care unit • • • 2. Does the patient head-wall Post-operative recovery rooms • • • manufacturer include the type Premature and pediatric nursery rooms • • • of medical-gas outlets required Pre-op holding rooms • • as part of the product? Radiology rooms • Special types of ceiling- Respiratory care unit • mounted, medical-gas out- Specialized surgeries (cardiac and neuro) • • 46  Plumbing Systems & Design 

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areas. The ceiling gas-service outlets are generally located at Medical-Gas Storage Simpo PDF and Unregistered - http://www.simpopdf.com both the head and Merge the foot of the Split operating table in orderVersion to After deciding the medical-gas services to be pro­vided at the facilprovide alternate positioning of the operating table. ity, the engineer should determine the storage capacity and the pipe sizing required and possible locations for the source. Local 2. Surgical ceiling columns Surgical ceiling columns are usucodes and references as well as the administrative authority having ally available in two designs: rigid (a predetermined length jurisdiction should be consulted for each medical-gas ­system. from the ceiling height above the floor) and retractable. Both Because of the unique characteristics of each medical-gas surgical ceiling columns provide medical-gas services within source, the gases are described separately in this section. Also, an enclosure that projects down from the ceiling. The ceil­ing an explanation of the techniques currently employed to exhaust columns are usually located at opposite ends of the operating anesthetic gases is provided. table in order to provide con­venient access to the medical-gas Oxygen (O )  Several factors must be known when estimating outlets by the anesthesiologist. In addition to the ­medical-gas 2 the monthly consumption of oxygen in new or existing healthoutlets, these ceiling columns can be equipped with electricare facilities: cal outlets, grounding receptacles, physiological monitor 1. Type of medical care provided. ­receptacles, and hooks for hanging intravenous-solution bottles. 2. Number of oxygen outlets or Most manufacturers offering surgical ceiling columns allow for 3. Number of patient beds. many variations in room ar­rangements of medical-gas services 4. Future expansion of facility. and related accessories, depending upon the specific cust­omer’s 5. In existing facilities, approximate consumption. needs and the engineer’s specifications. When specifying this Two methods can be used by the plumbing engi­neer to estitype of equipment, it is nec­essary to specify carefully all medicalmate the consumption of oxygen. The more accurate method is to gas service requirements and their desired arrangement(s). Also, obtain a detailed consump­tion record from the health-care facility the engineer must coordi­nate all other required services with the or obtain monthly oxygen shipment invoices from the supplier. If electrical engineer and medical staff. inventory records are not available from the health-care facility or 3. Surgical gas tracks Surgical gas tracks are forms of ceiling the sup­plier, use consumption records from a comparably sized outlet and hose-drop arrangements that allow the move­ment ­facility, with good judgment. of the hose drops from one end of the oper­ating table to the The second method is to apply the following rule of thumb to other on sliding tracks mounted on the ceiling. These prodestimate the monthly supply of oxygen. This estimating method ucts are currently avail­able from various manufacturers and should be used with good judgment. Always coordinate estimated all provide the same basic services. The proper selection and demand with the oxygen supplier during the design process. specification of specific types are based on indi­vidual cus1. In non-acute-care areas, allow 500 ft3 (14 m3) per bed per tomer preference. Many variations in products and particular month for supply and reserve oxy­gen storage. product applications are available in critical (intensive) care 2. In acute-care areas, allow 1000 ft3 (28 m3) per bed per month areas. Con­sultation with appropriate manufacturers for rec­ for supply and reserve oxy­gen storage. ommenda­tions is always advisable. Oxygen supply sources are di­vided into two categories: (1) bulk4. Articulating ceiling-service center Articulated ceiling-seroxygen systems and (2) cylinder-manifold-supply systems. Bulkvice centers are moved by pneumatic drive systems and are oxy­gen systems should be considered for health-care facilities designed for the con­venient dispensing of medical-gas and with an estimated monthly demand above 35,000 ft3 (991 m3) or electrical services in operating rooms. The medical-gas and equal to 70 oxygen outlets. Manifold systems are used in small electrical systems are complete for single-point connection to general hospitals or clinics. each outlet at the mounting sup­port platform. Bulk-oxygen systems  When selecting and placing bulk-oxygen High-pressure nitrogen (N2) dispensing equipment  Special systems, there are several factors to be considered: Oxygen transconsideration must be given by the plumb­ing engineer to the port truck size, truck access to bulk-storage tanks, and NFPA 50, placement of the nitrogen out­lets. The primary use of nitrogen gas Standard for Bulk Oxygen Systems at Consumer Sites. Bulk-oxygen in hospitals is for driving turbo-surgical instruments. Varia­tions of equip­ment, construction, installation, and location must comply these turbo-surgical instruments, in both their manufacture and with NFPA 50 recommenda­tions. If liquid oxygen is spilled or their intended use, will re­quire that several different nitrogen-gas leaked, an ex­treme fire or explosive hazard could occur. NFPA has pressure levels be available. For this reason, it is necessary that design standards to minimize fire exposure to and from surroundthe engineer provide an adjustable pressure-regulating device ing structures. near the nitrogen gas outlet. A nitrogen control panel is usually Bulk-storage systems consist of cryogenic tanks that store liquid located on the wall (in the surgery room) opposite the operat­ing oxygen at low pressures (225 psi [1551.3 kPa] or less). Cryogenic area sterile field. The installation should allow for the access and tanks are ASME unfired, double-walled, vacuum-insulated, presadjustment of pressure settings by a surgical nurse. sure vessels. Liquid oxygen has a boiling point (nbp) of –297.3°F Piping from the nitrogen control panel to a sur­gical ceiling outlet (–182.9°C) and a liquid density of 71.27 lb/ft3 (1141.8 kg/cm3). will provide a convenient source of nitrogen for surgical tools. This When vaporized into gas, it produces 900 times its liquid volume. will prevent hoses from being located on the floor or between the Furthermore, since the tank is changed less often, process stabil­ wall outlet and the operating table. Excess hose can be obstructive ity is maximized and the introduction of atmospheric impurities to the surgical team. is reduced. Tank systems are furnished with an integral pressurerelief valve vented to the atmosphere should the liquid oxygen convert to a gas. JANUARY/FEBRUARY 2006 

Plumbing Systems & Design  47

CONTINUING EDUCATION: Medical Gas and Vacuum Systems Figure 1  Typical Bulk Supply System (Schematic)

Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com

Most bulk-oxygen storage systems are furnished with vaporizers. Vaporizers are banks of finned-tube heat exchangers that convert the liquid to its gaseous state. The vaporizers come in several styles—including atmospheric, powered (forced-air, steam, and electric), waste-heat, and hy­brid—and sizes. The selection of vaporizers should be based on demand, intermittent or continuous usage, energy costs, and temperature zones. Poorly ventilated sites or undersized heat exchangers can cause ice to form on vaporizers during the conversion process. Excessive ice formations can clog and damage the vaporizer. Also, ice could allow extremely cold gas or the cryogenic liquid to enter the piped system; damage the valves, alarms, and medical components; and even injure patients. Figure 1 illustrates a typical bulk-oxygen system schematic. Automatic controls furnished with the tanks regulate the flow of liquid through the vaporizers. When there is a demand for oxygen, the supply system draws liquid from the bottom of the cryogenic storage tank through the vaporizers. The gas moves through a final line regulator. Thus, a constant supply of oxygen at a regu­lated pressure is provided. In case of mechanical difficulty or the depletion of the liquidoxygen supply, the reserve supply will begin to feed into the distribution system automatically. An alarm signal should alert appropriate hospi­tal personnel when the liquid in the oxygen stor­age tank reaches a predetermined level. The alarm signals should indicate low liquid levels, reserve in use, and reserve low. Cylinder-manifold supply systems  Compressed-oxygen systems are comprised of cylinder manifolds that allow a primary supply source of oxygen cylinders to be in use and an equal number of oxygen cylinders to be connected as a reserve supply. 48  Plumbing Systems & Design  JANUARY/FEBRUARY 2006

The controls of the cylinder mani­fold will automatically shift the flow of the oxygen gas from the service side to the reserve side when the service side is depleted. Manifold systems can be located indoors or out­doors. When manifolds are located indoors, the en­gineer should observe the following: • Location  Preferably, the manifold should be in a dedicated room on an outside wall near a loading dock and have adequate ventilation and service convenience. • Adjacent areas  There should be no doors, vents, or other direct communications between the anesthetizing location or the storage location and any combustible agents. If locating near or adjacent to an elevated temperature area is unavoidable, the engineer should specify sufficient insulation to pre­ vent cylinder overheating; • Fire rating  The fire-resistance rating of the room should be at least 1 h. • Ventilation  Outside ventilation is required. • Security  The room (or area) must be provided with a door or a gate that can be locked and labeled. Oxygen manifolds are sized taking into consid­eration the following: 1. The size of the cylinders, 244 ft3 (6909 L) H-cylinder (see Table 4 for a siz­ing chart). 2. The hospital’s usage of oxygen, in ft3 (L) per month.

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reconstituted from oxygen U.S.P. and ni­trogen N.F. must comply,

Table 4  Selection Chart for Oxygen Manifolds Simpo PDF Merge and Split Unregistered Versionas- ahttp://www.simpopdf.com minimum, with Grade D in ANSI ZE86.I, Commodity SpecifiHospital Usage Duplex Manifold Size 3 Cu. Ft. (10 L) per month Total Cylinders Cylinders per Side 5,856  (165.8) 6 3 9,760  (276.4) 10 5 13,664  (386.9) 14 7 17,568  (497.5) 18 9 21,472  (608.0) 22 11 25,376  (718.6) 26 13 29,280  (829.1) 30 15 33,154  (938.8) 34 17

Note: Based on use of 244 ft3 (6909.35 L) H-cylinders.

Nitrous oxide (N2O)  The common source of nitrous oxide is a cylin­der-manifold system. High-pressure manifold sys­tems consist of two banks of cylinders, primary and reserve. (See discussion under “Oxygen,” above.) System demands for nitrous oxide can be more difficult to determine than they are for other medical gases. The number of surgeries scheduled, the types and lengths of surgery, and the administering techniques used by the anesthesiologists cause extreme variations in the amount of nitrous oxide used. Because of this variation, considerations must be given to the size and selection of the nitrous-oxide manifold system. Avoid locating the nitrous-oxide manifold system outdoors in areas with extremely cold climates. Nitrous oxide is supplied liquefied at its vapor pressure of 745 psi (5136.6 kPa) at 70°F (21.1°C). At extremely cold temperatures, the cylinder pressure will drop dramatically, reducing the cylinder pressure to a point where it is impossible to maintain an ad­equate line pressure. This is due to a lack of heat for vaporization. For nitrous-oxide manifolds located indoors, the same precautions previously listed for oxygen systems must be observed. The following should be considered when select­ing and sizing nitrous-oxide manifolds and determining the num­ber of cylinders required: 1. The size of the cylinders: 489 ft3 (13 847 L) K-cylinders (see Table 5). 2. The number of anesthetizing locations or op­erating rooms. 3. Provide ½ of 1 cylinder per operating room for in-service and reserve supplies. Table 5  Sizing Chart for Nitrous Oxide Cylinder Manifolds Duplex Manifold Size Indoor Outdoor Number of Operating Cylinders per Cylinders per Rooms Total Cylinders Side Total Cylinders Side 4 4 2 4 2 8 8 4 10 5 10 10 5 12 5 12 12 6 14 7 16 16 8 20 10

cation for Air. Medical compressed air can be produced on site from atmospheric air using air compressors designed for medical applications. There are three major types of air compressor in the marketplace today: the centrifugal, reciprocating, and rotary screw. The reciprocating and rotary screw are “positive-displacement” type units, while the ­centrifugal compressor is a “dynamic” type compressor. The medical air compressor shall be designed to prevent the introduction of contaminants or liquid into the pipeline by one of two methods: Type 1 air ­compressors eliminate oil anywhere in the compressor. Type 2 air compressors separate the oil-containing section from the compression chamber. Examples of a type 1 compressor are the liquid ring, rotary screw, and permanently sealed bearing compressor. Type 2 compressors have extended heads. A positive-displacement compressor is normally rated in actual cubic feet per minute (acfm). This is the amount of air taken from atmospheric conditions that the unit will deliver at its discharge. Within a broad range, changes in inlet air temperature, pressure, and humidity do not change the acfm rating of ­either the reciprocating or the rotary screw compressor. The centrifugal compressor’s capacity, however, is affected slightly by the inlet air conditions due to the nature of the compression process. For example, as the air temperature decreases, the capacity of the dynamic compressor will increase. The capacity of a centrifugal compressor is normally defined in inlet cubic feet per minute (icfm) . In an effort to obtain an “apples to apples” comparison of various compressors, many manufacturers specify their capacity requirements in standard cubic feet per minute (scfm). This sometimes causes much confusion because many people do not fully understand how to convert from acfm or icfm to scfm. The design engineer specifying scfm must define a typical inlet air condition at the building site and their set of “standard” conditions (normally 14.7 psia [101.4 kPa], 60°F [15.6°C], and 0% relative humidity). Typically, the warmest normal condition is specified because as the temperature goes up scfm will go down. To convert from acfm to scfm, the following equation is used. Equation 1 scfm  = acfm ×

Pi – (Ppi × %RH) × Tstd Pstd – (Pp std × %RHstd) Ti

where Pi = Initial pressure Ppi = Partial initial pressure of water vapor in 100% humid air at the temperature in question RH = Relative humidity Pstd = Pressure under standard conditions Pp std = Partial standard pressure of water vapor in 100% humid air at the temperature in question RHstd= Relative humidity at standard conditions Tstd = Temperature at standard conditions, °F (°C) Ti = Inlet temperature, °F (°C)

Note: Based on use of 489 ft3 (13.85 × 103 L) K-cylinders.

Medical compressed air  Medical compressed air may be supplied by two types of system: (1) a high-pressure cylindermanifold system; and (2) a medical air-compressor system. The manifold systems for compressed air are similar in configuration to those for oxygen and ni­trous oxide (see discussion under “Oxygen,” above). Air supplied from cylinders or that has been JANUARY/FEBRUARY 2006 

Plumbing Systems & Design  49

CONTINUING EDUCATION: Medical Gas and Vacuum Systems Equation 1a dryers, in-line filters, regulators, dew-point monitors, and valves. Merge Split Unregistered VersionThe - http://www.simpopdf.com This Simpo equationPDF is derived fromand the Perfect Gas law, which is: compressor components are connected by piping that allows equipment isolation, provides pressure relief, and removes conP V P1V1 = 2 2 densate from re­ceivers. Medical-air compressors must draw out­ T1 T2 side air from above the roof level, remote from any doors, windows, or: P T 1 2 and exhaust or vent openings. Where the outside atmospheric air is V2 = V1 × P × T 2 1 polluted, special filters can be attached to the compressor’s intake where to remove carbon monoxide and other con­taminants. Refer to P1 = Initial pressure NFPA 99 for proper location of medical-air intakes. Medical com V1 = Initial volume pressed air must comply with NFPA 99 and/or Canadian Standards T1 = Initial temperature P2 = Final pressure Association’s (CSA’s) defi­nition of air-quality standards. V2 = Final volume Where more than two units are provided for the facility, any two T2 = Final temperature units must be capable of supplying the peak calculated demands. For a reciprocating or rotary-screw compressor, the conversion Pro­vide automatic alternators (duty-cycling controls) to ensure from acfm to scfm is simple. The inlet air conditions and standard even wear in normal usage. Alternator controls incorporate a posiconditions are inserted into the above formula and multiplied tive means of automatically activating the additional unit (or units) by the acfm capacity of the unit. It makes no difference what the should the in-service pump fail to main­tain the minimum required design conditions are for that compressor, as these do not figure pressure. Medical com­pressed air produced by compressors may be into the formula. In the case of a dynamic compressor, the icfm air defined as “outside atmosphere to which no con­taminants (in the flow at the given inlet conditions is inserted in place of the acfm form of particulate matter, odors, oil vapors, or other gases) have in the formula. Another design issue that the engineer should be been added by the compressor system.” Not every compressor is aware of is how altitude affects the output of the compressor. At suitable for use as a source for medical compressed air in healthaltitudes above sea level, all medical-air systems have reduced care fa­cilities. Only those compressor units specifically de­signed flow. In these cases, the required sizing will need to be adjusted and manufactured for medical purposes should be considered as to compensate. To do this, multiply the scfm requirements by the a reliable source of oil-free, moisture-free, and low-temperature correction factor in Table 6. compressed air. Acceptable compressor types include oil-free, oilTable 6  Altitude Correction Factors for Medical-Air Systems less, and liquid-ring compressors. Separation of the oil-containCorrection ing section from the compression chamber by at least two seals is Normal Barometric Factor for SCFM required by the compressor manufacturers. Altitude, ft (m) Pressure, in. Hg (mm Hg) (L/min) Air compressed for medical-breathing purposes are to be used   Sea level 29.92 (759.97) 1.0  (28.31) for this purpose only and should not be used for other applica  1,000   (304.8) 28.86 (733.04) 1.01 (28.6) tions or cross-connected with other compressed air systems.   2,000   (609.6) 27.82 (706.63) 1.03 (29.16) Table 7  Minimum Pipe Sizes for Medical Air-Compressor Intake Risers   3,000   (914.4) 26.82 (681.23) 1.05 (29.73) Pipe size, in. Flow rate, cfm   4,000 (1219.2) 25.84 (656.33) 1.06 (30.01) (mm) (L/min) 5,000 (1524) 24.90 (632.46) 1.08 (30.58) 2.5 (63.5) 50 (1416)   6,000 (1828.8) 23.98 (609.09) 1.10 (31.14) 3 (76.2) 70 (1985)   7,000 (2133.6) 23.09 (586.48) 1.12 (31.71) 4 (101.6) 210 (5950)   8,000 (2438.4) 22.23 (564.64) 1.15 (32.56) 5 (127.0) 400 (11330)   9,000 (2743.2) 21.39 (543.3) 1.17 (33.13) 10,000 (3048) 20.58 (522.7) 1.19 (33.69) Table 7 provides the minimum pipe sizes for medical air-comIn other words, to correctly size the medical-air system, you would apply the correction factor listed in the chart above to the peak-calculated load (scfm) at sea level.

pressor intake risers. Consult with the compressor manufacturer on intake recommenda­tions and allowable friction loss for the intake riser be­fore finalizing the pipe size equipment selection. ✺

Example 2 A facility is located at 5000 ft (1524 m) above sea level and the system demand is 29.4 SCFM. Take the 29.4 scfm and multiply it by 1.08 (correction factor from Table 5) to get the adjusted scfm requirement of 31.8 scfm at 5000 ft above sea level. Therefore, a medical-air system of greater capacity is needed at higher altitudes. Another handy formula for compressed-air systems is the following: to convert scfm to L/min multiply by 28.31685. Each compres­sor must be capable of maintaining 100% of the medical-air peak demand regardless of the standby com­pressor’s operating status. The basic compressor package consists of filter intakes, duplex compres­sors, after-coolers, receiving tanks, air

50  Plumbing Systems & Design 

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CONTINUING EDUCATION

Continuing Education from Plumbing Systems & Design Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com Kenneth G.Wentink, PE, CPD

Do you find it difficult to obtain continuing education units (CEUs)? Is it hard for you to attend technical seminars? Through Plumbing Systems & Design (PS&D), ASPE can help you accumulate the CEUs required for maintaining your Certified in Plumbing Design (CPD) status. ASPE features a technical article in every issue of PS&D, excerpted from its own publications. Each article is followed by a multiple-choice test and a simple reporting form. Reading the article and completing the form will allow you to apply to ASPE for CEU credit. For most people, this process will require approximately 1 hour. A nominal processing fee is charged—$25 for ASPE members and $35 for nonmembers (until further notice, the member fee is waived). If you earn a grade of 90% or higher on the test,

you will be notified that you have logged 0.1 CEU, which can be applied toward the CPD renewal requirement or numerous regulatory-agency CE programs. (Please note that it is your responsibility to determine the acceptance policy of a particular agency.) CEU information will be kept on file at the ASPE office for 3 years. No certificates will be issued in addition to the notification letter. You can apply for CEU credit on any technical article that has appeared in PS&D within the past 12 months. However, CEU credit only can be obtained on a total of eight PS&D articles in a 12-month period. Note: In determining your answers to the CE questions, use only the material presented in the continuing education article. Using other information may result in a wrong answer.

CE Questions—“Medical Gas and Vacuum Systems” (PSD 131) 1. When liquid oxygen is vaporized into a gas, it produces ________ times its liquid volume. a. 0 b. 450 c. 900 d. 1,350

7. In acute-care areas, allow ________ cubic feet per bed per month for supply and reserve oxygen storage. a. 250 b. 500 c. 750 d. 1,000

2. Nitrous oxide (N2O) is typically used by whom in the surgery room? a. the attending physician b. the attending physician’s assistant c. the surgical nurse d. the anesthesiologist

8. The exact number of medical-gas outlets required in the various areas or rooms is mandated by ________. a. the various codes that apply to work at the project site b. the American Institute of Architects (AIA) c. the National Fire Protection Association (NFPA) d. none of the above

3. The medical-gas and vacuum piping systems must be designed to ________. a. meet the specific requirements of each hospital b. anticipate any building expansion c. not cross connect to any existing system d. all of the above 4. The primary use of nitrogen gas in hospitals is ______ __. a. driving turbo-surgical instruments b. pressurizing piping systems c. in the laboratory Bunsen burners d. none of the above 5. Medical-gas flow rates ________. a. must include diversification b. must provide for the total connected load c. must provide the minimum required flow for the proper functioning of connected equipment d. must be estimated 6. Providing medical-gas service outlets in the surgery room may be accomplished by locating them in ______. a. the ceiling b. the surgical ceiling columns c. the surgical gas tracks d. any of the above noted areas and others not listed

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9. Medical-gas outlet types and configurations must meet the requirements of the local jurisdictional authority and ________. a. ANSI 1416 b. NFPA 99 c. NFPA 50 d. ANSI 1763 10. Several factors must be known when estimating the monthly consumption of oxygen, such as ________. a. the number of patient beds b. the type of medical care provided c. the future expansion plans of the facility d. all of the above 11. What is the SCFM correction factor for a medical-air system located in a facility at an altitude of 7,000 feet above sea level? a. 1.05 b. 1.08 c. 1.12 d. 1.17 12. The goal in designing medical-gas and vacuum systems is ________. a. to provide a safe system b. to provide a sufficient flow of gas or vacuum c. to provide the required pressure d. all of the above

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Medical Gas and Vacuum Systems (PSD 131)

Questions appear on page 52. Circle the answer to each question. Q 1. A B C D Q 2. A B C D Q 3. A B C D Q 4. A B C D Q 5. A B C D Q 6. A B C D Q 7. A B C D Q 8. A B C D Q 9. A B C D Q 10. A B C D Q 11. A B C D Q 12. A B C D

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Medical Gas and Vacuum Systems (PSD 131) Was the material new information for you? ❏ Yes ❏ No Was the material presented clearly? ❏ Yes ❏ No Was the material adequately covered? ❏ Yes ❏ No Did the content help you achieve the stated objectives? ❏ Yes ❏ No Did the CE questions help you identify specific ways to use ideas presented in the article? ❏ Yes ❏ No How much time did you need to complete the CE offering (i.e., to read the article and answer the post-test questions)?___________________

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Plumbing Systems & Design  53

Reflecting Pools and Fountains

PSD 133

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Continuing Education from Plumbing Systems & Design Kenneth G.Wentink, PE, CPD, and Robert D. Jackson

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Reflecting Pools and Fountains Introduction Reflecting pools and fountains provide visual and auditory pleasure, add charm to garden areas, and provide a retreat area in which to rest and relax. Fountains generate sound and provide a cooling effect on hot summer days. Fountains may be selfcontained units or pre-engineered kits or they may be custom designed and built. Self-contained fountains, consisting of pools, pumps, valves, lights, and other hardware, are shipped assembled, and the addition of water is all that is necessary to put the fountain into normal operation. No permanent connections to the plumbing system are required. Pre-engineered fountain kits, complete with equipment, need only assembly and hook-up to the water-supply, drainage, and power sources. Plumbing engineers, architects, and landscape architects are all involved in the creation of display fountains and reflecting pools. The architects are concerned with the overall aesthetics, whereas the engineers must be familiar with the available fountain equipment and the technical details of each component if they are to design systems that will achieve the desired display effects. The plumbing engineer should work closely with the architect and the landscape architect to achieve the desired display. In addition, the systems should be designed with provisions for cleaning, water treatment, and maintenance. Custom fountains providing small or large water displays with almost any desired decorative effects are discussed in this chapter. Also included are the technical details of pool design; mechanical equipment, including spray systems; and operation and maintenance. The engineer must also be aware that the fountain is usually represented on a set of architectural drawings as an undefined space or a rendering. It is also usually the last item to be coordinated. What this means is that the engineer usually designs the fountain in its entirety, including the water effect and its influence on the surrounding area. Then, he/she needs to quickly (and accurately) select the nozzles, determine flow rates, select the equipment, try to get space for the equipment, coordinate with the other disciplines involved, then coach contractors, who look upon a fountain as a glorified swimming pool. When all this is done, however, the engineer can look upon a beautiful piece of engineered art that will most likely never be duplicated and can be proud to claim it as his/ her work.

Pool Design General Considerations A number of general items of information should be kept in mind when designing a fountain. For an engineer or designer, the most important issue surrounding any body of water is safety. There is always a risk attached to a water feature. It is not the intent of this chapter to acquaint the engineer with drowning and entrapment issues, but the engineer is encouraged to study the available codes

and standards regarding swimming pools and spas and apply them as necessary. Many jurisdictions regard 18 in. (457.2 mm) of water as the maximum depth allowed without severe access restrictions, such as railings, fences, and gates. From a mechanical, operating perspective, the most important thing is to locate all pumps to ensure flooded suction lines. If at all possible, locate the pumps so that the operating water level of the fountain is above the suction inlet of the pump. This helps to prevent cavitation and to ensure that the pump primes quickly. Painting the pool interior a dark color helps to conceal piping, lighting, cable, junction boxes, and other equipment located in the pool, and, in addition, provides reflective qualities. But the dark color tends to cause an increase in water temperature by absorbing the sun’s heat. This, in turn, creates a requirement for more chlorine. Thin or fine-mist spray effects are difficult to see against light colors, mixed colors, or lace-type backgrounds. A massive display should be used under these conditions. The construction of pools at or below grade level creates a potential problem with leaves and other debris blowing into the pool, therefore, this should be avoided. Reflecting pools and fountains may be installed above or below grade. Above-grade fountains offer the advantage of adding more height to the water display. Multilevel pools provide the possibility of having numerous waterfall displays with only one water source. Aerating nozzles that use a venturi action to entrain air into the water stream can cause a wave action in circular pools. In such cases, surge collars or underwater baffles should be installed to minimize this action. Water will splash horizontally approximately one half the height of the water display except where wind is a problem. Since wind can push water long distances, it is important to locate nozzles so that the splash and wind effect will not create undue problems. It may be advisable to provide a wind control to lower the height of the display or to shut off the system when there is too much wind. Water hitting water creates a lot of noise. There are times and locations when this is desirable. When the noise is too loud, however, it can be reduced by locating various types of planting around a pool. Multilevel Pools Multilevel and multiple pools involve special considerations, which, if taken into account, do not present any difficulty. If these considerations are not taken into account, however, disaster can result. The amount of flow over a waterfall is determined by the height of the water flowing over the weir. This height over the weir is the same as the height of the pool behind the weir. When the pumps stop, this water will all come over the weir and spill into the pool below. The water in the air (i.e., the waterfall) will also come to rest in the lower pool. The lower pool must be sized

Reprinted from American Society of Plumbing Engineers Data Book Volume 3: Special Plumbing Systems, Chapter 5: “Reflecting Pools and Fountains.” © 2000, American Society of Plumbing Engineers. 62  Plumbing Systems & Design 

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to accommodate this extra water. For the water in the air, the actually measure the depth over a weir. If the client desires an Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com depth over the weir times the height of the water is sufficiently unbroken sheet of water over the weir into the pool, a rule of accurate to calculate the volume. thumb is about ¼ in. (6.35 mm) of water over the weir per 4 ft of Multilevel pools should have some method of draining the vertical drop. upper pools. A small drain line with a screw plug at the upper The four most common types of weir are the rounded edge; pool can be used. The drain line should be a maximum of 1¼ in. the upward-tapered weir; the downward-tapered weir; and the (31.75 mm) to restrict the discharge rate into the lowest pool. downward-tapered, metal-edge weir. The rounded-edge weir For multiple pools with different elevations, a common refer- is used when it is desired to have the water run down the wall ence must be established to drain the basins. An example would surface. The upward-tapered weir requires more water than the be waterfalls at several different elevations with basins at sev- other types and should not be used for waterfalls exceeding 5 ft in eral different elevations served by a single pump system. If the height. The downward-tapered weir is very ­effective in creating pumps were turned off, the water in the basins would all drain smooth sheets for waterfalls up to 15 ft in height. The downward- to the lowest basin through the common suction header. To pre- tapered, metal-edge weir achieves the same effect as the downvent this, either check valves must be installed in all suction and ward-tapered weir with the added advantage of being easier to discharge lines or all basins must drain to a surge pit. The surge level. pit provides a common reference for the pumps and allows The waterfall or weir is normally supplied from a trough each basin to drain independently of the others. The surge pit behind the weir edge. The trough can be supplied with water method is also much easier to balance than the method with by many methods as long as the surface disturbance is kept to check valves. (See Figure 1.) a minimum. A header can be installed with holes drilled along the length of the header to supply water equally along the length of Figure 1  Multilevel Pools with a Surge Pit the trough. Hydrophilic well piping, precut with slots along the length of the pipe, makes a very smooth supply method. Oversized inlets (to lower the water velocity) in the bottom of the trough with diverter plates can also be used. Weir lips must be level. This is difficult to achieve with poured concrete, therefore, a metal or plastic lip should be provided. If the spill lip is in the shape of an overhang, a drip lip in the shape of a ¼ in. (6.35 mm) deep rectangular slot should be provided under the slot. This will prevent the water from running down the wall. Filtration turnover  The filtration turnover rate is determined by the For multiple pools at the same elevation, an equalizer line volume of the pool and the desired number of hours per comshould be run between the pools. No matter how accurate the plete water change. The filtration turnover can vary from 4 to calculations and installation, two identical pools will have vary- 12 h per complete water change. This needs to be determined ing flow rates. The equalizer line should not tie into any other by the engineer. For areas with blowing dust and debris, a line except a valved drain. The equalizer should be sized so that faster water change is needed. For cleaner areas, such as those it is as large as the largest line coming into the pools. If each pool indoors, a slower water change can be used. The filtration flow receives the discharge through a 4-in. (100-mm) line, the equal- rate is determined by dividing the pool water volume, in gallons izer should be a 4-in. (100-mm) line. (liters), by the turnover time, in minutes. Example 1 Preliminary Display Selection and Determination of An 8000-gal pool divided by (12 h x 60 min) equals 11.1 gpm Flow Rates flow rate. Spray jets and nozzles The flow rates for spray jets and nozzles (A 30 283-L pool divided by [12 h x 60 min] equals 45.42 L/min should be determined by the manufacturer’s data. Most manuflow rate.) facturers publish catalogs showing the various types of jet in operation. The client should be given the opportunity to select Therefore, a filtration system sized for a flow rate of 12 gpm the jets from a subjective standpoint; the selection should then (45.42 L/min) would be adequate. be reviewed by the engineer for practicality. Weirs  Weirs are normally sized by the length of the weir and the depth of the water flowing over the weir edge. The engineer may have to assist the client in determining the effect desired. It is useful to have the client see an existing water feature then

Inlet/Outlet and Device Location By convention, an “inlet” is defined as a device allowing water to flow into the pool. An “outlet” is defined as a device allowing water to leave the pool. MAY/JUNE 2006 

Plumbing Systems & Design  63

CONTINUING EDUCATION: Reflecting Pools and Fountains Main drains  Main drains are provided for pump suction and Mechanical space or vault  The pumping equipment can be Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com draining the pool. Main drains should be located at the lowest located in the building, in an underground equipment vault, or point of the pool. There should be at least one main drain for outdoors above ground in a protected area. The determination the lowest basin. Main drains should be located so that there is as to whether or not to provide a vault depends on the following not more than 20 ft between drains or more than 15 ft from the factors: (1) the distance from the pool to the mechanical space sidewall of the pool. The main drains should be sized to accom- in the building vs. the distance from the pool to an underground modate the full flow of the system. Main-drain gratings should vault; (2) the difference in cost for piping, electrical wiring, and be sized at no greater than 1.5 fps through the grating. See the conduit between the two locations; (3) the cost of the mechanimanufacturer’s listings for the approved flow rate through anti- cal space vs. the cost of a vault; and (4) whether or not mechanivortex gratings. cal space is available. Main drains used for pump suction must have some method If the equipment is installed in an area remote from the founof preventing entrapment: either they must be the anti-vortex tain, it is advisable to have a remote-control panel located within type or they must be view of the fountain. installed in pairs at Figure 2  Main Drains Provide adequate space for all fountain equipment, including least 4 ft apart to preelectrical panels. Observe all code-mandated clearance requirevent suction entrapments. Allow some method of removing motors and pumps that ment. Although reflectwill not require the removal of parts of the building. This could ing pools and fountains be an overhead crane rail or merely an eye bolt attached to the are not intended to be structure over each motor for lifting. occupied by humans, A floor drain is required near the equipment. Specify a floor people do accidendrain with a backwater valve if there is any possibility of water tally (and on purpose) backing up through the drain, especially in a vault. If a floor fall into them. Pairdrain cannot flow by gravity to the sewer, a sump pit and pump ing drains and using is required. If the equipment is installed in a vault, a batteryanti-vortex drains operated, backup sump pump may be desirable. minimizes the risk of In a vault, provide an electric receptacle; a light; a hose bibb; suction entrapment and disembowelment. If paired drains are a ventilating blower; intake and exhaust vents; an access ladder; used, they must be connected to a common suction line without and a lockable, spring-loaded access hatch big enough for all any intervening valves. (See Figure 2.) equipment to pass through. A heavy manhole cover is not Main drains are used to empty the pool for cleaning and to recommended because the maintenance personnel become drain storm water when the pool is empty. A drain line is run to annoyed with lifting the cover and tend to forget their maintethe nearest storm drain line and a valve is installed in this line. nance duties. In some cases, a 3-ft deep vault with an access Skimmers  Skimmers are necessary in all pools to collect hatch covering the entire vault is adequate. windblown debris and dust. Even indoor pools can collect an Fountain Systems and Components amazing amount of floating debris that must be cleaned out The fountain system consists of the following major systems: periodically. Skimmers normally consist of a skimmer body that 1. Display system. is cast into the pool wall, a floating weir, and a strainer basket. The floating weir draws a thin layer of water into the skimmer. 2. Piping system. With a thin layer, the water’s velocity is higher and its influence 3. Water-treatment system. extends farther out into the pool. Skimmer strainer baskets need A. Mechanical-filtration system. to be cleaned out periodically, and access to the strainer defines B. Chemical-treatment system. the type of skimmer used. Top-access skimmers, while easiest to 4. Makeup-water system. maintain, are very visible. Since architects prefer to hide every 5. Overflow and drainage system. component possible, front-loading skimmers are preferred. In 6. Lighting system. addition, front-loading skimmers are less prone to vandalism. Skimmers should be located so that there is 1 skimmer pro- 7. Other miscellaneous systems. The reflecting pool may or may not have a display system, vided for each 500 ft2 (46.45 m2) of lower basin, with a minimum of 1 skimmer. The skimmer system should be sized to accom- depending on the desired effect. Each of these systems often overlaps or relies on another modate the full filtration flow. A 2-in. (50.8-mm) skimmer can accept about 30 gpm (113.56 L/min), but skimmers can be system to function correctly. For instance, if the filtration system ganged together to increase their capacity. A majority of the is not working properly, the spray heads will load up with debris skimmers should be located such that the prevailing winds and and not function correctly. If the water is not kept at the proper level with an autofill, the lighting system may overheat. current blow the debris toward them. Filtration return inlets  Filtration return inlets come from the Display System filters and return clean water to the pool. Return inlets should be There are two distinct display types: static and dynamic. Static placed at least 12 in. (304.8 mm) below water level to minimize displays have a constant or nearly constant volumetric flow rate surface disturbance. If the pool is too shallow, increase the inlet at all times. Examples include a waterfall weir and constantpipe size to reduce the velocity into the pool. Each pool should height jets. Dynamic displays vary the flow through the system. have a minimum of 2 inlets, with a sizing criteria of 1 inlet per Examples are dancing fountains, where the fountain appears to 600 ft2 (0.093 m2) of basin. Inlets should be sited to direct flow react to music or lights, and waterfalls and rivers that are part toward the ­skimmers. 64  Plumbing Systems & Design 

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of a simulated storm scenario. For either type of display, the System and Component Selection and Design Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com typical system consists of the following components: suction Criteria outlets and suction piping, pump(s), return piping, and disFilter Systems charge device(s). The display system for each type of effect, e.g., Types of filter  There are many types of filter on the market nozzles, weirs, whirlpools, and waves, should have a different today. Some of these are specialty filters for water treatment, pump system dedicated to it. RO systems and the like. For fountains, swimming pool and spa Piping System filters best fit the application. Mechanical filtration is required Two separate types of piping systems are defined for any foun- to remove suspended particulates down to about 50 µ. In this tain. These are the display systems and the filter system. The range, cartridge filters and high-rate, pressure sand filters are piping for these systems can normally share suction outlets but the best choice for fountains. should remain separate from there until returning to the pool. An There is a division in filter sizes that occurs around the 120 example of a poor design is a fountain system where the display gpm (454.25 L/min) flow rate. Above that rate are the commerwater and the filter water are combined such that a single pump cial filters used on larger pools and fountains and below are the draws from the pool and pumps through the filter then back to residential filters used on smaller pools and fountains. Many the nozzle. When the filter is clean, this system will work fine. As manufacturers do not make a distinction regarding quality at soon as the filter gets dirty, however, the flow from the nozzle will the different levels, but some do. Check with the distributors gradually drop until the filter is backwashed. Then the cycle will and pool contractors as to which filters cause the least trouble. begin again. When sizing filters, it is good practice to use more than one filter when the flow rate is above 120 gpm (454.25 L/min). For examWater-Treatment System ple, a system that requires 280 gpm (1059.92 L/min) of filtration The water-treatment system consists of two separate processes. would do better with two filters sized at 140 gpm (529.96 L/min) First, mechanical filtration removes the solids and some of the each than one filter sized at 280 gpm (1059.92 L/min). The reason suspended organics from the water. Second, the chemical filtrais cleaning time. Whether the filter selected is a cartridge, sand, tion disinfects and balances the water to provide clean, sparor diatomaceous earth (DE), it will have to be cleaned at some kling clear, odor-free water that is pleasing to the eye and not time. With multiple filters, the filtration process continues while detrimental to the pool and equipment. one filter is being cleaned. In the case of sand filters, the filter type Makeup-Water System of choice for most large systems, the backwash flow rate is lower, It is essential to maintain the proper water level in the pool. necessitating a smaller backwash pit and sewer line. The reasons are threefold. First, certain spray nozzles require With multiple filters, use multiple pumps. Although the pumps that the water level vary no more than ½ in. (12.7 mm) in are not to be piped individually to each filter, a pump can be order to achieve the desired display. A variation in the water shut down while a filter is serviced. This will prevent overrunlevel causes the nozzle display to become erratic and to differ ning the other filters while one filter is down. from the original design. Second, underwater lights must be Cartridge filters  Cartridge filters are lower in first cost than submerged to a specific depth to both protect the lights and to the other types of filters and are relatively easy to maintain. The remove heat. Third, a substantial water-level drop could cause filter consists of a body constructed of plastic or stainless steel the suction line to entrain air, resulting in pump cavitation and that contains a polyester element. The cartridge filter element is possible ­damage. cleaned by removing the filter top and pulling out the element. It can then be hosed clean and reinstalled in the body. These filOverflow and Drainage System The fountain must be equipped with an overflow system ters are available in sizes ranging from 150 gpm down to 5 gpm. to handle storm water and the possible malfunction of the The small-size filters are of the inline type made for filtering spas makeup-water system. In addition, mundane reasons, such as and are excellent for small fountains. Cartridge filters must be removed from the body to be cleaned draining the pool for winter and cleaning, mandate that a drain and require some space to be hosed down. This is a considersystem be installed. ation when the fountain is indoors and requires that the carWater-Heating System tridges be taken away to be cleaned. A second set of cartridges If a fountain is to be kept in operation during the winter months will be necessary for a swap. and it is possible for the water to freeze, an aquastat-controlled Cartridges should be sized at 0.375 gpm/ft2 maximum flow pool heater should be provided. The heater should be sized to rate. maintain pool water at about 35 to 40°F (1.67 to 4.44°C). High-rate, pressure sand filters  A pressure sand filter consists of a body constructed of plastic, fiberglass, or stainless steel Lighting System Underwater lights are used to provide illumination for the vari- that contains sand to filter the water. The term “high rate” comes ous displays. The number of lights depends on the overall size from the flow rate per square foot of sand bed. If the flow rate of the pool, the depth of the water, the height and width of the is above about 10 gpm (37.85 L/min), the filter is classified as water display, and possible interference from ambient lighting. “high rate.” There are sand filters that are considered “low” or “slow” rate, but they are seldom specified ­ today. Water enters Lights can be white or another color as desired. the filter at the top and is pumped down through the sand to an underdrain manifold with slots narrow enough so that the water will pass but the sand will not. The water is piped to the sand filter through a series of valves (see Figure 3) or a multiport valve. A multiport valve is a single-handle control with four ports MAY/JUNE 2006 

Plumbing Systems & Design  65

CONTINUING EDUCATION: Reflecting Pools and Fountains Figure 3  Fountain Components Simpo PDF Merge

tions allow effluent to flow to the

and Split Unregistered Version - http://www.simpopdf.com storm sewer, others require it to go to the sanitary sewer. Provision must be made to handle the large flow rates that are customary with a sand-filter backwash. Although the backwash only lasts 5 min at maximum, an enormous amount of water can be used in that time. Backwash rates are generally 20 gpm/ft2 of filter area. A high-rate, pressure sand filter is generally sized at 12 to 15 gpm/ ft2 of filter area, although the filter may be rated up to 20 gpm/ft2. Sizing filters  To size a filter, first determine the filtration rate through the pool. Once this is established, divide the filtration rate by 0.375 for cartridge filters or 12 to 15 for sand filters. This will determine the required filter area. For filtration rates over 120 gpm (454.25 L/min), dual filters should be considered, with the flow divided equally between them. Filters should never be sized at their maximum allowed flow rate. This will cause higher pressure drops through the filter over the filter run and will substantially increase the energy used by the pump.

that can be configured to either filter, backwash, rinse, shutoff, bypass, or drain. They are limited to filters with 3-in. (80-mm) or smaller connections. Either the valve series or the multiport valve may be automated. As the filter accumulates debris, the differential pressure across the filter will increase. When the differential pressure has increased to a specific point, normally about 15 psi, the filter has reached the limit of its effective filter run and requires cleaning. Cleaning is accomplished by backwashing. Backwashing a sand filter is exactly what it sounds like. Backwashing reverses the flow so that the pump now forces water through the underdrain manifold with enough flow to lift the sand bed and stir it around. The debris is floated out of the sand and flows out the inlet pipe to a drain. A backwash sight glass should be installed to allow the operator to see when the effluent is clear. Provisions must be made with the project plumbing engineer if a sand filter is to be used. Many jurisdictions require that a sand filter be backwashed into a sand trap to prevent sand from entering the sewer system. Some jurisdictions require that a sand filter backwash as an indirect waste into a pit. The ultimate destination of the backwash effluent must also be determined. Some jurisdic66  Plumbing Systems & Design 

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Pumps Display pumps  Display pumps can be the dry type, the self-priming dry type, or the submersible type. When it is necessary to locate the pump above water level, a self-priming pump should be used. If the size and cost of a self-priming pump preclude its use, a foot valve or check valve may be installed in the suction line. Submersible pumps are more expensive than dry-type pumps and may require additional ­ water depth in the pool. This can be accomplished by providing a pump pit in the water and installing a fiberglass grating over the pit. The grate offers protection from vandals and also hides the pumps from view. The advantage of using a submersible pump is that it can eliminate the need for long runs of pump suction and discharge piping, thereby saving on horsepower. Since there is less piping and corresponding friction loss, the required pump head is lower. In some cases, this can mean a substantial difference in horsepower. The National Electric Code does not allow submersible pumps over 230 V to be installed in fountains. Dry-type pumps are installed in a vault adjacent to the pool or a mechanical equipment room within the building. The preferred installation is one where the pump-suction inlet is located below the pool’s operating water level. If this is not allowed, a self-priming pump may be used. In most projects, an end-suction, close-coupled, centrifugal pump is used, but there are PSDMAGAZINE.ORG

some projects where a horizontal, split-case, centrifugal pump filter. There can be a substantial difference between these two Simpo PDF Merge and Split Unregistered Version - http://www.simpopdf.com is necessary. This can occur where the flow rate is high and the conditions in pump flow, and a variable flow-control device required pump head is low. In all cases, the pump selection might be considered for evening out the flow rates. should be made using the manufacturer’s pump curves. Mul- Pump strainers and suction screens  As a general rule, suction tiple pumps in parallel are preferred to one large pump. Redun- strainers protect the pumps and discharge strainers protect the dancy, wind control, and opportunities for different displays nozzles. Display pumps are not as likely to pick up waterborne are excellent reasons for multiple pumps. Some fountains have debris as are filter pumps, which are connected to skimmers displays that require high-pressure, low-flow nozzles; low-pres- and main drains. Provisions can be made for display pumps to sure, high-flow nozzles; and waterfall discharges. Where there have gratings over their suction outlets in the ­fountain. are multiple types of display, a separate pumping system should Basket strainers on the pump suction protect the pump be used for each type. from waterborne debris, which could get caught in the impelDisplay pumps are sized according to the hydraulic calcu- ler. Although display pumps can be protected somewhat from lations for friction loss and flow rate. Pumps can be cast iron, debris large enough to damage the pump, filter pumps should bronze or plastic. Pump materials should be suitable for contact always have basket strainers. with fresh water. Since vaults and mechanical spaces are freY-type strainers are mostly used to protect nozzles with small quently tight, it should be possible to remove the pumps’ motors openings. They are installed on the discharge side of display and impellers without disconnecting the piping. Pumps should pumps to intercept waterborne debris before it jams inside an be equipped with suction basket strainers with removable bas- actuator or orifice. The strainer should be equipped with a valve kets, suction and discharge gauge taps, isolation and balancing and hose connection to allow for easy blowdown. valves, eccentric and concentric reducers as required, and flexSuction diffusers are installed on the suction inlet to the pump ible connectors. Proper pump piping practices, as described and allow for rapid changes in the direction of piping close to elsewhere in the Data Book, should be followed. the pump. The diffuser slows the water down and straightens To size the display pump the following steps should be fol- it so that it enters the pump with less turbulence. Suction diflowed: fusers are also equipped with screens but they are very difficult to remove for cleaning and should probably not be used when 1. Determine the static head required between the lowest other methods are available. water level and the highest water level. This is important for multilevel fountains. Piping and Valves 2. Determine the head required at the discharge point. ManuMost piping for fountains is made of Schedule 40 PVC plastic. facturers provide charts that give the gpm and pressure Easy handling, light weight, and low friction losses make it the required at the nozzle. If the discharge is for a waterfall piping of choice in most fountains. Although PVC seems to be effect with the discharge point submerged, use 10 ft of head. the perfect choice, there are some caveats pertaining to its use. Piping installed through pool walls and floors and into the pool 3. Calculate the friction loss in the piping, fittings, and valves. should be copper or brass. PVC piping exposed to sunlight will 4. Add the results to obtain the required pump head. become brittle, unless it is specifically made to withstand the 5. Determine the total gpm as required for the nozzles, using effects of ultraviolet rays. Pump suction and discharge piping the manufacturer’s charts (or the gpm for a weir, as calcuinstalled underground or within a building can be PVC where lated using the weir length and depth). allowed by the local authorities. Be aware that smooth holes 6. Select the pump using the manufacturer’s pump curves. have been found in plastic piping installed underground. The If the exact flow rate and head cannot be obtained, select University of Illinois and the University of Florida both deterthe next larger size pump. In almost all cases, the pump mined that the holes were caused by termites. They do not eat selected should have a flat pump curve. ­Select the motor the PVC; they chew through it when it gets in the way of their that will provide a nonoverloading condition for the entire continued foraging for food. Also, be aware that most codes do length of the pump curve. Wide-open conditions are not allow plastic piping to be installed in a plenum. Ductile iron, common in water effects. galvanized steel pipe, or stainless-steel pipe can be used if large Filter pumps  Filter pumps may be of the same type as the dis- pipe sizes are required and PVC cannot be used. Carbon-steel play pumps. (See discussion above.) There are few reasons why piping should never be used in a fountain due to the highly oxygenated water running through the piping. all the pumps cannot be of the same type. All buried piping should be treated as a water-service applicaFilter pumps are sized to match the gpm (L/min) required for a proper filtration rate and the head required to give that rate with tion. Specifically, piping needs to be bedded in sand or clean, a dirty filter. Components in the filter system that contribute to rock-free backfill. All changes of direction in piping 3 in. (76.2 head loss include: skimmers and main drains (piped in paral- mm) and larger need to be restrained with poured concrete thrust lel so that the longest run must be determined), valves, basket blocks. Starts and stops in fountain systems can cause severe strainers, face piping (the piping connecting the pump to the water hammer and resultant failure in unrestrained systems. All piping penetrations into the pool wall should be water filter), return piping, and return inlets. Elevation changes need to be accounted for and added or subtracted. Generally, since stopped in some fashion. A common method is to use a “puddle return inlets are below the water level, there is no net elevation flange” attached to the pipe itself. For penetrating walls into mechanical rooms, a mechanical pipe seal can be used. (See change. It is important that the pump be sized to give the proper flow Figure 4.) Unions or flanges should be used at the final connection to rate with a dirty filter, but it is also important that the engineer calculate the operating point on the pump curve with a clean all equipment so that the equipment can be easily removed for MAY/JUNE 2006 

Plumbing Systems & Design  67

CONTINUING EDUCATION: Reflecting Pools and Fountains pump, should be properly braced within the mechanical room.

Figure 4  WallMerge Penetrations Simpo PDF and Split Unregistered VersionFire-protection - http://www.simpopdf.com bracing methods may be used. Return piping to multiple inlets (nozzles, etc.) must be hydraulically balanced. Filter return piping terminates in either adjustable or nonadjustable return fittings. Return fittings can be wall or floor mounted and should be adjusted to direct flow to the main drain and skimmers. Dead spots should not be allowed in a pool. Hydraulic balancing  Suction and return headers should be hydraulically balanced as closely as possible to ensure even flow throughout the fountain. (See Figure 5.) For applications where the fountain can be encircled by a header, this provides an excellent balancing tool. Nozzle patterns and return inlet headers can be sized using the following equation: Equation 1 qn = 2.45C(D2)(2ghn)

repairs. Drainage lines from the overflow and drain lines should be either PVC or cast iron, as required by local code. Water makeup and fill lines should be copper tubing. Different metal pipes carrying water or installed underground must not come into contact with each other (dielectric isolation). All piping systems should be pressure tested immediately after installation, and the test should be left on until the piping is ready to be connected to the inlet and outlet devices and equipment. This way, a glance at a pressure gauge can indicate immediately if a pipe has been broken during another phase of the construction. The test pressure should be limited to 50 psi (344.74 kPa), since the fountain piping systems are operated at relatively low pressures. If the system requires higher pressure, the pressure test should be made at a pressure that is 25 psi (172.37 kPa) higher than the operating pressure. Make sure that plastic piping is tested within the pressures recommended by the manufacturer. Prior to connecting the devices and equipment, piping systems should be flushed and cleaned. Caps should be left on until ready to make the final connection to prevent debris from entering the piping. More than one pump has been damaged or had reduced flow due to debris that was in the pipe before the pump was connected. Suction-line piping  Size the suction line at a velocity not to exceed 6 fps for copper piping and 10 fps (3.05 m/s) for plastic piping. Provide a suction inlet designed so that the drain will not trap a person in the pool. This is accomplished by having dual drains spaced at least 4 ft apart or dual drains located in different planes (such as a bottom drain and a sidewall drain) or by using anti-vortex drains. Some means of preventing vortexing should be used to prevent cavitation of the pumps. If a minimum of 18 in. (457.2 mm) of water cannot be provided over a suction drain, size the drain for ½ of the manufacturer’s recommended maximum flow and add more drains as necessary. Suction-line piping should be installed without vertical loops, which can become air bound. In addition, it is critical that suction piping pass a 25 psi (172.37 kPa) pressure test because a void as small as a pinhole can prevent a self-priming pump from pumping. Return piping  Return piping should be sized at 6 fps maximum for copper piping and 10 fps maximum for plastic piping. Return piping, especially piping close to the discharge of the 68  Plumbing Systems & Design 

MAY/JUNE 2006

where qn = Discharge from orifice n, gpm (L/min) 2.45 = Conversion factor used to express the discharge in gal/ min (L/min) when the diameter is expressed in inches (mm) and the velocity is expressed in fps (m/s). Figure 5  Hydraulic Balancing

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C = Orifice discharge coefficient ­(usually = 0.61 for holes throttling. Since adjusting the fountain is very subjective, almost Simpo PDF Merge and Split Unregistered Versionevery - http://www.simpopdf.com drilled in the field) valve in the system could be involved in the final adjust D = Diameter of orifice, in. (mm) ments. This limits the selection to ball-and-globe valves for the g = Acceleration due to gravity, 32.2 ft/s2 (9.81 m/s2) smaller pipe and butterfly valves for the larger pipe. Lug-type, hn = Head on orifice n, ft. (m) butterfly valves are normally used in applications where equipment needs to be disconnected while still under water pressure. The head on orifice n is equal to: A pump room that is much lower than the fountain will be best Equation 2 served by lug valves at the equipment connections so that the 1 2 equipment can be serviced without draining the fountain. hn = (2.45CD q 2 2 n ) 2g Check valves  There are several types of check valve, but 2 = kqn most are of two types: gravity and spring loaded. The gravity, or = k(mq1)2 swing-check, valve must be installed in a prescribed manner. The gravity check should be installed where water pressure will 2 = m h1 help provide a positive closure. Where a check valve must be where installed on a horizontal line, a spring check should be installed. k = Constant A foot valve is a special type of check valve that is installed in h1 = Head on orifice 1, ft (m) the pump-suction line. The purpose of a foot valve is to prevent m = Mass flow rate the suction line from draining back into the pool and causing The head loss between orifice 1 and n, which corresponds to the the pump to lose prime. A valved line from the makeup system should be installed between the pump and the foot valve to aid head loss in the distribution pipe between orifice 1 and n, is: in priming. It would be prudent also to install a drain in that secEquation 3 tion of pipe. ∆h(1–n) = h1 – hn Pressure-regulating valves  Dynamic fountains are designed Now it can be shown that the head loss between the first orifice using pressure-regulating valves. The regulating valve maintains and the last orifice in a distribution pipe with multiple, evenly a selected downstream pressure regardless of the changes in spaced orifices is approximately equal to one-third of the head the upstream pressure. Therefore, when the spray height of one loss that would occur if the total flow were to pass through the set of nozzles is raised or lowered, the regulating valve keeps a same length of distribution piping without orifices. Thus, second set of nozzles at the same spray height. Actuator-control valves  In addition, actuator-controlled, Equation 4 motorized, or pneumatic valves can be controlled using a 4 to hfdp = 1⁄3 hfp 20-milliamp (mA) electrical signal. The valve can be set to be = ∆h(1–n) fully closed at 4 mA and fully open at 20 mA. At any point in where between, the valve will be open an amount corresponding to the hfdp = Actual head loss through distribution pipe, ft (m) position of the point within this range. For example, at 6 mA, the hfp = Head loss through pipe without orifices, ft (m) valve will be slightly open and at 15 mA it will be almost fully The head loss through the pipe can be computed using the open. A computer can be programmed to provide signals to Hazen-Williams equation: open and close the valves in any pattern desired. Materials  A sample schedule of piping materials is shown in Equation 5 Table 1. hfp = 10.5 (L1–n) Q 1.85D – 4.87 C Discharge Devices where Many return methods are used to return the water into the pool. hfp = Head loss through the pipe from orifice 1 to orifice n, ft The designer must choose which method either creates the least (m) disturbance to the desired water effect or creates the desired L1–n = Length of pipe between orifice 1 and n, ft (m) water effect. Q = Pipe discharge, gpm (L/min) Weir pools  Common methods of return into upper weir pools C = Hazen-Williams coefficient (150 for plastic pipe) are: diverter plates (often anti-vortex drains used on the return D = Inside diameter of pipe, in. (mm) side), well screens, and double tees. (See Figure 6.) The difference in discharge between orifice 1 and n for a given Spray jets  Numerous types of nozzle are manufactured. The distribution pipe and orifice size can now be determined using designer should select the type of that will provide the desired Equations 5-1 through 5-5. If the computed value of m is too low (