PSD CEU 181Oct11-Automatic Sprinkler Systems
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Automatic Sprinkler Systems
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Continuing Education rom Plumbing Systems & Design
OCTOBER 2011
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continUing eDUcAtion
Automatic sprinklers were developed to control, conne, and extin- sprinkler Definitions guish res in order to prevent the loss o lie and minimize the loss o Tere are various types o xed-sprinkler system. Each system is clearly property. However, the existence o a sprinkler system should not cause dened in NFPA Standard no. 13., and these denitions ollow. apathy among building owners and occupants. Flammable products, Wet-Pipe System—Asystememployingautomaticsprinklersattached gases, liquids, or the accumulation o combustibles and other sensitive to a piping network containing water under pressure at all times and materials (e.g., explosives and rocket-propellant uels) require strict connected to a water supply so that water discharges immediately rom supervision and continuous prevention and control. sprinklers opened by a re. Approximately 75% o the sprinkler systems A “re-protection sprinkler system” is an integrated system o under- in use are o the wet-pipe type. Tis type o sprinkler system is easy to ground and overhead piping designed in accordance with re-protec- maintain and is considered the most reliable. It is installed where there tion engineering standards. Te design and installation o sprinkler is no danger o reezing or special requirements. systems is based on NFPA Standard no. 13, Installation of Sprinkler SysDry-Pipe Systems—A system employing automatic sprinklers tems. Tis standard was rst published in 1896 and is the oldest NFPA attached to a piping system containing air or nitrogen under pressure, standard. It was prepared in conjunction with: the release o which (as rom a sprinkler opening) permits the water • Fire-servicepersonnel. pressure to open a valve located in the riser known as a “dry-pipe • Fire-insurancerepresentatives. valve.” Te water then ows into the piping system and out the opened • Testinglaboratoriesforre-protectionitems. sprinklers. A dry-pipe system starts somewhat more slowly than a wet • Representativesfromre-protectionequipmentmanufacturers. one; however, the time between the sprinkler opening and the water • Contractorswhoinstalledsuchsystems. owing can be shortened by using quick-opening devices. Tis system Due to continuous improvements made in automatic sprinkler sys- is used where sprinklers are subject to reezing. tems, NFPA Standard no. 13 evolved into Standard no. 13A, Inspection, Te dry-pipe system uses a general compressed-air system or a local Testing, and Maintenance of Sprinkler Systems , in 1938. In 1960, NFPA’s air compressor. Te air-supply line must have a restrictive orice with sprinkler committee redeveloped the sprinkler standard. As with any a 1/16-in. diameter. Te sprinkler-head orice must be larger than the other code or standard, this standard gives only the minimum require- supply-pipe opening or the ai r pressure will not drop and the dry valve ments in order to provide a reasonable degree o protection. Based on will not open. the owner’s preerence, additional protection may be installed or a It should be emphasized that all components must be listed and higher degree o saety. approved. Pre-Action System—Asystem employing automatic sprinklers that History of sprinklers Te rst sprinkler system in the United States was installed in 1852 and is attached to a piping system containing air that may or may not be consisted o perorated pipe. Te rst automatic sprinkler was invented under pressure, with a supplemental detection system installed in the 12 years later. By 1895, sprinkler-system development was increasing, same areas as the sprinklers. I the air is under pressure in the pipes, and the Boston area alone had nine dierent systems. Boston experi- the pressure must be very low (just enough to help detect air leaks). enced the most signicant growth in this area because o the number o Actuation o the detection system opens a valve, which permits water to ow into the sprinkler piping system and to be discharged rom any hazardous textile mills in the vicinity. Beore 1950, sprinkler heads simultaneously discharged water sprinklers that may be open. Tis system is used where valuables are upward and downward. Te downward movement quenched the re, stored and accidental water discharge may cause damage. Deluge System—Asprinklersystememployingopenheadsattached while the upward movement kept the structure cool. Tese old-style to a piping system and connected to a water supply through a (deluge) heads were replaced by upright and pendent heads. valve, which is opened by the operation o a detection system installed Te current drive is to install automatic sprinkler systems even in inthesameareasasthesprinklers.Whenthisvalveopens,waterows residentialbuildings(NFPAStandardsnos.13Dand13Rcoverthese into the piping system and discharges rom all heads attached thereto. applications.) Tis system is used in very high-hazard areas. selecting tHe type of sprinkler system Combined Dry-Pipe and Pre-Action Sprinkler System—A system Te actors to consider (or questions to be asked by the designer) in employing automatic sprinklers attached to a piping system containselecting the type o sprinkler system or the type o suppression system ing air under pressure with a supplemental detection system installed are as ollows: in the same areas as the sprinklers. Operation o the detection system • Duetoitscontent(combustiblematerials),istheareatobeproactuates tripping devices, which open dry-pipe valves simultanetected expected to develop a ast-growing re? ously and without loss o air pressure in the system. Operation o the • Whatistheprincipalgoalofthere-suppressionsystem— detection system also opens approved air-exhaust valves at the end o occupants or content? the eed main, which usually precedes the opening o sprinklers. Te • Aretherevaluableitemsintheareaprotectedthatcanbedamdetection system also serves as an automatic re-alarm system. aged by water? Antifreeze System—Awet-pipesystememployingautomaticsprin • Isthereapossibilityoffreezing? klers attached to a piping system that contains an antireeze solution Answering these basic questions will determine the type o suppres- and is connected to a water supply. Te antireeze solution lls the sion system to be designed and i nstalled. pipes rst, ollowed by water, which discharges immediately rom Reprinted from Fire Protection Systems. © American Society of Plumbing Engineers, 2001.
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sprinklers opened by heat rom a re. Te antireeze system is no dierent than a wet system except that the initial charge o water is mixed with antireeze. Te system may be installed in unheated areas as can a dry system. Additional devices may be required to prevent air-pocket ormation. Tis system prevents the water rom reezing in the pipes.
sprinkler oper Ation Te sprinkler system inside a building is actually a network o pipes that are sized rom either pipe schedules or hydraulic calculations. Te system is installed overhead, and sprinkler heads are attached to the pipes in a systematic pattern. Te valve controlling each system riser is located in the system riser or its supply piping. Heat rom a re triggers the sprinkler system, causing one or more heads to open and discharge water only over the re area (except in deluge systems with permanently open heads). Each sprinkler system includes a device or activating an alarm when water starts to ow. Studies o more than 81,000 res perormed over a 44-year period indicate that sprinklers were eective in controlling 96.2% o the res.1 Te automatic sprinkler system is a very reliable and efcient suppression system because o the ollowing eatures: • Immediatedetection. • esoundingofanalarm. • Minimalresponsetime. • Continuousoperationuntilthereiscompletelyextinguished. Because sprinkler systems are so reliable, insurance companies reduce their rates considerably or buildings that are equipped with complete systems.
Te number o sprinkler heads expected to operate in case o a re depends on the ollowing items: • Occupancy. • Combustibilityofcontent. • Height of stock pile. • Combustibilityofconstruction. • Ceiling height. • Horizontalandverticalcutos. • Areashieldedfromproperwaterdistribution. • Typeofsprinklersystemused.
Strainers Strainers are ordinarily required in sprinkler-system supply lines where the sprinkler head orice is smaller than a in. Tey should have holes small enough to protect the smallest water passage in the nozzle or sprinkler head used. Te use o galvanized piping downstream o the deluge valve is recommended in water-spray systems so spray nozzles will not become clogged by rust.
Piping
Figure 8-1 illustrates the dierent components in an indoor-sprinkler piping network. Each component is dened as ollows: SystemRiser—Above-groundsupplypipedirectlyconnectedtothe water supply. Risers—Vertical pipes supplying the sprinkler system. All vertical pipes in a system are included in the denition o risers, with the exception o the system riser. FeedMains—Pipessupplyingrisersorcrossmains. Cross Mains—Pipes supplying the branch lines, either directlyor cAre AnD mAintenAnce Sprinkler heads shall never be stored where temperatures may exceed through risers. Branch Lines—Pipes in which the sprinklers are placed, either 100°F. Sprinkler heads shall never be painted, coated, or modied in any way after leaving the manufacturing premises. Care should be directly or through risers. All valves and components used in a sprinkler system must be UL exercised to avoid the damage o sprinkler heads during handling listed or approved.
system Design
Fire-protection design documents consist o drawings and specications. Tese documents must be prepared, approved, and kept readily available or urther inspection and modications i necessary. Ater installation, a re-protection system must be inspected and tested. Whendevelopingasprinkler-systemdesign,thecoderequirescer tain data to be listed on drawings. NFPA Standard no. 13 lists all the inormation required on the working design drawings, which includes the ollowing: • Name,location,addressofpropertyonwhichsprinklerswillbe installed. • Ownerandoccupant. • Pointofcompass(northdirection). • Typeofconstruction. • Distancefromhydrant. • Specialhazardrequirements,etc. It is essential that sprinkler systems be designed to t the particular hazardofabuildingorstructure.NFPAStandardsnos.231and231C cover sprinkler systems or storage areas that require specic arrangements and specialized sprinklers.
Water Supply An automatic sprinkler system should be connected to an automatic water-supply system, such as a municipal water main or an automatic re pump. NFPA standards do not actually speciy the type o automatic supply. In addition to being reliable, the water supply must have the required pressure and capacity needed or the sprinkler system. Te water quantity or the sprinklers is determined by adding the ow requirements or the number o sprinkler heads expected to operate plus 500 gpm or a hose station (unless otherwise directed by the authority having jurisdiction).
Figure 8-1 Indoor-Sprinkler Piping Network Sprinkler systems or re protection may also present public-saety risks. Preventing stale water rom a re-protection system rom mixing with potable water is now a code requirement. Installing backow pre venters in re-protection public supply or branches is a code requirement in most states and an essential component o re-saety design and installation.
Pressure and Temperature Sprinkler-system components are normally designed or a pressure o 175 psi, with a working pressure o 150 psi. Higher and lower design pressures may be used as required. I the pressure required in the system is higher than normal, then all system components must be rated or the higher pressure.
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CONTINUING EDUCATION: Automatic Sprinkler Systems Whenthesprinklersystemoperatingpressureis150psiorless,the or plumbing make this installation mandatory in order to protect the test pressure must be 200 psi and the length o the test must be 2 hours. potable water rom contamination. A schematic o the backow-preFor any other operating pressure, the test must be the maximum oper- venter location in the water supply is shown in Figure 8-2. ating pressure plus 50 psi. I the test takes place during the winter, air sprinkler components may be temporarily substituted or water. Tere are many components in a sprinkler system, including: Watertemperatureinasprinklersystemmustbebetween40and • Singleormultiplewatersupply. 120°F. However, when water temperature exceeds 100°F, intermediate • Pipingundergroundandabovegroundconnectingwatersupply or higher-temperature sprinklers must be used. to overhead sprinkler heads.2 Flushing • Fittings. Ater installation, underground mains, lead-in connections, and risers • Hangersandclamps. must be ushed. Tis operation is very important, because actory• Associatedhardware(controlvalves,checkvalves,alarmvalves, supplied pipes may contain dust, rust, etc., in addition to impurities dry-pipe valves, deluge valves, drain valve, and pipe). collected during installation. I not eliminated, these oreign materi- • Fire-departmentconnections(Siameseconnections). alsmayblockasprinkler’soriceandrenderitinoperable.Table8-1 • Alarmsandannunciators. shows the ushing rates prescribed by NFPA Standard no. 13. Whileallthesedierentcomponentsarevitaltopropersystemoper ation, the sprinkler head is one o the most important components. Table 8-1 Flushing Rates Te automatic sprinkler head is a thermo-sensitive device that is Pipe Size ( in.) Flow Rate (gpm) automatically activated when an area reaches a predetermined tem4 400 perature. Once this temperature is met, the sprinkler head releases a 6 750 stream o water and distributes it in a specic pattern and quantity over 8 1000 adesignatedarea.Waterreachesthesprinklersthroughanetworkof 10 1500 12 2000 overhead pipes, and the sprinklers are placed along the pipes at reguSource: NFPA Standard no. 13. lar, geometric intervals.
Area Limitation Te maximum oor area that may be protected by sprinklers supplied on each system riser on any one oor (as recommended by NFPA) is as ollows: • Lighthazard:52,000ft2(4831m2) • Ordinaryhazard:52,000ft2(4831m2) • High-piledstorage:40,000ft2(3716m2) • Extra Hazard: Pipe schedule—25,000 ft2 (2323 m2) Hydraulicallycalculated—40,000ft2(3716m2)
Restraining Elements Under normal conditions, water discharge rom an automatic sprinkler head is restrained by a cap held tightly against the orice. Tere are two types o restraining elements that are commonly used in sprinkler heads: usible links and rangible bulbs. In the usible-link sprinkler head, a system o levers and links, which are anchored on the sprinkler rame, press on the cap to keep it rmly in place (see Figure 8-3). Te system is constructed by using a metal alloy
System Drainage All sprinkler systems must be installed so that the system may be drained i necessary. I repairs or alterations are required, a main drain valvewillallowthesystemtobeemptied.Wet-pipesystemsmaybe installed level, while dry-pipe systems must be pitched or condensate drainage. Te pitch is usually ½ in. per 10 t or short branches and ¼ in.per10ftformains.Mainsmustbepitchedatleast½in.per10ftin rerigerated areas. Table 8-2 shows the recommended drain-pipe size as a function o the riser size. All valves and components should be UL listed or approved. Table 8-2 Drain-Pipe Size Pipe Size (in.) Drain-Pipe Size (in.) 2 and smaller ¾ or larger 2½ to 3½ 1¼ or larger 4 and larger 2
To determine thewater-supplyrequirements for a pipeschedule, consult NFPA Standard no. 13, which gives ow rates and operational durationforlightandordinaryhazards.Rememberthatthestandard gives only minimum requirements. Better protection may be selected at an additional cost. Te use o pipe sizes based on a pipe schedule is somewhat restricted, so the designer must check applicable codes and standards. Tere is also a nomogram that indicates the water density in gpm vs square oot area that must be considered in the calculation o wet-type systems, dependinguponthehazardtype(seeChapter10). I the water used or domestic purposes is common with the one used or re protection, a backow preventer must be installed on the re-protectionline.Moststatecodesapplicabletoreprotectionand/
Figure 8-2 Backow-Preventer Location 4 Plumbing Systems & Design
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with a predetermined melting point. Te metal is composed mainly o tin, lead, or cadmium (metals with low melting points). Tere are actually two dierent types o usible link: • Solder-linktype—Constructedofaeutectic3alloyoftin,lead, cadmium, and bismuth. Tese metals have sharply dened melting points and, when alloyed in proper proportions, establish the operating temperature o the sprinkler. • Frangible-pellettype—Hasapelletofeithersolderoranother eutectic metal under compression, which melts at the design temperature and releases the cap. Te rangible-bulb restraining element is constructed o glass (see Figure 8-4). It is an enclosed bulb containing a colored liquid that does not completely ll the bulb. Tere is a small air bubble entrapped in this colored liquid. When thetemperature rises, theliquid expands and the bubble is compressed and absorbed by the liquid. As soon as the bubble disappears, the pressure in the bulb rises rapidly and at a precise, preset temperature, the bulb shatters and releases the cap. Te exact operating temperature is regulated by bubble size and the amount o liquid in the bulb. Te higher the operating temperature, the larger the bubble. Te recommended maximum room temperature is usually closer to the operating temperature o the rangible-bulb type. Tis is because in the usible-link type, solder begins to lose its strength below the actual melting point o the usible link. I the duration o above-normal room temperature is excessive, premature sprinkler operation could occur.
Temperature Ratings Sprinkler heads have various operating temperature ratings that are the result o standardized tests. Te rating is stamped on the soldered link or restraining element. Te rangible-bulb liquid color also indicates thesprinklerheadtemperaturerating.Table8-3illustratesthetemper ature-rating color codes or usible-link and rangible-bulb automatic
sprinklers (with the exception o plated, ush, recessed, and concealed sprinkler heads) per NFPA Standard no. 13. Te color is usually applied on the rame arms.
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Table 8-3 Color Codes for Fusible-Link and Frangible-Bulb Sprinklers Temp. Temp. FusibleRating (°F) Classifcation Link Color 135 to 170 Ordinary No color or black 175 to 225 Intermediate White
225 300 375 475
250 to 300 325 to 375 400 to 475 500 to 575
Ceiling Temp. (°F) 100
High Extra high Extra high Ultra high
Blue Red Green Orange
GlassBulb Color Orange or red Yellow or green Blue Purple Black Black
Deectors edeectorisattachedtothesprinklerframe.Whenawaterstream is directed against the deector, it is converted into a spray o a certain shape designed to protect a dened area. Te spray pattern depends on the deector shape (see Figure 8-5). Te pattern is roughly that o a hal sphere lled with spray, in a relatively uniorm distribution o water. For example, a spray may cover a circular area having a diameter o approximately 16 t when the discharge rate is 15 gpm and the pressure is approximately 10 to 15 psi. In general, the gpm discharge is about 1.5 times the pressure required at the head (e.g., 15 psi and 22 gpm). Note: Do not use this or actual calculations. Te water discharge rate rom a sprinkler head ollows hydraulic laws and depends on the orice size and water pressure. Te standard sprinkler head has a ½-in.diameter orice. Other orice sizes can be easily identied by a protruding extension above the deector. Te orice may be o the ring-nozzle or tapered-nozzle type.
Figure 8-4 Frangible-Bulb Upright Sprinkler
Figure 8-3 Fusible-Link Upright Sprinkler OCTOBER 2011
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CONTINUING EDUCATION: Automatic Sprinkler Systems •
Flush—Allowstheworkingpartsofthesprinklerheadtoextend below the ceiling into the area in which it is installed without aecting the heat sensitivity or the pattern o water distribution. • Concealed—Entirebody,includingoperatingmechanism,is above a cover plate, which drops when a re occurs, exposing thermo-sensitive assembly. Deector may be xed or it may drop below the ceiling level when water ows. • Old style. • Residential. • On-osprinklerheads. Figures 8-6 through 8-12 illustrate some o these dierent types o sprinkler.
WAter-DelUge sprAy system A water-deluge spray system reers to specially designed nozzles (open head) that orce water into a predetermined pattern, particle size, velocity, and/or density. Because a water-deluge system has all the nozzles initially open, there is heavy water consumption; thereore, each hazard should be protected by its own separate system (riser). Piping and nozzle location, with respect to the surace or zone where the deluge system is applied, is inuenced by physical arrangement. Other elements to be determined are the size o the nozzle orice to be used (the ow required), the angle o the nozzle discharge sphere, and the required water pressure. Tere are various shapes and sizes o nozzles, including high-velocity spray nozzles, which discharge in the orm o a spray-lled cone, and low-velocity nozzles, which usually deliver a much ner spray in either a spray-lled sphere or cone shape. Another type o nozzle uses a slightly tilted deector, and the angle o the spray discharge is governed by the design o the deector.
Dry-Pipe or Deluge Valve Figure 8-5 Various Spray Patterns
Te dry-pipe valve or deluge valve is an important piece o equipment in dry-pipe and deluge systems. Tere are various types o valve, and while each dry-pipe valve type is o a slightly dierent design and conSprinkler-Head Types Standard sprinkler heads are made or installation in an upright or pen- struction, the operation is the same. Tis operation includes a clapper dent position and must be installed in the position or which they were (check valve), which has special design eatures allowing air pressure constructed. Architects sometimes require special sprinkler types to be on one side o the valve while the opposite side restrains higher water used or certain applications. Tere are over 20 types o commercially pressure (see Figure 8-13). When a re occurs and sprinkler heads open, the air pressure drops within the valve, opening the clapper and available sprinkler, including the ollowing: lling the pipes. Te valve trips an alarm when water ows through the • Upright—Normallyinstalledabovethesupplypipe. alarm connections. • Pendent—Installedbelowthepipe. Another type o deluge valve involves the water-supply pressure • Sidewall(horizontalandvertical)—Similartostandardsprinkler exerting pressure on the clapper in the diaphragm chamber. When heads except or a special deector, which allows the discharge o the activation devices operate, water rom the diaphragm chamber is water toward one side only in a pattern resembling one-quarter released aster than it can be replenished, destroying the pressure equio a sphere. Te orward horizontal range o about 15 t is greater librium and allowing water to ow into the piping system. than that o a standard sprinkler. For special applications, a sideDeluge valves are usually equipped with various trim arrange wall vertical type is used. ments or manual and/or automatic activation by an electrical signal, • Extendedcoverage—Coversmorethan225ft2perhead. which can be operated either pneumatically or hydraulically. It is up • Open to the design engineer and the owner to make the selection o the trim • Corrosionresistant—WaxorTeoncoatedbythemanufacturer arrangements. toprotectagainstcorrosives.Mostlyregularpendentorupright For areas where water damage and/or consumption is o great contype heads used in areas where corrosive substances are present cern, manuacturers have built a recyclable type o deluge valve that (e.g., chlorine storage rooms and salt-water reservoirs). permits automatic, remote on-o control. Te valve opens when a re • Nozzles. occurs and automatically shuts the water o when the heat is reduced • Drypendentanddryupright—Whenalimitedenclosureissub ject to reezing, it may be connected to a wet-pipe system through below the detector operating temperature. It has the capability o turning the water back on when the set temperature is exceeded again. All a special dry-pipe connector. other valves must be closed manually. • Fastorquickresponse(QR). • Quickresponse,extendedcoverage(QREC). sprinkler instAllAtion • Quickresponse,earlysuppression(QRES). It is critical to determine proper sprinkler location beore installing any • Earlysuppression,fastresponse(ESFR). system. Te ollowing points must be taken i nto consideration beore a • Ornamental. system is installed: • Recessed—Mostofthebodyismountedwithinarecessedhous• Maximumprotectionareapersprinklerhead. ing, and its operation is similar to a standard pendent sprinkler. • Minimuminterferencetothedischargepatternsbystructuralelements, piping, ducts, or lighting xtures. 6 Plumbing Systems & Design
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Figure 8-6 Upright Sprinkler
Figure 8-7 Pendent Sprinkler
(Courtesy of The Viking Corporation)
(Courtesy of The Viking Corporation)
• Correct location with respect to structural elements to obtain suitable sensitivity to potential res. In general, the maximum distance between sprinklers on branches or light and ordinary hazard occupancies is 15 t. Te protected area coverage per sprinkler head, as required by NFPA Standard no. 13, is as ollows: • Light-hazardoccupancy:168to225ft2depending on construction type. • Ordinary-hazardoccupancy:100to130ft2. • Extra-hazardoccupancy:90to100ft2. All codes require sprinkler systems to have devices that will sound an alarm when water ows through the risers or main supply due to a re, accidental rupture o piping, or head(s) opening. Tese devices also monitor all valves to ensure that they are in the correct operating position. Tis can be achieved by a remote signaling to a control station, sounding an alarm, or locking the valve in an open position. In other words, the devices supervise the system and sound an alarm when any tampering or undesired/unnecessary operation is detected. Only UL listed materials and equipment may be used in sprinkler installations. In addition, sprinkler heads must be installed in accordance with their listing, and sprinklers must not be altered (painted or any coat o protective material applied in the eld or at the job site). It is very easy to determine whether a sprinkler head is painted by the manuacturer or in the eld; i painted by the manuacturer, the operative parts are let unpainted. Whensprinklerheadsmustbereplaced,thesametype must be used. Tis means the same orice type and temperature rating, unless there are new conditions, such as a change o occupancy or structural modications (e.g., added or canceled ceiling).
AlArms
Figure 8-8 Residential Horizontal Sidewall Sprinkler
Figure 8-9 Pendent Sprinkler with Extra-Large Orifce
(Courtesy of The Viking Corporation)
(Courtesy of The Viking Corporation)
Figure 8-10 Upright with Large Drop Sprinkler (Courtesy of The Viking Corporation)
Tree basic types o alarm can be part o a sprinkler system: 1. Vane-typewaterow—Comesequippedwitha small paddle that is inserted directly into the riser pipe. Te paddle responds to water ow as low as 10 gpm, which then triggers an alarm. Tis type may be equipped with a delayed system (adjustable rom 0 to 120 seconds) to prevent alse alarms caused by normal water-pressure uctuations. 2. Mechanicalwater-owalarm(watermotorgong)— Involves a check valve that lits rom its seat when water ows. Te check valve may vary as ollows: (a) Dierential type has a seat ring with a concentric grooveconnectedbyapipetothealarmdevice.When the clapper o the alarm valve rises to allow water to ow to the sprinklers, water enters the groove and ows to the alarm-giving device. (b) Another type has an extension arm connected to a small auxiliary pilot valve, which, in turn, is connected to the alarm system. 3. Pressure-activatedalarmswitch—Usedinconjunction with dry-pipe valves, alarm check valves, and other types o water-control valve. It has contact elements arranged to open or close an electric circuit when subjected to increased or reduced pressure. In most cases, the motion to activate a switch is given rom a diaphragm exposed to pressure on one side and supported by an adjustable spring on the other side. Te alarm or a dry-pipe sprinkler system is arranged with a connection rom the intermediate chamber o a OCTOBER 2011
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CONTINUING EDUCATION: Automatic Sprinkler Systems
Figure 8-13 Deluge-Valve Schematic
Figure 8-11 Sprinkler Dimensions
Figure 8-12 Quick-Response, Specifc-Application, Upright Sprinkler (Courtesy of The Viking Corporation)
dry-pipevalvetoapressure-operatedalarmdevice.Whenthedry-pipe valve trips, the intermediate chamber, which normally contains air at atmospheric pressure, lls with water at the supply pressure, which operates the alarm devices. Sometimes both an outdoor water motor gong and a pressure-operated electric switch are provided. Te alarm devices or the deluge and pre-action systems are o the same type as those used or the dry-pipe system. Codesrequirewater-supplycontrolvalvestoindicateconditionsthat could prevent the unwanted or unnecessary operation o the sprinkler system. Tis can be achieved by using electric switches, also called “temper switches,” which can be selected or open or closed contact. Te signal that indicates valve operation is given when the valve wheel is given two turns rom the wide open position. Te restoration signal
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sounds when the valve is restored to its ully open position. Tis simply cancels the temper-switch alarm.
notes 1
In cases where the sprinklers were ineective, studies show the reasons or ailure include: improper water supply or system was not adequate, valve was in the wrong position (closed instead o open), and system was taken out o operation without temporary replacements. 2 Te lie line o a sprinkler system is the distribution-piping network, which conveys the agent to the re. It must be the correct size, well constructed, and well supported. 3 An alloy having the lowest melting point possible, which means lower than each o the components.
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CONTINUING EDUCATION: Automatic Sprinkler Systems
Continuing Education rom Plumbing Systems & Design Doyounditdiculttoobtaincontinuingeducationunits(CEUs)? Trough this special section in every issue o PS&D, ASPE can help you accumulatetheCEUsrequiredformaintainingyourCertiedinPlumbingDesign(CPD)status.
Now Online! Te technical article you must read to complete the exam is located at www.psdmagazine.org.Justclickon“ContinuingEducation”atthetop o the page. Te ollowing exam and application orm also may be downloadedfromthewebsite.Readingthearticleandcompletingtheformwill allowyoutoapplytoASPEforCEUcredit.Ifyouearnagradeof90percent or higher on the test, you will be noti ied that you have logged 0.1 CEU,whichcanbeappliedtowardCPDrenewalornumerousregulatoryagencyCEprograms.(Pleasenotethatitisyourresponsibilitytodetermine theacceptancepolicyofaparticularagency.)CEUinformationwillbekept on le at the ASPE ofce or three yea rs.
About This Issue’s Article The October 2011 continuing education article is “Automatic Sprinkler Systems.” Automatic sprinklers were developed to control, conne, and extinguish res to prevent the loss o lie and minimize the loss o property. This chapter denes the types o xed sprinkler systems and their components, explains how sprinklers operate, details system design, installation, and maintenance procedures, and describes the associated alarms. You may locate this article at psdmagazine.org. Read the article, complete the ollowing exam, and submit your answer sheet to the ASPE oce to potentially receive 0.1 CEU.
Note:Indetermin ingyouranswerstotheCEquestions,useonlythematerialpresented in the corresponding continuing education article. Using inormation rom other materials may result in a wrong an swer.
CE Questions — “Automatic Sprinkler Systems” (PSD 181) 1. When was the rst automatic sprinkler invented? a. 1852 b. 1864 c. 1895 d. 1950 2. About 75 percent o the sprinkler systems in use are o the ________ type. a. dry-pipe b. preaction c. wet-pipe d. deluge 3. Automatic sprinkler systems are very ecient at suppressing res because they ________. a. continuously operate until the re is extinguished b. sound an audible alarm c. immediately detect re d. all o the above 4. The number o sprinkler heads expected to operate in case o a re depends on the ________. a. ceiling height b. combustibility o the content c. area o the room being protected d. both a and b 5. In an indoor sprinkler piping network, the ________ is the vertical pipe supplying the sprinkler system. a. eed main b. riser c. cross main d. branch line 6. At what fow rate should a 6-inch riser be fushed? a. 400 gpm b. 750 gpm c. 1,000 gpm d. 1,500 gpm
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7. In rerigerated areas, mains must be pitched at least _______ per 10 eet. a. 1/8 inch b. ¼ inch c. ½ inch d. ¾ inch 8. A usible-link automatic sprinkler with a temperature rating o 250–300°F is colored ________. a. white b. purple c. red d. blue 9. The diameter o a standard sprinkler head orice is ________. a. 1/8 inch b. ¼ inch c. ½ inch d. ¾ inch 10. A water deluge spray system may use a _______ nozzle. a. high-velocity spray b. slightly tilted defector c. low-velocity spray d. all o the above
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11. One sprinkler head can protect ________ in an ordinary-hazard occupancy. a. 15 square eet b. 90 to 100 square eet c. 100 to 130 square eet d. none o the above 12. What type o alarm can be part o a sprinkler system? a. pressure-activated alarm switch b. water motor gong c. vane-type water fow d. all o the above
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CONTINUING EDUCATION: Automatic Sprinkler Systems
Plumbing Systems & Design Continuing Education Application Form This orm is valid up to one year rom date o publication. The PS&D Continuing Education program is approved by ASPE or up to one contact hour (0.1 CEU) o credit per article. Participants who earn a passing score (90 percent) on the CE questions will receive a letter or certifcation within 30 days o ASPE’s receipt o the application orm. (No special certifcates will be issued.) Participants who ail and wish to retake the test should resubmit the orm along with an additional ee (i required). 1. Photocopy this orm or download it rom 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 ound on www.psdmagazine.org and the appraisal questions on this orm. 4. Submit this orm with payment ($35 or nonmembers o ASPE) i required by check or money order made payable to ASPE or credit card via mail (ASPE Education Credit, 2980 S. River Road, Des Plaines, IL 60018) or ax (847-296-2963). Please print or type; this inormation 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 ____________________________________________________ PE State _____________________________________________ PE No. _________________________________________________ Notice or North Carolina Proessional Engineers: State regulations or registered PEs in North Carolina now require you to complete ASPE’s online CEU validation orm to be eligible or continuing education credits. Ater successully completing this quiz, just visit ASPE’s CEU Validation Center at aspe.org/CEUValidationCenter.
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Automatic Sprinkler Systems (PSD 181) Questions appear on page 9. 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.
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