Pneumatic Punching Machine

PNEUMATIC PUNCHING MACHINE CHAPTER 1 SYNOPSIS The main purpose of this project is punching the objects for much application, like sealing, name punching, plate designing and etc. Here we are designing a pneumatic spiral punching making machines are necessary for saving the manufacturing time in the process, pneumatic is act as a main role. INTRODUCTION Pneumatic systems operate on a supply of compressed air which must be made available in sufficient quantity and at a pressure to suit the capacity of the system. When the pneumatic system is being adopted for the first time, however it wills indeed the necessary to deal with the question of compressed air supply. The key part of any facility for supply of compressed air is by means using reciprocating compressor. A compressor is a machine that takes in air, gas at a certain pressure and delivered the air at a high pressure.

WORKING PRINCIPLE Pneumatic Cylinder. Compressor. Solenoid control valve Die (male, female) clamp The main objective is to designing and developing a very compact, punch making machine. Initially the switch unit operates the compressor which delivers the

air to the solenoid valve at certain pressure. The solenoid controls the flow direction of air to the pneumatic cylinder. Thus the reciprocating motion of the pneumatic cylinder creates high force to punch the work piece. This part consists of two parts one is fixed called upper die, at the base and other is fixed called lower die at the end of piston rod. This part is moved up and down to provide the force on the object. Here we used for carrying the objects from one side to another side the object when it comes, if it detects the object means it will out puts a low pulse to the controller. Pneumatic is act as punching equipment. We can connect seal or cup cast with the pneumatic for cup production. Different seals and casts are used for punching the different shapes. When control unit detects the low pulse from then that will ON the pneumatic for Punch. After a second the controller will OFF the pneumatic. After getting the punch from the pneumatic spiral punch making.

ADVANTAGES  It reduces the manual work  It reduces the production time  Uniform application of the load gives perfect removing of the bearing.  Damages to the bearing due to the hammering is prevented  It occupies less floor space  Less skilled operator is sufficient

LIMITATIONS  Initial cost is high  Cylinder stroke length is constant  Need a separate compressor APPLICATIONS  Pressing Operation in all industries  Paper punching industries  Leather washer operation in all industries  Punching operation also done

CHAPTER 2 LITERATURE REVIEW This chapter will cover all the information related to this project, such as die design, piercing punches, pneumatic function and tolerances. Using this information, the element in the project will be presented to give more understanding about the title, objective, problem statement and the scope of project. The source that may be taken is either from book, journal, patent, conference paper, research paper and website.

CHAPTER 3 PNEUMATICS 3.1. INTRODUCTION Pneumatics is the discipline that deals with the mechanical properties of gases such as pressure & density & applies the principle to use compressed gas as a source of power to solve engineering problem. The most widely used compressed gas is air & thus its use has become synonymous with the term pneumatics. Today the most important property of the medium air is the simple conversion of pressure into force & translational displacement using a piston in a circular bore. 3.1 Pneumatic System Pneumatic systems use pressurized gases to transmit and control power. As the name implies, pneumatic system typically use air (rather than some other gas) as the fluid medium because air is safe, low cost and readily available fluid. It is particularly safe inn environments where an electrical spark could ignite leaks from system components (Majumdar, 1995).There are several reasons for considering the use of pneumatic systems instead of hydraulic systems. Liquids exhibit greater inertia than do gases. Therefore, in hydraulic systems the oil is a potential problem when accelerating and decelerating actuators and when suddenly opening and closing valves. Liquids also exhibit greater viscosity than do gases. This results in larger frictional pressure and power losses. Also, since hydraulic system use a fluid foreign to the atmosphere, they require special reservoirs and no leak- system designs. Pneumatic systems use air that is exhausted directly back into

the surrounding environment. Generally speaking, pneumatic systems are less expensive than hydraulic systems (Majumdar, 1995). However, because of the compressibility of air, it is impossible to obtain precise, controlled actuator velocities with pneumatic systems. Also, precise positioning control is not obtainable. In applications where actuator travel is to be smooth and steady against a variable load, the air exhaust from the actuator is normally metered. Whereas pneumatic pressures are quite low to explosion dangers involved if components such as air tanks should rupture(less than 250psi), hydraulic pressure can be as high as 12000psi. Thus hydraulic pressure can be high-power systems whereas pneumatics is confined to low power application (Majumdar, 1995). Principles and Maintenance The technology of pneumatics has gained tremendous importance in the field of work place rationalization and automation from old fashioned timber works and coal mines modern machine shops and space robots. Certain characteristics of compressed air have made this medium quite suitable for use in modern manufacturing and production plants. It is therefore, important that technicians and engineers should have a good working knowledge of pneumatic system, air operated tools and other accessories, including a thorough and clear concept of the physical principles that govern the behavior of compressed air (Majumdar, 1995). 3.1.2 Application of Pneumatic With the introduction of pneumatics in the manufacturing process, the industry is benefited with a cheaper medium of industrial automation which s judiciously used, may bring down the cost of production to a much lower level. A few decades ago, maximum application of pneumatics was probably in the field of construction where main source of power for tools like power hammer drills and etc was compressed air

only. Now, compressed air is used in every walk of industrial life starting with pneumatic cranes to the use of air in the brake systems and so on. Advantageous of pneumatic: 1. Wide availability of air. 2. Compressibility of air 3. Easy transportability of compressed air in pressure vessels, containers and in long pipes 4. Fire proof characteristic of the medium 5. Simple construction of pneumatic elements and easy handling 6. High degree of controllability of pressure, speed, and force 7. Possibility of easy but reasonably reliable remote controlling 8. Easier maintenance 9. Explosion-proof characteristic of the medium comparatively cheaper in cost than other stems

Compared to hydraulic system, pneumatic system has better operational advantages but it cannot replace hydraulic system so far as power requirement and accuracy of operations are concerned. In areas of hazards, probably air will be a better medium of power than electrical system, hydraulic system and steam power system. It may not be necessary at this stage to dwell further on the multitude of advantages that may be derived from applying pneumatic energy on production plants and systems except what has been already mentioned earlier (Maunder, 1995).

ADVANTAGES OF AIR    

Does not generate sparks. Poses no health hazard. Can be easily stored. Atmospheric air is free & this had led to statement that compressed air is a cheap form of energy.

Due to low viscosity, air cannot be used to lubricate the machinery it actuates. However, advances in electronics helped to develop control systems for electric drives that made them superior to formerly used fluid power actuators. This technology can also enhance the performance of the pneumatic drives.

Examples are pressure

controlled chambers in lorry braking circuits or position controlled actuators for process valves. AREA OF APPLICATION OF PNEUMATICS          

Damp Hopper Stamping Mining (Door opening & closing) Material flow Automobile (Braking System, engine etc.) Tools (Jackhammer, drills etc.) Punching Motion Restriction in CNC machines Dental Care Pneumatic gun for bolt tightening

SCHEMATIC DIAGRAM OF PNEUMATIC CONTROL SYSTEM

CHAPTER-4

PRINICIPLES OF PNEUMATIC 2.1 INTRODUCTION OF PRINICIPLES OF PNEUMATIC Pneumatics is a branch of technology that deals with the study and application of pressurized gas to effect mechanical motion. Pneumatic systems are extensively used in industry, where factories are commonly plumbed with compressed air or compressed inert gases. This is because a centrally located and electrically powered compressor that

powers cylinders and

other

pneumatic

devices

through solenoid valves is often able to provide motive power in a cheaper, safer, more flexible, and more reliable way motors and actuators.

than a large number

Pneumatics

also

has

of electric applications

in dentistry, construction, mining, and other areas. Ian Mackenzie  8 years FIRST experience  Co-General Manager for Team 1114 in 2004, winning 8 FRC awards  Lead designer for two revolutionary FIRST drive systems (Hexadrive 2002,SimSwerve 2004)  Specific Areas of Mentorship – Mechanical Design, Competition Strategy  3rd year Systems Design Engineering student at the University of Waterloo  Current member of the Waterloo Regional Planning Committee

BLOCK DIAGRAM OF PNEUMATIC SYSTEM

Fig4.0 BLOCK DIAGRAM OF PNEUMATIC SYSTEM

Why Use Pneumatics?

 Weight o Much lighter than motors (as long as several used)  Simple o Much easier to mount than motors o Much simpler and more durable than rack and pinion  More rugged o Cylinders can be stalled indefinitely without damage o Resistant to impacts  Disadvantage: All the way in or all the way out

2.2 PNEUMATIC COMPONENTS

2.2.1 COMPRESSOR   

Generates pressure of 120 psi Always run off relay module, in forward Do not use to generate a vacuum!

Reservoir(s)  Up to two  Store compressed air at 120 psi  Top up before each match – Slow leaks can decrease pressure between pit and field – Tether robot beside field to top up pneumatics

4.2.2 REGULATOR, FILTER

● Allows air from reservoirs to flow to rest of pneumatic system ● Limits pressure in valves, cylinders to 60 psi A pressure regulator is a valve that automatically cuts off the flow of a liquid or gas at a certain pressure. Regulators are used to allow high-pressure fluid supply lines or tanks to be reduced to safe and/or usable pressures for various applications. Gas pressure regulators are used to regulate the gas pressure and are not appropriate for measuring flow rates. Flow meters, Roometter or Mass Flow Controllers should be used to accurately regulate gas flow rates.

Operation

A pressure regulator's primary function is to match the flow of gas through the regulator to the demand for gas placed upon the system. If the load flow decreases, then the regulator flow must decrease also. If the load flow increases, then the regulator flow must increase in order to keep the controlled pressure from decreasing due to a shortage of gas in the pressure system. A pressure regulator includes a restricting element, a loading element, and a measuring element:  The restricting element is a type of valve. It can be a globe valve, butterfly valve, poppet valve, or any other type of valve that is capable of operating as a variable restriction to the flow.  The loading element applies the needed force to the restricting element. It can be any number of things such as a weight, a spring, a piston actuator, or more commonly the diaphragm actuator in combination with a spring.  When the actuator is forced against an expansion disk, the force is distributed among the pressure walls. This allows the gas to flow at the proper rate and not to be continually vaporized and diluted.  The measuring element determines when the inlet flow is equal to the outlet flow. The diaphragm is often used as a measuring element because it can also serve as a combine element. In the pictured single-stage regulator, a diaphragm is used with a poppet valve to regulate pressure. As pressure in the upper chamber increases, the diaphragm is pushed upward, causing the poppet to reduce flow, bringing the pressure back down. By adjusting the top screw, the downward pressure on the diaphragm can be

increased, requiring more pressure in the upper chamber to maintain equilibrium. In this way, the outlet pressure of the regulator is controlled. 2.2.3 PRESSURE SENSOR

 Detect pressure in pneumatic system – Indicate whether system is above or below a set pressure – Can be calibrated  Usually two (one set for 115 psi, one set for 105 psi) – Pressure below 105 psi: Compressor on

– Pressure above 115 psi: Compressor off A pressure sensor measures pressure, typically of gases or liquids. Pressure is an expression of the force required to stop a fluid from expanding, and is usually stated in terms of force per unit area. A pressure sensor usually acts as a transducer; it generates a signal as a function of the pressure imposed. For the purposes of this article, such a signal is electrical. Pressure sensors are used for control and monitoring in thousands of everyday applications. Pressure sensors can also be used to indirectly measure other variables such as fluid/gas flow, speed, water level, and altitude. Pressure sensors can alternatively be called pressure transducers, pressure transmitters, pressure senders, pressure indicators and pyrometers, manometers, among other names. Pressure sensors can vary drastically in technology, design, performance, application suitability and cost. A conservative estimate would be that there may be over 50 technologies and at least 300 companies making pressure sensors worldwide. There is also a category of pressure sensors that are designed to measure in a dynamic mode for capturing very high speed changes in pressure. Example applications for this type of sensor would be in the measuring of combustion pressure in an engine cylinder or in a gas turbine. These sensors are commonly manufactured out of piezoelectric materials such as quartz. Some pressure sensors, such as those found in some traffic enforcement cameras, function in a binary (on/off) manner, i.e., when pressure is applied to a pressure sensor, the sensor acts to complete or break an electrical circuit. These types of sensors are also known as a pressure switch.

Types of pressure measurements Pressure sensors can be classified in terms of pressure ranges they measure, temperature ranges of operation, and most importantly the type of pressure they measure. Pressure sensors are variously named according to their purpose, but the same technology may be used under different names.  Absolute pressure sensor This sensor measures the pressure relative to perfect vacuum.  Gauge pressure sensor This sensor measures the pressure relative to atmospheric pressure. A tire pressure gauge is an example of gauge pressure measurement; when it indicates zero, then the pressure it is measuring is the same as the ambient pressure.  Vacuum pressure sensor This term can cause confusion. It may be used to describe a sensor that measures pressures below atmospheric pressure, showing the difference between that low pressure and atmospheric pressure (i.e. negative gauge pressure), but it may also be used to describe a sensor that measures low pressure relative to perfect vacuum (i.e. absolute pressure).  Differential pressure sensor This sensor measures the difference between two pressures, one connected to each side of the sensor. Differential pressure sensors are used to measure many properties, such as pressure drops across oil filters or air filters, fluid levels (by comparing the pressure above and below the liquid) or flow rates (by measuring the change in

pressure across a restriction). Technically speaking, most pressure sensors are really differential pressure sensors; for example a gauge pressure sensor is merely a differential pressure sensor in which one side is open to the ambient atmosphere.

Sealed pressure sensor This sensor is similar to a gauge pressure sensor except that it measures pressure relative to some fixed pressure rather than the ambient atmospheric pressure (which varies according to the location and the weather). Pressure-sensing technology There are two basic categories of analog pressure sensors. Force collector types These types of electronic pressure sensors generally use a force collector (such a diaphragm, piston, bourdon tube, or bellows) to measure strain (or deflection) due to applied force (pressure) over an area.  Piezoresistive strain gauge Uses the piezoresistive effect of bonded or formed strain gauges to detect strain due

to

applied

pressure.

Common

technology

types

are

Silicon

(Monocrystalline), Polysilicon Thin Film, Bonded Metal Foil, Thick Film, and Sputtered Thin Film. Generally, the strain gauges are connected to form a Wheatstone bridge circuit to maximize the output of the sensor. This is the most commonly employed sensing technology for general purpose pressure

measurement. Generally, these technologies are suited to measure absolute, gauge, vacuum, and differential pressures.  Capacitive Uses a diaphragm and pressure cavity to create a variable capacitor to detect strain due to applied pressure. Common technologies use metal, ceramic, and silicon diaphragms. Generally, these technologies are most applied to low pressures (Absolute, Differential and Gauge)  Electromagnetic Measures the displacement of a diaphragm by means of changes in inductance (reluctance), LVDT, Hall Effect, or by eddy current principle.  Piezoelectric Uses the piezoelectric effect in certain materials such as quartz to measure the strain upon the sensing mechanism due to pressure. This technology is commonly employed for the measurement of highly dynamic pressures.  Optical Techniques include the use of the physical change of an optical fiber to detect strain due to applied pressure. A common example of this type utilizes Fiber Bragg Gratings. This technology is employed in challenging applications where the measurement may be highly remote, under high temperature, or may benefit from technologies inherently immune to electromagnetic interference. Another analogous technique utilizes an elastic film constructed in layers that can change reflected wavelengths according to the applied pressure (strain).

 Potentiometric Uses the motion of a wiper along a resistive mechanism to detect the strain caused by applied pressure. Other types These types of electronic pressure sensors use other properties (such as density) to infer pressure of a gas, or liquid.  Resonant Uses the changes in resonant frequency in a sensing mechanism to measure stress, or changes in gas density, caused by applied pressure. This technology may be used in conjunction with a force collector, such as those in the category above. Alternatively, resonant technology may be employed by expose the resonating element itself to the media, whereby the resonant frequency is dependent upon the density of the media. Sensors have been made out of vibrating wire, vibrating cylinders, quartz, and silicon MEMS. Generally, this technology is considered to provide very stable readings over time.  Thermal Uses the changes in thermal conductivity of a gas due to density changes to measure pressure. A common example of this type is the Pirani gauge.  Ionization

Measures the flow of charged gas particles (ions) which varies due to density changes to measure pressure. Common examples are the Hot and Cold Cathode gauges.  Others There are numerous other ways to derive pressure from its density (speed of sound, mass, index of refraction) among others. 4.2.4 CYLINDERS

● Force = Pressure x Area – 2” diameter piston – Area = 3.14 x 12 = 3.14 in2

– Pressure = 60 psi – 3.14 in2 x 60 psi = 188 lbs – Force while extending greater than while retracting

● Main decisions: Length and diameter – Diameter based on required force – Larger diameter: more force, but more air

Cylinder Tips ● If you need the piston to stay extended or retracted, add a mechanical latch ● Be careful to ensure the piston rod cannot get bent

● Hard to get locknuts/lock washers in large sizes, so nuts on pistons likely to come Loose

2.2.5 FLOW CONTROLS

Regulate flow of air into and out of a cylinder ● Used to control speed of a pneumatic cylinder ● if used, attach directly to cylinder (only one end needed)

● seems to regulate air flowing in both directions, but one direction is restricted a Little more

4.2.6 FITTINGS

4.2.7 EXHAUST VALVE

● Use to release pressure (especially at the end of a match)

● Useful if you need to be able to release a grabber after a match is over

CHAPTER-3 PNEUMATIC MECHANISM 3.1 LINEAR MOTION

A linear actuator is an actuator that creates motion in a straight line, as contrasted with circular motion of a conventional electric motor. Linear actuators are used in machine tools and industrial machinery, in computer peripherals such as disk drives and printers, in valves and dampers, and in many other places where linear motion is required. Hydraulic or pneumatic cylinders inherently produce linear motion; many other mechanisms are used to provide a linear motion from a rotating motor.

3.2 Advantages and disadvantages Actuator

Advantages

Type

Disadvantages

Cheap. Repeatable. No power Mechanical

source required. Self contained. Manual operation only. No Identical behavior extending or automation. retracting. Cheap. Repeatable. Operation can

Electromechanical

be

automated.

Self-contained.

Identical behavior extending or Many moving parts prone to wear. retracting. DC or stepping motors. Position feedback possible.

Linear motor

Simple

design.

moving

parts.

Minimum High

of

speeds

possible. Self-contained. Identical

Low force.

behavior extending or retracting. Requires position feedback to be repeatable. Short travel. Low speed. Piezoelectric Very small motions possible.

High voltages required. Expensive. Good in compression only, not in tension.

Hydraulic

Very high forces possible.

Can

leak.

Requires

position

feedback for repeatability. External hydraulic pump required. Some

designs good in compression only. Pneumatic

Strong, light, simple, fast.

Wax motor

Smooth operation.

Segmented

Very compact. Range of motion

spindle

greater than length of actuator.

Precise position control impossible except at full stops Not as reliable as other methods. Both linear and rotary motion.

Force, position and speed are controllable

and

repeatable.

Moving coil Capable of high speeds and precise positioning. Linear, rotary, and

Requires position feedback to be repeatable.

linear + rotary actions possible.

CHAPTER-5 PRESSURE CONTROL APPLICATIONS

There are many good reasons for reducing (and sometimes maintaining) steam pressure. This tutorial details common applications for direct operating, pilot operated, pneumatic, electric and electro-pneumatic pressure control systems, including the advantages and disadvantages of each different control method.

There are many reasons for reducing steam pressure:  Steam boilers are usually designed to work at high pressures in order to reduce their physical size. Operating them at lower pressures can result in reduced output and 'carryover' of boiler water. It is, therefore, usual to generate steam at higher pressure.  Steam at high pressure has a relatively higher density, which means that a pipe of a given size can carry a greater mass of steam at high pressure, than at low pressure. It is usually preferable to distribute steam at high pressure as this allows smaller pipes to be used throughout most of the distribution system.  Lower condensing pressures at the point of use tend to save energy. Reduced pressure will lower the temperature of the downstream pipe work and reduce standing losses, and also reduce the amount of flash steam generated when condensate from drain traps is discharging into vented condensate collecting tanks. It is worth noting that if condensate is continuously dumped to waste, perhaps because of the risk of contamination, less energy will be lost if the condensing pressure is lower.

 Because steam pressure and temperature are related, control of pressure can be used to control temperature in some processes. This fact is recognized in the control of sterilizers and autoclaves, and is also used to control surface temperatures on contact dryers, such as those found in papermaking and corrugators machines. Pressure control is also the basis of temperature control in heat exchangers.  For the same heating duty, a heat exchanger designed to operate on lowpressure steam will be larger than one designed to be used on high-pressure steam. The low-pressure heat exchanger might be less expensive because of a lower design specification.  The construction of plant means that each item has a maximum allowable working pressure (MAWP). If this is lower than the maximum possible steam supply pressure, the pressure must be reduced so that the safe working pressure of the downstream system is not exceeded.  Many plants use steam at different pressures. A 'stage' system where highpressure condensate from one process is flashed to steam for use in another part of the process is usually employed to save energy. It may be necessary to maintain continuity of supply in the low pressure system at times when not enough flash steam is being generated. A pressure reducing valve is ideally suited for this purpose.

5.1 DIRECT OPERATING, SELF-ACTING PRESSURE REDUCING VALVE - BELLOWS TYPE

Description

With this self-acting type of pressure controller, the downstream (control) pressure is balanced (via a bellows) against a spring force.

Advantages: 1. Inexpensive.

2. Small.

3. Easy to install.

4. Very robust, giving long life with minimum maintenance.

5. Tolerant of imperfect steam conditions.

6. Self-acting principle means that no external power is required.

Disadvantages: 1. Proportional only control.

2. Proportional band is 30% to 40% of the upstream pressure.

3. Wide proportional band means that maximum flow is only achieved when the downstream pressure has dropped considerably. This means that the reduced pressure will vary depending on flow rate.

4. Limited in size.

5. Limited flow rate.

6. Variation in upstream pressure will result in variation in downstream pressure.

Applications: Non-critical, moderate load applications with constant running flowrates, for example: 1. Small jacketed pans.

2. Tracer lines.

3. Ironers.

4. Small tanks.

5. Acid baths.

6. Small storage clarifiers.

7. Unit heaters.

8. Small heater batteries.

9. OEM equipment.

Points to note: 1. Different versions for steam, compressed air, and water.

2. Soft seat versions may be available for use on gases.

3. A wide range of body materials means that particular standards, applications and preferences can be satisfied.

4. A wide proportional band means care is needed if the safety valve needs to be set close to the working pressure. The system shown in Figure, works by having the pressure controller set at the required downstream pressure and operating the steam pressure control valve accordingly. The 4-20 mA signals from the pressure transmitter is relayed to the pressure controller and the saturation temperature computer, from which the computer continuously calculates the saturation temperature for the downstream pressure, and transmits a 4-20 mA output signal to the temperature controller in relation to this temperature.

The temperature controller is configured to accept the 4-20 mA signal from the computer to determine its set point at 5°C to 10°C above saturation. In this way, if the downstream pressure varies due to any of the reasons mentioned above, the temperature set point will also automatically vary. This will maintain the correct water/steam ratio under all load or downstream pressure conditions.

CHAPTER-6 ENDING REPORT 6.1 ADVANTAGE  Simplicity of Design And Control o Machines are easily designed using standard cylinders & other components. Machines operate by simple ON - OFF type control.

 Reliability o Pneumatic systems tend to have long operating lives and require very little maintenance. o Because gas is compressible, the equipment is less likely to be damaged by shock. The gas in pneumatics absorbs excessive force, whereas the fluid of hydraulics directly transfers force.  Storage o Compressed gas can be stored, allowing the use of machines when electrical power is lost.  Safety o Very low chance of fire (compared to hydraulic oil). o Machines can be designed to be overload safe.

6.2 CONCLUSION Pneumatics is a branch of technology that deals with the study and application of pressurized gas to effect mechanical motion. Pneumatic systems are extensively

used in industry, where factories are commonly plumbed with compressed air or compressed inert gases. This is because a centrally located and electrically powered compressor that powers cylinders and other pneumatic devices through solenoid valves is often able to provide motive power in a cheaper, safer, more flexible, and more reliable way than a large number of electric motors and actuators. Pneumatics also has applications in dentistry, construction, mining, and other areas. Such as  Air brakes on buses and trucks  Air brakes, on trains  Air compressors  Air engines for pneumatically powered vehicles  Barostat systems used in Neuro gastroenterology and for researching electricity  Cable jetting, a way to install cables in ducts  Compressed-air engine and compressed-air vehicles  Gas-operated reloading  Holman Projector, a pneumatic anti-aircraft weapon  Inflatable structures  Lego pneumatics can be used to build pneumatic models

5.3 COST ANALYSIS S. No

Particulars

Cost

1

System Designing

Rs. 2800.00

2

Components

Rs. 3000.00

3

Project Report Expenses

Rs. 1000.00

4

Traveling Expenses

Rs. 300.00

5

Miscellaneous

Rs. 400.00

TOTAL

5.4 BIBLIOGRAPHY

Rs. 7500.00

1. "Gone with the wind: Tubes are whisking samples across hospital". Stanford School of Medicine. 2010-01-11. Retrieved 12 February 2010. 2. Buxton, Andrew (2004). Cash Carriers in Shops. Princes Risborough: Shire Publications. ISBN 978-07478-0615-8. 3. Becker, D.A. (1998). "Characterization and use of the new NIST rapid pneumatic tube irradiation facility". Journal of Radioanalytical and Nuclear Chemistry 233: 155–160. doi:22 June 10. 4. "Pneumatic

Air

Drive-Thru

McDonald's".

Waymarking

website.

Retrieved 12 February 2010. 5.

"Prague's pneumatic post". Telefónica O2 Czech Republic. 2002. Retrieved 12 February 2010.

6. George Medhurst, Calculations and remarks tending to prove the practicability ... of a plan for the rapid conveyance of goods and passengers upon an iron road through a tube of 30 feet in area, by the power and velocity of air, London: 1812 7. Hadfield, Charles (1967). Atmospheric Railways. Newton Abbot: David & Charles. ISBN 0-7153-4107-3. 8. Allen, Oliver E... "New York's Secret Subway". AmericanHeritage.com website. Retrieved 12 February 2010. 9. "Capsule Pipelines - Mainland Europe". Capsu.org website. Retrieved 12 February 2010.