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Operation of pneumatic cylinders requires compressed air. The easiest solution to the supply of compressed air is to own an air compressor. However, if you don't already own one, the cost may be prohibitive, especially for just one pneumatic project. There are several options, many are low cost and we'll review them here. But first, let's discuss the best option, using your own air compressor.

Air compressors have a couple key measurements, the tank size (in gallons) and the cubic feet per minute (CFM). The tank size, simply identifies the quantity of air that can be stored. The CFM, identifies how much air, at a given pressure (PSI), can be delivered to the storage tank per minute.

Pneumatic cylinders don't use very much air per cycle, and so even a small compressor can be more than adequate to operate a pneumatic system. However, if the cylinder is cycled rapidly or for extended periods of time, or many cylinders are being driven by one compressor, then the tank size and CFM may become relevant in calculating whether they can drive your pneumatic system.

If you want to minimize compressor noise during operation of your pneumatic props, multiple storage tanks may be the solution. You can place storage tanks in series near the compressor or in-line near each prop. Place a tank with a regulator near a prop and it can be charged to the tanks rated PSI and then the pressure reduced at the valve to suit the individual prop. The system will take longer to charge, because of the added storage capacity, but it will reduce the cycling of the compressor.

Air Compressor Alternatives

Combined with a portable air tank, any compressor will do. You can charge a tank at a gas station, a neighbor's house, anywhere you can gain access to an air compressor. One cheap alternative is to use the air compressor designed to be carried in your car to inflate flat tires. This compressor is slow, but it is cheap and is capable of producing the required PSI. The trick is getting the fittings to mate the compressor with the tank and then being able to disconnect the tank without losing your pressure. On the tank side, use a female quick-connect fitting. This will allow air to enter the tank, but when the filler is disconnected, the quick-connect prevents air from being released. On the compressor side, a connection for Shraeder valve (tire valve stem) is standard. Various fittings are available to put into the filler valve, such as inflator valves for balls, pools, toys etc. Some valves are threaded and if yours has this, you may be able to purchase a fitting to screw into the filler and then connect an adapter to make the transition to air hose quick-connects. Another alternative is to cut off the filler and install an air-hose fitting used for repair of damaged air hoses. You'll have to be a little bit resourceful, but you should be able to make the connection between the small compressor and a storage tank.

Storage Tanks

If you don't have a compressor, storage tanks may be your solution. You can fill storage tanks at a gas station, or anywhere you can gain access to a compressor, such as at a neighbor's home. The storage tank is connected to the pneumatic system in just the same way as if you were using a compressor.

Storage tanks are less expensive than a compressor but they still are an expense. Many people make there own storage tanks out of PVC or galvanized pipe. These homemade storage tanks are inherently dangerous, as they can explode and send out shrapnel if over pressurized. Furthermore, the safe pressure limit of the tank cannot be precisely determined as it will vary from device to device. PVC also degrades over time and so a PVC tank may function the first time it is used, but slowly degrade and explode under even low pressure. This is especially true of PVC exposed to sunlight. While we do not recommend making homemade air tanks, if you do, it absolutely must be fitted with a pressure relief valve and the tank should never be used for anything more than minimal air pressure.

If you happen to have access to a scuba tank or can find one cheap at a garage sale, that will do fine as an air supply tank. Another possibility is to rent a tank from a local gas supply company. Companies that sell helium, hydrogen, CO2 etc in those tall tanks (like balloon vendors use) can fill one with compressed air. Look for Welding Supply or Gases in the yellow pages.

 

Read about How To Set Up a Pneumatic Control for a Prop




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