Design, Engineering, Prototyping.

It is important to determine the actual flow rate of your compressor so that you purchase the correct Nitrox Controller system.  Purchasing a system that does not deliver enough oxygen will not meet the Dive Shop operator's needs, while purchasing a system that is oversized is unnecessarily expensive.  While all air compressors have a rating, most of them deliver less air flow than this rating.  The actual flow rate of your compressor might surprise you.

You can determine the average flowrate of your air compressor by timing how long it takes your compressor to fill a known volume of air to a pre-determined pressure.

1.  Depending on the size of your charging system, you should hook up multiple empty (0 psi) air tanks.  Filling up more tanks will yield a more accurate evaluation of your air compressor's flow rate.  If you can, use your compressor to fill at least 4 air tanks.  Standard aluminum 80 cylinders in fact contain 77.4 cubic feet of air at 3000 psi. (Catalina Cylinders)

2.  Start with the air tanks completely empty and the valve on the air tanks closed.  Hook the air tanks up to your charging station.  Isolate your air banks, and charge your header up to 3000 psi using your air compressor.  The air in your system from the compressor all the way to the valves on the air tanks themselves should be at 3000 psi.

3.  Now start your timer and open the valves on the air tanks that you are filling.  When the pressure in the tanks and in the air header reaches 3000 psi, you have effectively charged the volume in the air tanks. (i.e. 4 air tanks x 77.4 cubic feet per tank =  309.6 cubic feet)  Now divide this volume by the amount of time it took, and you have your actual compressor flowrate. ( i.e. 309.6 cubic feet / 22.0 minutes = 14.1 cfm flowrate )

Last modified: 12/23/08