## What Is The Difference Between Pressure & Flow In A Compressed Air System?

There is rarely a day that goes by that I don’t receive a call from someone who has a need for a compressed air product and when I state the SCFM requirements of the device they respond back with the psi rating of their air compressor.  Many technicians simply do not understand the difference between the two.  Simply put psi (pounds square inch) is force and CFM (cubic feet per minute) is flow.

A simple illustration would be to contrast a 12 VDC powered air compressor that many people carry in their trunks to inflate car tires.  They will inflate your car tire to 35 psi in a matter of minutes.  While the air compressor at a tire shop can inflate a car tire in a minute or less.  What is the difference?

Simply put, the flow. Both inflate the tire to the desired pressure but the one with largest flow (volume) does it much faster.  In the case of a compressed air product such as an air nozzle, the pressure required to operate is only one part of what is necessary to operate the device effectively, you need to have enough flow or CFM.

Let us now consider an EXAIR 1100 Super Air Nozzle, its rated performance of 13 ounces of force at 12″ distance from the nozzle is derived from supplying 14 SCFM @ 80 psi.  The typical home use air compressor that runs on 110 VAC (Generally 2 HP maximum) will not generate the flow (volume /CFM) at 80 psi to run the nozzle at peak force, just as it would not generate enough flow to fill the tire as quickly as the industrial compressor at a tire shop.

When an open tube, pipe or inefficient nozzle is placed at the end of an air line to provide blow off for cooling or cleaning it demands much greater volume from the compressor. If the compressor cannot keep up the force (pressure) of the system will decline. Replacing an open tube or pipe with an EXAIR engineered nozzle will require less compressed air volume which, in turn, will give the compressor more ability to provide full pressure and force upon your application.

If you would like to discuss air consumption of any of EXAIR’s engineered solutions, I would enjoy hearing from you…give me a call.

Steve Harrison
Application Engineer
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