What do I need to calculate CFM of a system?

by Jim
(Pittsburg, Ca, USA)

I know the size of the compressor, the size of the piping, and the system pressure. How can I calculate the maximum CFM going to a tool, tank, or valve connected to the system?





Bill sayss...

Jim, good of you to visit and to write in.

If you didn't have an air compressor and were looking to buy one, you could contact the various compressor manufacturers and ask them to do an air audit, towards them generating a quotation for your needs.

Since you have the compressor, I'm not sure why you need to do a calculation as, when your shop is running, you either have enough air or you don't.

There's no easy way to figure out how much air you are using now, except by looking at every air using device, reading the specs to know what flow and pressure they require, estimate the actual run time to come up with an average, and go from there.

These pages on compressor sizing will help. Read them, and follow the links to the other pages.

Cheers,

Bill




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What do I need to calculate CFM of a system?

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Dec 10, 2009
 To answer this question...
by: Sorlozer

The formula FAD = (P2-P1)/Pa * Q / t * Tin / Tout
Where: P2 = Final Pressure after filling;
P1 = Initial Pressure after bleeding;
Pa = Atmospheric Pressure;
Q = Storage volume in m3 which includes
receiver, after cooler and delivery
piping;
t = time required to build pressure to P2
Tin = inlet Air Temperature;
Tout = outlet Air Temperature;
FAD = Free Air Delivery, cfm or m³/min
I hope you find this formula helpful.

__________________

While I am grateful to "Sorlozer" for providing this information, I am not attesting to it's accuracy. I can just about count my paycheck, and formulas, by and large, are beyond my skills. :-)

Bill

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