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Ned Simmons
 
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Default SCFM vs. CFM, also air flow/pressure across a regulator

In article ,
says...
Yes, I started that thread too. The reason that this has come back is that
I was never convinced the last time. Let me ask YOU, Ned, to answer my
question? I'll repeat it:

Postulate a big air tank pressurized to 180 psi, with a long (long
enough so the air has time to cool to ambient) pipe to an ideal
regulator which regulates the pressure down to 90 psi. The regulator's
output is a pipe of the same size which is connected to a constant
load of such a size as to make the cfm going into the regulator
measured to be 10 cfm @ 180 psi. What cfm will come out of the regulator
at 90 psi?


If we assume that the air behaves as an ideal gas and the
pressures are absolute, then there'll be 20 CFM @ 90 psia
flowing out of the regulator. I don't think there's ever
been any question about that. But that doesn't mean that
there isn't a loss in the potential of that air to do work.

CFM X psi for a compressible gas is not analogous to volts
X amps.

Ned Simmons