Chris,
I've researched this issue on and off for a few months now and haven't been able to find a simple answer, or at least one I can wrap my brain around without getting a headache!
The best so far is the example for "Gas Applications" on
page L27 of this pdf. The valve in the sample problem has a flow factor (C
v) of .58 with a flow of 500 SCFH (8 CFM) at 35 psi and a pressure drop of 5 psi.
Unless I am missing something, looking at the equation, C
v varies directly with Q (flow) so with the same flow, temp, pressure, and pressure drop, a valve with a 7 C
v should flow 12 times as much in that situation, although I think the main purpose is to calculate the pressure drop.
Using 10 CFM (600 CFH) flow, 55 deg. 135 psi inlet, assuming a 100 psi outlet I get a required C
v of .84. So either a C
v of 7 is way more than enough, a decimal is missing and it should be .7, or I'm doing something else wrong.
Come on, somebody with a little Fluid Dynamics background, please weigh in!
I'm considering putting a solenoid-actuated valve on my air tank, so I can turn that on/off remotely from the shop. My lines leak a little, so I'd prefer to only have the compressor run when I'm actually using it. The flow specification for the
valve says "cv 7". The valve has 3/4" fittings which, I think, will be correct for my compressor. Anyone know what effect that flow spec will have in effective flow rate? IIRC, my compressor is rated for ~10 CFM at 135 psi - I do not foresee every using more than one tool at a time, but do hope to try my hand at spraying with an HVLP system.
TIA!
Chris