ACFM = SCFM x x Ps – (RHs x PVs) Where: Pb – (RHa x PVa) Ta Ts x Pb Pa

Where:

Ps = Standard pressure (PSIA)
Pb = Atmospheric pressure – barometer (PSIA)
Pa = Actual pressure (PSIA)
RHs = Standard relative humidity
RHa = Actual relative humidity
PVs = Saturated vapor pressure of water at standard temperature (PSI)*
PVa = Saturated vapor pressure of water at actual temperature (PSI)*
Ts = Standard temperature (°R) NOTE: °R = °F+460
Ta = Actual temperature (°R)