Real life “actual conditions” are seldom “standard conditions”. When
- pressure is applied a volume of air – it gets smaller
- vacuum is applied to a volume of air – it expands
The actual air volume flow is often termed ACFM – Actual Cubic Feet per Minute.
The Actual Cubic Feet per Minute – ACFM – depends on the
of the actual air.
The conversion from SCFM to ACFM can be expressed
ACFM = SCFM [P std / (P act – P sat Φ)](T act / T std )
where,
ACFM = Actual Cubic Feet per Minute
SCFM = Standard Cubic Feet per Minute
P std = standard absolute air pressure (psia)
P act = absolute pressure at the actual level (psia)
P sat = saturation pressure at the actual temperature (psi)
Φ = Actual relative humidity
T act = Actual ambient air temperature (o R)
T std = Standard temperature (o R)
Note!
P sat Φ ƒ < P act