Acfm

       

ACFM Formula
\(acfm \;=\; scfm \cdot \left( \dfrac{ P_s  }{ P_a - (ppm \cdot RH ) } \right) \cdot \left( \dfrac{T_a + 460 }{ T_s + 460 } \right) \)
Symbol	English	Metric
\(acfm\) = actual cubic feet per minute	\(ft^3 \;/\; min\)	-
\(scfm\) = standard cubic feet per minute	\(ft^3 \;/\; min\)	-
\(P_s\) = standard pressure	\(lbf \;/\; in^2\)	-
\(P_a\) = atmospheric pressure	\(lbf \;/\; in^2\)	-
\(ppm\) = partial pressure of moisture at atmospheric temperature	\(lbf \;/\; in^2\)	-
\(RH\) = relative humidity	\(dimensionless\)	-
\(T_a\) = atmospheric temperature	\(F\)	-
\(T_s\) = standard temperature	\(F\)	-

Actual cubic feet per minute is a unit of volumetric flow.  It is primarily used by manufacturers of blowers and compressors to measure how much air is being moved across the equipment.  This number is equal to the volumetric measurement, standard cubic feet per minute, adjusted to the actual conditions (pressure and temperature).  This is important because scfm is measured at standard conditions.  Typically, this is 60F at 14.7 psia.