Air compressor consumption is commonly expressed as standard cubic feet per minute. SCFM is defined as at standard conditions, which in the United States means sea level. Because in real life, conditions are often not the ones defined for SCFM, actual cubic feet per minute is often used instead. AFCM varies according to the pressure, temperature and humidity levels of the actual operating conditions.
Measure the actual air temperature in Rankine units
Divide the actual air temperature by standard air temperature, which is defined as 520 degrees Rankine, or the equivalent of 60 degrees Fahrenheit.
Measure the humidity
Multiply the relative humidity by the saturation pressure in pounds per square inch. The saturation pressure can be obtained by looking it up on a chart that expresses the saturation pressure at each temperature. Relative humidity can be measured using a wet and dry bulb hygrometer.
Measure the air pressure
Subtract the answer obtained in step 2 from the air pressure. A barometer can be used to measure the air pressure.
Divide and multiply
Divide the standard defined air pressure by the answer obtained in Step 3. The standard defined air pressure is 14.696 pounds per square inch. Multiply the SCFM by this answer, and then multiply that answer by the answer obtained in step 2. This is the ACFM.