CFM vs SCFM

John Draper · Jan 28, 2006

Anyone know what these initials mean and the difference between them; as they pertain to air flow.

Thanks,

Gary DiPietroSr · Jan 28, 2006

Does this help?

When manufacturers list performance for blowers and compressors it is stated as "Capacity" in CFM (Cubic Feet per Minute). This refers to the volume of air at the inlet to the unit, therefore this is often referred to as Inlet CFM (ICFM) or Actual CFM (ACFM). These terms are used interchangeably and mean basically the same thing (CFM, ICFM, ACFM).

In many process applications there is a critical demand for a specific minimum flow in terms of some base or reference pressure, temperature and relative humidity. Many standards are used, the most common being the Compressed Air & Gas Institute (CAGI) and the American Society of Mechanical Engineers (ASME) standards, which are 14.7 PSIA, 68Deg. F and 36% relative humidity. When you express your "Demand" in Standard CFM (SCFM), you are saying that you want this compressor or blower to deliver this CFM even at your worst case conditions.

Doess this help?

John Draper · Jan 28, 2006

Gary,

Yes, helps a lot, really appreciate it. I was looking at some air brushes hopefully to work with my .79 SCFM compressor. The airbrush is .50 CFM. So I guess that would work.

Also, I must add that I am very impressed with your knowledge on the subject.

BTW, I lived in CT for a few years, New Britain (Nu Britaaannn), CT.

Attended Conn State Univ college while there.

Thanks again,

Michael Cacioppo · Jan 29, 2006

jj, if using an air brush you should have a tank, not tankless, compressor. The reason being that the variation in pressure, even with a regulator, will show in the spray output for each piston cycle. A tank is like a large capacitor and will remove the ripple. For an air brush you don't need a large compressor and a small tank is more than adequate. This has been my experience, others may have had different ones.