Compressed Air Units

[kelley038]

In a house compressed air system... since mass flow is conserved, is 100ACFM at 125psig more than 100SCFM at 100psig?

...Can someone explain this thought/question to me, I am not understanding acfm vs scfm in compressor selection.

Thanks for any help.

 

[PEDARRIN2]

You are mixing things up.

With compressors, it is all about capacity and comparison.

ACFM is actual cubic feet per minute - which is measured at the actual conditions of pressure, temperature, relative humidity typically at the location of your compressor. So you could not have 125 psig for ACFM. SCFM is standard cubic feet per minute - which is measured at standard conditions which can differ, but according to CAGI (Compressed Air & Gas Institute) is 14.5 psia, 68 F, and 0% relative humidity.

To convert between the two, look at

https://www.engineeringtoolbox.com/scfm-acfm-icfm-d_1012.html

When comparing compressors, it is important to use the same designation.

 

[LittleInch]

First define what you mean by ACFM.

It could and probably is the way pedarrin and eng tool box define it ( i.e. taking note of the inlet conditions that exist at the actual location of the compressor,

OR

it could be the actual volumetric flow that is happening with gas compressed to 125 psig.

If the former, then the pressures are irrelevant, it's the cfm that defines the mass flow. In most locations acfm will be a lower mass as actual conditions are usually lower than standard conditions.

If the latter definition then it's probably the other way around.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.