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CFM vs. SCFM vs. ACFM?
- Thread starter bmwpower
- Start date
74NovaSS
Member
I'll give it a try. Air is compressible so the mass of the air flowing can change
CFM - cubic feet per min: rating of a motor at speed will push a certain volume.
SCFM - standard cubic feet per min: volume of air flow corrected to standard density conditions; pressure, temp and relative humidity. Puts everyone in the same conditions.
ACFM - actual cubic feet per min: the volume of air after it is pressurized flowing anywhere within the system (independent of air density).
CFM - cubic feet per min: rating of a motor at speed will push a certain volume.
SCFM - standard cubic feet per min: volume of air flow corrected to standard density conditions; pressure, temp and relative humidity. Puts everyone in the same conditions.
ACFM - actual cubic feet per min: the volume of air after it is pressurized flowing anywhere within the system (independent of air density).
As you've already probably guessed, I'm looking at compressor specs and everyone seems to specify different units. I want to make sure I'm not getting some hype from the manufacturer.
So from what I gather, there is no significant difference between them?
So from what I gather, there is no significant difference between them?
I believe you want to compare SCFM's. These would all be corrected values and would make comparisons have more value. Kind of like the EPA fuel economy numbers for cars and trucks, they're not real world but they do have value if you use them as a comparison between vehicles.
Aahz
Well-known member
Make sure you look at the "delivery" SCFM numbers....Some manufacturers will tell you a they have a certain CFM or SCFM...but they will be talking about the "Input" or free air number rather than the "Output" delivery number (ACFM).
It gets a bit confusing, but try to remember that the DELIVERED AIR (ACFM) is what drives your tools, so that's what's really important. The FREE AIR is how much needs to be compressed to GET the ACFM.
It gets a bit confusing, but try to remember that the DELIVERED AIR (ACFM) is what drives your tools, so that's what's really important. The FREE AIR is how much needs to be compressed to GET the ACFM.
Read somewhere that ACFM was Assisted Cubic Feet/Minuite which uses stored air from the tank to give a higher number than what the pump actually can do. Kind of like how they get the ratings on small universal electric motors. I think it's best to stay away from anyone who advertises that way & stick with the ones that give honest numbers like Eaton, Quincy, Rol Air, IR, etc. Generally when a compressor is claimed to make way more cfm than others with the same hp or amp rated motor this is what they're doing.