SCFM, FAD and ACFM in dryer selection

What the labels mean

SCFM means standard cubic feet per minute: flow stated at a defined reference state. ACFM means actual cubic feet per minute: volume at the stated actual conditions. FAD means free air delivery: delivered compressor air referred back to stated inlet conditions. Keep the definition supplied with your compressor; these labels alone are not a conversion rule.

CAGI's glossary defines its standard flow using temperature, absolute pressure and relative humidity. A dryer rating needs its own documented basis before you apply those definitions to the number.

Preserve the source label

Copy the flow value, unit and reference conditions from the compressor data sheet. If the sheet says FAD, ACFM or SCFM, retain that label. Do not replace it with a different one just to fill a form.

A valid comparison needs the applicable reference temperature, absolute pressure and humidity basis. If those details are missing, ask the supplier to reconcile the compressor delivery with the dryer rating.

Keep nominal capacity separate

Parker labels its SPE flow ratings in SCFM and gives pressure, inlet and ambient rating conditions. That supports a nominal model reference. It does not resolve every missing definition in a different compressor's data sheet.

California Air Tools' current RD product pages use CFM and show both a 52 CFM headline and a 52.97 CFM feature value. Our references preserve the headline and the source limitation rather than silently treating the extra digits as a better rating.

A practical comparison

Suppose the compressor sheet says 50 ACFM while the dryer page says 50 SCFM. Record both labels and their conditions. Equal numbers do not establish equal flow. Ask for a conversion using the documented reference states before applying the dryer correction table.

Avoid a shortcut through horsepower

The worksheet asks for delivered flow. It does not turn motor horsepower into a positive dryer match. If delivered flow is unknown, obtain the compressor's rated output and supporting conditions before final selection.

Compare the model records for power and published flow, then ask the supplier to confirm comparable capacity. Read which sizing inputs to collect for the rest of the operating record.