Grant Erwin writes:

CFM does not equal mass flow

No, this is wrong again. CFM *does* equal mass flow.

I think you don't understand what "CFM" and "SCFM" mean.

One CFM means a cubic foot of air at 1 atm pressure ("free" air), flowing
per minute. Or the equivalent mass of air at any other pressure. It does
NOT mean one cubic foot of air at any other pressure.

The "S" prefixed simply specifies the input free air is understood to be at
68 deg F and 36 percent relative humidity, to simplify the variations of
system performance (usually, but not always, slight) due to those
variables.