Which gallon does US gal/min use?

The U.S. liquid gallon, exactly 231 cubic inches. It is not the Imperial gallon.

Does converting CFM change actual flow to standard or normal flow?

No. This page changes only the volume/time unit. Actual, standard and normal gas flows require a separately specified reference state and gas correction.

Exact unit definitions — signed volume flow

Exact Volumetric Flow Rate Converter

Convert the same volumetric flow quantity between SI,U.S. liquid-gallon and international-foot units without changing fluid state or reference conditions.

m³/s · m³/hL/s · L/minUS gal/min · ft³/min

Converted values

Cubic metres per second

—

Cubic metres per hour

—

Litres per second

—

Litres per minute

—

U.S. liquid gallons per minute

—

International cubic feet per minute

—

Single SI base

Q_m³/s=value×factor_sisend
value_output=Q_m³/s/factor_output

Exact factors to m³/s are:m³/s=1;m³/h=1/3600;L/s=0.001;L/min=1/60000;US gal/min=0.0000630901964;ft³/min=0.0004719474432.

Traceable definitions

NIST SP811 AppendixB identifies exact conversion factors and defines the international foot as exactly0.3048m. NIST Handbook44 AppendixC defines the U.S. liquid gallon as exactly231in³. Together with1in=0.0254m exactly,this gives1US gal=0.003785411784m³ exactly. One litre is1dm³,so1L=0.001m³ exactly;1min=60s and1h=3600s.

State and density are unchanged

For liquids and gases,the numerical conversion assumes the same volumetric-flow quantity at the same stated conditions. Mass flow requires density on a compatible basis. Standard/normal gas flow requires the exact reference pressure,temperature,humidity/compressibility convention and a gas-state calculation;none is inferred here.