Assuming the same temperature inside the pipe as outside, the expansion ratio for this gas will be
approximately 18:1, meaning the “actual” flowing rate of 430 ft3/min is equivalent to approximately
7740 ft3/min of gas flow at “standard” atmospheric conditions. In order to unambiguously
distinguish “actual” volumetric flow rate from “standardized” volumetric flow rate, we commonly
preface each unit with a letter “A” or letter “S” (e.g. ACFM and SCFM).
If a volumetric-registering flowmeter is equipped with pressure and temperature sensors, it may
automatically scale its own output signal to measure gas flow rate in standard volumetric units. All
we need to determine is the mathematical procedure to scale actual conditions to standard conditions
for a gas