The gas industry deals with flowing gas. Flow calculations for gases have unique units and definitions. Two sets of conditions exist for the determination and definitions of gas flow: standard conditions and normal conditions. A specified quantity of gas varies depending on the temperature and pressure of its environment. Two common units of flow are standard cubic feet per minute (SCFM) and normal cubic meters per hour (Nm3/hr). Converting between these units requires conversions of both standard to metric volume measurements and conversion of the amount of time.
Generate the formula for the conversion of SCFM to Nm3 based on the the conversion factor of SCFM divided by Nm3 equals 1.71928. By algebraic rearrangement: Nm3 equals SCFM divided by 1.71928.
Reduce the Nm3/hr flow to flow in 1 minute so that it matches the time period given by SCFM by dividing Nm3 per hour by 60. For example, assume a flow of 15.6 Nm3 per hour. Convert to flow per minute by dividing by 60 to yield Nm3 = (Nm3 / hr) / 60 = 0.26 Nm3 per minute.
Substitute the values of SCFM into the conversion formula and evaluate to yield Nm3. Continuing the example, Nm3 equals SCFM divided by 1.71928, or 0.26 divided by 1.71928 equals 0.15 Nm3.