by Guest » Tue Jul 26, 2005 5:34 am
Well the seconds to minutes or hours is the easy part.
Basically, you need to know the density of the gas at the standard conditions (temperature and pressure) implied by the "S" in SCFM. While natural gas is mostly methane, it also contains ethane and traces of other things, and the composition varies some depending on the source of the gas.
If you know the composition, you can construct a composite or average molecular weight for gas just as is done for atmospheric air, then use the ideal gas equation.
For legal metering (for trade), the ideal gas law isn't exactly right and you need to consider compressibility factor.