The most common unit for measuring natural gas is the therm. A therm is 100,000 British Thermal Units (BTUs), a quantity of energy, and it is also equal to 29.3 kilowatt-hours or 105.5 megajoules. A therm's worth of natural gas contains 96.7 cubic feet, which people roughly estimate as 100 cubic feet. Since the energy in natural gas is equivalent to the gas's volume, you can freely convert between BTUs per hour and cubic feet per minute (CFM).
Divide the energy transfer rate in BTUs per hour by 100,000, which is the number of BTUs in a therm. For instance, if you are converting a rate of 500,000 BTUs per hour: 500,000 ÷ 100,000 = 5 therms/hr.
Multiply this answer by 96.7, which is the volume of a therm of natural gas: 5 × 96.7 = 483.5 ft³/hr.
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Divide this answer by 60, which is the number of minutes in an hour: 483.5 ÷ 60 = 8.06. This is the gas transfer rate, measured in cubic feet per minute.