The amount of gas that would occupy 1 ft3 (0. 03 m3) when at a temperature of 60oF (16oC), saturated with water vapor and under a pressure equivalent to that of 30 in. of mercury (101. 6 kPa)
NFPA 54 ANSI Z223.1-2002 National Fuel Gas Code, 2002 ed. https://law.resource.org/pub/us/code/ibr/nfpa.54.2 006.pdf, (Code: Nat Fuel Gas - Amer) {210 NFC}