No natural gas shall be delivered and sold to any consumer which shall contain less than 1,000 British thermal units per cubic foot of the natural gas, as determined at a temperature of 60°F and a pressure equivalent to 30 inches of mercury at 32°F and water vapor saturated. The British thermal unit content of the natural gas shall be determined and calculated from the gas discharged from the service main.
(1964 Code, § 17-5)