Haw. Rev. Stat. § 486-50
As used in this part, unless the context otherwise requires:
"Cubic foot" means that amount of liquefied petroleum product, vapor, or natural gas vapor, or synthetic natural gas vapor, or any blend of the above, which will occupy 1728 cubic inches when its temperature is sixty degrees Fahrenheit at a pressure of 760 mm of Hg (mercury). The density of the Hg shall be 13.5951 grams per cubic centimeter per second, per second.
"Petroleum product" includes automotive gasoline, diesel fuels, fuel oils, liquefied petroleum gas both liquid and vapor, residuals, distillates and fractions, kerosene, aviation fuels, turbine fuels, solvent, hydro-carbons or synthetics, crude oil, lubricating oil, or any other oil or distillate or blends of the above or any other product or byproduct normally considered a petroleum product, and synthetic natural gas or natural gas and manufactured gas or blends thereof.
"U.S. petroleum gallon" means that amount of petroleum product which occupies 231 cubic inches exactly when its temperature is sixty degrees Fahrenheit, or the expanded or contracted equivalent thereto at any other temperature.
HRS § 486-50