The heating values for liquid fuels in units of Btu/lb are calculated based on heating values in unit of Btu/gal and the corresponding fuels density values. The heating values for gaseous fuels in units of Btu/lb are calculated based on the heating values in units of Btu/scf and the corresponding fuel density values.

Btu = British thermal units scf = standard cubic feet.The higher heating value (also known gross calorific value or gross energy) of a fuel is defined as the amount of heat released by a specified quantity (initially at 25☌) once it is combusted and the products have returned to a temperature of 25☌, which takes into account the latent heat of vaporization of water in the combustion products. It resembles Jet A1 to a great extent but contains more special additives.The lower heating value (also known as net calorific value) of a fuel is defined as the amount of heat released by combusting a specified quantity (initially at 25☌) and returning the temperature of the combustion products to 150☌, which assumes the latent heat of vaporization of water in the reaction products is not recovered. However, NATO military aircraft rely on the JP-8 fuel (this abbreviation stands for Jet Propellant 8). Its usage is normally limited with civic aviation. General aviation representatives purchase it for compatible diesel engine planes as well. Jet A1 is considered the optimal fuel for the most modern aircraft and the primary fuel for jet turbine engines. In particular, it meets the following standards. Since the demand for it is steadily high on an international level, it is subject to strict quality specifications. This fuel is suitable for most types of jet aircraft. Its maximum freezing point is -47☌ and its minimum flashpoint is +38☌. Jet A1 does not freeze in such an environment. At cruising altitude, the air temperature might drop below -30☌. Plus, certain additives serve as the basis for the above-mentioned frost resistance. Get rid of the organisms that otherwise would have grown in the fuel.Do not allow the fuel to ignite uncontrollably.Prevent deposits from forming in the turbine.Prevent the fuel from becoming electrically charged.These additives carry out the following functions. Very small amounts of additives are added to the substance after refining. It consists of light petroleum that was thoroughly refined. Thanks to its thermal and storage stability, it reduces the risks of the fuel's deterioration. Even at the highest altitudes, it will not crystallize. Due to its outstanding heat output, it increases flight autonomy. Professionals value it highly because it enables the aircraft to get the maximum energy with a minimum fuel load.

Jet a1 density vs temperature table