1.1 This International Standard describes a procedure for the estimation of the net specific energy of aviation fuels from their aniline point, density and sulfur content. It is not applicable to pure hydrocarbons. The method is purely empirical and is applicable only to liquid hydrocarbon fuels derived by normal refining processes from conventional crude oil which conform to the requirements of specifications for aviation gasolines, or aircraft turbine and jet engine fuels of limited boiling ranges and compositions. NOTE 1 Internationally understood designations used by the air transport industry may be encountered, for example: - 100/l 30, 1 OOLL and 115/l 45 for aviation gasolines; - Jet A, JetA-1, Avtur and JP-8 for aviation turbine fuels, kerosine type; - Avcat, and JP-5 for aviation turbine fuels, high flash; - Jet B, Avtag and JP-4 for aviation turbine fuels, wide cut. 1.2 The method is intended for use as a guide in cases where an experimental determination of net specific energy is not available and cannot be made conveniently, and where an estimate is considered satisfactory. It is not intended, for specific specifications and similar purposes, that estimated values of the net specific energy shall be used in place of experimentally determined values. NOTE 2 The estimation of the net specific energy of hydrocarbon fuel from its aniline point and density is justifiable only when the fuel belongs to a well-defined class for which a relationship between net specific energy and aniline point and density has been derived from accurate experimental measurements on representative samples of that class. Even in this class, the possibility that the estimates may be in error by large amounts for individual fuels should be recognized.