ASTM D3343 Test Method for Estimation of Hydrogen Content of Aviation Fuels
3. Summary of Test Method
3.1 A correlation has been established between the hydrogen content of a fuel and its distillation range, API gravity, and aromatic content. This relationship is given by the following equations:
Type fuel - All aviation gasolines and aircraft turbine fuels
% H = 0.063 17G - 0.041 089A + 0.000 072 135AV + 0.000 056 84GV - 0.000 496 0GA + 10.56
or in SI Units,
% H = (9201.2 + 14.49T - 70.22A)/D + 0.026 52A + 0.000 129 8AT - 0.013 47T + 2.003
where:
%H = mass percent hydrogen;
G = gravity, °API;
A = volume percent aromatics;
V = average of 10, 50, and 90 % distillation data, °F (using Test Method D86);
T = average of 10, 50, and 90 % distillation data, °C; and
D = density in kg/m3 at 15°C.
3.2 Eq 1 was empirically derived for the mass percent hydrogen by the method of least squares from accurate data on fuels using inch-pound units of measurement. Eq 2 was derived directly from Eq 1 by simply converting from inch-pound to SI units of measurement.
4. Significance and Use
4.1 This test method is intended for use as a guide in cases in which an experimental determination of hydrogen content is not available. Table 1 shows a summary for the range of each variable used in developing the correlation. The mean value and its distribution about the mean, namely the standard deviation, is shown. This indicates, for example, that the mean density for all fuels used in developing the correlation was 783.5 kg/m3 and that two thirds of the samples had a density between 733.2 and 841.3 kg/m3, that is, plus and minus one standard deviation. The correlation is most accurate when the values of the variables to be used in the equation are within one standard deviation of the mean, but is useful up to two standard deviations of the mean. The use of this correlation may be applicable to other hydrocarbon distillates similar to aviation fuels, but only limited data on nonaviation fuels were included in the correlation.
4.2 Hydrogen content is required to correct gross heat of combustion to net heat of combustion. Net heat is used in aircraft calculation because all combustion products are in the gaseous state, but experimental methods measure gross heat.
