ASTM D3343 Test Method for Estimation of Hydrogen Content of Aviation Fuels
6. Calculation and Report
6.1 Inch-Pound Units - Calculate the percent hydrogen of the sample using Eq 1 in 3.1. Round the value obtained to the nearest 0.01 %.
Example: Sample: Aviation kerosine fuel
Determined Values:
API gravity, G = 44
Aromatic volume percent, A = 12
Average distillation temperature, V 5 400°F (10 % = 350°F, 50 % = 390°F, 90 % = 460°F; V = (350 + 390 + 460)/3 = 400°F
Using Eq 1 in 3.1:
% H = 0.063 17(44) - 0.041 089(12) + 0.000 072 135(12) (400) + 0.000 056 84(44) (400) - 0.000 496 0(44) (12) + 10.56
% H = 13.9311 = 13.93
6.2 SI Units - Calculate the percent hydrogen of the sample using Eq 2.
Eq 2 of 3.1. Round the value obtained to the nearest 0.01 %.
Example: Sample: Aviation kerosine fuel
Determined Values:
Density, D = 805.9 kg/m3
Aromatics, volume %, A = 12
Average distillation temperature, T = 205°C (10 % = 178°C, 50 % = 200°C, 90 % = 237°C, T = (178 + 200 + 237)/3 = 205°C)
Using Eq 2 in 3.1.
% H = [9201.2 + 1 14.49(205) - 70.22(12)]/805.9 + 0.026 52(12) + 0.000 129 8(12) (205) - 0.013 47(205) + 2.003
% H = 13.9367 = 13.94
6.3 An alternative method for calculating the percent hydrogen is by summing the values of F1(H2) and F2(H2) determined from the nomographs in Fig. 1 and Fig. 2, respectively.
6.3.1 Determine the F1(H2) value using the nomograph of Fig. 1. Enter the nomograph at the abscissa with the density or the API gravity value, then move vertically upward to the volume percent aromatics line, and then move horizontally to the left and read off the value of F1(H2).
6.3.2 Determine the F2(H2) value using the nomograph of Fig. 2. Enter the nomograph at the left ordinate using the density or the API gravity. Move horizontally to the right to the volume percent aromatics line, then vertically downward to the average boiling point line (average of the 10, 50, and 90 % distillation temperatures) using either °F or °C, and then horizontally to the right ordinate and read the F2(H2) value.
6.3.3 Sum the F1(H2) and the F2(H2) values to obtain the estimated hydrogen content in mass percent.
6.4 Report the result from 6.1, 6.2, or 6.3 to the nearest 0.01 % as weight percent of hydrogen of the fuel sample.
7. Precision and Bias
7.1 The following criteria should be used for judging the acceptability of estimated hydrogen content results (95 % confidence):
7.1.1 Repeatability - Duplicate results by the same operator (using a second set of measured values for aromatics content, density, and distillation data) should be considered suspect if the calculated hydrogen content values differ by more than the following amount:
Repeatability = 0.03 %
7.1.2 Reproducibility - With two independent laboratories making independent measurements of the density, aromatics content, and distillation data for an identical fuel sample, the calculated hydrogen content values should not be considered suspect unless they differ by more than the following amount:
Reproducibility = 0.10 %
7.2 Bias - The correlation equation was developed using 331 fuels, 247 of which were aviation fuels (or similar thereto) and 84 of which were pure hydrocarbons, commercial products of nearly pure hydrocarbons, and special high-temperature fuels (HTF) produced for Air Force tests. The standard error of estimate for the hydrogen content of all fuels is 0.20 % and for aviation type fuels is 0.16 %.
NOTE 3 - The repeatability and reproducibility stated in this section is based on the summation of the repeatability and reproducibility of the test methods used in the calculations. It does not include the effect of the scatter of the original data about the regression line, described by Eq 1 and Eq 2. Therefore, the possibility that individual estimates may be in error in excess of the precision discussed in this section should be recognized.
8. Keywords
8.1 aviation fuels; hydrogen content
