ASTM D1405 Test Method for Estimation of Net Heat of Combustion of Aviation Fuels
5. Procedure
5.1 Determine the aniline points of the sample to the nearest 0.05 C (0.1 F) as described in Test Method D611.
5.2 Determine the API gravity of the sample to the nearest 0.1° API as described in Test Method D287. Alternatively, determine the relative density by Test Methods D941, D1217, and D4052 and correct the result to API gravity by Guide 1250.
5.3 Determine the sulfur content of the sample to the nearest 0.02 % sulfur as described in Test Methods D129, D1266, D2622, D3120, D4294, or D5453 depending upon the volatility of the sample.
6. Calculation
6.1 Calculate the product of the aniline point in degrees Fahrenheit and the gravity in degrees API; round off the value obtained to the nearest integer.
6.2 From Tables 1-8, make a linear interpolation between rows bracketing the aniline-gravity products and within columns bracketing the sulfur content of the sample. Use the table applicable to the type of product being tested. Thus, use Table 1 or Table 5 for Aviation Gasolines, Table 2 or Table 6 for JP-4 jet-type fuels; Table 3 or Table 7 for JP-5 jet type fuels, and Table 4 or Table 8 for kerosene-type aviation turbine fuels (Specification D1655, Jet A or A-1).
6.3 From the values obtained in 6.2, make a linear interpolation for the sulfur content within the row for the calculated aniline gravity constant.
6.3.1 Example:
Sample: JP-4 Fuel
6.3.1.1 Determined Values:
Aniline point, A = 137°F
Gravity, G = 54.8° API
Sulfur content = 0.10 mass %
6.3.1.2 Calculated Value:
A x G product = 7508
6.3.1.3 Estimated Net Heat of Combustion:
43.625 MJ/kg
18 755 Btu/lb
