ASTM D4868 Estimation of Net and Gross Heat of Combustion of Burner and Diesel Fuels
7. Report
7.1 Report the result as the estimated gross or net heat of combustion in MJ/kg to the nearest 0.01.

8. Precision and Bias
8.1 Precision - The precision of the estimated values will be dependent upon the accuracy of the determined density and sulfur, water and ash contents. The following precision is the aggregate precision of the measurements used to calculate the heat content by (Eq 1) and (Eq 2) and does not indicate the precision of the heat content of an individual sample. That precision is estimated in Note 4. When using data on the density, sulfur, water and ash content of a fuel determined by Test Methods D4052, D4294, D1796, and D482, respectively, the following criteria shall be used for judging the acceptability of estimated heat of combustion results.
8.1.1 Repeatability - The difference between successive results obtained by the same operator with the same apparatus under constant operating conditions on identical test material would, in the long run, in the normal and correct operation of the test method exceed the following value only in one case in twenty:
Repeatability 0.05 MJ/kg

8.1.2 Reproducibility - The difference between two single and independent results, obtained by different operators working in different laboratories on identical test material would, in the long run, and in the normal and correct operation of the test method, exceed the following value only in one case in twenty:
Reproducibility 0.15 MJ/kg

8.2 Bias - Bias cannot be determined for the procedure in Test Method D4868 since the data used to determine the correlation cannot be compared with accepted reference materials.

NOTE 5 - The correlation equations were tested using 199 present day fuels. The data is included in ASTM Research Report RR:D02-1233. About 95% of the calculated data were within 0.35 MJ/kg of measured heats of combustion.

9. Keywords
9.1 burner fuels; diesel fuels; gross heat of combustion; heat energy; heat of combustion; heating tests; net heat of combustion