ASTM D4737 Test Method for Calculated Cetane Index by Four Variable Equation
7. Report
7.1 Report the result of Procedure A or Procedure B to one decimal place (XX.X) as:
Cetane Index by D4737 (Procedure A or B) = _____________
8. Precision and Bias
8.1 The determination of Calculated Cetane Index by Four Variable Equation from measured density at 15°C and measured 10 %, 50 % and 90 % recovery temperatures is exact.
8.2 Precision - The precision of the Calculated Cetane Index by Four Variable Equation is dependent on the precision of the original density and recovery temperature determinations which enter into the calculation. Test Method D1298 has a stated repeatability limit of 0.0006 kg/L and a stated reproducibility limit of 0.0015 kg/L at 15°C. Test Method D4052 has a stated repeatability of 0.0001 g/mL and reproducibility of 0.0005 g/mL. Test Method D86 has stated repeatability and reproducibility limits which vary with the rate of change of recovery temperature. See Figs. 2 through 7 and Tables 7 through 10 of Test Method D86 for details.
8.3 Bias - No general statement is made on bias of this test method since a comparison with accepted reference values is not available.
9. Keywords
9.1 cetane; cetane index; diesel fuel
