ASTM D976 Test Methods for Calculated Cetane Index of Distillate Fuels
6. Precision
6.1 Correlation of index values with ASTM cetane number is dependent to a great extent upon the accuracy of determination of both API gravity and midboiling point.
6.2 Within the range from 30 to 60 cetane number, the expected correlation of the Calculated Cetane Index with the ASTM cetane number will be somewhat less than +/-2 cetane numbers for 75 % of the distillate fuels evaluated. Errors in correlation may be greater for fuels whose cetane numbers are outside this range. Correlation is best for straight-run and catalytically cracked distillates and blends of the two, and least satisfactory for blends containing substantial proportions of thermally cracked stocks.
7. Keywords
7.1 cetane; cetane index; diesel fuel
