NOTE 1— The term carbon residue is used throughout this test method to designate the carbonaceous residue formed after evaporation and pyrolysis of a petroleum product. The residue is not composed entirely of carbon, but is a coke which can be further changed by pyrolysis. The term carbon residue is continued in this test method only in deference to its wide common usage.
NOTE 2— Values obtained by this test method are not numerically the same as those obtained by Test Method D524. Approximate correlations have been derived (seeFig.X1.1), but need not apply to all materials which can be tested because the carbon residue test is applied to a wide variety of petroleum products.
NOTE 3— The test results are equivalent to Test Method D 4530,(see Fig.X1.2).
NOTE 4— In diesel fuel, the presence of alkyl nitrates such as amyl nitrate, hexyl nitrate, or octyl nitrate causes a higher residue value than