(Equivalent Tests: IP 398 and ISO 10370)
EXPLANATION
The carbon residue values of the various petroleum materials serve as an approximation of the tendency of the material to form carbonaceous type deposits under degradation conditions similar to those used in the test method, and can be useful as a guide in the manufacture of certain stocks. The test results are equivalent to those by Conradson Carbon Method, Test Method D189; however, this test method has the advantage of better control of test conditions, smaller samples, and less operator attention. Up to twelve samples can be run simultaneously. This test method is applicable to petroleum products that partially decompose on distillation at atmospheric pressure and was tested in the carbon residue range of 0.10 to 30 m/m %.
Ash-forming constituents as defined in Test Method D482, or nonvolatile additives present in the sample will get included in the total carbon residue reported. Also, in diesel fuels thepresence of alkyl nitrates such as amyl, hexyl, or octyl nitrate causes a higher carbon residue value leading to the erroneous conclusion as to the coke-forming tendency of the fuel.
TEST SUMMARY
A weighed quantity of the sample placed in a glass vial is heated to 500° C under an inert (nitrogen) atmosphere in a controlled manner for a specific time. The sample undergoes coking reactions and volatiles formed are swept away by the nitrogen gas. The carbonaceous-type residue remaining is reported as a percent of the original sample as "carbon residue (micro)".
TEST PRECISION
This test method has no bias.