Conradson Carbon Residue, commonly known as "Concarbon" or "CCR" is a laboratory test used to provide an indication of the coke-forming tendencies of an oil. Quantitatively, the test measures the amount of carbonaceous residue remaining after the oil's evaporation and pyrolysis. In general, the test is applicable to petroleum products which are relatively non-volatile, and which decompose on distillation at atmospheric pressure. The phrase "Conradson Carbon Residue" and its common names can refer to either the test or the numerical value obtained from it.
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Test method
A quantity of sample is weighed, placed in a crucible, and subjected to destructive distillation. During a fixed period of severe heating, the residue undergoes cracking and coking reactions . At the termination of the heating period, the crucible containing the carbonaceous residue is cooled in a desiccator and weighed. The residue remaining is calculated as a percentage of the original sample, and reported as Conradson carbon residue.