text: 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.