Conradson residue, fuels

The determination of carbon residue in fuels is intended to approximate the tendency of the fuel to form carbonaceous deposits. This tendency may cause, e.g. deposits on injectors of diesel engines, resulting in a deterioration of the injection pattern, and, ultimately, incomplete combustion of the fuel in the cylinder.

For fuels, the expected values are well below those of e.g. heat transfer oils. Therefore, the carbon residue for fuels is determined after evaporating 90% of the starting fuel. Usually, a value of less than 0.1% is expected. Ash-forming components and non-volatile additives present in the sample can contribute to increased carbon residue levels.