scope:

This document specifies a test method for the determination of cetane numbers ("CN") in diesel fuel, using a standard single cylinder, four-stroke cycle, indirect injection engine. The cetane number provides a measure of the ignition characteristics of diesel fuels in compression ignition engines. The cetane number is determined at constant speed in a compression ignition test engine equipped with a swirl chamber. The cetane number scale covers the range from zero to 100, but typical testing is performed in the range from about 40 CN to about 75 CN. The precision of this test method covers the range from 44 CN to about 66 CN. This document is applicable to distillate as well as paraffinic diesel fuels intended for use in diesel engines, including those containing fatty-acid methyl esters (FAME), ignition-improvers or other diesel fuel additives. This engine test procedure may be used for other fuels such as synthetics and vegetable oils. However, samples with fuel properties that interfere with the gravity-based pre-supply pressure to the fuel pump e.g. due to high viscosity can only be used to a limited extent. Precision data for such fuels are not available at this stage. Precision data for paraffinic diesel fuels are currently under development.