This document specifies a test method for the determination of cetane numbers ("CN") of diesel fuels, 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 0 to 100, but typical testing is performed in the CN range from about 40 to about 75. The precision of this test method covers the CN range from 44 to about 66.
This document is applicable to distillate as well as paraffinic diesel fuels intended for use in diesel engines, including those containing up to a volume fraction of 10 % fatty-acid methyl esters (FAME), ignition-improvers or other diesel fuel additives.
When this engine test procedure is used for other fuels such as synthetics and vegetable oils, 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.
NOTE The test method is also suitable for determining cetane numbers outside the range of the scope; however, the precision statement only applies for fuels in the specified range.
WARNING - The use of this document can involve hazardous materials, operations and equipment. This document does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of this document to take appropriate measures to ensure the safety and health of personnel prior to application of the document, and fulfil statutory and regulatory requirements for this purpose.