An empirical measure of ignition quality. Defined as the percentage by volume of cetane in a mixture of cetane and methyl naphthalene which has the same ignition quality when used in an engine as a fuel under test
EESiFlo North America, Terminology and Glossary: Fuel and Oil Terms, Pennsylvania, USA 2002. flowmeterdirectory.com/flowmeter_terminology, (Oil - Amer) {564}