Rationale

Rationale: Cetane number as measured by D613, Standard Test Method for Cetane Number of Diesel Fuel Oil, is an important property of diesel fuels and biodiesel, but D613 is a challenging test method to maintain and perform properly. In recent years there have been efforts in Subcommittee 1 to provide other test methods as alternatives to D613. These test methods measure ignition delay in constant volume combustion chambers. D6890, Test Method for Determination of Ignition Delay and Derived Cetane Number (DCN) of Diesel Fuel Oils by Combustion in a Constant Volume Chamber, is one such method and has been added to D975 and D6751 as a D613 alternate.