scope:

This document specifies a test method for the quantitative determination of ignition delay of middle distillate fuels intended for use in compression ignition engines. The method utilizes a constant volume combustion chamber designed for operation by compression ignition, and employing direct injection of fuel into compressed air that is controlled to a specified pressure and temperature. An equation is given to calculate the derived cetane number (DCN) from the ignition delay measurement. This standard is applicable to diesel fuels, including those containing FAME. The method is also applicable to middle distillate fuels of non-petroleum origin. However, users applying this standard especially to unconventional diesel fuels are warned that the relationship between derived cetane number and combustion behaviour in real engines is not yet fully understood. The standard covers the ignition delay range from 3,3 ms to 6,4 ms (61 DCN to 34 DCN). The combustion analyser can measure shorter or longer ignition delays, but precision can be affected.