Cetane

A fuel’s cetane number, or index, is an indicator of its combustion speed and the compression needed for ignition. Diesel with a lower cetane number has longer ignition delays and requires more time for the combustion process to be completed. Hence, diesel with a higher cetane number is preferred by engine makers as it influences the engine’s efficiency.

The cetane number in diesel also influences the concentration of carbon monoxide (CO) and particulate emissions. A Concawe study showed that for each one number increase in cetane number, there is a reduction of about 5% of CO and particulate emissions. Similarly, hydrocarbon emissions are also reduced with the increase of the cetane number.

In Malaysia, the mandatory diesel standards stipulated in Federal Government Gazette No. P.U.