Cetane number

Cetane number (diesel fuel) measures the tendency of the fuel to ignite spontaneously.
The Cetane number of a fuel is defined as the volume by percentage of n-hexadecane in a mixture of n-hexadecane and 1-methylnaphthalene.
The Cetane Number is a measure of the combustion quality of diesel fuel under compression.
Cetane number is actually a measure of a fuel’s ignition delay; the time period between the start of injection and start of combustion of the fuel.