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Cetane number

This is the most universally accepted measure of ignition quality for diesel fuel.

In a diesel engine, fuel is not ignited with a spark plug. The piston compresses the air. It is the heat released during the compression which makes the fuel ignite in a shorter or longer period of time. Cetane number is a measure of the ease with which the atomised diesel fuel will ignite and burn, as the air in the engine cylinder is heated during the compression stroke.

Graphic about functionment of motor engine

Cetane number is a measure of the ease with which the atomised diesel fuel will ignite and burn, as the air in the engine cylinder is heated during the compression stroke. In other words, it determines the ignition quality of diesel fuel when injected in the combustion chamber of a diesel engine.

This value influences cold startability, fuel consumption, exhaust emissions and noise combustion:

  • As they will auto-ignite more readily, high Cetane number fuels will guarantee an easier engine start, a more complete combustion and a reduction of diesel consumption. This will, in turn, help to reduce pollutant smoke, hence better preserving the environment.
  • A higher Cetane number is also associated with lower rates of pressure rise in the engine cylinder during combustion. This leads to less severe shock loading of the piston/crankshaft members, which results in smoother performance and less potential wear. The characteristic diesel combustion “knock” is also reduced.

 

Since 2000, European specifications for diesel fuel require a Cetane number of 51 minimum.