The effect of particles on fuel/water separation is ignored in evaluating the ability of a fuel/water separator for common rail diesel engines. This cannot reflect the actual operation of the fuel/water separator. Therefore

the effect of particles on the separating efficiency and service life of the fuel/water separator was investigated by adding ISO A3 particles to the fuel system and the experiment was carried out according to SAEJ1839—1997 standard. Under the conditions of flow rate of 5 L/min

upstream reference weight concentration of 30mg/L and water content of 0.25%

the pressure difference increased by 1.5 kPa and the water separation efficiency reduced to below 88% after the fuel/water separator worked for about 125 minutes. The experiment results show that the fuel/water separator can only work for about half its proposed service life because particles reduce its water filtering efficiency. It is suggested that either the replacement cycle of the fuel/water separator should be shortened

or an extra particle filter should be added in the upstream of the fuel/water separator to prolong its service life.