Diesel fine filter is usually opened and closed under the diesel fuel water separator to drain water. 

1. Diesel fine filter is a diesel fine filter designed for the current two-stage filtration commonly used in diesel engines. It forms a two-stage filter together with the diesel fuel water separator. The fuel water separator is used to filter the water in the diesel, and the diesel fine filter is the fine particles in the diesel;
2. Models that use high-pressure common rail engines under the National Three Standards have higher requirements for diesel quality. Because high-pressure fuel injectors need to accurately control fuel injection pressure, fuel injection time and fuel injection volume, they require more refined workmanship. If there is water or impurities in the diesel fuel that are not filtered cleanly, it will cause wear and tear on the plunger and even parts of the fuel injector until the fuel injector is stuck. Damage to the fuel injector will cause unstable or weak acceleration of the engine, or malfunctions such as black smoke emission, which will affect the normal operation of the vehicle;
3. As the main filter in the two-stage filtration, the diesel fine filter is also the last line of defense against impurities. It has high requirements for filtration efficiency and service life. At present, for diesel heavy trucks of the National Three Standards, the filtration efficiency of 35 micron particles is required to be as high as 98.6%, the filtration efficiency of particles above 510 microns is 99.8%, and the filtration efficiency of particles above 10 microns is required to be 99.9%. While ensuring high filtration efficiency, small flow resistance must also be met to ensure the reliable operation of the engine and sufficient power.