1、 Different concepts
The diesel filter is used to filter harmful impurities and water in the fuel system, protect the normal operation of the engine, reduce wear, avoid blockage, and improve the engine life.
The fuel water separator is a device, which is divided into two types: catering fuel water separator and industrial fuel water separator. The catering fuel water separator is used to treat sewage in the catering industry; Due to the requirements of environmental protection, the sewage discharged into the ships and machinery spaces in rivers, lakes and seas must be treated, and the industrial fuel water separator needs to be used.
The diesel fine filter is a diesel fine filter designed for diesel engines that currently use two-stage filtration. It forms two-stage filtration together with the fuel water separator of diesel. 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、 Different structure
1. The structure of the diesel filter is roughly the same as that of the oil filter, including replaceable type and spin-on type.
2. As the main filter in two-stage filtration, diesel fine filter is also the last line of defense for impurity filtration, and has high requirements for filtration efficiency and service life. At present, for the diesel heavy truck with the third national standard, the filtration efficiency of particles with 3-5 microns is required to be as high as 98.6%, the filtration efficiency of particles with 5-10 microns or more is required to be 99.8%, and the filtration efficiency of particles with 10 microns or more is required to be 99.9%.
While ensuring high filtration efficiency, it is also necessary to meet small flow resistance to ensure reliable operation of the engine and sufficient power.
3. The compressed air fuel water separator is used to separate the condensed water, oil and other impurities in the compressed air, so that the compressed air can be initially purified. The general service pressure is 0.1Mpa - 2.5Mpa.
The other kind of fuel water separation system uses stainless steel mesh coalescent filler inside, and the shell is made of steel welded tank structure, and the general service pressure is 0.1Mpa - 2.5Mpa. Its principle is to effectively remove dust, water and oil mist in compressed air by using the organic combination of cyclone and stainless steel wire mesh mist capture, as well as the mechanism of direct interception, inertial collision, Brownian diffusion and condensation. The amount of water and oil removal is large, and the range of applicable conditions is wide.

3、 Role
The diesel filter is used to filter harmful impurities and water in the fuel system, protect the normal operation of the engine, reduce wear, avoid blockage, and improve the engine life.
In order to make the engine drink clean and good diesel oil and avoid the abnormal wear of common rail parts used by the engine, only by fine filtration of diesel oil can the high-pressure pump, electronic injector and common rail nozzle be effectively protected and the unnecessary high maintenance cost be reduced. The diesel fine filter is generally installed on the engine.