The main working principle of oil-water separator is the application of fluid mechanics theory. At the moment when oily sewage flows continuously and synchronously (oil and water flow at the same speed, that is, relatively turbulent flow), the kinetic energy of oil beads and sewage flowing at high speed constantly collides, thus accelerating the movement, separating oil and water with different specific gravity, layering and separating, and finally achieving the purpose of oil-water separation.

The main function is to remove water from diesel oil, thus reducing the faults of fuel injectors and prolonging the service life of engines. According to the density difference between water and fuel oil, the principle of gravity sedimentation is used to remove impurities and moisture, and there are separation elements such as diffusion cone and filter screen inside. The oil-water separator also has other functions, such as preheating fuel to prevent wax deposition and filtering impurities.