Filters are used to filter contaminants out of the hydraulic system. As actuation occurs and components age, contaminants like dirt, dust, and metal enter the system. These contaminants can be harmful because they can become trapped in the small openings of the components, which can damage the system. Filters are used in the downstream of the hydraulic line, before the tank. The higher the micron rating, the better filtration your system will have. However, the more fluid cycling through the system, the fewer microns your filter must have. Filters need to be changed in regular intervals to keep the system and fluid clean.