Requirements for Filters in Hydraulic Systems

This varies depending on the purpose:
1. The oil suction filter is used to protect the hydraulic components of the system from damage caused by contaminating particles. However, it also increases the suction resistance of the pump, so it is necessary to choose a pump with high flow capacity, high filtration efficiency, large scale capacity, and small pressure loss. Filters such as mesh and wire gap filters. Filtering accuracy and efficiency are a contradiction, and the accuracy of the filter is generally selected between 80-200 μ m to meet the needs. If it is a plunger pump, it is even possible to consider not using a filter.
2. The pressure oil circuit filter is used to protect hydraulic components other than the pump. Due to the high installation pressure, high pressure resistance should be considered first. If used to protect components with poor anti pollution capabilities (such as servo valves), filtration accuracy and flow capacity need to be considered. It is recommended to use a high-pressure oil filter with a housing, such as the domestically produced ZU-H63X3.
3. The purpose of the return oil pipeline filter is to filter out the dirt in the system before returning the system oil to the tank, ensuring the cleanliness of the oil in the tank. The filtering accuracy is generally between 10-50 μ m. In this filtering method, the filter may be clogged, which in turn can clog the hydraulic components of the system. It is recommended to use a return oil filter with a bypass valve. In addition, sudden connection of the return oil under high pressure will cause impact, so a high flow filter should be selected. If the pressure is too high, a back pressure valve should be added to protect the filter.
4. The bypass filter is a filtering device composed of a filter and a small pump, independent of the hydraulic system and not affected by the system. The use of this filtration method can compensate for the decrease in filtration capacity at low flow rates in the main system of variable displacement pumps. The bypass filter generally selects a filtration flow rate of about 20% of the main system pump flow rate (max), and the filter accuracy should be high.