The filter is used for oil return accurate filtration of a hydraulic system, and metal particles generated by element abrasion in a hydraulic system and pollutants such as rubber impurities of a sealing element are removed through filtration, so as to enable the oil, which flows back to an oil tank, to keep clean.

1.The filter can be directly installed on the cover plate of an oil tank and can also be installed by using a pipe.

2. A filter element pollution blockage signal transmitter and a bypass valve are arranged to improve the reliability of hydraulic exchange; when the filter element is blocked by pollutants or the liquid temperature of a system is too low, and the oil-taking pressure caused by factors such as flow pulsation is 0.35MPa, the signal transmitter gives out a signal to indicate that replacement of the filter element or raise of temperature should be timely performed; if the engine cannot be stopped immediately to treat the fault, the bypass valve arranged on the filter element will be automatically opened (the opening pressure is 0.4MPa).

3. Glass fiber material is adopted to prepare the filter element, which has the advantages of high filtration accuracy, great oil passing capacity, small original pressure loss, large pollutant holding quantity and the like; the filtration accuracy of the filter element is calibrated by absolute filtration accuracy; the filtration ratios β3, 5, 10 and 20, which are greater than 200, and the filtration efficiency n, which is greater than or equal to 99.5%, conform to the ISO standard.