The strainer valves of ZhengFeng are divided into two types according to their discharge performance, Y filter and dirt separator. The Y filter is suitable for pipes containing more than 300 microns of impurities. Although the mesh size of the filter can continue to decrease, it will seriously affect the flow rate. In addition, after the accumulation of impurities, the flow will be less and less, which will not only affect the flow of normal medium, but also increase the load of the pump causing unnecessary losses; The dirt separator is suitable for pipelines containing all kinds of impurities, because it can filter all impurities above 5 micron, which is totally dependent on the centrifugal design of advanced filter core. ZhengFeng obtained Chinese invention patent by the design of filter core. Both types of filters can be equipped with two discharge devices: One is a simple drain ball valve, which can regularly clean up impurities accumulated on the filter screen or at the bottom of the drain device. Another is a magnetic device, which can adsorb impurities containing iron in the medium. When cleaning, pull out the magnetic bar and open the drain ball valve to discharge.