It is an indispensable device for the pipeline series of conveying media. It is usually installed in the inlet end of hydraulic control valve, pressure reducing valve, pressure relief valve, constant water level valve and other equipment. It is used to eliminate impurities in the media, prevent granular impurities from entering the channel, causing wall plugs, and protect the accessories on the pipeline of equipment from wear and blockage. Need to clean, as long as the detachable cartridge out, processing after reload can, therefore, the use of maintenance is very convenient.