If the outlet pipe is blocked, the internal pressure of the chamber type filter press will increase continuously. When the pressure is greater than the equipment supply pressure, the filtrate will flow out from the gap of the filter plate, and then the filtering effect of the box filter press can not be realized. High pressure plunger pump, high pressure filter press, hydraulic ceramic plunger pump, The diaphragm filter plate consists of a flat plate filter plate and a hollow filter frame. The filter cloth is fixed on the plate frame, which is the main form of filter press in the early stage. The filter chamber of the box type filter press is composed of two adjacent concave filter plates. The main advantage is that it is convenient to change the filter cloth, but the disadvantages are low efficiency, poor filtering effect and easy damage of the filter plate. There are pitting and boss on the surface of the filter plate of sand washing and pressure filter to support the filter cloth. High pressure plunger pump, high pressure filter press, hydraulic ceramic piston pump, diaphragm filter plate, through holes are arranged in the center and corner of the filter plate. After assembly, a complete channel can be formed to pass in suspension, washing water and extract filtrate. There are handles on both sides of the filter plate to support on the beam, and the filter plate is pressed by the pressing device. The filter cloth between the filter plates plays a sealing role.