The micro-retarded check valve is a hydraulic control valve, which is mainly used to prevent the backflow of the medium in the pipeline and protect the normal operation of the pump and equipment. Its main feature is that during the closing process, the resistance between the valve and the sealing surface is small, which can slow down the closing speed and avoid pressure fluctuations. Swing check valve is a kind of valve that can be opened and closed by rotating the valve disc. It has simple structure and convenient operation. The heavy hammer pump is a pump driven by gravity, which generates power through the fall of the heavy hammer, so that the pump can absorb water and drain water. Backflow waterproof hammer is a device that prevents the backflow of the pump, usually used in conjunction with the check valve to ensure that the pump does not backflow when it stops running. The check valve is a valve that prevents the backflow of the medium, which is usually installed at the outlet of the pump to prevent the backflow of the medium in the pump when the pump is stopped, and to protect the safe operation of the pump and equipment.