Swing check valve is an important fluid control valve, which is mainly used to prevent the backflow of media in the pipeline. The working principle of the swing check valve is that when the pipeline fluid flows in the specified direction, the disc inlet pressure is higher than the outlet pressure, the disc is pushed away from the seat, and the valve is open. When the pressure difference between the two sides of the valve disc decreases to a certain level, the valve disc falls and returns to the closed state, preventing the backflow of the medium.