The lift check valve and the swing type check valve are collectively referred to as a check valve, and their main function is to prevent backflow of the medium and protect the safety of the pipeline and the pump. Lifting check valve: The check valve and the lift check valve that slide along the center line can only be installed on the horizontal pipe. On the high pressure small diameter check valve, the valve can adopt the ball. The shape of the lift check valve is the same as that of the shut-off valve (common to the shut-off valve), so its fluid resistance coefficient is large. Its structure is similar to a shut-off valve. The valve body and disc are the same as the shut-off valve. The upper part of the valve flap and the lower part of the valve cover are processed with a guiding sleeve, and the valve guiding sleeve can be freely raised and lowered in the valve guiding cylinder. When the medium flows downstream, the valve flap is opened by the medium thrust. When the medium stops flowing, the valve flap is closed. The self-weight falls on the valve seat to prevent the medium from flowing back. The direction of the medium outlet passage of the straight-type lifting check valve is perpendicular to the direction of the valve seat passage. The vertical lift check valve has the same direction of the medium outlet passage and the direction of the valve seat passage, and the flow medium resistance is smaller than that of the straight-through type.