Lift check valve: a check valve whose disc slides along the vertical centerline of the valve body. The internal thread check valve can only be installed on a horizontal pipeline. The disc can use a ball on the high-pressure small-diameter check valve. Its structure is similar to the stop valve, and the valve body and disc are the same as the stop valve. The upper part of the valve disc and the lower part of the valve cover are processed with guide sleeves. The disc guide can be moved up and down freely in the valve guide sleeve. When the medium flows downstream, the disc opens by the thrust of the medium. When the medium stops flowing, the disc depends on its own It drops down on the valve seat to prevent the medium from flowing back.