1. Swing check valve: The disc of the swing check valve is disc-shaped and rotates around the rotating axis of the valve seat channel. Because the channel in the valve is streamlined, the flow resistance is smaller than that of the lift check valve. It is suitable for large-diameter occasions with low flow velocity and infrequent flow changes, but it is not suitable for pulsating flow, and its sealing performance is not as good as the lifting type. Swing check valves are divided into three types: single-disc type, double-disc type and multi-disc type. These three forms are mainly divided according to the valve diameter. The purpose is to prevent the medium from stopping the flow or backflow and weakening the hydraulic impact.
2. Lift check valve: a check valve in which the valve disc slides along the vertical centerline of the valve body. Lift check valves can only be installed on horizontal pipelines. On high-pressure small-diameter check valves, the valve disc can be made of round balls. . The valve body shape of the lift check valve is the same as that of the stop valve (can be used universally with the stop valve), so its fluid resistance coefficient is larger. Its structure is similar to that of a globe valve, and its valve body and disc are the same as those of a globe valve. The upper part of the valve disc and the lower part of the valve cover are processed with guide sleeves. The valve disc guide sleeve can be freely raised and lowered in the valve guide sleeve. When the medium flows forward, the valve disc opens by the thrust of the medium. When the medium stops flowing, the valve disc opens by itself. It falls vertically on the valve seat to prevent the backflow of the medium. The direction of the medium inlet and outlet channels of the straight-through lift check valve is perpendicular to the direction of the valve seat channel; the direction of the medium inlet and outlet channels of the vertical lift check valve is the same as the direction of the valve seat channel, and its flow resistance is smaller than that of the straight-through type.
3. Disc check valve: a check valve in which the valve disc rotates around the pin in the valve seat. The disc check valve has a simple structure and can only be installed on horizontal pipelines, so its sealing performance is poor.
4. Pipeline check valve: a valve whose disc slides along the center line of the valve body. The pipeline check valve is a new type of valve. It is small in size, light in weight and has good processing technology. It is one of the development directions of check valves. However, the fluid resistance coefficient is slightly larger than that of the swing check valve.
5. Pressure check valve: This valve is used as a boiler water and steam cut-off valve. It has the comprehensive functions of a lift check valve and a stop valve or angle valve.
In addition, there are some check valves that are not suitable for installation at the pump outlet, such as foot valves, spring-type, Y-type, etc.