Installation methods and precautions for check valves

Installation Method
1. Swing Check Valve: The valve disc of a swing check valve is disc-shaped and rotates around the valve seat passage. Due to the streamlined internal passage, the flow resistance is smaller than that of a 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 that of a lift check valve. Swing check valves are divided into single-disc, double-disc, and multi-disc types. These three types are mainly classified according to the valve port diameter to reduce hydraulic impact when the medium stops flowing or backflows.
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 spherical. The valve body shape of a lift check valve is the same as that of a globe valve (it can be used with a globe valve), so its fluid resistance coefficient is larger. Its structure is similar to that of a globe valve, with the valve body and valve disc being the same as those of a globe valve. The upper part of the valve disc and the lower part of the valve cover are machined with guide sleeves. The valve disc guide sleeve can freely rise and fall within the valve seat guide sleeve. When the medium flows smoothly, the valve disc is opened by the medium thrust. When the medium stops flowing, the valve disc falls onto the valve seat by its own weight, preventing the medium from backflowing. In a straight-through lift check valve, the direction of the medium inlet and outlet passages is perpendicular to the direction of the valve seat passage; in a vertical lift check valve, the direction of the medium inlet and outlet passages is the same as the direction of the valve seat passage, and its flow resistance is smaller than that of a straight-through type.
3. Butterfly Check Valve: A check valve in which the valve disc rotates around a pin inside the valve seat. Butterfly check valves have a simple structure, can only be installed on horizontal pipelines, and have poor sealing performance.
4. Pipeline Check Valve: A valve in which the valve disc slides along the centerline of the valve body. Pipeline check valves are a newly emerged type of valve. They are small in size, light in weight, and have good machinability. They are one of the development directions of check valves. However, the fluid resistance coefficient is slightly larger than that of a swing check valve.
5. Clamping Check Valve: This type of valve is used as a shut-off valve for boiler feed water and steam, and it has the combined functions of a lift check valve and a globe 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 valves, and Y-type valves.
Precautions
1. Do not allow the check valve to bear weight in the pipeline system. Large check valves should be independently supported so that they are not affected by the pressure generated by the pipeline system.
2. During installation, pay attention to the direction of medium flow, which should be consistent with the direction of the arrow marked on the valve body.
3. Vertical lift check valves should be installed on vertical pipelines.
4. Horizontal lift check valves should be installed on horizontal pipelines.