Swing check valve is a common automatic valve. The following is a detailed introduction about it:
Definition and principles
Definition: Swing check valve, also called one-way valve or check valve, is a check valve whose valve disc rotates around the rocker axis in the body cavity.
Principle: It moves automatically under the action of fluid pressure and the deadweight of the valve disc. When the fluid flows forward, the valve disc opens under the action of fluid pressure to allow the fluid to pass; when the fluid stops flowing or flows back, the valve disc closes under the action of deadweight and reverse fluid pressure to prevent the fluid from flowing back.
Structural composition
It is mainly composed of valve body, valve cover, valve seat, valve disc, rocker, pin shaft and other parts. The valve disc is disc-shaped and rotates around the pin shaft outside the valve seat channel. The back of the valve disc is fixedly installed on one end of the rocker through a connecting screw and a nut, and the other end of the rocker is hingedly installed on the inner wall bracket of the valve body.
Type
Single disc type: There is only one valve seat channel and one valve disc, which is suitable for medium-caliber swing check valves.
Double-flap type: There are two valve discs and two valve seat channels, suitable for larger diameter swing check valves.
Multi-flap type: The opening and closing parts are composed of many small-diameter valve discs, suitable for check valves with a nominal size of DN600 or more, which can greatly reduce hydraulic impact, and the impact force of the valve disc on the valve seat is small.
Features
Advantages: The channel inside the valve is streamlined, and the flow resistance is smaller than that of the straight-through lift check valve, which is suitable for large-diameter pipelines; the rotation of the valve disc around the pin is not easily hindered by dirt and viscous media.
Disadvantages: At low pressure, its sealing performance is not as good as that of the lift check valve; due to the weight of the valve disc, the resistance to the fluid when opening is relatively large, and the valve disc is suspended in the fluid, which can cause turbulence in the fluid, resulting in the pressure drop of the fluid through the swing check valve being greater than the pressure drop through other forms of check valves; when the flow direction changes suddenly, the valve disc will close violently on the valve seat, causing great wear of the valve seat and water hammer along the pipeline.
Installation and Application
Installation: Generally horizontal installation, but vertical installation is also possible as long as the valve disc rate does not reach the dead point position. When installed on a vertical pipeline, the medium should flow from bottom to top.
Application: Widely used in pipeline systems in the petroleum, chemical, metallurgy, electric power, pharmaceutical, water supply and drainage industries to prevent medium backflow and protect the safe operation of equipment and pipelines.
