Swing check valve working principle

Swing check valve is a check valve with disc rotating around the rocker shaft in the body cavity.The opening and closing principle of swing check valve and lifting check valve is the same, also depends on the pressure of the fluid and the dead weight of the disc self action, different is that the opening and closing mode of the disc is rotary motion rather than moving up and down, the fluid inlet direction should be in the side that can impact the disc rotation.

The shut-off of a swing check valve is a disc or disc of the same size as the pipe, suspended in the valve cavity, the disc opens under the action of fluid pressure when the fluid is flowing forward, and closes under the action of dead weight and countercurrent fluid pressure when the pressure drops.

Swing check valves consist of a body, cover, disc and rocker.The disc is disc shaped and rotates around the pin outside the seat path.The channel in the valve is streamlined, flow resistance is smaller than straight-through lifting check valves, suitable for large diameter pipelines.But when low pressure, its sealing performance is inferior to lifting type check valve.In order to improve the sealing performance, auxiliary spring or heavy hammer structure can be used for auxiliary sealing.

Due to the weight of the disc, the swing check valve opens with relatively high resistance to fluid flow.In addition, because the disc is suspended in the fluid, the fluid can produce turbulence.This also indicates that the fluid pressure drop through the swing check valve is greater than the pressure drop through other check valves.When the direction of flow changes suddenly, the disc will be closed on the seat violently, causing great wear on the seat and water hammer along the pipe. To overcome this problem, the disc can be damped with a metal seat to reduce seat wear.