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The working principle of Swing check valve

What are the three types of swing check valves? A valve that opens and closes with the force of the medium flow to prevent the backflow of the medium is called a check valve. Check valves belong to the category of automatic valves. Mainly used in pipelines where the medium flows in one direction, allowing the medium to flow in only one direction to prevent accidents.
Structural classification: According to different structures, it can be divided into three types: lift check valve, swing check valve and butterfly check valve.
1. Lift check valve can be divided into vertical and horizontal.
2. Swing check valve can be divided into three types: single, double and multiple.
3. Straight through butterfly check valve.
How the swing check valve works
Flanged check valves include swing check valves and lift check valves:
1. The swing check valve with built-in swing arm swing structure and all the opening and closing parts of the valve are installed in the valve body and will not penetrate the valve body.
Except for the gaskets and seals used for the intermediate flange section, there is no leakage in general, which prevents the valve from leaking.
Since the swing arm of the rotary check valve adopts a spherical connection structure at the connection part between the rocker arm and the valve disc, the valve disc has a certain degree of freedom within a range of 360 degrees, and can perform proper micro-movement position correction.
Swing check valves are widely used in many fields such as chemical industry, metallurgy and pharmaceuticals.
2. The valve disc of the lift check valve is located on the sealing surface of the valve body and the valve seat. The rest of the valve is similar to a globe valve. The difference is that the disc is free to move up and down. The pressure of the fluid lifts the disc from the sealing surface of the seat. When the media returns, the disc returns to the base and flows. prohibit. Depending on the conditions of use, the disc can be an all-metal structure, or it can be installed in the disc holder in the form of rubber pads or rubber rings. Like globe valves, the fluid flow through the lift check valve is also narrow, so the pressure drop across the lift check valve is greater than the pressure drop across the rotary check valve, limiting the rotary flow check valve.
3. Basic introduction of swing check valve
A rotary check valve is a check valve in which the disc rotates around a rocker arm axis in a body cavity. The opening and closing principle of a rotary check valve is the same as that of a poppet check valve, but it moves on its own according to the fluid pressure and the weight of the disc, but the disc opens and closes by rotating instead of moving up and down . When moving, the inlet direction of the fluid must be on the side that will affect the rotation of the disc. The closing part of the swing check valve is the disc or disc. The diameter is the same as the pipe, suspended in the valve cavity. As the fluid flows forward, the pressure of the slam shut valve fluid will open the disc. When the pressure drops, the disc will open. It closes under the pressure of its own weight and countercurrent fluid. Swing check valve consists of valve body, bonnet, valve disc and rocker. The valve crack is disc-shaped and rotates around the pin outside the seat passage. The passages in the valve have been simplified and the flow resistance is lower than that of in-line poppet check valves suitable for large diameter pipes. However, at low pressures, its sealing performance is not as good as that of a lift check valve. Auxiliary springs or heavy duty hammer constructions can be used to assist the seal to improve sealing performance. Open swing check valves provide relatively high fluid resistance due to the weight of the disc. Additionally, the disc is suspended in the fluid, which can cause turbulence. This also shows that the hydraulic drop from the rotary check valve is greater than from other types of check valves. Sudden changes in flow direction can cause the disc on the seat to close violently, resulting in wear on the seat and greater water hammer along the pipe. To solve this problem, damping devices can be installed on the disc and metal. The valve seat reduces wear on the valve seat.

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