What Is the Structure and Principle of the Swing Check Valve?

I. Valve structure

1. Valve body: It is the main part of the check valve, usually with a streamlined design to reduce fluid resistance.

2. Valve cover: It covers the top of the valve body and is used to fix and protect the parts inside the valve.

3. Valve disc: It is a key component of the check valve, usually in the shape of a disc, and rotates around the pin outside the valve seat channel.

4. Rocker: Also called a rocker arm, it is connected to the valve disc and is used to assist the rotation of the valve disc.

5. Sealing ring: It is located between the valve disc and the valve seat to ensure the sealing when the valve is closed.

6. Auxiliary spring or heavy hammer structure: It is used to improve the sealing performance of the valve, especially under low pressure conditions.

According to the number of valve discs, swing check valves can be divided into single-disc type, double-disc type and multi-disc type. Single-disc type is suitable for medium-caliber swing check valves, double-disc type is suitable for larger diameters, and multi-disc type is suitable for large-caliber check valves to reduce hydraulic shock.

II. Working principle of valve

The working principle of swing check valve is based on fluid pressure and the deadweight of valve disc:

1. Closed state: When the fluid does not flow into the pipeline system, the valve disc fits tightly against the valve seat, forming a sealed state to prevent the fluid from passing through.

2. Open state: When the fluid flows to the valve, the fluid pressure acts on the valve disc, causing it to rotate around the pin and open the valve. At the same time, the valve disc will remain open due to the impact of the fluid, allowing the fluid to flow normally.

3. Closed state (backflow): When the fluid stops flowing or flows in the opposite direction, the valve disc will rotate around the pin under the action of deadweight or spring force and close the valve, thereby preventing the fluid from flowing back.

The valve disc of the swing check valve is connected to the rocker and can rotate around the pin at a certain angle. When the pipeline fluid flows in in the specified direction, the inlet pressure of the valve disc is higher than the outlet pressure. At this time, the valve disc is pushed away from the valve seat and rotates around the pin to a certain position, and the valve is in the open state. When the fluid flows from right to left, that is, reverse flow, the pressure on the right side of the valve disc is higher than the pressure on the left side. The force generated by the pressure difference on both sides presses the valve disc against the valve seat, and the fluid cannot pass through, so the medium cannot flow back; and the greater the fluid pressure, the tighter the sealing surface is pressed, and the better the sealing effect.