Check valve is a one-way valve, check valve is widely used, there are many types, water supply and
heat.
There are three types of check valves commonly used:
1. Spring type:
The liquid moves from bottom to top, relying on the pressure to push up the valve disc controlled by the spring. After the pressure disappears, the spring force will press the valve disc down to seal the liquid backflow. It is often used for check valves with small diameters.
2. Gravity type:
Similar to the spring type, it relies on the self-gravity of the disc to close to prevent backflow.
3. Swing type:
The liquid passes straight through the valve body, and the rotating disc on one side is pushed open by the pressure. After the pressure is lost, the valve disc returns to its position by its own weight, and the reverse liquid pressure closes the valve disc.