Application of Two-stage Slow-closing Check Valve in Water Hammer Protection

Water hammer is when the power is suddenly cut off or the valve is closed too fast, due to the inertia of the pressure water flow, a water shock wave is generated, just like a hammer hit, so it is called water hammer. The force generated by the shock wave of the water flow can sometimes be very large, which can damage the valve and the pump.

The water hammer effect means that inside the water pipe, the inner wall of the pipe is smooth and the water flows freely. When the opened valve is suddenly closed, the water flow on the valve and pipe wall, mainly the valve will generate a pressure. Because the pipe wall is smooth, the subsequent water flow quickly reaches the maximum under the action of inertia, and produces a destructive effect. This is the “water hammer effect” in fluid mechanics, that is, positive water hammer.

Swing check valve working principle

The disc of the swing check valve is disk-shaped, rotating movement around the rotating shaft of the seat passage, by its own weight and medium pressure action to block the medium flow back;

Because the passage in the valve is streamlined, flow resistance is smaller than the lift check valve, suitable for low flow rate and flow does not often change the large diameter occasions, but should not be used for pulsating flow, its sealing performance is not as good as the lift.

 Working principle of axial flow check valve

Through the valve inlet end and outlet end pressure difference to determine the valve disc open and close.

When the inlet pressure is greater than the sum of the outlet pressure and spring force, the disc opens.

As long as there is a pressure difference, the disc is always open, but the opening degree is determined by the pressure difference.

When the sum of the outlet pressure and spring force is greater than the inlet pressure difference, the disc is closed and has been closed.

Because the valve disc opening and closing is in a dynamic force balance state, so the valve operation balance, no noise, water hammer phenomenon is greatly reduced

Post time: Aug-04-2021