Gate valve working principle and pressure test method
Gate valve working principle
The opening and closing part of the gate valve is a gate. The movement direction of the gate is perpendicular to the fluid direction. The gate valve can only be fully opened and fully closed, and cannot be adjusted and throttled.
The closing principle of the gate valve is that the sealing surface of the gate and the sealing surface of the valve seat are highly smooth, flat and consistent with each other, which can prevent the flow of medium, and rely on the shape of the top mold, spring or gate to enhance the sealing effect.
Gate valve function
The gate valve mainly cuts off in the pipeline. It has low fluid resistance, saves effort when opening and closing, and can be used in the case of two-way flow of the medium. It has no directionality, and the sealing surface is not easy to erode when it is fully opened. Valves, and suitable for large valves.
Gate valve pressure test method
The strength test for gate valves is the same as for globe valves.There are two ways to test gate valves for tightness.
The gate opens so that the pressure in the valve rises to the specified value;Then close the gate, immediately remove the gate valve, check the seal on both sides of the gate for leakage or directly into the plug on the cover to the specified value, check the seal on both sides of the gate.The above method is called intermediate pressure test.This method is not suitable for seal test on gate valves of nominal diameter DN32mm or less.
Another method is to open the gate so that the valve test pressure to the specified value;Then close the gate, open the blind end and check the sealing surface for leakage.Repeat the above test until it is qualified.
Seal test for pneumatic gate valve packing and gasket shall be conducted prior to gate seal test.