Gate valve structure and working principle
Gate valve structure:
The gate valve refers to a valve in which the shutter closing member moves in the vertical direction of the center line of the passage. It is generally composed of valve body, valve seat, valve stem, gate plate, bonnet, and sealing ring. It can be transformed into a variety of electric gate valves and pneumatic gate valves through the installation of transmission devices and gate valves. It is used for full-open and full-close cut-off, and cannot be used for regulation and throttling.
Gate valve working principle:
The gate of the gate valve moves linearly with the valve stem. Usually, there is a trapezoidal thread on the lifting rod. Through the nut at the top of the valve and the guide groove on the valve body, the rotary motion becomes linear motion, that is, the operating torque Thrust for operation.
When the gate valve is closed:
The sealing surface can be sealed only by the medium pressure, that is, the medium pressure can be used to press the sealing surface of the gate to the valve seat on the other side to ensure the sealing of the sealing surface, which is self-sealing. Most gate valves are forced to seal, that is, when the valve is closed, it is necessary to force the gate plate against the valve seat by external force to ensure the sealing of the sealing surface.
When the gate valve opens:
When the lifting height of the gate is equal to 1: 1 times the valve diameter, the fluid channel is completely clear, but during operation, this position cannot be monitored. In actual use, the apex of the valve stem is used as a mark, that is, the position where it cannot be moved, as its fully open position. In order to consider the phenomenon of temperature lock-up, it is usually opened to the apex position, and then back to 1 / 2-1 circle as the position of the fully open valve. Therefore, the fully open position of the valve is determined according to the position of the gate (ie, stroke).