Gate valve construction:
Gate valve refers to the valve where the gate closure moves in the vertical direction along the path centerline. It is generally composed of valve body, valve seat, stem, gate, bonnet and seal ring. Through the configuration of transmission device and gate valve, diversified electric gate valve and pneumatic gate valve can be transformed. In the pipeline, it can only be used for full open and full close cut-off, not for adjustment and throttling.
Working principle of gate valve:
The gate of the gate valve moves in a straight line with the valve stem. Usually, there is a trapezoid thread on the lifting rod. Through the nut at the top of the valve and the guide groove on the valve body, the rotary movement is changed into a straight-line movement, that is, the operating torque is changed into an operating thrust.
When the gate valve is closed
The sealing surface can only be sealed by the medium pressure, that is, the sealing surface of the ram is pressed to the valve seat on the other side by the medium pressure to ensure the sealing of the sealing surface, which is self sealing. Most gate valves adopt forced sealing, that is, when the valve is closed, the gate shall be forced against the valve seat by external force to ensure the sealing of the sealing surface.
When the gate valve is open
When the lifting height of the ram is equal to 1:1 of the valve diameter, the flow passage is completely unblocked, but this position cannot be monitored during operation. In actual use, the vertex of the valve rod is taken as the mark, that is, the position that can not be opened is taken as its full open position. In order to consider the phenomenon of locking due to the change of temperature, the valve is usually opened to the vertex position, and then turned back 1 / 2-1 circle as the position of fully open valve. Therefore, the full open position of the valve is determined by the position of the RAM (i.e. stroke).