The opening and closing member of the gate valve is a gate. The direction of movement of the gate is perpendicular to the direction of the fluid. The gate valve can only be fully open and fully closed, and cannot be adjusted and throttled. The gate has two sealing faces. The two sealing faces of the most common mode gate valves form a wedge shape. The wedge angle varies with the valve parameters, usually 50, and is 2°52''' when the medium temperature is not high. The gate of the wedge gate valve can be made into a whole, called a rigid gate; it can also be made into a gate that can produce a small amount of deformation to improve its processability and compensate for the deviation of the sealing surface angle during the machining process. The board is called a resilient shutter.
When closed, the sealing surface can be sealed only by the medium pressure, that is, the sealing surface of the ram is pressed against the valve seat on the other side by the medium pressure to ensure the sealing of the sealing surface, which is self-sealing. Most of the gate valves are forced to seal, that is, when the valve is closed, the external force is forced to press the gate to the valve seat to ensure the sealing of the sealing surface.
The gate of the gate valve moves linearly with the valve stem. The liftgate gate valve is also called the open gate valve. Usually there is a trapezoidal thread on the lifting rod, and the rotary motion is changed into a linear motion by the nut at the top end of the valve and the guide groove on the valve body, that is, the operating torque is changed to the operating thrust.
In the case of a valve, when the lift height of the gate is equal to 1:1 times the diameter of the valve, the passage of the fluid is completely unblocked, but this position cannot be monitored during operation. In actual use, the apex of the valve stem is used as a mark, that is, the position where the valve is opened, as its fully open position. In order to consider the temperature change, the lock phenomenon is usually turned on to the apex position, and then back to 1/2-1 turn as the position of the fully open valve. Therefore, the fully open position of the valve is determined by the position of the shutter (ie stroke).
In some gate valves, the stem nut is arranged on the gate plate, and the rotation of the hand wheel drives the valve stem to rotate, and the shutter is lifted. This valve is called a rotary lever gate valve or a dark rod gate valve.