When the gate valve is closed, the sealing surface can only be sealed by means of the medium pressure, that is, the pressure of the medium is only 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. This is self-sealing. Most of the gate valves are forced to seal, that is, when the valve is closed, it is necessary to force the gate plate to press against the valve seat in order to ensure the sealing of the sealing surface.
Movement mode: The gate of the gate valve makes linear motion with the valve stem. It is also called a stem valve. Trapezoidal threads are usually provided on the lift rods. The nut on the top of the valve and the guide groove on the valve body change the rotational motion to linear motion, that is, the operating torque becomes the operating thrust. When the valve is opened, when the lifting height of the gate is equal to 1:1 of the valve diameter, the channel of the fluid is completely open, but this position cannot be monitored during operation. In actual use, the vertex of the valve stem is used as a mark, that is, a position that does not move, as its fully open position. To account for temperature changes in the locking phenomenon, usually in the open to the top position, and then rewind 1/2-1 lap, as a fully open valve position. Therefore, the fully open position of the valve is determined by the position of the gate (that is, the stroke). Some valve stem nut is located on the gate, and the hand wheel rotates to drive the valve stem to rotate, so that the gate is lifted. This type of valve is called Rotary rod gate valve or called the dark rod gate valve.