A gate valve is a shutter gate. The direction of movement of the gate is perpendicular to the direction of the flow. The gate valve can only be fully opened and fully closed and cannot be adjusted or throttled. The gate valve is sealed by the contact between the valve seat and the gate plate. Usually, the sealing surface will be surfacing with a metal material to increase the wear resistance, such as surfacing 1Cr13, STL6, stainless steel, and the like. The gate plate has a rigid gate plate and a flexible gate plate. According to the gate plate, the gate valve is divided into a rigid gate valve and an elastic gate valve.
The opening and closing parts of the gate valve are gate plates, and the direction of movement of the gate plate is perpendicular to the direction of the fluid. The gate valve can only be fully opened and fully closed and cannot be adjusted or throttled. The gate plate has two sealing surfaces. The two sealing surfaces of the most commonly used mode gate valves form a wedge shape, and the wedge angle varies depending on the valve parameters, usually 5°, and 2° 52′ when the medium temperature is not high. Wedge gate valve gate can be made into a whole, called the rigid gate; can also be made to produce a slight deformation of the gate, in order to improve its craft, to make up for the deviation of the sealing surface angle in the process, this gate The board is called a flexible shutter. When the gate valve is closed, the sealing surface can be sealed only by the medium pressure, that is, relying on the medium pressure to press the sealing surface of the gate plate to the valve seat on the other side 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, it is necessary to force the gate plate to press against the valve seat in order to ensure the sealing of the sealing surface. The gate of the gate valve makes linear movement with the valve stem. It is called lifting rod gate valve, also called open rod gate valve. Trapezoidal threads are usually provided on the lifting rods. The nuts on the top of the valve and the guide grooves on the valve body convert the rotation into 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 lock-up phenomenon, usually in the open to the top position, and then back 1/2 -1 turn, 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 gate valves, stem nut is located on the gate plate, the hand wheel rotates to drive the valve stem to rotate, and the gate plate is lifted. Such a valve is called a rotary rod gate valve or a dark rod gate valve.