Basic introduction to national standard gate valves.

The gate valve can only be fully opened and closed, and cannot be adjusted or throttled. Gate valve is a widely used valve. Generally, cutting devices with a diameter of DN ≥ 50mm are used. Small diameter shutoff devices can also be used for gate valves. The gate has two sealing faces. The two most commonly used gate valves form a wedge for each sealing surface, and the wedge angle depends on the valve parameters. If the medium temperature is not high, it is typically 50,2 ° 52 '. The gate of a wedge gate valve can be referred to as the entire gate of a rigid gate. It can also be used as a gate to cause slight deformation, improve manufacturability, and compensate for deviation in the angle of the sealing surface during processing. This board is called an elastic door. Gate valves are the main control equipment for the flow and transportation of powder, grain, particles, and small items. In industries such as metallurgy, mining, building materials, food, and chemical engineering, gate valves can control or quickly prevent flow changes.

The national standard gate valve refers to the type of cast steel gate valve. According to the configuration of the sealing surface, it can be divided into wedge gate valves and parallel gate valves. Wedge gate valves are divided into single gate, double gate, and elastic gate. Gate and parallel gate valves are divided into single gate and double gate. According to the screw position of the valve stem, it can be divided into two types: open valve stem gate valve and dark valve stem gate valve.

If the national standard gate valve is closed, the sealing surface can only be sealed according to the medium pressure. In other words, due to the medium pressure, the sealing surface of the gate presses against the valve seat on the opposite side to ensure the sealing of the sealing surface. This is self sealing. Most gate valves are forced sealed. In other words, when the valve is closed, the gate must be pressed against the valve seat by external force to ensure the sealing performance of the sealing surface.

The gate of a national standard gate valve moves linearly with the stem of a valve called a lift stem gate valve. Typically, the lift rod has a trapezoidal thread, and the rotational motion becomes linear through the nuts and guide grooves on the top of the valve body. In other words, the operating torque is the operating thrust.

When the valve is opened and the lifting height of the gate is equal to 1:1 of the diameter of the valve (gate valve manufacturer), the fluid channel will not be completely blocked, but this position cannot be monitored during operation. In practical use, the top of the valve stem, which cannot be opened, is marked as the fully open position. Considering the locking phenomenon caused by temperature changes, it is usually opened to a higher position and reversed by 1/2-1 turn at the fully open valve position. Therefore, the fully open position of the valve depends on the position of the gate.

For some gate valves, the valve stem nut is installed on the gate valve, and the rotation of the handwheel drives the rotation of the valve stem to lift the gate valve. This valve is called a rotary valve or a dark valve gate valve.