Several kinds of gate valve classification and working principle

The valve industry plays an important role in the development of the national economy as an important part of preparing for manufacturing. The domestic demand and export value of valve products are showing an upward trend in every quarter of each month. The overall situation is good, and the competition among domestic valve companies is gradually improving. Products are developing in the direction of green energy conservation and environmental protection.

A gate valve is a valve that moves in a vertical direction along the centerline of a passageway (closer). The gate valve is mainly used for cutting in the pipeline. Forged steel gate valve is a kind of valve which is widely used. Generally, the cutting device with diameter DN≥500mm is selected, and sometimes the cutting device with small diameter is also used for gate valve. The gate valve is a relatively low-level valve and is more common. The electric gate valve has a larger operating force than the electric valve. The speed of the electric valve can be adjusted, the structure is simple, and it is easy to maintain. Because of the buffering characteristics of the gas during the operation, it is not easy to damage due to jamming, but it must have a gas source and its control. The system is also more complicated than electric valves. The electric gate valve responds sensitively and is safe and reliable. Many factories with high control requirements set up a compressed air station for the pneumatic instrument control elements. Electric is to electricity. And can control its flow device.

An electric valve is simply an electric actuator that controls a valve to open and close the valve. It can be divided into upper and lower parts. The upper part is the electric actuator and the lower part is the valve.

There are two kinds of electric valves, one is a quarter-turn electric valve: the electric actuator with a corner stroke is used together with the valve of a quarter-turn to achieve the control of the fluid flow of the valve within 90 degrees of the rotation; the other is a linear motor valve: Straight-stroke electric actuators are used in conjunction with straight-stroke valves to control the on-off movement of the pipe to control the on-off of the pipe fluid. It is usually used on equipment with a high degree of automation. This valve has the best horizontal adjustment accuracy.

The electric valve is usually driven by a motor and is relatively resistant to voltage shocks. Solenoid valves are quick-opening and fast-closing. They are generally used in small flow and small pressure, where the switching frequency is large, and the electric valve is reversed. The opening degree of the electric gate valve can be controlled, and the state is on, off, half-open and half-close, which can control the flow of medium in the pipeline and the solenoid valve can not meet this requirement. Pneumatic gate valve: Valve driven by compressed air.

Flat gate valve

The flat gate valve is a sliding valve whose closing member is a parallel gate. The closing part can be a single gate or a double gate with a spreading mechanism in between. The pressing force of the gate to the valve seat is controlled by the medium pressure acting on the floating gate or the floating valve seat. If it is a double gate flat gate valve, the expansion mechanism between the two gates can supplement this pressing force.

Flat gate valve can be divided into manual plate gate valve, pneumatic plate gate valve and electric plate gate valve according to the driving mode. According to the purpose and use of occasions can be divided into diversion gate plate gate valve, non-diversion plate gate valve, oilfield plate gate valve, pipeline plate gate valve and gas plate gate valve. Flat gate valve is suitable for natural gas, petroleum, chemical industry, environmental protection, urban pipelines, gas pipelines and other pipelines, venting systems and gas storage devices, used as opening and closing equipment. Z43 type single gate plate gate valve with diversion hole is suitable for long-distance pipelines for natural gas exploitation and purification.

Stainless steel valve

The types of stainless steel gate valves can be divided into wedge type gate valves and parallel gate type gate valves according to the configuration of the sealing surface. The wedge gate type gate valves can be further classified into: single gate type, double gate type and flexible gate type; parallel gate type gate valves Can be divided into a single gate and double gate plate. Divided according to the thread position of the valve stem, it can be divided into two kinds: open rod gate valve and dark rod gate valve. This type of valve should generally be installed horizontally in the pipeline.

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 motion 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 (ie stroke).