Ⅰ. The introduction of the Gate valve
Gate valve is an opening and closing member of the gate, the movement direction of the gate is perpendicular to the direction of the fluid, the gate valve can only be fully open and fully closed, and does not vary with the parameters of the gate, usually 5 °, the medium temperature is not high for the 2 °52′. Improve its craftsmanship, and make up for the angle of the sealing surface in the processing of the deviation, this gate is called the elastic gate. The gate valve is the opening and closing parts of the gate, the movement direction of the gate is perpendicular to the direction of the fluid, the gate valve only can open fully and close fully, and can not regulate and throttle.
The gate valve opening and closing member is the gate, gate movement direction perpendicular to the direction of the fluid, the gate valve can only be fully open and fully closed, and can not be used for regulation and throttling. The gate has two sealing surfaces, the most commonly used mode gate valve two sealing surfaces to form a wedge, wedge angle varies with the valve parameters, usually 5 °, and the temperature of the medium is not high for 2 °52 ‘. Wedge gate valve gate can be made into a whole, called the rigid gate; can also be made to produce a trace of deformation of the gate, in order to improve its craftsmanship, to make up for the angle of the sealing surface in the processing of the deviation, this gate is called the elastic gate.
The gate valve is closed, the sealing surface can only rely on media pressure to seal, that is, relying on the media pressure will be the sealing surface of the gate to the other side of the valve seat to ensure that the sealing surface of the seal, which is self-sealing. Most of the gate valve is used to force sealing, that is, when the valve is closed, to rely on external forces to force the gate to the valve seat to ensure that the sealing surface of the sealing.
Gate valve gate plate with the valve stem together for linear movement, called the lifting stem gate valve, also called the open stem gate valve. Usually, there are trapezoidal threads on the lifting stem, and through the nut at the top of the valve and the guide groove on the valve body, Rotary motion becomes linear motion, in other words, working torque becomes working thrust. When the valve is opened, the passage of the fluid is completely free when the height of the gate lift is equal to 1:1 times the through diameter of the valve, but this position cannot be monitored during operation. In actual use, it is the apex of the valve stem as a mark, i.e., the position of opening motionless, as its fully open position. In order to take into account the locking phenomenon that occurs when the temperature changes, the valve is usually opened to the apex position, and then reversed 1/2-1 turn, as the fully open position of the valve.
Therefore, the valve’s fully open position, according to the position of the gate trip to determined. For some gate valves, the stem nut is located in the gate, and the hand wheel rotation drives the stem rotation and makes the gate lift. These valves are known as rotary stem gate valves or concealed stem gate valves.
1.Flow regulation
In large industrial piping systems, to ensure the productivity of each process and product quality, the a need for real-time control and regulation of flow. In this case, the gate valve becomes an indispensable equipment. Through the opening and closing control of the gate, you can effectively regulate the size of the flow in the pipeline, so as to meet the needs of the production process.
2.Cut-off role
In some cases, it is necessary to divide the pipeline into several parts, so as to facilitate the maintenance or replacement of one of the parts. In order to achieve this purpose, the pipeline needs to be installed on the gate valve. When a part of the need to close, only the need to close the corresponding valve can be done, thus realizing the pipeline division.
3.Pressure regulation
In some high-pressure systems, in order to ensure the safe operation of the pipeline system, it is necessary to control and regulate the pressure in the pipeline in real-time. The gate valve in this case has also become an indispensable piece of equipment, by adjusting the opening of the gate, you can control the size of the pressure in the pipeline, this ensures that the system operates safely.
4.Prevent back flow
In some special circumstances, the pipeline may change the direction of the media flow, then need to set up a reverse valve on the pipeline to prevent back flow of media in the pipeline. A gate valve can be used as a reverse valve, by controlling the opening of the gate valve, you can effectively prevent back flow of media in the pipeline.
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