"Valve" is defined as a device used to control the direction, pressure and flow of fluid in a fluid system. The valve is a device that makes the medium (liquid, gas, powder) in the piping and equipment flow or stop and can control its flow.
The valve is the control component in the pipeline fluid transmission system. It is used to change the passage section and the medium flow direction, and has the functions of diversion, cut-off, regulation, throttling, check, diversion or overflow pressure relief. The valves used for fluid control range from the simplest cut-off valve to various valves used in extremely complex automatic control systems, with a variety of varieties and specifications. The nominal diameter of the valves ranges from extremely small instrument valves to industrial pipeline valves with a diameter of 10m. The valve can be used to control the flow of various types of fluids such as water, steam, oil, gas, mud, various corrosive media, liquid metal and radioactive fluid. The working pressure of the valve can be from 1.3 х The working temperature ranges from - 269 ℃ to 1430 ℃. The valve can be controlled by various transmission modes, such as manual, electric, hydraulic, pneumatic, worm gear, electromagnetic, electromagnetic hydraulic, electric hydraulic, pneumatic hydraulic, spur gear, bevel gear drive, etc; Under the action of pressure, temperature or other sensing signals, the valve can act according to the predetermined requirements, or simply open or close without relying on the sensing signals. The valve relies on the driving or automatic mechanism to make the hoist move up, down, slide, swing or rotate, so as to change the size of its flow passage area to achieve its control function.