Definition:
valve is in the fluid system, used to control the direction of the fluid, pressure, flow device. The
valve is a device that make piping and equipment within the medium (liquid, gas, powder) flow or stop and can control the flow. Valves can be used to control air, water, steam, a variety of corrosive media, mud, oil, liquid metals and radioactive media and other types of fluid flow. Valve is control unit in the pipeline fluid conveying system, it is used to change the channel section and flow direction of medium, have river diversion, cut-off, throttling, non-return, diversion or overflow pressure relief, and other functions. Used for fluid control valve, valve from the simple to the very complex automatic control system used in a variety of valves, its breed and specification is various, nominal size of the valve from the tiny instrument valve to size up to 10 m industrial pipe with a valve. Valve can be used to control water, steam, oil, gas, mud, all kinds of corrosive medium, liquid metal and radioactive fluid and so on various types of fluid flow, working pressure valves are available from 0.0013 MPa to 1000 MPa ultrahigh pressure, working temperature from 269 ℃ ultra-low temperature to 1430 ℃ high temperature. Valve control can use a variety of transmission way, such as manual, electric, hydraulic, pneumatic, turbine, electromagnetic actuator, electromagnetic hydraulic, electric hydraulic, hydraulic, spur gear, bevel gear drive, etc; Under pressure, temperature or other forms of sensor signal, according to the predetermined requirement, or does not rely on the sensing to carry on the simple open or shut down, valve to rely on drive or automatic mechanism makes opening and closing parts for lifting, slip, swirl pendulum or rotary motion, thus changing the area of the channel size in order to achieve its control function.
