Valve is in the fluid system, used to control the direction of the fluid, pressure, flow of the device, is to make the pipe and equipment in the medium (liquid, gas, powder) flow or stop and control the flow of the device.
The valve is the control part of the pipeline fluid conveying system, used to change the passage section and medium flow direction, with diversion, cut-off, throttle, check, diversion or overflow pressure relief functions. Valve used for fluid control, from the most simple globe valve to a very complex automatic control system used in a variety of valves, its variety and specifications, the nominal size of the valve from the very small instrument valve to the size of the industrial pipeline valve up to 10m. Can be used to control water, steam, oil, gas, mud, a variety of corrosive media, liquid metal and radioactive fluid and other types of fluid flow, the working pressure of the valve can be from 0.0013MPa to 1000MPa of ultra-high pressure, the working temperature can be C-270 ℃ of ultra-low temperature to 1430℃ of high temperature.
The valve can be controlled by a variety of transmission modes, such as manual, electric, hydraulic, pneumatic, turbine, electromagnetic, electromagnetic, electro-hydraulic, electro-hydraulic, gas-hydraulic, spur gear, bevel gear drive; In pressure, temperature or other form under the action of sensor signals, action, according to the requirement of the reservation or not depend on the sensor signals for simple open or shut down, rely on the drive or automatic mechanism makes opening and closing valve for lifting, sliding, place or rotary movement, so as to change the size of the port in order to realize the control function.