Valve (famen) is a fluid delivery system control unit, with the cut-off, regulation, diversion, to prevent reflux, regulation, diversion or overflow relief functions.
Valves for fluid control systems, from simple shut-off valve to a variety of highly complex automatic control valves used in the system, which is quite wide varieties and specifications. The valve can be used to control the flow of air, water, steam, corrosive media, mud, oil, liquid metals and radioactive fluids and other types of media. Valve is also divided into cast iron valves, cast steel valves, stainless steel valves (201,304,316, etc.), chromium-molybdenum steel valve, chromium molybdenum vanadium steel valves, dual-phase steel valves, plastic valves, and other non-standard custom valve material according to the material .

Chinese name 阀门（famen）
English name valve
Should use fluid transport, cut circulation
For the control unit
Function is off, diversion, regulation, diversion
Material steel, plastic, and other materials to order non-standard

Definitions

The valve is in a fluid system for controlling the direction of the fluid, the pressure device, is to make the flow pipe and the medium inside the device (liquid, gas, powder) or stopped flow apparatus and its flow control.
Pipeline valves are controlled fluid delivery system components, which is used to change the channel section and flow direction of medium, with diversion, off, throttling, non-return, diversion or overflow relief functions. For fluid control valves, valves off from the most simple to the most complex automatic control valve used in the system, and its many varieties and specifications, the valve nominal diameter from large to tiny instrument valve diameter up to 10m Industrial pipeline valves. EHV can be used to control the water, steam, oil, gas, mud, corrosive media, liquid metals and radioactive fluids and other types of fluid flow, the valve working pressure from 0.0013MPa to 1000MPa, the working temperature from 1430 ℃ ultra-low temperature to a high temperature of -270 ℃ of.
Control valve can be a variety of drive, such as manual, electric, hydraulic, pneumatic, turbine, electromagnetic move, electromagnetic hydraulic, electro hydraulic, pneumatic and hydraulic, spur gears, bevel gear drive and the like; in pressure, temperature or the role of other forms of sensor signals, according to the requirements prescribed action, or do not rely on the sensor signal and a simple on or off, the valve is being driven or automatic mechanism to open and close member for lifting, sliding, rotating or rotary pendulum movement, thus changing the size of its flow area to achieve its control function.
Cleaning step

Valve parts before assembly process must go through the following procedure:
1, according to the processing requirements, some parts need to be polished, the surface can not have working glitches;
2. All parts degreasing treatment;
3, after completion of pickling and passivation degreasing, cleaning agents phosphorus;
4, pickling rinse with pure water purification and clean, can not have drug residues, steel parts omitted this step;
5, non-woven fabrics were dry parts individually, not wired wool retained the part surface, or be dry with a clean nitrogen;
6, non-woven fabrics or paper dipped analytical precision parts alcohol to wipe one by one, until there are no dirty color.
Assembly requirements

Clean the parts must be kept under seal for installation. The installation process requires the following:
1, the installation workshop must ensure clean, or clean up temporary area, for example, the purchase of a new color of the cloth or plastic film to prevent dust entering during the installation process.
2, assembly workers must clean cotton overalls dressed, wearing cotton caps, hair can not leak, clean and wearing shoes, wearing plastic gloves, degreasing.
3, the assembly tools must be degreased before assembly cleaning to ensure cleanliness.
Other requirements

1, the valve assembly is completed with a nitrogen purge at least one minute.
2, air tightness test must be with pure nitrogen.
3, airtightness test after passing the encapsulation, sealing polyethylene cap with a clean, apply a polyethylene cap before using an organic solvent soaked wipe clean.
4, and then vacuum sealed.
5, the final packing.
6. During transport to take measures to ensure that the encapsulation is not damaged.
Acceptance Requirements

Acceptance follow HG 20202-2000 “skimmed construction and acceptance of norms”, before assembly of each component are used to wipe clean, fine filter, select members dead, the same color filter as qualified.