When design valve, selcect valve type, purchase valve, we need to know valve classfication first.
The first category
Automatic valve: to rely on the media (liquid, gas) own abilities and self-action of the valve. Such as check valves, safety valves, control valves, steam traps, valves, etc.
The second category
Actuated valves: With manual, electric, hydraulic, pneumatic valves to manipulate the action. Such as gate valves, globe valves, throttle valves, butterfly valves, ball valves, plug valves, etc.
In addition, there are other valve classification method :
First, according to structural features, according to the closure member movement direction relative to the valve seat can be divided into:
1. Gate-shaped cut: off pieces move along the center seat
2. Gate shape: off pieces move along the vertical center seat
3. Cock and ball: shut down parts of the plunger or ball, rotating around its own center line
4. Swing-shaped; closed parts around the outside of the valve shaft rotation
5. Dish: closed parts of the disc around the axis of rotation of the seat
6. Spool-shaped: the closure member in a direction perpendicular to the channel slide
Second, according to use, according to the different usage of the valve can be divided into:
1. Breaking with: Used to connect or disconnect the line media, such as cut-off valve, gate valve, ball valve, butterfly valve and so on.
2. Reuse ended: used to prevent the media back, such as check valves.
3. Adjustment: adjust the pressure and flow of media, such as adjusting valves, valves.
4. Assignment with: to change the media flow, distribution media, such as three-way stopcock, dispensing valve, slide valve.
5. Safety valve: pressure in the medium exceeds a predetermined value, for discharging excess media, to ensure piping systems and equipment
Safety equipment, such as safety valves, valves accident.
6. His special purposes: such as traps, vent valve, drain valve.
Third, by drive, depending on the driving mode can be divided into:
1. Manual: With hand wheels, handles, levers or sprockets, etc., there are human-powered, large torque transmission when equipped
Worm and gear reducer unit.
2. Electric: With motor or other electrical devices to drive.
3. Hydraulic: means (water, oil) to drive.
4. Pneumatic; using compressed air to drive.
Fourth, according to the pressure, according to the valve nominal pressure can be divided into:
1. Vacuum valve: absolute pressure <0.1Mpa ie 760mm Hg high valve, usually mm Hg or mm
Water column indicates stress.
2. Low pressure valve: Nominal pressure PN ≤ 1.6Mpa valve (including PN ≤ 1.6MPa steel valves)
3. Medium pressure valve: Nominal PN2.5-6.4MPa valve.
4. Pressure valve: Nominal PN10.0-80.0MPa valve.
5. High pressure valve: Nominal pressure PN ≥ 100.0MPa valve.
Five, according to the temperature of the medium, according to the valve working medium temperature can be divided into:
1. General valve: for medium temperature -40 ℃ ~ 425 ℃ valve.
2. High temperature valve: for medium temperature 425 ℃ ~ 600 ℃ valve.
3. Heat valve: for medium temperature above 600 ℃ valve.
4. Cryogenic Valves: Suitable for medium temperature -40 ℃ ~ -150 ℃ valve.
5. Cryogenic Valves: Suitable for medium temperature -150 ℃ below the valve.
Six, according to DN points, according to the nominal diameter of the valve can be divided into:
1. Small valves: nominal diameter DN <40mm valve.
2. In diameter valve: Nominal diameter DN50 ~ 300mm valve.
3. Large diameter valves: nominal diameter DN350 ~ 1200mm valve.
4. Large diameter valve: Nominal diameter DN ≥ 1400mm valve.
Seven, according to the pipe connection method, according to the valve and pipe connections can be divided;
1. Flanged valves: valve with flange, and the pipe flange connection valve.
2. Screw valves: valve with internal thread or external thread, and pipeline valves with threaded connections.
3. Welded connection valve: valve with weld, welded connections and pipeline valves.
4. Clamp valves: valve with a clip on the mouth, and the pipe clamp connection using valves.
5. Ferrule connection valve: The card sleeve and pipe connection of the valve.