In fluid piping systems, valves are control elements whose primary functions are to isolate equipment from piping systems, regulate flow, prevent backflow, and regulate and discharge pressure.
The valve can be used to control the flow of air, water, steam, all kinds of corrosive media, mud, oil, liquid metal, radioactive media and other fluids. Because it is very important to choose the best valve for the piping system, it is also important to understand the characteristics of the valve and the steps and basis for selecting the valve.
Valves can be divided into two categories:
1 Automatic valve
The valve operates by itself according to the capacity of the medium (liquid and gas).
Such as
Check Valve, safety valve,
Regulating Valve, drainage valve, reducing valve and so on.
2 Drive valve
Valve operation mode has manual, electric, hydraulic and pneumatic and other ways.
Such as
Gate Valve,
Globe Valve, throttle valve,
Butterfly Valve,
Ball Valve, plug valve, etc.
According to the structural characteristics and the direction of movement of the closed part relative to the valve seat, it can be divided into:
Truncated ram: The closed part moves along the center of the seat;
Gate shape: The closed part moves along the center of the vertical seat;
Cock and ball: The closing part is a plunger or ball that rotates around its center line;
Swing type: the closed part rotates around the shaft outside the valve seat;
Disc: the closed part of the disc rotates around the shaft in the seat;
Spool type: The closed part slides in a direction perpendicular to the channel.
Valves can be divided into:
Cut off: Used to connect or cut off pipeline medium, such as globe valve,
Gate valve, ball valve, butterfly valve, etc.
Check valve: used to prevent dielectric backflow check valve, etc.
Regulation: Used to adjust the pressure and flow of the medium, such as regulating valves, reducing valves, etc.
Distribution: Used to change the flow direction of the medium, distribution medium, such as three-way cock, distribution valve, slide valve, etc.
Safety valve: When the medium pressure exceeds the specified value, used to discharge the excess medium, to ensure the safety of pipeline system and equipment, such as safety valve, emergency valve, etc.
Other special uses: such as drainage valve, exhaust valve, blowdown valve, etc.
According to the driving mode, it can be divided into:
Manual: Manually driven with the help of a hand wheel, handle, lever or sprocket. When the transmission torque is larger, there are worm gear, gear and other reduction devices.
Electric: Driven by an electric motor or other electrical appliance.
Hydraulic: driven by (water, oil).
Pneumatic: driven by compressed air.
According to the connection with the pipeline, it can be divided into:
Flange valve: The valve body adopts flange connection, and the pipe adopts flange connection.
Threaded valve: The body has internal or external threads and is connected to the pipe with threads.
Welded connection valve: Valve body and pipe welded connection.
Clamp connection valve: The clamp port of the valve is located on the valve body and connected to the pipe clamp.
Ferrule valve: A valve connected to a pipe by a ferrule.
WUXI KVC-VALVE