As the name indicates, Butterfly valve contains a metal disk commonly referred to as butterfly.
A butterfly valve is a type of quarter turn valve. A quarter turn valve can open or close whenever the handle is turned 90 degrees. In the pneumatic control system, control is done by the use os an SOV or I/P Converter and a pneumatic positioner. The butterfly valve allows to pass the flow of liquid in the open position and blocks the flow of liquid in the closed position.
The butterfly valve is categorized into two categories
- Manual Control
In Manual control, the controlling is made by a manual valve. we open the valve according to our requirement manually.
2. Automatic control
Automatic control is also categorized into two categories
- On-Off Control
In On-Off Control, An SOV and an actuator is used to control the butterfly valve
As shown in the image, air connection is provided to control the valve, also an indication is available showing open and close so that an engineer or technician will come to know it is open or close.
- Percentage Control
In the Percentage control, an I/P converter and a pneumatic positioner or an electro-pneumatic positioner are used to control. Normally this type of valve is controlled by a controller or a PLC or DCS Panel. Percentage control butterfly valve maintains the parameter at a desired set-point.
The use of the butterfly valve is limited because it uses a rubber seat so this valve cannot be used in the high pressure and high-temperature applications.