Butterfly valve introduction
A butterfly valve is a valve that isolates or regulates the flow of a fluid. The closing mechanism is a disc that rotates.
Principle of operation
A butterfly valve is from a family of valves called quarter-turn valves. In operation, the valve is fully open or closed when the disc is rotated a quarter turn. The "butterfly" is a metal disc mounted on a stem/shaft. When the valve is closed, the disc is turned so that it completely blocks off the passageway. When the valve is fully open, the disc is rotated a quarter turn so that it allows an almost unrestricted passage of the fluid. The valve may also be opened incrementally to throttle flow.
Application of butterfly valve
Butterfly valves can be used for a wide range of applications like water supply, wastewater treatment, fire protection and gas supply, in the chemical and oil industries, in fuel handling systems, power generation etc. Some of the advantages for this type of valve are the simple construction not taking up too much space, and the light weight and lower cost compared to other valve designs.
The valves can be operated by handlever, gears or actuators according to any specific need.
Main design of butterfly valves
The butterfly valve can be centric or eccentric. On a centric (concentric) butterfly valve the stem is centered in the middle of the disc and the disc centered in the bore. The eccentric butterfly valve has one or more stems (stub shafts) located offset from the center according to the categories of double and triple offset valves.
