A butterfly valve is a shut-off valve with a relatively simple construction. In closed position, the disc blocks the valve bore while in open position, the disc is turned to allow flow. A quarter turn takes the valve from fully open to fully closed position, or opposite, and thus the butterfly valve allows for quick opening and closure.
Butterfly valves can be used for a broad range of applications within 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 handles, 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 single, double and triple offset valves.