Butterfly Valves

Butterfly valves are quarter turn having disc attached to a shaft with bearings facilitating rotation.
These are considered high recovery valves, since only the disc obstructs the valve flow path .The flow capacity is relatively high and the pressure drop across the valve is relatively low. The butterfly valves are used for limited throttling where a tight shut off is not required.
Butterfly valves are the most economical for larger lines i.e. chemical services, water treatment etc. general sizes are 2’’ to 48 ‘’ & goes up to 96’’.Butterfly valves generally have small face to face dimensions due to which they weigh less than most of the other valves. Moreover these comply with ASME face-to-face dimensions and pressure ratings enabling the valve to be easily retrofitted in line regardless of the manufacturer.
Applicable standards for design in butterfly valves include AWWA C204, API 609, and MSS SP-69 and API 598 for testing requirements.