Butterfly Valve
A butterfly valve is a quarter-turn valve that controls flow with a circular disc mounted on a shaft in the centre of the flow path. Rotating the disc 90 degrees moves it from fully closed to fully open, where the disc remains in the stream and causes a modest pressure drop. Butterfly valves are compact, lightweight and economical in large diameters. Concentric (resilient-seated) designs suit water and low-pressure services; double-offset (high-performance) and triple-offset designs reduce seat wear and provide tight shut-off at higher pressures and temperatures, with triple-offset valves using metal seats. Body styles include wafer, lug and double-flanged. Typical applications include water treatment, cooling water, HVAC, fire protection and process isolation or throttling. Selection considers pressure class, disc and seat materials, shut-off class and actuator torque. Applicable standards include API 609, EN 593 and AWWA C504.
Examples
- Resilient-seated wafer butterfly valve for chilled water
- Triple-offset butterfly valve for high-temperature steam isolation
- Double-flanged butterfly valve in a water treatment plant