Butterfly valve is a valve that isolates or regulates the flow of a fluid. The closing mechanism is a disc that rotates.

A butterfly valve is from a family of valves called "Quarter Turn Valves". In operation, the valve is fully opened or closed when the disc rotates a quarter turn. The "Butterfly" is a metal disc mounted on a rod. Butterfly valves can be manual operated, motorized or geared operation for more precise control.