Butterfly valves are flow regulating shut off disc valves. The “butterfly” denotes the disk that is connected to the rod. It works similar to a ball valve. Due to its relatively light weight, lower cost and large size availability, it is being increasingly preferred over other similarly functioned valves. These valves can be operated either by handles, actuators or gears. There are different variations of butterfly valves, defined by the alignment of the stem to the disc and the seating position, with unique features and applications (Both Flanged Type, Wafer Type, Lug Type, Butt Welded Type). Butterfly valves can be used for applications in water supply, wastewater treatment, fire protection and gas, chemical, etc.