The Grooved End & Wafer type Butterfly valves are indicating type designed for use in fire protection systems where a visual indication is required as to whether the valve is open or closed. They are used, for example, as system, sectional, and pump water control valves. They have cut groove inlet and outlet connections that are suitable for use with grooved end pipe couplings that are listed and approved for fire protection systems. For applications requiring supervision of the open position of the valve, the Gear Operators for the Model BO-G Butterfly Valves are provided with two sets of factory-installed internal switches each having SPDT contacts. The supervisory switches transfer their electrical contacts when there is movement from the valves normal open position during the first two revolutions of the hand wheel.