Rapidrop HRG 4 Inch Butterfly valve is a rotary type valve with a visual indication of whether the valve is in a fully open position or not. Butterfly valves are commonly used in fire protection systems as system control valves, and sectional or pump water control valves. These valves have been designed with minimum flow restriction and pressure loss when in a fully open position. To reduce the risk of a water hammer Rapidrop Butterfly Valves are provided with a slow close hand wheel operated gearbox.