Butterfly valves start, stop, and throttle the flow of media. They are compact, lightweight, and have a slim disc profile that minimize pressure drops and ensure efficient flow. These valves can be set to a fully open, fully closed, or intermediate positions for throttling applications by manual, pneumatic, or electric actuation. Manually-operated butterfly valves are actuated by hand with a lever or handwheel. Pneumatically-actuated butterfly valves use compressed air, have higher closing force than electrically-actuated valves and are suitable for systems moving viscous liquids. Electrically-actuated butterfly valves use an electric motor, provide precision control over valve positioning for throttling applications, and open and close faster and quieter than pneumatic butterfly valves.