A Butterfly valve isa quarter-turn rotational motion valve, that is used to stop, regulate, andstart flow.
Butterfly valves areeasy and fast to open. A 90 rotation of the handle provides a complete closureor opening of the valve. Large Butterfly valves are usually equipped with aso-called gearbox, where the handwheel by gears is connected to the stem. Thissimplifies the operation of the valve, but at the expense of speed.