When a Butterfly Valve is in the open position, the disc has made a quarter turn past its original position. This allows for an unobstructed flow of the material in the pipe or tube. When the valve is in the closed position, the disc fully blocks the passageway and isolates the material in the pipe.

Butterfly Valves are installed inside tubes or pipes between each section. The disk fills the round shape of the pipe or tube. There is a lever located on the outside of the butterfly valve. The placement of the valve into the opened or closed position is adjusted with this mechanism. Butterfly valves come in various styles and sizes. The pressure ratings vary as well.