Wafer Butterfly valve
A butterfly valve is a valve which forms part of a greater piping system, it blocks or regulates the flow of a fluid. In a butterfly valve the closing mechanism is a disk that rotates.
How does a butterfly valve work ?
The butterfly valve works similar to a ball valve. The "butterfly" is a metal disc mounted on a rod. The disc of the butterfly valve is the part that blocks off the flow and it is positioned in the center of the pipe. The rod is attached to an external mechanism. Rotating the mechanism turns the disc parallel or perpendicular to the flow; when the disc is parallel the valve is shut and when it is perpendicular it allows the flow to pass. A disadvantage of these valves is that unlike a ball valve, the disc is always in the way of the flow, so it naturally affects the pressure, even when open fully, although this pressure drop is negligible.
why use a butterfly valve ?
Butterfly valves are generally favored because they cost less than other valve designs, and are lighter weight so they need less support.