The appearance of the valve is much like what the name implies—a butterfly. Essentially, it is a metal disc mounted on a rod. The rod goes down the center of the disc and appears as the body of a butterfly with the two disc halves as the wings on each side.


    1. In the closed position, which is achieved by rotating the valve a quarter turn, the disc blocks off the pipe or passageway in which it is mounted. Unrestricted flow or passage occurs when another quarter turn of the valve opens the disc. Control of the opening or closing is outside of the valve


    1. Butterfly valve use occurs throughout our daily life. Probably the most common is within the car carburetor. The gas pedal is the outside source that controls the air-intake valve (butterfly) to make your car go. Many industrial machines depend on butterfly valves as part of their operation. Applications where steam, liquids, gas or air need to be controlled rely on butterfly valves.


    1. Depending on the usage and pressure encountered, butterfly valves come in a wide assortment—from resilient (which uses the flexibility of rubber), to low or high pressure (tricentric) valves, industrial, wafer, plastic to stainless steel and manual or automatic.


    1. The inability to thoroughly remove all residual substances due to its design is a drawback to using the butterfly valve in some situations. Highly corrosive or abrasive material will wear a valve down quickly; the valves are not recommended for those types of application. Improper (or careless) installation often leads to complaints about the butterfly valve.


  1. There are many benefits in the use of a butterfly valve. On the whole they are priced lower than other types of valves. Due to the minimum parts involved in a butterfly valve they have a long operational life and are reliable. Their simple design makes them easy to maintain. Most butterfly valves are lightweight and compact. Butterfly valves are designed to withstand a wide range of temperatures and still work.