The butterfly valve should be perpendicular to pipes. Its round disc is rotatable around the axis. The valve can be divided into two types, namely, double-clip butterfly valve and flange butterfly valve.
With simple structure, compact size and light weight, the valve consists of a few parts. Meanwhile, the valve does well in flow control, because when it opens, the only resistance comes from the width of the disc. There are two kinds of seals can be applied in the butterfly valve, namely, elastic seal and metal seal. The elastic seal can been mounted on the valve body or around the disc.
The valve with a metal seal possesses longer service life, worse sealing performance and better high-temperature resistance than that with an elastic seal. It is important to choose a stainless steel ready-package butterfly valve in proper size and type, if the valve is used for flow control. Butterfly valves are commonly seen in petroleum, gas, chemical, water treatment and other industries.