The disc of a butterfly valve is installed at the diameter direction of a lipeline, such as a stainless steel pipe. In the cylindrical channel of butterfly valve body, disc is rotated around the axes within a angle of 0°-90°, when 90°, the valve is full opening.

Butterfly valve is constituted by only several components, possessing the features of simple structure, small size, and light weight. It is only need to rotate 90°can switch quichly which presents its handleability. Aother advantage of butterfly valve is the outstanding fluid control property. When it is at the full open position, the thickness of disc is the only resistance of fluid passing through valve, so there is a small pressure generated by passing. Thus the butterfly valve is bring a excellent control characteristic.

A butterfly valve with metal sealing ring, generally, has a longer service life than the one with elastic sealing, however, it is hard to achieve completely sealing. The valve with metal sealing can used in a higher temperature, while not the elastic sealing which is temperatnre limited.

If the butterfly valve is applied to control flow, there is a exact selection of size and type. The structural principle of it is especially fit to produce heavy calibred valve.

Butterfly valve is widely applied in the fields of petroleum, coal gas, chemical industry, and water treatment, as well as water cooling system in thermal power plant.