Butterfly valve, made by few accessories, has simple structure, small volume and light quality. Only rotated into 90 degrees, butterfly valve can be opened or closed quickly. It has simple operation and good characteristics of fluid control system. When butterfly valve is in full open position, the thickness of disc is the only resistance while medium passing through valve. For that, pressure caused by medium is very low. So filter has the characteristics of flow control. There are two sealing mode for butterfly valve: elastomer seal and metallic seal. For the valve adopting elastomer seal, seal ring can be mounted on the valve or attached to the disc. Valve which utilizes metallic seal has longer service life than the valve adopting elastomer seal, while metallic seal can not seal completely. Metallic seal can be used under high temperature while elastomer seal has the limitation of temperature. When using butterfly valve for controlling flow,  the size and types if valve should be chose exactly. The structure of butterfly valve is quite suitable for manufacturing large caliber. Butterfly valve is not only widely utilized in industries such as petroleum, gas and chemical engineering, it also can be used for cooling water system of thermal power station. 

 

Two types of butterfly valves are commonly used: wafer type butterfly valve and flange butterfly valve. Wafer type butterfly is connected between two pipeline flanges by bolt stud. Flange butterfly valve means that flanges are on valves which can be connected to the pipeline flange by bolt. When valve is in higher throttling range, the back of disc can cause cavitation, which may damage to valve.