According to the structural characteristics and uses, they can be divided into two categories:
1. Sealed butterfly valves
This type of butterfly valve can ensure complete sealing when closed, and can be used as a cut-off in the pipeline. Its sealing pair can adopt soft seal (rubber or plastic) or metal seal structure.
Sealed butterfly valves with soft seal structure often adopt center line rubber lining, fluoroplastic lining or three eccentric structure.
Sealed butterfly valves with metal seal structure often adopt double eccentric or three eccentric structure. Common metal seal butterfly valves include multi-layer three eccentric metal seal structure, U-shaped resilient seal ring metal seal butterfly valve and high-performance metal seal butterfly valve.
2. Non-sealed butterfly valves
Non-sealed butterfly valves cannot ensure complete sealing when closed, and their leakage should meet the B, C, and D grades of ISO5208. This type of valve is used for adjustment in pipelines or in pipelines with lax sealing requirements. Its sealing pair material usually adopts metal seal structure.
