The sealing pair of the Butterfly Valve usually adopts an elastic sealing material such as rubber or plastic and a metal-to-metal sealing pair, and also partially uses a fluorine-lined or ceramic sealing pair. When used as a shut-off valve, the soft seal butterfly valve seal performance is much better than the metal hard seal butterfly valve. Metal hard seal Manual Butterfly Valve, although able to adapt to higher operating temperatures, have a longer service life than soft seals, but metal hard seal butterfly valves are difficult to completely seal, so they are generally used for throttling. In the domestic valve manufacturers, due to the different structural forms of the sealing pair, when the metal hard sealing butterfly valve is used as a shut-off valve, the sealing performance is also different.