Classified by structure: (1) center seal butterfly valve (2) single eccentric seal coal valve (3) double eccentric sealing butterfly valve (4) three eccentric sealing butterfly valve seal material classification: (1) soft seal butterfly valve. 1) The sealing pair is made of non-metallic soft material to non-metallic soft material. 2) The sealing pair is made of metal hard material to non-metal soft material. (2) metal seal butterfly valve. The sealing pair is made of metal hard material to metal hard material. Classified by seal (1) Forced seal butterfly valve 1) Elastomeric seal butterfly valve. Sealing pressure ratio by the valve is closed when the valve plate squeeze valve seat, valve seat or valve plate flexibility 2) plus torque butterfly valve. Sealing than the pressure applied by the valve shaft torque (2) pressure sealing butterfly valve. Sealing than the pressure from the valve seat or valve plate elastic seal components generated pressure (3) automatic sealing butterfly valve. Sealing pressure is automatically generated by the media pressure. According to the connection classification (1) on the butterfly valve. (2) Flanged butterfly valve. (3) Bellow butterfly valve. (4) welded butterfly valve. Search Keyword: More Valve Technical Articles