I. According to the driving method:

  (1) electric butterfly valve

  (2) pneumatic butterfly valve

  (3) pneumatic butterfly valve

  (4) manual butterfly valve

Second, according to the structure of the way points:

    (1) center sealed butterfly valve

  (2) single eccentric seal butterfly valve

  (3) double eccentric seal butterfly valve

  (4) three eccentric seal butterfly valve

Third, the sealing surface material points:

  (1) soft seal butterfly valve.

  a) sealing vice by non-metallic soft material to non-metallic soft material composition.

  b) sealing vice by metal hard material to non-metallic soft material composition.

  (2) metal hard seal butterfly valve.

  Seal vice by metal hard material to metal hard material composition.

Fourth, according to the sealing method:

  (1) forced seal butterfly valve.

  a) elastic seal butterfly valve. Seal specific pressure by the valve closed when the valve plate extrusion valve seat, valve seat or valve plate elasticity occurs.

  b) external torque seal butterfly valve. The sealing pressure is generated by the torque applied to the valve shaft.

  (2) pressurized seal butterfly valve.

  Seal pressure by the valve seat or valve plate on the elastic sealing element pressure generation.