2、 There are many kinds of butterfly valves, and there are many classification methods.
1. Classification by structure
(1) Center sealing butterfly valve
(2) Single eccentric sealing butterfly valve
(3) Double eccentric sealing butterfly valve
(4) Triple eccentric sealing butterfly valve

Structure of non-metallic compensator and device of non-metallic contraction joint
The structure of non-metallic contraction joint mainly includes skin, stainless steel wire mesh, insulation cotton, insulation filler layer, frame and baffle. Skin is a kind of high-strength sealing composite material, which is composed of a variety of silicone rubber and other materials with excellent performance, and has the function of waterproof and air leakage.
Stainless steel wire: It is an effect to prevent sundries from flowing out, and it is the lining of non-metallic contraction joint.
Insulation cotton: non-metallic contraction joint has sound absorption, vibration isolation and transmission functions, and has good extensibility and tensile strength.
Thermal insulation filler layer: an important guarantee for thermal insulation of non-metallic contraction joints, which is composed of a variety of high-temperature resistant materials.
Rack: It has sufficient strength and rigidity, and the material is consistent with the temperature of the medium.