Butterfly valves can be divided into many types according to different classification standards. However, if we want to summarize the three main types of butterfly valves from a broader perspective, we can consider them from the perspectives of their structural form, connection method or sealing surface material.
1. Classification by structural form
Central axis butterfly valve: This is the most common type of butterfly valve. Its structural feature is that the valve plate rotates around a central axis. This butterfly valve is usually used in large-diameter pipeline systems and has the characteristics of simple structure and convenient operation.
Double eccentric butterfly valve: The structural feature of the double eccentric butterfly valve is that there are two eccentricities, so that the valve has two axes rotating when opening and closing. This butterfly valve has good sealing performance and is suitable for occasions with high requirements for sealing.
Triple eccentric butterfly valve: The triple eccentric butterfly valve increases the inclination angle of the valve disc on the basis of the double eccentric butterfly valve, so that the valve will not contact the valve seat when opening or closing, thereby reducing wear and wear of the sealing surface. This butterfly valve has the best sealing performance, but the structure is also the most complex.
2. Classification by connection method
Although this classification method does not directly give three specific types of butterfly valves, in order to meet the requirements of the problem, we can select three common connection methods as representatives:
Flange connection butterfly valve: The valve is connected to the pipeline through a flange, which is suitable for large-diameter pipeline systems and has the advantages of easy disassembly and simple maintenance.
Wafer connection butterfly valve: The valve is connected to the pipeline through two bolts, which is suitable for small and medium-diameter pipeline systems and has the characteristics of simple structure and convenient installation.
Threaded connection butterfly valve: The valve is connected to the pipeline through threads, which is suitable for low-pressure and small-diameter pipeline systems.
3. Classification by sealing surface material
Soft sealing butterfly valve: It uses elastic materials such as rubber as the sealing surface, has good sealing performance and corrosion resistance, and is suitable for occasions with high sealing requirements and strong corrosive media.
Metal hard sealing butterfly valve: It uses metal materials as the sealing surface, has high wear resistance and high temperature resistance, and is suitable for high temperature, high pressure and occasions containing solid particles in the medium.
(Optional type): In addition to the two common sealing surface material classifications mentioned above, other types of butterfly valves can also be selected according to specific needs, such as elastic sealing butterfly valves (the sealing specific pressure is generated by the elasticity of the valve plate squeezing the valve seat or the valve plate when the valve is closed), external torque sealing butterfly valves (the sealing specific pressure is generated by the torque applied to the valve shaft), etc. However, since these types do not directly constitute the three major classifications of butterfly valves, they are provided here as supplementary information.
