What are the three types of butterfly valves?

The butterfly valve is a simple regulating valve, usually used for the switch control of low-pressure pipeline media. Butterfly valves can be divided into many types according to different classification standards. If they are divided into three main types, they can be divided from the perspectives of function, structure or connection form, as follows:

1. Classification by function

• Regulating type: This butterfly valve is mainly used to regulate the flow of the medium.
• Cut-off type: The main function of this butterfly valve is to cut off the flow of the medium.
• Regulating cut-off type: It combines the two functions of regulating and cutting, which can both regulate the flow and cut off the flow of the medium.

2. Classification by structural form

• Center seal butterfly valve: Its sealing surface is located in the center of the valve body.
• Single eccentric seal butterfly valve: The sealing surface has a certain eccentricity relative to the center of the valve body.
• Double eccentric seal butterfly valve or triple eccentric seal butterfly valve: It has a more complex eccentric structure, providing better sealing performance and longer service life.

3. Classification by connection form

• Wafer-type butterfly valve: This type of butterfly valve has flanges on both sides of the valve body, and the butterfly valve is clamped in the middle by bolts. It has a short structure and a small size. It is mostly used for water pipes and is not suitable for large diameters.
• Flange-type butterfly valve: It is connected to the pipe through a flange and has the widest range of applications, with diameters ranging from DN50 to DN3000.
• Other connection forms: Such as clamp connection and welding connection, which are respectively suitable for specific pipeline systems and working conditions. For example, clamp butterfly valves are more common in fire protection systems; welded butterfly valves can withstand high temperatures and high pressures.

In addition, there are other ways to classify butterfly valves, such as diamond, discus, flat and oblique, double flat plate, etc. according to the valve disc structure; small-diameter butterfly valves (50mm1400mm), etc. according to the nominal diameter.

In summary, the three main types of butterfly valves can be defined according to different classification standards. In practical applications, it is necessary to select the appropriate butterfly valve type according to specific working conditions and requirements.