From the structure of valve, butterfly valves can be classified into concentric butterfly valve, double offset butterfly valve, and triple offset butterfly.

For concentric type, the center of the stem is on the center line of the valve body and passes through the center of the sealing surface section.

For double eccentric type, the stem center forms a deviation from the valve seal section and deviates from the valve body centerline.

For triple eccentric butterfly valve, the third eccentric is valve body center forms an angular deviation from the center of the valve body sealing surface.

From the connection type of butterfly valve, there wafer butterfly valve, lug butterfly valve, flanged butterfly valve and butt-weld butterfly valve.

For wafer type, there are two or more center holes to help with valve installation.

For lug type, the around bolted holes make lug type a safer choice compared to wafer type.

The double flanged butterfly valve are often used for large-size butterfly valves.

The butt welded butterfly vale are used in high pressure application.

From the seat type, we have soft seat butterfly valve and metal seat butterfly valve. Generally speaking, concentric butterfly valve and double offset butterfly valve own soft sealing. While, the triple offset butterfly valve has metal-to metal seat.