The animation illustrates the structural characteristics of a butterfly valve: it utilizes a central circular disc that rotates in tandem with the valve stem to open or close the fluid flow channel.
Butterfly valves feature a simple structure, compact size, light weight, and large nominal diameters, offering flexible and rapid operation. Standard butterfly valves provide effective sealing under low-to-medium pressure conditions; while their sealing stability and durability are slightly inferior to those of three other common valve types, they offer superior flow regulation capabilities.
Although butterfly valves can be categorized in numerous ways, I generally classify them into two primary types: concentric butterfly valves and eccentric butterfly valves. The former relies on the inherent elasticity of the sealing surface material to achieve an adaptive seal, whereas the latter allows for the application of auxiliary external force to achieve a reinforced seal-a distinction somewhat analogous to the relationship between parallel gate valves and wedge gate valves.
Eccentric butterfly valves are further subdivided into single-eccentric, double-eccentric, and triple-eccentric types. These distinctions correspond to specific design offsets: an axial offset between the sealing surface center and the disc's axis of rotation; a radial offset between the valve flow channel center and the disc's axis of rotation; and an angular offset of the sealing surface. These design refinements are implemented with the specific objectives of enhancing sealing performance and minimizing wear.
