Insight into Butterfly Valve Operation, Characteristics, and Applications

Butterfly Valve Working Principle:
 
A butterfly valve is a type of valve that operates by rotating the valve stem to simultaneously turn the disc, allowing or blocking the flow. Inside the cylindrical or conical passage of the valve body, flow is controlled. When the disc reaches a 90° angle, the valve is in the fully open position. The angle of the disc can be adjusted to regulate the flow of the medium. However, it lacks locking capability. To effectively control the flow, a worm gear reducer is installed. The addition of a worm gear reducer not only provides self-locking capability to the butterfly valve but also enhances its operational performance for more precise flow regulation.
 
Characteristics of Butterfly Valves:
 
(1) Simple structure and compact size. Due to its compact design, short structure length, small size, and lightweight construction, it is suitable for larger diameters.
 
(2) Minimal fluid resistance. In the fully open position, the valve seat channel offers a substantial flow area, resulting in minimal fluid resistance.
 
(3) Quick and convenient operation. The butterfly disc only needs to rotate 90° to open or close the valve. By adjusting the angle of the disc, flow control can be achieved in stages.
 
(4) Low operating torque. Since the disc on both sides of the pivot experiences nearly equal pressure from the medium, and the torque directions counteract each other, opening and closing the valve requires less effort.
 
(5) Good low-pressure sealing performance. The sealing surface materials generally include rubber and plastics, ensuring effective sealing. Due to the sealing ring material limitations, the pressure and temperature range for using butterfly valves is relatively small. However, the utilization range has greatly expanded with the introduction of hard-sealed butterfly valves.
 

When fully open, butterfly valves exhibit low flow resistance. With an opening angle between approximately 15° and 70°, they allow sensitive flow control. Therefore, butterfly valves are widely used in applications requiring large-diameter adjustments. Since the movement of the butterfly disc involves a wiping action, most butterfly valves can be used with media containing suspended solid particles. Depending on the strength of the sealing components, they can also handle powdery and granular media.
 
Butterfly valves are suitable for flow regulation. However, due to the relatively high pressure loss in pipelines—about three times that of gate valves—when selecting butterfly valves, the impact of pressure loss in the pipeline system should be carefully considered. Additionally, the strength of the butterfly disc in withstanding the pipeline medium pressure during closure must also be evaluated. Moreover, the working temperature limit of the elastic valve seat material at high temperatures must be taken into account.
 
With a compact structural length and overall height, quick opening and closing speeds, and excellent fluid control characteristics, the structural principles of butterfly valves are particularly suitable for manufacturing large-diameter valves. When using butterfly valves for flow control purposes, the most crucial aspect is the accurate selection of the valve's specifications and type to ensure its proper and effective operation.