The principle of butterfly valves
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A butterfly valve, also known as a flap valve, is a regulating valve with a simple structure; it can also be used for opening and closing control in low-pressure pipelines. A butterfly valve is a type of valve in which the closing element (the valve disc or butterfly plate) is circular in shape; it rotates around the valve shaft to achieve opening and closing, and is primarily used for shutting off flow or regulating flow rate in pipelines. The operating element of a butterfly valve is a disc-shaped butterfly plate that rotates around its own axis within the valve body, thereby achieving the purpose of opening, closing, or regulating flow. The rotation range of a butterfly valve from fully open to fully closed is usually less than 90°. The butterfly valve and its shaft do not possess self-locking capabilities; therefore, a worm gear reducer must be installed on the shaft in order to position the butterfly plate. The use of a worm gear reducer not only enables the butterfly valve disc to have self-locking capability, allowing it to stay in any position, but also improves the operating performance of the valve. Industrial butterfly valves are characterized by their ability to withstand high temperatures, a wide pressure range, a large nominal diameter. The valve body is made of carbon steel, and metal rings are used as seals for the valve plates instead of rubber rings. Large high-temperature butterfly valves are manufactured by welding steel plates, and are primarily used in flue gas ducts and gas pipelines handling high-temperature media.
I would like to ask what are the main differences in application between butterfly valves and gate valves?
In terms of operation, butterfly valves are easier to use than gate valves, but their sealing performance is inferior to that of gate valves； Compared to gate valves, butterfly valves take up much less space, and they are also cheaper. For large-diameter applications where high technical requirements are not necessary, butterfly valves are recommended.
From an application perspective, butterfly valves are mainly used in spaces with limited dimensions; gate valves are larger in size while butterfly valves have a shorter body. In terms of performance, butterfly valves are inferior to gate valves, as they are prone to internal leakage and may not be able to be closed completely... However, butterfly valves do have advantages, such as being easy and flexible to operate. In my opinion, gate valves are the best choice when the on-site space permits.
The response speed is different; it’s more flexible, but its sealing performance is usually not as good as that of gate valves
Today’s triple-eccentric butterfly valves have excellent sealing performance