Butterfly valve and its Development history - (1)

Butterfly valve, also referred to as flap valve, is a type of simple structure regulating valve that can control the on-off function of low-pressure pipeline mediums. It features a round plate as the closing part (flap or disc), which rotates around the valve axis for opening and closing operations.

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The valve is versatile, capable of managing various fluid types, including air, water, steam, corrosive media, mud, oil, liquid metal, and radioactive media.

Primarily, it is used to cut off and throttle the flow in pipelines. The opening and closing part of the butterfly valve is a disc-shaped butterfly plate that rotates around its own axis within the valve body, enabling the control of opening, closing, or adjustment.

Invented in the United States during the early 20th century, the butterfly valve was first introduced to Japan in the 1950s and gained widespread use in the 1970s. In our country, its adoption became significant after the 1980s. Key features of butterfly valves include low operating torque, compact installation space, and lightweight design. For instance, a DN-sized butterfly valve weighs about 2T compared to approximately 3.5T for a gate valve. Additionally, butterfly valves can easily be paired with various driving devices and offer good durability and reliability. However, a drawback of rubber seal butterfly valves is the risk of cavitation during throttling; improper usage can lead to the rubber seat peeling off and sustaining damage. Therefore, choosing the correct model depends on the specific working conditions.

The relationship between the butterfly valve's opening and the flow rate typically exhibits a linear correlation. When used for flow control, the valve's characteristics closely relate to the piping’s flow resistance. For example, if the diameter and types of valves are the same in two pipelines but their loss coefficients differ, the flow rate will vary considerably.

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In cases of large throttle ranges, the valve plate's back is prone to cavitation, which may damage the valve. Usually, butterfly valves operate effectively outside of 15°. When the valve is positioned at a mid-opening, the configuration formed by the valve body and the front end of the butterfly plate centers on the valve shaft, leading to different conditions on each side. The front end of the butterfly plate on one side moves with the flow direction, while the opposite side counteracts it. This results in a nozzle-shaped opening on one side and an orifice-shaped opening on the other, causing flow rates on the nozzle side to exceed those on the throttle side, often leading to negative pressure beneath the throttle side valve; consequently, the rubber seal may detach. The operational torque of a butterfly valve varies depending on its opening degree and the valve's opening and closing direction. Particularly in horizontal butterfly valves, especially those with large diameters, the impact of water depth and the torque from the water head differing from the valve shaft cannot be overlooked. Moreover, when the inlet side forms a biased flow at an elbow, the torque will also increase. At mid-opening, the operating mechanism may require self-locking to counteract the water flow torque.

TH Valve is a specialized manufacturer of butterfly valves, gate valves, check valves, globe valves, knife gate valves, and ball valves compliant with API, JIS, and DIN standards, used across Oil, Gas, Marine industries, Water supply and drainage, fire fighting, shipbuilding, water treatment, and more, with sizes ranging from DN50 to DN, utilizing materials like NBR/EPDM/VITON, and holding various Certificates & Approvals such as DNV-GL, Lloyds, DNV, BV, API, ABS, and CCS. Standards adhered to include EN 593, API609, and API6D.

For further information, please check out the Difference Between a Gate Valve and a Butterfly Valve.