Butterfly valve, also called flap valve, is a regulating valve with a simple structure. It can be used for switching control of low-pressure pipeline media. The butterfly valve refers to a closing member (valve disc or butterfly plate) that is a disc and surrounds the valve. A valve that opens and closes by rotating its shaft.
Valves can be used to control the flow of various types of fluids such as air, water, steam, various corrosive media, mud, oil, liquid metal and radioactive media. It mainly plays the role of cutting and throttling on pipelines. The butterfly valve opening and closing part is a disc-shaped butterfly plate that rotates around its own axis in the valve body to achieve the purpose of opening and closing or adjustment.
The angle from fully open to fully closed of a butterfly valve is usually less than 90°. The butterfly valve and butterfly rod themselves do not have self-locking capabilities. In order to position the butterfly plate, a worm gear reducer must be installed on the valve rod. The use of worm gear reducer not only makes the butterfly plate self-locking, allowing the butterfly plate to stop at any position, but also improves the operating performance of the valve.
The characteristics of the industrial butterfly valve are: it can withstand high temperatures, has a high applicable pressure range, has a large nominal diameter, the valve body is made of carbon steel, and the sealing ring of the valve plate uses a metal ring instead of a rubber ring. Large high-temperature butterfly valves are manufactured by welding steel plates and are mainly used in flue ducts and gas pipelines for high-temperature media.
Extended information:
When the butterfly valve is fully open, it has a small flow resistance. When it is opened between about 15° and 70°, it can perform sensitive flow control. Therefore, butterfly valves are very commonly used in the field of large-diameter adjustment.
Since the movement of the butterfly plate of the butterfly valve is wiping, most butterfly valves can be used in media with suspended solid particles. Depending on the strength of the seal, it can also be used for powdery and granular media.
Butterfly valves are suitable for flow regulation. Since the pressure loss of butterfly valves in the pipe is relatively large, about three times that of gate valves, when selecting butterfly valves, the impact of pressure loss on the pipeline system should be fully considered, and the strength of the butterfly plate to withstand the pressure of the pipeline medium when closed should also be considered. . In addition, the operating temperature limitations of the elastomeric seat material at elevated temperatures must also be considered.
The butterfly valve has a small structural length and overall height, fast opening and closing speed, and good fluid control characteristics. The structural principle of butterfly valve is most suitable for making large diameter valves. When a butterfly valve is required to control flow, the most important thing is to correctly select the specification and type of the butterfly valve so that it can work properly and effectively.
Generally, in throttling, regulating control and mud media, which require short structural length, fast opening and closing speed, and low pressure cutoff (small pressure difference), butterfly valves are recommended. Butterfly valves can be used when there are double-position adjustments, reduced-diameter channels, low noise, cavitation and vaporization, a small amount of leakage into the atmosphere, and abrasive media. Throttle adjustment under special working conditions, or working conditions requiring strict sealing, severe wear, low temperature (cryogenic), etc.
Baidu Encyclopedia-Butterfly Valve