How Butterfly Valve Works
A butterfly valve is a type of valve that opens and closes and regulates a fluid passage by using a circular disc as an opening and closing member and rotating with a valve stem. Butterfly plate of butterfly valve is installed in the pipe diameter direction. In the cylindrical channel of butterfly valve body , the disc-shaped butterfly plate rotates around the axis, with the rotation angle ranging from 0 ° to 90 °. When the angle is 90 °, the valve is in fully opened state. If the deflection angle of the butterfly plate gets changed , the media flow could be controled.
Butterfly Valve Advantages
The structure of butterfly valve is simple, with only a few components,and it consumes fewer materials. It has advantages as small size, light weight, small installation size, small driving torque. It is easy and efficient to operate, just when the rotating angle turns to 90 °, it will be opened and closed quickly. It also functions well in flow controlling and has the feature of closure and sealing. The butterfly valve is the leading form in the field of large medium caliber and low medium pressure. When the butterfly valve is fully opened , the thickness of the butterfly plate is the only resistance to the flow of the medium through the valve body, so the pressure which drops across the valve is small . Therefore butterfly valve has good characteristics in flow controlling.
Butterfly Valve Application
The structure length and the overall height of the butterfly valve are minor. It operates quickly when being opened and closed. When it is fully opened, it has less fluid resistance. When it is opened between about 15 ° and 70 °, sensitive flow control is available. Accordingly, under the following conditions, butterfly valve is recommended :
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Require cutting, regulating flow controlling;
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Mud media and media containing solid particles;
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Require the occasion that valve structure is of the short length ;
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Requiring the occasion that opening and closing is of high speed ;
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Minor pressure occasions.
The butterfly valve can be chosen in the two-bit regulation, narrow mouth of the channel, low noise, cavitation and gasification phenomenon, a small amount of leakage to the atmosphere and corrosive media situations. When using the butterfly valves under special operating conditions such as in throttling regulation, or requiring strict sealing, or being severe wearing and tearing, or in cryogenic (extremely cryogenic) conditions and so on, special designed metal seal with the regulation of three eccentrics or double eccentrics butterfly valves should be put into use.
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