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Butterfly valve principle and characteristics

Posted by Bundor valve
The butterfly valve is a very simple adjustment valve.The main structure of butterfly valve is composed of valve body, butterfly plate, stem, valve seat, drive device and operating mechanism.
 
Butterfly valve principle is by a disc-shaped butterfly plate as the opening and closing part, connected with the stem, and in the body with the stem around its own axis rotation, to achieve the opening and closing of the pipeline and regulation.When the disc rotates 90° in the closed position, the valve is in the fully open state. At this time, the thickness of the disc is the only resistance of medium flow, and the resistance is very small.In addition, changing the Angle of the disc can be used to adjust the medium flow.Butterfly valve is generally installed in the pipe diameter direction, can be installed at any position.
butterfly valve
The structure principle of butterfly valve is very suitable for making large diameter valves, which are used in petroleum, gas, chemical industry, water treatment and other general industries.The butterfly valve in the use of the most common fault is that the butterfly valve sealing rubber in the long time continuous use process, corrosion, wear and tear, aging and even fall off phenomenon, resulting in the valve can not be closed, affect the sealing performance of the valve.In order to solve this problem, the structure of butterfly valve is constantly optimized.
 
The simplest butterfly valve is concentric butterfly valve, that is, the stem axis, butterfly plate center, body center in the same position.The butterfly valve structure is very simple.The defect is due to the butterfly plate and seat by the extrusion, scraping serious, sealing surface wear fast.
 
In order to make up for the shortcomings of concentric butterfly valve, the single eccentric butterfly valve was born, the single eccentric butterfly valve stem axis away from the center of the valve plate seal, so that the butterfly plate is no longer the center of rotation, reducing the pressure of the butterfly plate and the valve seat of excessive pressure.
 
The double - eccentric butterfly valve is improved on the basis of single - eccentric butterfly valve.The stem axis of the double - eccentric butterfly valve deviates from the center of the seal and the valve body.The advantage of double eccentric butterfly valve is that after the valve is opened, the butterfly plate can be quickly removed from the seat, largely eliminate the unnecessary squeeze between the butterfly plate and the seat, scraping, but also reduce the valve open and close resistance, reduce wear, improve seat life.
 
The above valves have a defect, they are not resistant to high temperature soft seal, but the use of high temperature resistant metal material butterfly valve, sealing performance is not guaranteed.To solve this problem, the triple eccentric butterfly valve was developed.
 
The biggest characteristic of the triple eccentric butterfly valve is fundamentally changed the butterfly valve seal structure, triple eccentric butterfly valve is torque seal, and is no longer a position seal, that is to say, is no longer dependent on the seat of the elastic deformation to seal, but completely rely on the seat of the contact surface pressure to achieve the sealing effect.Therefore, triple eccentric butterfly valve in high temperature, high pressure, corrosion resistance at the same time, but also can have a good sealing effect.