Advantages and disadvantages of three eccentric butterfly valve

Structural features: three eccentric butterfly valve is in the double eccentric stem axis position eccentric at the same time, plus the conical sealing surface center line relative to the valve center line deflection an angle, forming the third eccentric.

Advantages: the first two eccentricities reduce the friction between the valve seat and the sealing ring, and the valve seat and the valve plate are out of contact after opening about 15 degrees. The third eccentricity can completely separate the valve seat and the valve plate in the whole stroke of the valve, and the contact between the valve plate and the valve seat is only at the moment of sealing, 1) The friction between the valve seat and the valve plate in the switching process is greatly reduced, the wear is reduced, and the service life is prolonged; 2) Due to the reduction of friction, the operating torque of the valve is reduced, and a smaller actuator can be used to reduce the labor intensity of workers; 3) Because the sealing is realized by the extrusion between the valve seat and the sealing ring on the valve plate, the higher the torque, the higher the sealing grade. If the valve structure design is reasonable, it can achieve very high sealing effect. 4) Reasonable design of sealing contact angle can eliminate the possibility of valve sticking. Therefore, the reliability of operation is improved; 5) Compared with the general butterfly valve, the tri eccentric butterfly valve adopts metal seal, which overcomes the weakness of soft seal and has a wider temperature range. It can not only replace gate valve for high and low temperature conditions, but also for corrosion and erosion resistant conditions.

Disadvantages: three eccentric butterfly valve has strict requirements on structure design and material selection, especially for the sealing ring, which has precise elliptical section size and harsh working conditions. Due to the elastic deformation of butterfly plate and valve seat, there is still friction at the moment of contact and separation, and it is difficult to achieve zero leakage due to two different working conditions of positive flow and reverse flow