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What is the eccentricity of a butterfly valve? What is the function of eccentricity?

Release time:

Sep 23,2025

Double eccentric butterfly valve has two eccentrics，generally do two-way sealing，the opening of double eccentric butterfly valve can make the valve disc quickly detach from the valve seat。

      Compared to centerline butterfly valves （the valve disc and seat are always in the state of extrusion and friction. resulting in large valve torque and valve seat wears fast）and single eccentric butterfly valves（although it disperses and reduces the excessive extrusion between the upper and lower ends of the valve disc and the valve seat, the friction between the butterfly disc and the valve seat does not disappear during the whole switching process of the valve.）the opening of double eccentric butterfly valve （Click the blue text r detailed information.）can make the valve disc quickly detach from the valve seat, which greatly reduces the excessive squeezing and scraping between the valve disc and the valve seat, reduces the opening torque, reduces the wear and tear, and significantly improves the service life of the valve.

      This design allows the double eccentric butterfly valve to have a metal seat, improving the butterfly valve's use in high temperature applications. however, because of its sealing principle belongs to the position sealing, that is, the sealing surface of the butterfly disc and the valve seat is linear sealing, through the butterfly disc extrusion of the valve seat caused by the elasticity of the deformation of the sealing effect, so for the position of the closure of the requirements of the very high, so the pressure capacity is low.

      The characteristics of the double eccentric butterfly valve determine that its sealing material is a seal between rubber and metal. this combination of seals provides a good sealing effect with zero leakage at low to medium pressures. although metal-to-metal seals can be applied to high-temperature operating conditions, they cannot achieve a zero-leakage seal.

      According to the position where the rubber ring is located, it can be divided into body seal butterfly valve and disc seal butterfly valve.

      Double eccentric butterfly valve with two eccentrics:

    First, the valve stem and the valve disc seal are not in a center（2 and 4)；Secondly, the valve stem and the valve body are not on the same center(1 and 3）;

    Double eccentric butterfly valve （Click the yellow text to watch the video.）can generally do two-way sealing, as soon as possible, in the actual installation and using that need to distinguish between the primary and secondary sealing direction, the general direction of the arrow on the valve body is the main sealing direction, i.e., the direction of the medium from the valve outflow. The correct installation direction can effectively extend the service life of the valve.

 

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