| 摘要 |
In a butterfly valve having a valve casing 1, a valve member 2 centrally mounted in the valve casing, within an elastomeric lining 5 co-operating with the valve member 2 to provide sealing tightness, the peripheral sealing surface 6 of the valve member 2 has the form of part of the surface of a sphere and co-operates with a sealing bead 9 formed on the inside of the lining 5, the bead being narrower than the sealing surface 6 of the valve member 2 and dividing, to extend with clearance around either side of each pivot shaft 3, 4 of the valve member, the bead 9, in the closed position of the valve, lying everywhere within the limits, in the direction of flow through the valve, of the part-spherical surface 6. <IMAGE> |
