JPS5510104A - Butterfly valve - Google Patents

Abstract

PURPOSE: To improve the sealability of a butterfly valve in a passage having large temperature variation range by so forming the seat of the valve that the seat bent due to thermal expansion enhances the surface pressure between the seat and the disc of the valve.

CONSTITUTION: The inner peripheral portion 6 of the seat 4 fixed onto the inner peripheral wall of a valve box 1 is radially inwardly projected in L shape in cross section in a butterfly valve, and the inner peripheral wall 7 of the seat 4 is formed in taper shape. The seat is so formed that the vertical line Q drawn from the bent fulcrum P of the seat 4 toward the outer peripheral wall 11 of a disc 10 making close contact with the seat 4 may pass the interior of the inner peripheral portion 6 of the seat 4. When the seat 4 is bent due to the thermal expansion, the seat 4 bites at the end 28 or projection 8 thereof the outer peripheral wall 11 of the disc 10 to thereby enhance the sealing effect therebetween. The back pressure of the high pressure fluid to the projection 8 or cutout portion 9 of the seat 4 also enhances the surface pressure between the seat 4 and the disc 10 to thereby improve the sealabilty of the valve.

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