VALVE SEAT DEVICE IN ECCENTRIC BUTTERFLY VALVE

PURPOSE: To constantly secure excellent sealability by applying a spherical surface in a butterfly valve body to a seal part in an inner circumferential surface at one end of a seat part of a ring of a valve seat member to be pressed in the axial line direction at the time of rotating the butterfly valve body in the closing direction. CONSTITUTION: An outer circumference of a butterfly type valve body 11 is formed in a spherical surface 11a, and a rotation center of this valve body 11 is set at a position eccentric from a center of a radius in the spherical surface 11a for a specified distance. Inside a valve box 10, a ring of a valve seat member 14 integrally provided with a cylindrical seat part 15 and a thin support part 16 extended outward in a curvature from one end of it is fixed. In this case, a seal part 17 to be applied to the spherical surface 11a of the valve body 11 is formed in an inner circumferential surface at one end of the seat part 15, and a regulation ring part 23 for a pressure ring body 19 is provided in the valve box 10, so by applying the inner circumferential surface at the other end of the seat part 15 to a conical surface 24 in an outer circumference of the regulation ring part 23, the seal part 15 is pressed in the axial direction.