Butterfly type fluid control valves

Claim 1

A butterfly type fluid control valve comprising a body having a through passage, said body being provided with an internal circular recess at one end of the through passage, an annular retaining member having a first flange and a second flange extending at right angles to the first flange, said first flange being positioned in the recess, with said flanges cooperating with the recess to provide an internal annular groove, means detachably securing the annular retaining member to the body, a mounting ring within the annular groove and displaceable in the groove in a plane perpendicular to the axis of the through passage, a sealing element positioned between the mounting ring and the body, a seat ring carried by the mounting ring, said seat ring having an inner face extending into the passage and a face engaging the body inwardly of the sealing element, a valve closure member defined by a disc having a part spherical peripheral surface, means pivotally mounting the disc to the body to be axially offset from the plane of the disc and from the axis of the through passage, the part spherical peripheral surface of the disc being engageable with the inner face of the seat ring, and when the valve is shut, the center of the part spherical peripheral surface of the disc is the same distance from the plane of the disc as the axis of the pivotal mounting means and the center of the surface lies on the axis of the through passage.