Disc valve with improved seal ring

A butterfly valve comprising a tubular vave housing including a valve seat angularly inclined relative to a plane that is perpendicular to an axis through the housing;

• a valve disc disposed within the housing, the disc having an annularly recessed portion communicating with a periphery of the disc and a locking ring positioned over the recessed portion to define an annular, peripherally open groove, of a given width, opposing surfaces of the disc and the locking ring having a smooth surface finish to reduce friction between the surfaces and an object in contact therewith;
• means rotatably mounting the disc to the housing for pivoting it between an open position in which the disc is substantially parallel to an axis of the housing and a closed position in which the disc is substantially parallel to the plane of the inclined valve seat;
• an annular seal ring disposed in the groove and having a thickness that is greater than the width of the groove, an inner diameter that is greater than an inner diameter of the groove, and an outer diameter that is greater than an outer diameter of the disc so that the seal ring can move in the groove relative to the disc when the locking ring is released;
• and means for securing the locking ring against the disc and the seal ring to clamp and immovably lock the seal ring to the disc;
• whereby the seal ring can be centered relative to the disc and the valve seat by first loosening the securing means, thereafter closing the valve to engage the seal ring with the seat, and thereafter tightening the securing means to firmly engage the seal ring with said opposing surfaces of the disc and the locking ring, respectively.

A butterfly valve comprising a tubular housing including a valve seat on the interior of the housing which is angularly inclined relative to a plane that is perpendicular to an axis through the housing;

• a disc pivotally mounted to the interior of the housing and pivotable between an open position in which the disc is substantially parallel to the axis through the housing and a closed position in which the disc is substantially parallel to the angularly inclined valve seat;
• the disc including a peripheral seal defined by at least two annular seal rings disposed in an annular, peripherally open groove in the disc for engagement with the valve seat in the closed position, the combined thickness of the seal rings being less than a width of the groove;
• means for maintaining a peripherally open space between the seal rings;
• and means for injecting a pressurized fluid from an exterior of the housing into the space between the seal rings;
• whereby the pressurized fluid cleans the valve seat of foreign objects when the disc is closed and maintains a physical barrier between the upstream side and the downstream side of the disc in the closed position.

A method for centering a seal ring of a butterfly valve having a tubular valve housing with a valve seat that is angularly inclined relative to a plane that is perpendicular to an axis through the housing, a pivotally mounted valve disc movable between an open position and a closed position in which a disc is substantially parallel to the valve seat, the disc including an annular recess at its periphery, a locking ring releasably secured to the disc and defining an annular, peripherally open groove of a given width between the locking ring and the recessed portion of the disc, and at least one seal ring disposed in the groove, the seal ring having a thickness greater than the width of the groove, an inner diameter which is greater than the diameter of a bottom of the groove by a given amount, and an outer diameter which is greater than the diameter of the disc by an amount in excess of said given amount, the method comprising the steps of placing the seal ring in the groove and loosening the locking ring sufficiently so that the seal ring can float in the groove until its inner diameter engages the groove bottom diameter, centering the seal ring relative to the valve seat and the disc by closing the disc until the seal ring engages the valve seat whereby the engagement of the seal ring and the disc automatically centers the seal ring, and thereafter tightening the locking ring against the seal ring while maintaining the disc in its closed position to securely and immovably retain the seal ring in its centered position.