Butterfly valve

Claim 2

In a butterfly valve for use in a piping system and which comprises a body pierced by a duct to be located between two sections of the piping system and a closure disc rotatably mounted on the valve body and offset laterally with respect to its axis of rotation, wherein the valve disc is provided at its periphery with an annular bearing surface and wherein the valve body has an annular seal which projects into the interior of the duct for engagement with said annular bearing surface, when said disc is in the closed position; the improvement in which the valve-disc seal is clamped between an annular shoulder formed by a stepped recess in the valve body both in the duct and in the adjacent face and a retaining ring having an annular flange which is positioned in said stepped recess, said stepped recess being L-shaped in cross section, said retaining ring being L-shaped in cross section, said annular flange having a projecting annular seal on that face of said annular flange which is directed towards the adjacent pipe section.

Claim 3

A valve as claimed in claim 1, in which the material of said first-mentioned seal is polytetrafluoroethylene.

Claim 4

A valve as claimed in claim 1, in which the material of said first-mentioned seal is a mixture of polytetrafluoroethylene and glass fibers.

Claim 5

A valve as claimed in claim 1, at least one of said annular shoulder and retaining ring having thereon ribs forming projections that indent the first-mentioned seal.

Claim 6

A valve as claimed in claim 4, in which said ribs terminate in sharp edges.

Claim 7

A valve as claimed in claim 4, said ribs being formed both on said annular shoulder and on said retaining ring.

Claim 8

In a butterfly valve for use in a piping system and which comprises a body pierced by a duct to be located between two sections of the piping system and a closure disc rotatably mounted on the valve body and offset laterally with respect to its axis of rotation, wherein the valve disc is provided at its periphery with an annular bearing surface and wherein the valve body has an annular seal which projects into the interior of the duct for engagement with said annular bearing surface, when said disc is in the closed position; the improvement in which the valve body has a double-stepped annular recess at one end of said duct, said double-stepped recess comprising two radial shoulders and two peripheral faces, said annular seal resting on the inner of said shoulders, and tightening means for tightening said seal against said inner shoulder, said tightening means comprising a ring comprising a tubular part slidable within the inner of said peripheral faces, the end of said tubular part being in contact with said seal, said ring having an outwardly extending annular flange on the end thereof opposite the end that contacts said seal, the last-named flange being housed at least partially between the outer peripheral face and the outer radial shoulder of said recess, the face of said last-mentioned flange opposite said outer radial shoulder having a seal fitted therein and projecting therebeyond to contact and seal with an adjacent pipe section.

Claim 9

In a butterfly valve for use in a piping system and which comprises a body pierced by a duct to be located between two sections of the piping system and a closure disc rotatably mounted on the valve body and offset laterally with respect to its axis of rotation, wherein the valve disc is provided at its periphery with an annular bearing surface and wherein the valve body has an annular seal which projects into the interior of the duct for engagement with said annular bearing surface, when said disc is in the closed position; the improvement in which the valve body has a double-stepped annular recess at one end of said duct, said double-stepped recess comprising two radial shoulders and two peripheral faces, said annular seal resting on the inner of said shoulders, and tightening means for tightening said seal against said inner shoulder, said tightening means comprising a ring comprising a tubular part slidable within the inner of said peripheral faces, the end of said tubular part being in contact with said seal, said ring having an outwardly extending annular flange on the end thereof opposite the end that contacts said seal, the last-named flange being housed at least partially between the outer peripheral face and the outer radial shoulder of said recess, the face of said last-mentioned flange opposite said outer radial shoulder having a seal fitted therein and projecting therebeyond to contact and seal with an adjacent pipe section.

Claim 10

A valve as claimed in claim 7, at least one of the first-mentioned end of said tubular part and said inner radial shoulder having ribs thereon forming projections that indent the first-mentioned seal.