Ball valve having valve chamber venting seal assemblies

An improved seal assembly for a valve of the type having a rotatable valve member disposed in a valve chamber of a body of the valve between first and second passages intersecting the valve chamber and extending therefrom to form inlet and outlet passages for the valve and having seal assemblies about each passage to cooperate with the valve member and adjacent walls of the body to close the flow passageway in a closed position of the valve member, whereby portions of the valve chamber between the seal assemblies are isolated from the first and second passage to form a trapped fluid chamber about the valve member, comprising:

• a seal support ring having a forward side facing the valve member and a rear side facing away from the valve member, the seal support ring characterized as having means communicating fluid pressure in the trapped fluid chamber to the rear side of the seal support ring;
• means on the forward side of the seal support ring for forming a seal between the seal support ring and the valve member;
• and
• means on the rear side of the seal support ring for relieving excess pressure in the trapped fluid chamber, said means comprising an elastomeric ring extending about the passage encircled by the seal assembly, said elastomeric ring having an inner periphery exposed to fluid pressure in said passage and said elastomeric ring having an outer periphery exposed to fluid pressure in the trapped fluid chamber, said elastomeric ring being bonded to one of the seal support ring and the body of the valve and extending therefrom to the other of the seal support ring and the body of the valve, wherein the one of the seal support ring and body of the valve to which said elastomeric ring is bonded includes means supporting the outer periphery of said elastomeric ring, whereby said elastomeric ring forms a unidirectional seal between the passage encircled thereby and the trapped fluid chamber, said elastomeric ring disengaging said other of the seal support ring and the body of the valve engaged thereby in response to an excess fluid pressure in the trapped fluid chamber to permit venting of said excess pressure to the passage encircled by said elastomeric ring.

A valve comprising:

• a body having formed therein a first passage and a second passage to provide inlet and outlet passages for the valve, and having formed therein a valve chamber interposed between the first passage and the second passage;
• a valve member supported in the valve chamber for rotation between open and closed positions, the valve member having means communicating the first passage with the second passage in the open position thereof;
• and
• a seal assembly extending about the first passage comprising:
• a first seal support ring having an annular first thrust ring groove formed in a forward side thereof facing the valve member;
• means for urging the first seal support ring toward the valve member and for forming a fluid seal between the first seal support ring and the body, said fluid seal extending about the first passage;
• a first sealing ring of a relatively flexible organic polymer attached to the forward side of the first seal support ring and engaging the valve member to form a fluid seal between the first seal support ring and the valve member, said fluid seal extending about the first passage and a portion of the valve member extending across said fluid seal in the closed position thereof, whereby the first seal assembly cooperates with the body and with the valve member to close the flow passageway in the closed position of the valve member;
• and
• a first thrust ring of a relatively inflexible organic polymer mounted in the first thrust ring groove and protruding therefrom to engage the valve member for limiting axial thrust exerted on the first sealing ring by the valve member.