GB862189A - Rotary ball valve - Google Patents

Abstract

862,189. Valves. WORCESTER VALVE CO. Inc. Aug. 6, 1958, No. 25160/58. Class 135. A valve comprises a body 10, 12 having a rotary floating valve ball disposed within a bore extending through the body and providing opposed seat ring retaining walls 18 and inlet and outlet passages on opposite sides of the ball which has a through port for alignment with these passages to open the valve, means for turning the ball including a valve stem 30 having a free-fitting connection with the ball permitting a slight downstream movement of the ball under inlet pressure, annular seat rings 20 on opposite sides of the ball having faces shaped to seat respectively against the outer surface of the ball, one of the retaining walls and a portion of the peripheral wall of the bore adjacent thereto, the valve being provided with a pressure equalizing passage independent of the inlet and outlet passages arranged to establish fluid communication between the inlet passage and the interior of the ball in the closed position to equalize the fluid pressure on opposite sides of the upstream seat ring when the pressure of the ball on this ring is reduced and fluid can pass between the ring and the adjacent retaining wall and thus escape to and through said pressure equalizing passage to the interior of the valve and thus reduce friction between the ball and the seat ring and hence the torque required to turn the ball by the stem. In the embodiment shown, the pressure equalizing passage is duplicated so that the inlet and outlet of the valve may be interchanged, the passage in either case being constituted by a number of grooves 50 across the outer peripheral face of the seat ring 20 (Fig. 2). In modifications (Figs. 6, 7 and 8, not shown) the pressure equalization passage is formed by a groove extending from end to end across the bore of the body part 10 (Fig. 6), or by a passage through the body part 10 which communicates both with the interior of the ball in closed position and with the faces of the seat rings which contact the walls 18 (Fig. 8), or by a hole through the seat ring from side to side, located near its outer peripheral face (Fig. 7). The seat rings may be made of an elastomer, including a plastic or other material such as a vulcanized rubber or a synthetic polymer such as rubber hydrochloride or a tetrafluoroethylene resin.