GB1291929A - Improvements relating to fluid flow valves - Google Patents

Abstract

1291929 Valves HILLS-McCANNA CO 2 Feb 1970 4904/70 Heading F2V Sealing of a ball-valve closure member 20 with respect to its housing 110, is effected by means of two annular sealing and seating rings 56, of yieldable polymeric material, each of which surrounds one of the flow passages 16 formed in the housing 110. Each such sealing ring is formed with a concave ball-contacting projection 62 and an annular recess 120, and is provided with a first spring 114 which engages the body 110 and urges the ring axially in the direction of arrows 130, and a second spring 116 which is contained in the recess 120 and tends to urge the ring radially inwardly in the direction of arrows 124, the resultant of the spring forces acting generally in the direction of arrows 134. Excessive axial displacement of the ring is prevented by the provision of an L-shaped cage 9 and a circlip 106. The ring surrounding the flow passage 16 on the upstream side of the valve may be additionally provided with a plurality of grooves 136 which enable upstream pressure to penetrate behind each ring and so enhance its following of the ball when pressure moves the latter towards the downstream seating ring. The ring and housing are so shaped that excessive pressure in the region between the rings may, by acting on the ring surface 138, detach the respective ring from the closure member and so discharge to one of the flow passages (Fig. 3, not shown). Also, in the event of the ring being destroyed by excessive heat, adequate sealing is provided by engagement between the ball and a projecting portion 112 of the housing 110 (Fig. 4, not shown).