GB1181228A - Improvements in or relating to Ball Valves and Parallel Plate Valves - Google Patents

Abstract

1,181,228. Valves. BRYAN DONKIN CO. Ltd. 11 Oct., 1967 [14 Oct., 1966; 3 July, 1967], Nos. 46121/66 and 30557/66. Heading F2V. In a ball or sliding plate valve, enhanced sealing without an increase in wear of the sealing rings is effected by an arrangement whereby fluid pressure is introduced to annular chambers formed between the sealing rings, which are movable, and the valve body subsequent to the valve being closed, and is released from the same prior to the valve being opened, the arrangement being operable by the valve actuating system and incorporating a lost-motion coupling. In the case of a ball valve, opening of the ball valve 14 is initiated by rotation of a handle 246 and hence of a pinion 276, the pinion meshing with a gear segment 274 which has formed integrally therewith a cam surface (298, Fig. 2, not shown), the surface together with a follower (300) serving to actuate the pressurizing arrangement 242. The gear segment is connected through a lost-motion coupling 244 to the valve spindle 18. The follower is mounted on a piston biased against the cam by a spring 306, such that as the cam follower rides down the surface, pressure within chamber 304, and hence within the chambers formed between seat rings 32 and valve body 10, is reduced. Such reduction permits leftward movement of a differential piston 250, the larger face 256 of which is acted upon by fluid pressure present in chamber 258, which pressure is derived from the inlet 12, and by a further piston 266 acted upon by pressure derived from the outlet. The interconnection between pistons 256 and 266 carries a pointer 310 which indicates the state of the valve. As the pressure within chamber 304 is being reduced, a pin 284, pivotally connected to a link 280 which is similarly connected to a lever 278 fixed to the spindle 18, moves inwardly within radial slots 290 formed in the gear segment 274, such inward motion being due to a further cam 274 riding on a cam surface (294, Fig. 2) formed on the housing 296. Upon the pin reaching a stop 288, at which stage pressure within chamber 304 has been fully reduced, further rotation of the gear causes the lever 278 and hence the spindle to be rotated to effect opening of the valve. A similar actuating arrangement, incorporating a lost-motion coupling, may be provided for the sliding plate valve, this, however, being modified to include a rack-and-pinion. In either case, the pressurizing arrangement 242 is such that it permits the flow through the valve to be reversed without changing the operation of the same. Also the differential piston 250 is designed to relate the pressure acting on the seats to that present in the inlet 12.