GB190510589A - Improvements in Stop Valves - Google Patents

Abstract

10,589. Hopkinson, J., and Hopkinson & Co., J. May 20. Lift valves.-Stop valves for steam or other fluids are provided with a balancing-piston to which pressure is admitted by a by-pass valve, the spindles of both valves, which work in opposite directions, being operated by a single lever or control. Pressure is admitted to the underside of a piston D, Fig. 2, on a continuation of the main spindle, by a passage (not shown) and by-pass valve E, the spindle of which is connected by a framework to a bar S on a threaded sleeve Q on the main spindle. On a hand-wheel R being turned, the framework lifts the by-pass valve since there is less pressure on it than on the main valve. As soon as the by-pass valve opens, pressure on the piston D balances pressure on the valve B, which is easily opened, as a shoulder coming in contact with the casing allows a lift to be given to this valve and prevents further opening of the by-pass. The balancing-piston may be packed with rings, or may be made to allow a little steam to pass in order to warm the pipes. In a modification, shown in Fig. 3, the valves are operated by levers Z, V. The lever Z is connected to the main valve spindle N, and, when raised to open the valve, merely turns on the valve spindle, thereby opening the pilot valve E. When, however, the fixed collar 6 on the rod Y reaches the projection 7, the lever Z turns about the fulcrum on the rod Y, thus opening the main valve B. In closing the valve, in order to keep the pilot valve open until the main valve is closed, a mechanism of the kind described in Specification No. 27,798, A.D. 1903, is used. This comprises a sliding plate 8 which is caused by means of a spring 10 to engage the top of the collar 6 as the valve is opened, and prevents the rod Y from moving during the closing of the valve, until, when the valve is nearing the seat, the wedge cam 12 on a rod 11 withdraws the plate 8 and releases the collar 6, whereupon the pilot valve is closed by the final movement of the lever Z. Reference is also made to Specification No. 12,164, A.D. 1904, to differentiate the invention described therein from the present invention.