GB190517869A - Improvements in or relating to Steam Valves. - Google Patents

Abstract

17,869. Farmer, A. H. Sept. 4. Lift valves; actuating valves.-Lift valves are actuated by fluid pressure through the medium of differential pistons connected to the valve. A lift valve k, Fig. 1, is secured to a spindle carrying a piston h. The spindle passes through the top of the casing, where a hand-wheel r is threaded upon it. By screwing this wheel until it takes a bearing against a cross-bar o, the spindle is depressed and the valve closed. Normally, however, the valve is actuated by fluid pressure. A piston 11, subjected to the inlet pressure, is attached to a spindle which is connected to the main spindle by a rocking lever 13 hinged to the pillar n. On the exterior of the casing is arranged a four-way plug cock for connecting either of the spaces above or below the piston h with the space below the piston 11 or with a waste pipe. The plug cock may be operated from a distance. When the spaces below the pistons are connected, the excess pressure on the larger piston h causes the valve to open. When the spaces below the piston 11 and above the piston h are connected, the pressure on both sides of the latter is equalized and the pressure on the piston 11 closes the valve. In the event of a serious leakage or break in the outlet pipe f, the fall of pressure in the valve chamber will be such that the pressure beneath the piston h will be insufficient to overcome the pressure on the piston 11 and the valve will automatically close.