Abstract: Main steam isolation valves are required for both PWR and BWR nuclear steam supply systems. In the event of a main steam line rupture, these valves must prevent gross loss of steam. The pressure drop across the valves is a direct factor in the efficiency of the generating plant. The rate of steam flow through the valves is high. These conditions require large port diameter valves that are reliable, can close rapidly, have low pressure drops, and are suitable for operation at specified design pressure and temperature. The valve of the present invention includes a parallel seat, fully revolving, double disc gate valve and fully satisfies the above requirements. The valve of the present invention embodies a valve operating mechanism which is fully enclosed within the primary pressure containment of the valve. This precludes any part of the operator being damaged by missiles resulting from other system failures.

Abstract: A fluid flow control valve having a valve member which is urged away from a cooperating seat by the combined pressures at the valve inlet and outlet and urged towards the seat by fluid pressure prevailing in a chamber which is connected to the valve inlet or outlet, respectively, dependent upon whether an order signal requires the valve to close or to open. Connection between said chamber and the valve inlet and outlet is controlled by an auxiliary valve which in turn is actuated through pressure transmitting lines connected to the inlet and outlet via a switch valve actuated by the order signal.

Abstract: In a combined starting and quick shut-off mechanism, for steam and gas turbines, having a valve controlled by pressure medium by means of an auxiliary valve the valve has a secondary control piston and a counterpressure closure upon opening as well as an adjustable damping which is adjustable by means of a flow cascade from the inlet side of the valve to an outlet chamber, controlled by the auxiliary valve, at the end of the valve spindle, from the inlet side of the valve to the pressure chamber of the valve piston here exists, via a radial piston chamber, stepped in its outer diameter, of the secondary control piston a further flow passage can be provided in the interior of the valve piston, which passage can be shut-off at the step of the radial piston chamber by means of an annularly projecting control collar of the secondary control piston in the open position thereof.

Abstract: The invention relates to drain devices in hydraulic control circuits, particularly for hydraulic ultrarapid release control of a circuit breaker. In order to enable rapid decompression and draining of high pressure fluid in an hydraulic jack which controls the circuit breaker, a plurality of drain valves are mounted directly on the jack in a cascade arrangement. The valves are hydraulically controlled by oil pressure on pilot jacks and are of progressively increasing cross-sectional areas. All the valves in cascade are physically coupled to one another and the setting to drain of the valve with the smallest cross-section is controlled by an electrovalve.

Abstract: A hydraulic servo system for steam turbines providing rapid closing of the main valve between the turbine and the boiler to stop the operation by opening a drainage valve whereby hydraulic fluid is drained immediately from the servo motor which normally maintains the main valve in open position. Secondary valve means are actuated by the resultant pressure drop to drain hydraulic fluid from a portion of the servo system, which is throttled from the servo motor portion, after a predetermined time lapse, and to block off supply of hydraulic fluid to the system. The main valve may be reopened by closing the drainage valve and by actuating the secondary valve means to reconnect the hydraulic fluid source to the throttled portion of the system whereby pressure therein is rapidly restored to a degree sufficient to supply fluid to the servo motor.

Abstract: Fluid control systems for controlling machine tool operations or other automated mechanical devices. An unlimited number of multiple function systems can be assembled from a basic simple function system employing two-way relay valves which, in their normally blocked state, have a "controlled leakage" venting feature effective to prevent any leakage to outlet and possible system malfunction. Fluid memory can also be built in the system. Simple relay valves, limit valves, pressure control relay valves, time delay relay valves and other variations in spool and slide form provide controlled leakage.