Abstract: The invention relates to a device for protecting a container containing a pressurized fluid.The device comprises a protection valve and an isolating valve, connected in series and whose opening is controlled by ancillary means, which are sensitive to two pressure thresholds in the container for successively controlling the opening of the isolating valve and then that of the protection valve, when the pressure rises. The isolating valve replaces the protection valve in the case where the latter becomes locked in the open position.Application more particularly to the protection of primary circuits in a pressurized water nuclear reactor.

Abstract: A blocking-type valve for isolating or closing a fluid path comprises a housing body forming a throughgoing fluid passage and, at an intermediate location along this passage, a valve seat inclined to the general direction in which the passage extends. A valve-closure member is axially shiftable into engagement with the seat and is provided on a sliding rod. The valve body also contains a tubular member or sleeve concentric with the end of the rod carrying the valve-closure member and of a length and cross section such that, in the open position of the valve, the interior of this sleeve is sealed off by the closure member.

Abstract: Isolating device for positioning in a circuit upstream of the safety valve, wherein it comprises a valve member which can sealingly bear on a valve seat formed in the said circuit, neutralization means which normally maintain the valve member remote from its seat, said means being actuatable to bring the valve member in sealing engagement with its seat when it is necessary to isolate the safety valve and calibration means acting on the valve member when it is sealingly engaged with its seat to enable it to move away from the latter when the pressure upstream of the isolating device exceeds a determined value.

Abstract: A safety valve for a pressure vessel, e.g. a marine boiler, comprises a piston-operated valve mounted on the pressure vessel and provided with a cylinder which is connected to a pressure detector. According to the invention, a pair of juxtaposed control valves are provided for selectively opening and blocking communication between the cylinder and the pressure vessel and between the cylinder and the atmosphere, respectively, these control valves being actuated by an element disposed between them and connected by a rod to a control piston which is displaced by the pressure in the vessel against the force of an adjustable spring.

Abstract: A control device for a fluid-operated safety valve of a boiler or the like comprises two chambers, each connected to the vessel to be protected and provided with respective valves. The first chamber is connected also to the cylinder of the safety valve via the first valve so that, when a pressure excess in the vessel develops the first chamber closes the connection between the vessel and the control cylinder while the second chamber vents the control cylinder to the atmosphere.