Patent Number: 044908369
Section: claims

1. A shut-off valve comprising a housing defining a valve chamber;  a cover mounted on said housing and defining a cylinder;  a valve stem having a lid at one end and a piston at an opposite end slidably disposed in said cylinder to divide said cylinder into a first chamber on one side of said piston and a second chamber on an opposite side of said piston;  a first duct extending from said first chamber through said cover;  a second duct of fixed minimum cross-section extending from said second chamber through said cover;  a third duct extending from said valve chamber through said cover to said first chamber;  a fixed throttle means in said first duct;  at least one control valve in said third duct;  a first connecting line extending from said first duct;  a second connecting line extending from said second duct;  a third connecting line extending from said control valve for controlling said control valve;  a low pressure chamber connected to said first connecting line and to said second connecting line;  a first closing valve in said first connecting line to selectively connect said first chamber to said low pressure chamber; and  a second closing valve in said second connecting line to selectively connect said second chamber to said low pressure chamber.  a wall of a nuclear reactor plant;  a shut-off valve within said wall, said shut-off valve comprising  a housing defining a valve chamber;  a cover mounted on said housing and defining a cylinder;  a valve stem having a lid at one end and a piston at an opposite end slidably disposed in said cylinder to divide said cylinder into a first chamber on one side of said piston and a second chamber on an opposite side of said piston;  a first duct extending from said first chamber through said cover;  a second duct of fixed minimum cross-section extending from said second chamber through said cover;  a third duct extending from said valve chamber through said cover to said first chamber;  a fixed throttle means in said first duct;  at least one control valve in said third duct;  a first connecting line extending from said first duct through said wall;  a second connecting line extending from said second duct through said wall;  a third connecting line extending from said control valve through said wall for controlling said control valve;  a low-pressure chamber outside said wall and connected to said first connecting line and said second connecting line;  a first closing valve in said first connecting line adjacent and within said wall to selectively connect said first chamber to said low-pressure chamber; and  a second closing valve in said second connecting line adjacent and within said wall to selectively connect said second chamber to said low-pressure chamber. 2. A shut-off valve as set forth in claim 1 which further comprises a non-return valve in said third duct between said valve chamber and said control valve, a fourth connecting line connected to said cover in communication with said first chamber for delivering an external pressure medium into said first chamber, a closing valve in said fourth connecting line for controlling flow therethrough, and a non-return valve in said cover in communication with said fourth connecting line to prevent a return flow into said fourth connecting line. 3. A shut-off valve as set forth in claim 2 which further comprises a non-return valve in said fourth connecting line located near said first closing valve and said second closing valve, and wherein each of said closing valves is remotely-controlled. 4. A shut-off valve as set forth in claim 1 which further comprises a redundant control valve in said third duct and a cylindrical insert within said cover containing said control valves in coaxial relation to each other. 5. A shut-off valve as set forth in claim 1 which further comprises a third closing valve in said third connecting line for controlling a flow of a control medium therethrough. 6. In combination, 7. The combination as set forth in claim 6 wherein each said closing valve is remotely-controlled. 8. The combination as set forth in claim 6 which further comprises a remote-controlled third closing valve in said third connecting line adjacent and within said wall to selectively connect said control valve to a pressure medium. 9. The combination as set forth in claim 6 which further comprises a non-return valve in said third duct between said valve chamber and said control valve, a fourth connecting line extending through said wall and connected to said cover in communication with said first chamber for delivering an external pressure medium into said first chamber, a closing valve in said fourth connecting line and outside said wall for controlling flow therethrough, and a non-return valve in said cover in communication with said fourth connecting line to prevent a return flow into said fourth connecting line. 10. The combination as set forth in claim 9 which further comprises a non-return valve in said fourth connecting line adjacent and within said wall.