| 摘要 |
<p>A spring-loaded safety valve, esp. for nuclear reactors, has a controlled additional loading system comprising a pneumatic cylinder connected to the valve closure member and capable of being actuated towards either closure or opening. The supply to this pneumatic cylinder is through air valves actuated by pressure monitors connected to the fluid line in which the safety valve is mounted. The piston of this pneumatic cylinder is a stepped piston with only a slight inward step on its upper face. The cylinder carries a guide projection which extends sufficiently far down into the narrow annular gap between the step and the cylinder wall for the depth of the thus formed air chamber acting upon the piston to be equal only to the stroke of the valve closure member plus the necessary clearance. The base of the pneumatic cylinder is sufficiently near the bottom of the piston for the depth of the air chamber located between them (the air chamber providing the valve opening motion) to be equal only to the necessary min. clearance to enable the valve to operate correctly to the open position. The periods required for the build-up and decrease in the air pressure for either direction of the valve are considerably reduced, so that a rapid-opening and rapid-closing, power-assisted safety valve suitable for reactor purposes is obtd.</p> |
