| 摘要 |
<p>A pilot operated pressure relief valve unit has a main valve having a main piston movable between two control spaces interconnected by a passage provided with a nozzle; one of the control spaces is constituted by two separate control chambers delimited by corresponding areas of the main piston whereby one of the chambers is directly connected to the pilot valve and the other control chamber is connected to the pilot valve via a nozzle.</p> |
