| 摘要 |
<p>A pipeline surge relief system including a relief valve of the type that opens when line pressure exceeds pressure in a pilot chamber. A bleed valve, which is operable to evacuate the pilot chamber is opened when pipeline pressure acting against a diaphragm or piston overcomes an opposing reference signal or pressure. The reference pressure is normally maintained at the pipeline pressure by a pressure differential valve which opens to a source of fluid pressure when reference pressure falls below line pressure. However, the differential valve has limited flow capacity so that, in the event of a surge, flow of the reference pressure fluid lags behind the pipeline fluid, whereby reference pressure does not build up as rapidly at bleed valve and is overcome by pipeline pressure to open the bleed valve.</p> |
