摘要 |
<p>A fluid pressure reduction system includes at least two streams. A working stream includes valves (19) and (20) with associated pressure sensors (22,23) for modulating output pressure. A control system (50) monitors pressure via sensor (18) and actuates slam shut valve (16) in the event of a fault. In the event that another stream is at fault the arrangement allows slam shut (16) to be opened. In the faulty stream only, pressure again rises, the slam shut is again shut and cannot be reopened until manually reset following fault clearance. Independent control in each stream assists in system integrity. All streams can close and reopen once. The second closure determines the faulty stream. <MATH></p> |