LP disposal system is a system where the back-pressure must be maintained low, even at maximum relief flowrate. Therefore the flowrate sent to such a system is relatively small with regards to the pipework diameter to ensure a low back-pressure at any time, including emergency situations. LP flare typically collects disposed gas from equipment with design pressure less than 10 barg (example standard).
HP disposal system is a system where the back pressure can be higher than what is admissible in the LP relief system. The HP disposal system collects the high flowrate sources which cannot be routed to the LP disposal system because they would create excessive back pressure. This generally includes:
• Excess gas which must be released for pressure control of high pressure processing units;
• The release of PSVs and BDVs from high pressure equipment.
HP flare typically collects disposed gas from equipment with design pressure above 10 barg (example standard).
