Typical Pressure Relief Scenarios (includes vacuum case)

Case Scenario1 Liquid Movement in and Breathing Out2 Liquid Movement Out and Breathing In3 Pool Fire Exposure4 Pressure Transfer Blow Through5 Blanket Gas Regulator Failure6 Failure or Loss of Control - Heat Transfer Devices7 Failure of Internal Heating / Cooling Coils8 Failure Closed of Vents and exiting Streams9 Open Failure of Utilities (Steam, Nitrogen, air, CWS)10 Chemical Reaction(Note 3)11 Liquid Overfill12 Flashing Liquid Feed13 Steam Out (Note 4)

Notes:1. Vent valve fails closed.2. Either or both could be applicable depending on system.3. If this case can cause a reaction4. Steam Out is a special case that is handled and calculated independently in another

spreadsheet; a properly sized nozzle is usually specified to be left open for this case.