Fires, emergency relief

Fires, emergency relief, 450—454 External, 450, 463 Heat absorbed, 451... 

Crozier, R. A., Jr., Sizing Relief Valves for Fire Emergencies, Chem. Engr., Oct. 1985, p. 49. 

Fauske, H. K, et al, Emergency Relief Vent Sizing for Fire Emergencies Invoking Liquid-Filled Atmospheric Storage Vessels, Plant/Operations Progress, 5 (4), 205-208, October 1986. 

Explosions emergency relief, 450 Explosions, vapor cloud, 520 Explosive limits, 485 External fires, see fires Factors of safety, llow, 56 Fiber bed/pads impingement separator, 254, 255... 

Emergency venting prevents an explosion during a fire or other emergency. All third-party laboratory standards except UL 80 include emergency relief provisions, since these tanks are designed for atmospheric pressure conditions. 

Inconsistencies for sizing relief valves for fire emergencies arise among published codes. This is because of varying interpretations of the heat flux caused by fire exposure. These variations are based on the area in which the heat flux applies and the protection factors used to characterize the installations. Crozier [ 13] has summarized these variations and evaluated the pertinent correlations. Here, the API 520 correlation is used because it contains an implied protection factor of 0.5 for good drainage. 

Selection and sizing of emergency relief systems Protection against external fires and other heat sources Blast walls, barricades, blow-out panels... 

Pressure-Vacuum Relief Valves For apphcations involving atmospheric and low-pressure storage tanks, pressure-vacuum relief valves (PVRVs) are used to provide pressure relief. These units combine both a pressure and a vacuum relief valve into a single assembly that mounts on a nozzle on top of the tank and are usually sized to handle the normal in-breathing and out-breathing requirements. For emergency pressure rehef situations (e.g., fire), ERVs are used. API RP 520 and API STD 2000 can be used as references for sizing. 

Install flame arresters on atmospheric vents to prevent fire on the outside of the tank from propagating back into the vapor space inside the tank. Provide fire resistant insulation for critical vessels, piping, outlet valves on tanks, valve actuators, instruments lines, and key electrical facilities. Provide remote controlled, automatic, and fire-actuated valves to stop loss of tank contents during an emergency provide fire protection to these valves. Valves should be close-coupled to the tank, and must be resistant to corrosion or other deleterious effects of spilled fluids. Vessels should be provided with overpressure relief protection. 

In the third e.vample, the line terminates at 53%. This means DO NOT run this pump at less than 53% of the BEP. 53% of 4500 gpm is 2385 gpm. Because this is a firewater pump and because firemen need to throttle the nozzles on their fire hoses, then we need to install a pressure relief valve on this system with a discharge bypass line so that the pump dumps the restricted water (less than 2400 gpm) back into the suction tank or lake. If not, this firewater pump is likely to suffer bearing failure during an emergency. 

Emergency Pressure Relief Fires and Explosions Rupture Disks... 

Steam service, 426 Type, 400 Valves, parts, 412 Pressure-vacuum relief, 466 Calculations, 469 Emergency venting, 476-479 Equipment (valves), 468, 478, 480 Fire exposure, 479 Free air, 469, 474 Specification work sheet, 481 Thermal oulbreathing, 468, 469 Vacuum inbreathing, 468, 469, 475 Process check list, 35 Process design organization, 1, 2 Calculations, 37-39 Costs, 43 Manhours, 40-43 Scope, 2... 

Pressure relief valves are provided to cater to two main conditions of the process -normal conditions and emergency conditions. Normal conditions relate to the designed operation of the process which emergency conditions can be caused by either (1) external fire conditions, (2) failure of reflux or cooling, (3) Failure of the power supply, (4) failure of steam supply, (5) heat exchanger failure (6) introduction of incompatible materials, (7) thermal expansion with outlets closed. 

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