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FIRE FIGHTING PROCESS HAZARDS

FIRE FIGHTING PROCESS HAZARDS. DRY DISTILLATIONS CHEMICAL REACTIONS BOILER UPTAKE FIRES FIRE IN WATER TUBE BOILERS. Dry Distillation. Combustion process which flammable material burns with sufficient oxygen to achieve complete combustion of the material

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FIRE FIGHTING PROCESS HAZARDS

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  1. FIRE FIGHTING PROCESS HAZARDS DRY DISTILLATIONS CHEMICAL REACTIONS BOILER UPTAKE FIRES FIRE IN WATER TUBE BOILERS

  2. Dry Distillation • Combustion process which flammable material burns with sufficient oxygen to achieve complete combustion of the material • Example – process in making the charcoal

  3. Sequence of events, danger of dry distillation • Fire outbreak in closed space • Heat builds up but incomplete burning • Opening of access will introduces fresh air • Result - flash towards the opening access • Persons in process of entering will be injured / burned unless protected

  4. Dangers of dry distillation may mitigated by • Cooling the compartment externally by water hosing • Entering access in crouched position behind water screen (spray nozzle) • Directing water towards ceiling of fire space

  5. Because of that, it is inadvisable of taking hurried action when smoke is seen issuing from closed cabin

  6. Chemical reactions • The effect of addition one or more following substances to a chemical • Water • Heat • Steam • Oil • Foam • Carbon dioxide • Sand

  7. Effects of chemical reaction • Explosion from development of flammable gas • Spontaneous combustion • Development of toxic fumes • Generation of smoke Chemical reactions during fire fighting are likely to occur with fire in cargoes and accommodation areas

  8. Examples chemical reactions causing / exacerbating fires • Production of acetylene - calcium carbide contact with water • Steam decomposition when applied to coal fires • Production of hydrogen - Direct Reduced Iron (DRI) contact with water • Cargo oxidizing (fertilizers) – sustain fire even blanketed in extinguishing gas • Cargoes spontaneously igniting in air - phosphorous when its packaging gets damaged • Self heating cargoes - grain when wet • Production of methane in coal cargoes to dangerous levels when ventilation restricted

  9. Correct response to fire in dangerous goods given under “Emergency Procedures for Ships Carrying Dangerous Goods” • Correct response to fire in bulk materials possessing chemical hazards given under “Emergency Schedules of the Code of Safe Practice for Solid Bulk Cargoes” • List of fire response action for given substance given under “General Index of the IMDG Code” & “Emergency Procedures for Ships Carrying Dangerous Goods” • List of fire response action for given bulk cargo given under “Code of Safe Practice for Solid Bulk Cargoes”

  10. Boiler Uptake Fires • Occurring in: • Uptakes, economizers & air heaters – steamships • Exhaust pipes, economizers & waste heat boilers - ships propelled by ICE • Usual cause - accumulation of carbon deposits, with / without oil, become overheated & catch fire

  11. Difficulties & hazards of fighting these fires • Inaccessibility to all sections of uptake in upper section • Possibility of explosion if access doors to economizer are opened

  12. Possibility of economizer tubes reaching temperature of 700°C • Iron in the tubes will burn in steam • Reaction – self sustaining & will generate heat • Combustion products - black oxide of iron & free hydrogen • Iron burning in steam are independent of oxygen supply • Hydrogen produced will burn if air introduced • Explosion

  13. Procedure containing & extinguishing the fire • shut down boiler and/or main engine • Spray external surfaces iwo fire with water - keep temperature down • Close necessary dampers and boiler change valve (if any) – halt supply air to fire • Protect essential electrical & other equipment below fire zone against water damage • Continue cooling until considered safe to open economizer for examination & thorough cleaning on fire side

  14. Fires in water tube boilers • Iron-in-steam fires can occur in water tube boilers due to • shortage of water in boiler causing tubes overheating above water level and undue delay in boiler shut down • Uncontrollable soot fire in furnace after boiler shut down in a port • Coupled with water shortage in boiler causing tubes overheating above water level

  15. If fire discovered before tubes reached 700°C, the preferred method of fire fighting • Direct maximum amount of water available as solid jets through burner apertures (or equivalent) and through feed pumps to source of fire – assuming boiler tubes have fractured or burned • Keep air casings and uptakes cool by hose down them with water • Avoid using fire spray nozzles, foam appliances or carbon dioxide directly on the fire

  16. Fire fighting procedures under “boiler uptakefire” can be used if the iron-in-steam fire has developed

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