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Chapter 2 classes & spread

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  • 1. (0.25) Fire Prevention and Fire Fighting Chapter 2  Classification of fires  How Fire Spreads Sept 2007/chenck/May2002/V3 Chapter 2 1
  • 2. Previous Chapter In chapter 1, you learn all about chemistry of fire and their properties In chapter 2, you will understand there are different types of fire e.g  Wood fire  Oil fire  Electrical fire etcSept 2007/chenck/May2002/V3 Chapter 2 2
  • 3. Classifications of fires There are 4 Classes of fires  Class A Fires  Class B Fires  Class C Fires  Class D FiresSept 2007/chenck/May2002/V3 Chapter 2 3
  • 4. Classifications of fires Class A fires  Class A fires are wood fires or carbonaceous firesSept 2007/chenck/May2002/V3 Chapter 2 4
  • 5. Carbonaceous Fires Carbonaceous fires are fires that is made majorly of carbon or organic materials eg  Coal  Paper  Clothes  Ropes  Rubber etcSept 2007/chenck/May2002/V3 Chapter 2 5
  • 6. Class A FiresSept 2007/chenck/May2002/V3 Chapter 2 6
  • 7. Classifications of fires What about oil fires? What about petrol fires, cooking oil fires? Fires that come from grease, from tar… Fires that come from gas – like your those in your house or cigarette lighter? How are these fires classified?Sept 2007/chenck/May2002/V3 Chapter 2 7
  • 8. Class B Fires These fires are classified as Class B fires  Oil fires  Liquid fires  Grease fires  Gas firesSept 2007/chenck/May2002/V3 Chapter 2 8
  • 9. Class B FiresSept 2007/chenck/May2002/V3 Chapter 2 9
  • 10. Class B Fires Liquid fires are divided into two types  Oil fires Combustible liquids  Liquid fires  Grease fires Flammable liquids  Gas firesSept 2007/chenck/May2002/V3 Chapter 2 10
  • 11. Class B Fires You must remember that only vapour catches fire Combustible liquid means you have to heat the liquid to a point where there is sufficient vapour given off to allow ignition e.g. cooking oil, fuel oil, diesel oil etcSept 2007/chenck/May2002/V3 Chapter 2 11
  • 12. Class B Fires Flammable Liquid means that it is flammable, it can burn straight away  It means there is always sufficient vapour emitted, you don’t have to heat it to get vapour  There is sufficient vapour for immediate ignition e.g. petrolSept 2007/chenck/May2002/V3 Chapter 2 12
  • 13. Class B Fires Discussion A cook is cooking vegetable in a pan. He pours some liquid into the pan and it catches fire immediately . Explain why does the original oil in the pan does not ignite? What did he put into the pan to cause this effect?Sept 2007/chenck/May2002/V3 Chapter 2 13
  • 14. Class C fires Class C fires are fires involving electricity i.e. electrical fires  Electrical motors  Electrical switchboards  Electrical plugs  Radios, fans etcSept 2007/chenck/May2002/V3 Chapter 2 14
  • 15. Class C FiresSept 2007/chenck/May2002/V3 Chapter 2 15
  • 16. Class D fires Involving metals  Fine metal powder  Magnesium  Potassium  Sodium etcSept 2007/chenck/May2002/V3 Chapter 2 16
  • 17. Class D FiresSept 2007/chenck/May2002/V3 Chapter 2 17
  • 18. Summary on Classes of FiresClasses of Fire What It InvolvesClass A Wood, ropes, clothes, mattress, plastics etcClass B Oil, gas, grease, fuel oil, diesel oil, petrol, kerosene,Class C Electrical equipmentClass D Fine metal powder, potassium,Sept 2007/chenck/May2002/V3 sodium, magnesium etc Chapter 2 18
  • 19. How Fire Spread Fire is spread by an equalization of temperature between two bodies. There are 3 ways how fire spread.  Conduction  Convection  RadiationSept 2007/chenck/May2002/V3 Chapter 2 19
  • 20. Fire Spread by Conduction Heat transmission through contact of one body to another e.g. metalSept 2007/chenck/May2002/V3 Chapter 2 20
  • 21. Fire Spread by Convection Heat transmission through air or fluidSept 2007/chenck/May2002/V3 Chapter 2 21
  • 22. Fire Spread by Radiation Heat transmission through spaceSept 2007/chenck/May2002/V3 Chapter 2 22
  • 23. Summary of how fire spread  Conduction  Convection  RadiationSept 2007/chenck/May2002/V3 Chapter 2 23
  • 24. Development of Fire There are 4 phases of fire  Ignition  Developing  Absolute fire  Burning outSept 2007/chenck/May2002/V3 Chapter 2 24
  • 25. 4 Phases of Fire Ignition – the starter (incipient) 1 IgnitionSept 2007/chenck/May2002/V3 Chapter 2 25
  • 26. 4 Phases of Fire Developing ( surface fires) 2 developingSept 2007/chenck/May2002/V3 Chapter 2 26
  • 27. 4 Phases of Fire Absolute  Heat has gone into the depth of the material 3 Absolute fireSept 2007/chenck/May2002/V3 Chapter 2 27
  • 28. 4 Phases of Fire Most of the fuel has been burned. Fire is about to be extinguished. 4 burning outSept 2007/chenck/May2002/V3 Chapter 2 28
  • 29. Summary of 4 Phases of Fire  Ignition  Developing  Absolute fire  Burning outSept 2007/chenck/May2002/V3 Chapter 2 29
  • 30. End of ChapterSept 2007/chenck/May2002/V3 Chapter 2 30