The document discusses fire prevention and firefighting. It covers the classification of fires into four main classes (A, B, C, D) based on the material that is burning. Class A includes wood and organic materials, Class B includes oils, grease and gases, Class C relates to electrical fires, and Class D involves combustible metals. The document also examines how fire spreads through three methods - conduction, convection and radiation - and outlines the four phases of fire: ignition, developing, absolute fire and burning out.

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 etc
Sept 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 Fires
Sept 2007/chenck/May2002/V3 Chapter 2 3

4. Classifications of fires
 Class A fires
 Class A fires are wood fires or
carbonaceous fires
Sept 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 etc
Sept 2007/chenck/May2002/V3 Chapter 2 5

6. Class A Fires
Sept 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 fires
Sept 2007/chenck/May2002/V3 Chapter 2 8

9. Class B Fires
Sept 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 fires
Sept 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 etc
Sept 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. petrol
Sept 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 etc
Sept 2007/chenck/May2002/V3 Chapter 2 14

15. Class C Fires
Sept 2007/chenck/May2002/V3 Chapter 2 15

16. Class D fires
 Involving metals
 Fine metal powder
 Magnesium
 Potassium
 Sodium etc
Sept 2007/chenck/May2002/V3 Chapter 2 16

17. Class D Fires
Sept 2007/chenck/May2002/V3 Chapter 2 17

18. Summary on Classes of Fires
Classes of Fire What It Involves
Class A Wood, ropes, clothes, mattress,
plastics etc
Class B Oil, gas, grease, fuel oil, diesel oil,
petrol, kerosene,
Class C Electrical equipment
Class 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
 Radiation
Sept 2007/chenck/May2002/V3 Chapter 2 19

20. Fire Spread by Conduction
 Heat transmission through contact of one
body to another e.g. metal
Sept 2007/chenck/May2002/V3 Chapter 2 20

21. Fire Spread by Convection
 Heat transmission through air or fluid
Sept 2007/chenck/May2002/V3 Chapter 2 21

22. Fire Spread by Radiation
 Heat transmission through space
Sept 2007/chenck/May2002/V3 Chapter 2 22

23. Summary of how fire spread
 Conduction
 Convection
 Radiation
Sept 2007/chenck/May2002/V3 Chapter 2 23

24. Development of Fire
 There are 4 phases of fire
 Ignition
 Developing
 Absolute fire
 Burning out
Sept 2007/chenck/May2002/V3 Chapter 2 24

25. 4 Phases of Fire
 Ignition – the starter (incipient)
1
Ignition
Sept 2007/chenck/May2002/V3 Chapter 2 25

26. 4 Phases of Fire
 Developing ( surface fires)
2
developing
Sept 2007/chenck/May2002/V3 Chapter 2 26

27. 4 Phases of Fire
 Absolute
 Heat has gone into the depth of the
material
3
Absolute fire
Sept 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 out
Sept 2007/chenck/May2002/V3 Chapter 2 28

29. Summary of 4 Phases of Fire
 Ignition
 Developing
 Absolute fire
 Burning out
Sept 2007/chenck/May2002/V3 Chapter 2 29

30. End of Chapter
Sept 2007/chenck/May2002/V3 Chapter 2 30