LASISI ADEDOYIN K.S MNES, MICCON, NWMSON

There were 14,561 fires reported in Minnesota in  39 civilian deaths  137 reported civilian injuries  $152 million in property damage

 People feel the safest in their homes, however residential properties are where most fires and fire deaths occur.  76% of all structure fires occurred in residential properties.  97% of structural fire deaths occurred in residential properties.

 The top fire causes include:  Cooking (49%)  Open Flame (10%)  Heating (9%)  Incendiary/Arson (8%)  Smoking (4%) *leading cause of fire fatalities Personal vigilance is the best way to avoid and survive fires!

FIRE SCIENCE

What elements are needed to start a fire?

HEAT CHEMICAL CHAIN REACTION FUEL OXYGEN The Fire Tetrahedron

FUEL CAN BE  LIQUID:Grease, Oil, Fuel;  SOLID:Wood, Paper, Metal;  GAS: Natural Gas, Propane, Acetylene.

CLASS “A” FIRES - Ordinary combustibles such as wood,paper, cloth.

CLASS “B” FIRES - Flammable liquids such as oil, grease

CLASS “C” FIRES - Energized electrical equipment

CLASS “D” FIRES - Flammable Metals

What is smoke?

WHAT IS THE DIFFERENCE BETWEEN COMBUSTIBLE AND FLAMMABLE MATERIAL? Combustible material has a flashpoint of 100 F or above Flammable material has a flashpoint below 100 F [Ref. NFPA 96]

16

17 Essentials of Fire Oxygen Fuel FIRE Heat

18 Oxygen Heat Fuel OXYGEN SOURCEHEAT SOURCES Approx. 16% Required Normal air contains 21% of oxygen Some Fuels contains its own oxygen supply GASES To Reach Ignition Temp. Open Flame, the Sun,Hot Surface, Sparks & Arcs, Friction, Chemical Action, Elec. Energy & Gas Compression LIQUIDSSOLIDS Natural Gas, Propane, CO, Butane, Hydrogen, Acetylene, Gasoline, Kerosene, Turpentine, Alcohol, Paint, Varnish, Olive oil, Lacquer Coal, Wood, Paper, Cloth, Wax, Grease, Leather, Plastic, Sugar, Grain, Hay, FIRE TRIANGLE

19 Fire Tetrahedron

20 It depends on the following factors i. The amount of time the fire has burnt. ii. The ventilation characteristics of the confining structure iii. The amount and type of combustibles present.

21 Three progressives stages of burning Incipient or beginning phase Free burning phase Smoldering phase

22 Oxygen Rich Atmosphere Oxygen Deficient Atmosphere

23 Oxygen plentiful Temperature has not built up to high peak Thermal updraft rises, accumulates at highest point Breathing not difficult Fire extinguishments : – Direct application of water at base of fire. Ventilation :not a problem Little steam production

24 Fire has involved more fuel Oxygen supply is being depleted Heat accumulated at upper areas Breathing difficult : Masks recommended Fire extinguishments is reaching the area of major involvement Ventilation : Not a definite need Good steam production

25 Oxygen supply not equal to demands of fire Temperature throughout building is very high Normal breathing is not possible Oxygen deficiency may cause back-draft Fire extinguishments indirect method Ventilation : A must Maximum steam production from water fog

26

27 Conduction It occurs only in solids i.e. metallic objects. Convection It occurs both in liquids & gases Radiation It is neither conduction nor convection. These are heated rays emanating from the hot object. Modes of spread of fire

28 Heat energy is passed on from one molecule to the next The molecule vibrates above its mean position Pass on heat energy by colliding with their neighbors The ability to conduct heat varies between materials. Highly ExcitedLess Agitated

29

30 conduction

31 When a liquid or gas heated, it expands It becomes less dense The lighter fluid arises being displaced by colder and therefore denser fluid In turn becomes heated and so a circulation is set up Heat energy is carried throughout the fluid by actual movements of molecules.

32 Fig: Fire Plume

33 It does not involved any contact between bodies It is independent of any material in the intervening space These are the heated rays, travels in straight line in all directions with same intensity

34 Other chemical reactions which produce 1. Combustion (heat & light) 2. Combustion (without heat & light) 3. Combustion ( without heat)

35 Rusting of iron

36 i. Slow or incipient combustion- in which the amount of heat & light emitted is feeble. ii. Rapid or active combustion- in which a considerable amount of heat & light is emitted within a short time

37

38 iii. Deflagration - which takes place with a considerable rapidity, evolving heat & light iv. Explosion - is a very rapid combustion with a loud noise within an extremely short time with generation of very high pressure & temperature.

39 A rate of combustion or the spread of fire would depends on : The area of solid/liquid in contact with air. The amount of heat generated to raise the temperature of un-burnt portion. The ability of materials to conduct heat away. Atmospheric humidity. Wind velocity. Temperature. Atmospheric pressure.

40 EXOTHERMIC REACTION When heat is liberated in chemical reaction is known as Exothermic Reaction. Ex : N 2 +3H 2 =2NH 3 + H (-24Kcal) C+O 2 =CO 2 + H (-94.5 K cal) Bond Being Broken Heat Liberated

41 ENDOTHERMIC REACTION When heat is absorbed from the reacting substances is known as Endothermic Reaction. Ex: 2C + H 2 = C 2 H 2 + H (54 Kcal) 3O 2 2O 3 + H (69 Kcal) Heat Absorbed Bond Being Formed

42 It is the surface area in square centimeter per gram of that solid substance. Liquids & gases have no specific surface, these two take the shape of container. On the basis of specific surface and fire susceptibility, all combustible solids classified into three : »Tinder »Kindling »Bulk fuel