Fire Science

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Fire Science
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Chemistry of Fire

• Fire, or combustion, may be defined as rapid
  oxidation with the evolution of light and heat
  or,
• It may be said that fire is a rapid chemical
  reaction of FUEL, HEAT, and OXYGEN in the proper
  proportions.

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Fire Triangle

• FUEL a burnable material. Any material
  consisting primarily of carbon and hydrogen can
  be oxidized
• OXYGEN or other oxidizing agent. 20.9 in the
  air
• HEAT or sufficiently high temperatures to bring
  the fuel to its ignition temperature

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Chemical Reaction (Oxidation)

• Rusting slow oxidation
• Fire rapid oxidation
• Explosion extremely rapid oxidation
• Exothermic product of reaction is heat

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Ignition and Combustion

• Combustion takes place after a solid or liquid
  fuel has been vaporized or decomposed by heat to
  produce a vapor or gas. A gas cant readily mix
  with a solid or liquid.
• A visible flame is the burning gas.

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Ignition temperature

• Minimum temperature required to initiate
  self-sustained combustion
• Gasoline 8500F
• Wood 4000 7000F
• Paper 4500F
• JP4 4680F

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Sources of Heat

• Direct flame
• Friction Mechanical sparks
• Electricity
• Static electricity
• Lightning
• Spontaneous heating
• Decomposition

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Heat Transfer

• Conduction
• Direct contact
• Convection
• Circulating medium
• Radiation
• Heat rays

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Extinguishment

• Removal of heat
• Cool fire with water
• Removal of Oxygen
• Cover fire with foam
• Halon
• Carbon Dioxide

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• Removal of Fuel
• Turn off the fuel source
• Cutting of brush. Back burns
• Removal of chemical reaction
• Chemical Free Radical Quenching
• Dry Chemical
• Taking the place of oxygen so that oxidation
  cant occur. A chemical barrier

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Class A Fire

• Ordinary combustibles in which cooling is of
  first importance
• Wood, paper, rubbish

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Class B Fire

• Flammable liquids of which smothering is of first
  importance
• Gasoline
• Oils
• Paint

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Class C Fire

• Energized electrical equipment of which cooling
  or smothering is of importance
• Removing the electrical energy is important to
  make it a Class A fire
• The extinguishing agent must not conduct
  electricity

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Class D Fire

• Combustible metals
• Titanium, Magnesium, Sodium, Potassium
• Specific extinguishing agents
• Met-L-X Powder
• Sand
• Soda Ash

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Water

• Extinguishes 90 of our fires
• Removes heat and oxygen from the fire
• Cools the temperature below ignition temperature
• Turns to steam at 2120F and expands 1700 times
  crowding out the oxygen