Combustion

Combustion reactions — oxidation reactions that involve oxygen and produce flames

Heat of combustion — excess heat energy

Exothermic reactions — chemical reactions that release heat

1

The Fire TetrahedronFour ingredients are

required to start a fire and keep it burning Oxygen

Fuel

Heat

Chain reaction 2

Hydrocarbons

Compounds made only of hydrogen and carbon Used for Fuels Examples: natural gas, gasoline, kerosene, lighter

fluid

Can be used as accelerants

Flash Point & Ignition Temperature

4

Finding the Igniter

Matches — often burns in the fire

Cigarette lighters — often removed by arsonist

Molotov cocktail — may leave glass fragments

Faulty electrical wiring — causes an arc which causes a predictable pattern

Knowing the igniter helps form the criminal profile 5

Function of a Fire Investigator

Investigation must begin quickly, before evidence is lost

First Priority: Find the fire’s point of origin

Examine possible causesAccidentalArson

Classify the fire6

Psychology of an Arsonist Sense of power An emotional high No typical arsonist; possible

characteristics:

7

• Less than 25 years old• Father not in the home• Domineering mother• Academically challenged• Emotionally and/or psychologically disabled

• Unmarried• Living with parents• Inadequacy, insecurity• Fascination with fire• Alcoholism• Parental neglect or abuse

Motives for Arson

Financial Gain Revenge Excitement Vanity Crime Concealment Vandalism