Fire Basics

Fire

produce when a substance undergoes rapid oxidation involving heat and light

fire triangle

Fuel heat and oxygen

ficish point

Lowest temperature to which a substance must be heated in order for the substance to give off vapors which will burn when exposed to flame or ignition source

point of origin

Location where the fire started

burn patterns

noticeable patterns created by fire as it burns

Point of origin

burn patterns and other damage can help determine the point of origin or the location where the fire started

Char patterns

created by very hot fires that burn very quickly and move fast along its path so that there can be sharp lines between what is burned and what isn’t

V patterns

Fire burns up in a V-shaped pattern so a fire that starts at an outlet against a wall leaves a char pattern that points to origin

Heat shadows

occur when heavy furniture, shields part of a wall can help determine the origin point

glass

Glass fragments windows & light bulbs can provide clues to a fire

Chimney effect

Since fire burns upwards, there can be an effect where the fire ignites at a point, the superheated gases rise upward and form of fireball, which continue straight up to burn a hole in the ceiling.

Color of smoke

Determine what type of material was burning

Color of flames

indicates at what temperature the fire was burning

Accidental fires

Heating system, smoking

How should an investigator manage a fire scene?

• work from the least damage areas to most heavily damaged areas

• Document with notes, photographs, and videos

• Collect evidence (accelerant samples, fire items, and other crime scene evidence)

• Interview witnesses

• Determine point of origin

• Determine the heat source(s)

• Hypothesize the reasons for the fire

What can you do to help prevent arson or arson damage?

• Report suspicious people in activities that may result in arson

• If you have a friend or classmate that has set a fire in the past or plans to set a fire, tell an adult

• Start or participate in a community watch program with your parents

• Install and properly maintain fire alarms in your home. Your family should have a fire escape plan for your home.