Section 20 - Fire Cause Detection Flashcards
3 sides of the Fire Investigation triangle
- Firefighters
- Police Dept.
- the Arson Investigator
Firefighters Observations at fire scenes such as:
- Are there any vehicles leaving the scene (or individuals)-
- What’s burning and where?
- What colour is the smoke or flames?
- How and where did you enter the building?
- How many fires?
- Is water supply ok?
- Anything unusual or foreign to the area during fire or mop-up?
The second triangle (the fire Dept. Investigator)
- Police Dept.
- Provincial Investigators
- Fire Dept. Investigator
Assembling the facts of a fire scene….. requires help of many different people.
- Firefighters
- Officers
- Chiefs
- Investigators
- Police
- Insurance Companies
- Lawyers
To establish the cause of a fire, we must determine 3 things…
1-Determine the fire spread 2-Determine the point of origin 3-Cause determination (i) source of ignition (ii) combustible materials present (iii) the act
Fire and heat may spread throughout a building either by…
- Conduction
- Convection
- Radiation
- Actual Flame Contact
Fire Spread
Fire can travel up the outside of concrete and brick building vertically, floor by floor, via windows and not spread horizontally through floors. Fire can also spread horizontally between floor joists, between ceilings and floors, through attic cocklofts, along beams, through furnace ducts. The fire may also spread by flying embers or debris.
Fire Burns upwards
Preheated gases and fire unobstructed and under normal conditions, always travel upwards seeking the highest point.
Point of Origin
To determine the point of origin we must locate the lowest point of burning in the building with the greatest amount go of charring.
Remember that fire can travel Horizontally or downwards to reach a source of oxygen
Once you have established the point of origin, you must ask yourself 3 questions.
1-What combustible materials were present?
2-What is our ignition source?
3-What act brought these together? (Providential, Accidental, Intentional)
Principle cause of fire
2 conditions being permitted to come into contact,
an ignition source and a fuel supply
3 sides to a fire triangle theory(fire ignition sequence)
- Heat source
- Fuel
- the Act
The Act - Providential, Accidental, Intentional
Providential - acts of nature
Accidental - careless use of smoking materials, improper use of flammable liquids, faulty appliance
Intentional - Incendiary fires are arson, a criminal act.
3 things that must be identified separately if the fire cause is to be fully explained.
- ignition source
- combustible materials
- the act
Black smoke
indicates a lack of air