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
Black smoke with large red flames
generally indicates the burning of a material with petroleum base.
No flames or comparatively small flames indicates
lack of air.
10 steps to follow in fire observations
1- One of the prime responsibilities of FF is to determine the origin and cause of fire
2- Realize that you and your officers are the first eyes on the fire scene
3- Observe the unusual - what is present that wouldn’t normally be there? What isn’t present that normally would be there
4-Be quick to observe vehicles or persons leaving the scene as you are arriving
5- the first impressions of what you see on arrival is critical such as smoke, flame, etc.
6- Is the building secure? How and where was entry made? Is their indication of forcible entry prior to your arrival
7- Where is the main body of the fire? Does there appear to be more than one fire burning?
8-Is the fire harder than normal to extinguish? Does it keep on reigniting?
9-What can you smell that seems odd?
10-What did people say to you and can you positively assure that you or an investigator can locate these people later if necessary?
200-watt bulb
base up mounting - 307F (163C)
side mounting - 493F (256C)
Is guilty of an indictable offence, and is liable to imprisonment for 14 years….
Everyone willfully sets fire to:
- a building or structure, whether complete or not
- a stack of vegetation produce of mineral or vegetable fuel
- a mine
- a well or combustible substance
- a vessel or aircraft, whether complete or not
- timber or materials placed in a shipyard for building, repairing or fitting out a ship
- military or public stores or munitions of war
- a crop, whether standing or cut down
- any wood, forest or natural growth or any lumber, timber, log, float, boom, dam or slide
Everyone who willfully and for fraudulent purposes sets fire to personal property not mentioned in subsection 1 is guilty of an indictable offence an is liable to imprisonment for…..
5 years
Everyone who willfully sets fire to anything that is likely to cause anything mentioned in subsection 1 to catch fire: or willfully and for a fraudulent purpose sets fire to anything that is likely to cause personal property not mentioned in subsection 1 to catch fire, is guilty of an indictable offence and is liable to imprisonment for…
5 years
6 Main reasons for Incendiary or arson fires
1-Profit or economic gain by defrauding the insurance company
2-Economic gain where the assured is innocent but the perpetrators benefits
3-Personal satisfaction has cause numerous and costly fires
4-Arson to conceal another crime
5-Arson by the mentally afflicted, such a pyromaniacs, etc.
6-Miscellaneous Circumstances
Exclusion of Accidental Causes
- the Electric system
- Electric Equipment-broken and rotted insulation, overloading circuits
- Gas leaks in piping or defective equipment.
- Pets
- Heating equipment
- Sun
- Lightning
- Children
- Smoking
- Storage of hay
3 vital questions in any investigation of fire setting
- Identity of the witnesses
- their business in the area
- what attracted their attention to it
Forces that cause fire to happen
-Combustibles involved
-Openings and Ventilation
-Winds and Draught
-Explosions
-Variations from normal Burning
-
How to retrace or reconstruct the path of fire by the effects produced
- Charring
- Remains and debris
- Room temperature
- sequence of shorted electrical circuits
- sequence of sprinkler eruptions
- the interiors of partitions - feeling change in wall temps
- Adjoining properties - the path may often be reconstructed by damage done to adjoining properties
- Colour of smoke and flames
Fire Cause Detection - All firefighters should note
- persons or cars leaving the scene or present upon arrival of apparatus
- whether doors or windows were open, unlocked or locked when entrance was made
- any disarrangement of furnishings or contents, drawn shades or the absence of valuable or personal articles or pets which are ordinarily present.
- the attitude of owner r occupants and any statements made by them
- unusual bystanders, particularly those seen at other fires and those who appear unduly excited or interested as to the cause of the fire
- all evidence and preserve it until the arrival of the investigator
Fire Cause detection - The fire officer in charge should:
- have notes made as facts are reported to him (small details may later become important to the trial of a case)
- take prompt and proper action when fire is deemed suspicious, particularly in guarding the scene until the arrival of investigators
- ensure entry to the building be denied to all persons except firefighters and police officers until the arrival on investigators
- seek to determine the exact point of origin, taking particular note if there is any indication of more than one point of origin.
Fire cause detection - Firefighting personnel should not!!!
- move, remove, or handle anything that may be evidence
- damage the scene in overhauling and cleaning up when a fire is suspicious
- open drawers or search to determine the absence of valuables
- offer public statements as to suspicions of any kind
- attempt to act as investigators, but give their ideas to the investigators when they arrive
Physical Evidence in Auto Fires
- the fire scene
- Footprints
- tire tracks
- location of container
- unburned matchsticks in the motor compartment
- missing lug bolts
- unburned tire pads
- removal of scented soil from the fire scene
- seat and lazy back springs - loss of temper
- location of gas tank drain plug
- missing gas tank cap
- missing vital engine accessories
- fuel systems and electrical systems
- finding of ignition key in debris
- finding of remains of contents claimed in car by owner
