Fire Flashcards
4 Reasons why fire investigation is needed?
- Find out where a fire started
- Find out why the fire started there
- Find out if a criminal act has taken place
- Fire brigade need to prevent it from happening again
What are the 3 elements of the fire triangle?
Heat
Fuel
Oxygen
What are the 4 types of heat?
Convection
Conduction
Radiation
Spontaneous Ignition
What is the definition of Heat?
Heat of an object is the aggregate energy of all molecular movement inside the object
Heat is a _____ of _____ that _____ from one _____ to another
Form
Energy
Transfers
Object
What is the definition of Conduction?
Heat transfer of molecules in direct contact with each other, without the movement of particles.
What is the definition of Convection?
Transfer of heat due to the movement of particles from one object to another
What is the definition of Radiation?
Heat transferred through a medium or vacuum wherein space in-between is not heated up
What is Oxidation?
This is when fuel burns and reacts with oxygen from the surrounding air
Examples of Conduction?
Using ice to cool down your hand
Touching a stove and burning your hand
Boiling water by plunging a red hot iron into it
Examples of Convection?
Hot air rising, cooling and falling (convection current)
Old fashion radiator, draws cool air in at bottom emits hot air at the top
Examples of Radiation?
Sun heating your face
Heat from a lightbulb
Heat from a fire
How do you extinguish fires
Remove any of required components
Usually heat or oxygen
Methods of extinguishing fires
Water Carbon Dioxide Foam Dry Powder Sand / Blankets Vaporising liquids
Deliberate causes of fire?
Naked flame Accelerants Point of entry Vandalisms Delay devices Suicide
Accidental causes of fire?
Naked flame Electrical appliances Gas Chip pans Smoking materials Spontaneous combustion
What are the 3 types of fire?
Flaming fire
Smouldering fire
Explosions
What fire type is the most commonly encountered?
Flaming fire
Most ____ go through the ___ stage at some point
Fires
Stage
5 features of a Smouldering fire?
- Flameless combustion
- Can proceed at low oxygen concentrations
- smoke / fire products may be deposited
- can develop into flaming fire
- may produce considerable localised damage
What are the 2 Explosion fire phases?
Dispersed phase
Condensed phase
Dispersed phase 3 features?
Vapour phase explosions
Typically petrol or gases
Less damage than high explosives
Condensed phase 3 features?
High explosives
Commercial explosives; TNT, Semtex, RDX
Cause severe damage
what does BLEVE stand for?
Boiling Liquid Expanding Vapour Explosion
What is methanes LEL and UEL?
LEL 5%
UEL 15%
What is propanes LEL and UEL?
LEL 2.2%
UEL 9.5%
What is butanes LEL and UEL?
LEL 1.5%
UEL 7.8%
What is acetylenes LEL and UEL?
LEL 2.5%
UEL 80%
What is petrols LEL and UEL?
LEL 1.1%
UEL 8.7%
Spontaneous combustion 3 types?
Industrial
Agriculture
Laundrettes
Why commit Arson 5 reasons?
To commit a crime To disguise a crime To remove or obscure evidence To claim against an insurance policy To commit suicide
5 Factors that may suggest Arson?
- Discovery of another crime
- Signs of a disturbance
- The use of an accelerant
- Multiple seats of fire
- Background info.
4 General fire rules?
- Fire burn upwards and outwards
- Spread quicker on vertical surfaces
- Flame height varies with position of fire
- Flashover
Locating the seat of the fire, 8 features that can help
- Most extensive burning
- Lowest point of burning
- Smoke pattern
- Directional effects
- Witness / Fire Brigade information
- Info from alarm system
- Electric Arc Mapping
- Secondary location / seat of fire.
What 7 evidential materials may be recovered from a fire?
- Glass
- Accelerant residues
- Footwear marks
- Blood
- DNA
- Fingerprints
- Remains of devices; such as petrol bombs
What are the 3 types of hazards at fire scenes?
Physical
Chemical
Biological hazards
Chemical hazards 4 examples?
Drugs/poisons
Drug laboratories
Corrosive Chemicals
Explosives
Biological hazards 3 examples?
Injection
Infection
Inhalation
Flammable liquid analysis 5 methods?
Organic vapour analyser (sniffer) Headspace sampling Gas chromatography Interpretation Liquid comparisons and "branding"
Petrol bombs are classified under the ____ _____ substances ___
1883
Explosive
Act
R v Bouch 4 criteria for a petrol bomb?
- Readily breakable container
- Wick of absorbent material in the neck
- Some of wick must protrude from neck
- Free liquid petrol in container
What is the most important toxic effect of a fire?
Carbon Monoxide
Fatal limits of CO?
50%+
Burnt bodies generally do not ____
Bleed
3 Main causes of a Vehicle fire
- Deliberate acts
- Accidents / unintentional acts
- Design faults of the car or poor care of the car
Flash fires have low/high level of CO?
LOW
Smouldering fires have low/high level of CO?
HIGH
What are the 3 main areas vehicle fires are found?
- Engine compartment
- Passenger compartment
- Boot
