Fire Science Flashcards
What is the definition of combustion?
The chemical reaction in which fuel combines with heat and oxygen
What is the definition of pyrolysis?
The thermal decomposition golf a substance by heat.
What is the process of pyrolysis!
Thermal capacity is reached.
Gases given off.
Gasses ignite.
What is a passive agent?
Something that absorbs heat from fire
3 characteristics of passives?
Already present or produced in combustion process.
They take no part in the chemical reaction.
Passives absorbing heat will have an effect on the fires behaviour.
2 types of fire gases and examples?
Non flammable gases-co2, water vapour.
Flammable gases- due to incomplete combustion. Includes carbon monoxide
Between what 2 limits will fire gases burn?
Too lean -LEL, lower explosive limit.
Too rich-UEL, upper explosive limit
The exact conditions for oxygen in the air for combustion with maximum force is known as what?
The Ideal mixture
Factors that effect fire development?
Position of fire-4,2,1 rule.
Ceiling height
Smoke layer ( over pressure, under pressure).
Ventilation
4 phases of fire?
Early phase
Growth phase
Fully developed phase
Decay phase
3 extinguishment methods?
Direct
Indirect
Gas Cooling
What is the direct cooling technique?
Narrow jet aimed directly at seat of fire.
Painting is a more controlled version of this.
What is indirect cooling?
A spray aimed at the fire gases and hot compartment boy fires.
Can be used outside the compartment to cool and dilute fire gases.
3 methods of gas cooling?
Short pulse-above BA team
Long pulse -forward into fire gases
Coning down -pockets of ignited flames
