Fire science Flashcards
three states of matter in which fuel can exist
Solid
Liquid
Gas
Explain the triangle of fire
Heat - Compression, electrical, friction
Fuel- A combustable material
Oxygen- 16% required
three states of matter in which fuel can exist
Solid
Liquid
Gas
Difference between them depends on the spacing and movement of their molecules.
Explain Pyrolosis
The chemical decomposition of an a substance by heat.
Explain flash point
The lowest temperature at which sufficient vapours are being produced for a momentary ‘flash’ to occur when a ignition source is introduced.
Burning doesn’t continue without the ignition source.
Explain Fire point
The lowest temperature at which sufficient vapours are being produced for the fuel to ignite and continue to burn once an ignition source is introduced.
Temperature above flash point
Temperature at which the fuel will continue to burn for more than 5 seconds after ignition by an open flame.
Explain auto ignition temperature (AIT)
The lowest temperature at which a fuel will ignite and continue to burn without the need for an ignition source
What is temperature ?
Measure of heat energy in a substance/object
Methods of extinguishing ?
Cooling- Removes the heat energy with water
Starvation- remove the fuel source (Turn off gas)
Smothering- Covering a pan with a fire blanket
Classifications of fire
A- Carbonaceous materials (solids)
B- Liquids and liquifiable solids
C-Gases and Liquified gases
D-Metals
E- Electiricity
What is ignition ?
A process leading to combustion. When a sufficiently high source of energy is introduced to enable the reaction between fuel and oxygen.
Media to extinguish a Class B fire?
Foam
Fire Blanket
Dry powder
Smothering
How is heat energy spread ?
Convection -The mass movement of hotter, less dense gas through its cooler, denser surroundings (hot air rises)
Conduction - Passage of heat through a material, some materials (such as metal) conduct heat better than others.
Radiation- Transfer of heat through electro-magnetic waves. Does not heat gases but will heat solids and liquids it comes into contact with.
Properties of extinguishing media
Water- Reduces fuel (stops pyrolosys and coools gasses)
Reduces heat - Absorbs heat into water droplets and through steam
Reduces Oxygen- Steam limits amount of oxygen
Foam- smothers by creating a barrier between oxygne and the fuel.
Dry powder - Interference with the chemical reaction by preventing particles from meeting
CO2 - Smothers by removing oxygen
Fire Blanket- Smothers by forming a barrier
