Fire Science Flashcards
What is the definition of combustion? Give an example
An irreversible chemical reaction producing heat and light
Burning wood will produce ash, but ash cannot be transformed back into it original state wood.
What three components form the triangle of fire?
Heat
Oxygen
Fuel
What is the difference between vapour and permanent gas?
Vapour has the potential to change back to liquid with a change of pressure
Heat is a form of what?
Energy
What is an ignition source?
Name some examples of an ignition source
The heat energy required for combustion to occur. Naked flames Electrical arcs or sparks Frictional heat or sparks Chemical reaction Pressurisation of gas Spontaneous heating
Heat energy is measured in what?
Joules
Joules per kilogram
Temperature is measured in what?
Celsius
How much oxygen is in the air and how much is needed for combustion?
21% in the air
16% needed for combustion
What is an oxidising agent?
A substance that releases oxygen when heated, that can lead to combustion
What are passive agents or
Passive?
Name some examples
Substances that take no part in the chemical reaction of combustion, but can have an effect on the fire’s behaviour by absorbing heat
Non flammable gases
Weather, temperature and humidity
Nitrogen in the air
Walls and ceilings, furniture
The amount of oxygen available for combustion will determine what three things?
How quickly and efficiently a substance will burn
The type of fire gases that are released
The amount of smoke produced
What is pyrolysis?
What is the process of pyrolysis?
The self-sustaining decomposition of a substance by heat
Heat from the flame radiates onto the surface of the fuel, causing it to pyrolyse, producing flammable gases to feed the flames
What is the flash Point?
The lowest temperature at which vapours are being produced for a momentary flash to occur when an ignition source is introduced.
Does not continue to burn once the ignition source is removed
What is a Fire point?
The lowest temperature at which sufficient vapours are being produced for the fuel to ignite and continue to burn once the ignition source is removed
Temperatures are only very slightly above the flash point
What is the auto-ignition temperature (A/T)?
The lowest temperature at which fuel will spontaneously ignite and continue to burn without the need of an ignition source to be introduced
Often referred to as the spontaneous ignition temperature (SIT)