3 different causes of fire:
Natural –
A natural cause of a fire is when a fire is caused by natural ignition such as
lightning, these are not deliberate causes rather caused by the environment as they
tend to occur in places away from human presence. Forest fires are a common
example of what can cause a natural fire, lightning can immediately set a tree on
fire especially if it is in very dry conditions.
Accidental –
An accidental cause of a fire occurs when there was no intention that was proved to
cause and spread a fire, they mainly happen due to the circumstances. These fires
are not caused by a deliberate human act, rather caused by acts of omission. An
example, would be a malfunction of an electrical appliance as the spread of fire was
accidental even if the initial fire was deliberate.
Deliberate –
A deliberate fire is caused by a clear motive or intention, these fires are said to
cause deliberate damage to an individual’s property. There is a thought that there
was a deliberate act and intention to cause these type of fires, these fires are
deliberately ignited in their circumstances even when the person knows that no
ignition should occur there.
Phases of a fire:
Incipient phase – this is the stage after ignition, at this point a fire can either be
extinguished or spread further. Heat, oxygen and a fuel source all join together to
create a chemical reaction which produces a fire, it is also usually represented by a
small fire which can go out on its own. However, this stage cannot be easily
recognized as the factors are not very visible, some factors include the vicinity of
other flammable fuels, the fire’s access to oxygen and whether there are people
nearby to extinguish the fire. If a fire is recognized in time during this stage, there is
a good chance of escaping it or conquering it.
Growth phase – at this point the fire has begun generating plenty of it’s own heat
whilst engulfing fuels to continuously burn, it is one of the shortest stage but this
stage will end once a ‘flashover’ occurs. This heat can cause combustion of
surrounding fuels, a continuous loop is created of heat. Factors that affect this stage
include where the fire started, what combustible materials are around or near it,
ceiling height and the possibility for ‘thermal layering’. To identify when a fire is in
it’s growth stage you would see a layer of smoke that’s visible above the fire, the
room temperature will have increased and windows start to crack.
Free burning/fully developed phase – a fire will be considered fully developed at its
hottest and dangerous point as all combustible materials have been ignited and
engulfs all the available fuel sources, unless a new fuel source is added the fire’s
intensity is only mostly decline here. This remains as the most dangerous phase for
a fire, it is also quite hot and ferocious. Whilst extinguishing, firefighters will keep a
distance and ensure that new fuels are not introduced to the fire.
Smouldering/decay phase: - this is a stage when a fire runs out of oxygen or fuel to
sustain it, this stage is quite long and take weeks for large fires such as wildfires. A
danger of this stage is that there is a possibility of new oxygen or fuel being
introduced to the fire.
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Heat release rate:
Heat release rate is the rate at which fire releases energy, a fire with a high heat
release rate will transfer more energy to its surroundings than a fire with a smaller
heat release rate .
At the first stage, there is an incipient phase where ignition has occurred but there
has not been a spread yet. This is where the fire is developing but has not fully
spread yet, it can be identified by factors such as the fire not affecting anything
beyond its immediate vicinity, visibility has not been affected by smoke, people
around can still breathe and can escape without too much trouble and the heat of
the fire is relatively low. A feature of a developing fire is it’s uncertainty as it is at
the point where it can extinguish itself and avoid a catastrophe or begin to spread
further. An example of a fire during it’s incipient stage could occur when a candle
has tipped over and flames have just started to flow across table, there is a
possibility of this fire entering the growth stage if there are any flammable objects
on the table.
Once a fire initiates itself and burns itself, it is in the growth stage. The fire will
produce its own heat in order to sustain itself, the heat used by the fire will cause
the combustion of the surrounding fuel sources. During this stage, the fire will
spread around the area and cover fuels in its path. Factors to identify a fire in its
growth stage include a layer of smoke visible above the fire or a gathering of smoke
if indoors, feeling of room’s temperature increasing and no sight of any
condensation on windows. The growth stage may be the shortest fire stage, but the
flames will spread rapidly.
Fire assignment
The growth stage will often end once a flashover occurs, if a fire has generated
enough heat, usually around ‘1150 degrees’, the fuels in the fire’s vicinity catch fire
spontaneously. During a flash over, the fire spread vastly in just a matter of
seconds.
When a fire is fully developed, it will reach the hottest point and engulf all available
fuel sources. The fires intensity is most likely going to decline from here unless it
gets a new fuel source.
Once an oxygen runs out of oxygen or fuel to sustain itself, it enters the long,
decay stage. There is a potential for new oxygen or fuels reaching the fire, these
will cause the fire to reignite.
Fire patterns
Fire patterns can give you information about the behaviour of fire, its point of origin,
the location where it started and how it was caused such as if it was deliberate or
Natural –
A natural cause of a fire is when a fire is caused by natural ignition such as
lightning, these are not deliberate causes rather caused by the environment as they
tend to occur in places away from human presence. Forest fires are a common
example of what can cause a natural fire, lightning can immediately set a tree on
fire especially if it is in very dry conditions.
Accidental –
An accidental cause of a fire occurs when there was no intention that was proved to
cause and spread a fire, they mainly happen due to the circumstances. These fires
are not caused by a deliberate human act, rather caused by acts of omission. An
example, would be a malfunction of an electrical appliance as the spread of fire was
accidental even if the initial fire was deliberate.
Deliberate –
A deliberate fire is caused by a clear motive or intention, these fires are said to
cause deliberate damage to an individual’s property. There is a thought that there
was a deliberate act and intention to cause these type of fires, these fires are
deliberately ignited in their circumstances even when the person knows that no
ignition should occur there.
Phases of a fire:
Incipient phase – this is the stage after ignition, at this point a fire can either be
extinguished or spread further. Heat, oxygen and a fuel source all join together to
create a chemical reaction which produces a fire, it is also usually represented by a
small fire which can go out on its own. However, this stage cannot be easily
recognized as the factors are not very visible, some factors include the vicinity of
other flammable fuels, the fire’s access to oxygen and whether there are people
nearby to extinguish the fire. If a fire is recognized in time during this stage, there is
a good chance of escaping it or conquering it.
Growth phase – at this point the fire has begun generating plenty of it’s own heat
whilst engulfing fuels to continuously burn, it is one of the shortest stage but this
stage will end once a ‘flashover’ occurs. This heat can cause combustion of
surrounding fuels, a continuous loop is created of heat. Factors that affect this stage
include where the fire started, what combustible materials are around or near it,
ceiling height and the possibility for ‘thermal layering’. To identify when a fire is in
it’s growth stage you would see a layer of smoke that’s visible above the fire, the
room temperature will have increased and windows start to crack.
Free burning/fully developed phase – a fire will be considered fully developed at its
hottest and dangerous point as all combustible materials have been ignited and
engulfs all the available fuel sources, unless a new fuel source is added the fire’s
intensity is only mostly decline here. This remains as the most dangerous phase for
a fire, it is also quite hot and ferocious. Whilst extinguishing, firefighters will keep a
distance and ensure that new fuels are not introduced to the fire.
Smouldering/decay phase: - this is a stage when a fire runs out of oxygen or fuel to
sustain it, this stage is quite long and take weeks for large fires such as wildfires. A
danger of this stage is that there is a possibility of new oxygen or fuel being
introduced to the fire.
, ../2
Heat release rate:
Heat release rate is the rate at which fire releases energy, a fire with a high heat
release rate will transfer more energy to its surroundings than a fire with a smaller
heat release rate .
At the first stage, there is an incipient phase where ignition has occurred but there
has not been a spread yet. This is where the fire is developing but has not fully
spread yet, it can be identified by factors such as the fire not affecting anything
beyond its immediate vicinity, visibility has not been affected by smoke, people
around can still breathe and can escape without too much trouble and the heat of
the fire is relatively low. A feature of a developing fire is it’s uncertainty as it is at
the point where it can extinguish itself and avoid a catastrophe or begin to spread
further. An example of a fire during it’s incipient stage could occur when a candle
has tipped over and flames have just started to flow across table, there is a
possibility of this fire entering the growth stage if there are any flammable objects
on the table.
Once a fire initiates itself and burns itself, it is in the growth stage. The fire will
produce its own heat in order to sustain itself, the heat used by the fire will cause
the combustion of the surrounding fuel sources. During this stage, the fire will
spread around the area and cover fuels in its path. Factors to identify a fire in its
growth stage include a layer of smoke visible above the fire or a gathering of smoke
if indoors, feeling of room’s temperature increasing and no sight of any
condensation on windows. The growth stage may be the shortest fire stage, but the
flames will spread rapidly.
Fire assignment
The growth stage will often end once a flashover occurs, if a fire has generated
enough heat, usually around ‘1150 degrees’, the fuels in the fire’s vicinity catch fire
spontaneously. During a flash over, the fire spread vastly in just a matter of
seconds.
When a fire is fully developed, it will reach the hottest point and engulf all available
fuel sources. The fires intensity is most likely going to decline from here unless it
gets a new fuel source.
Once an oxygen runs out of oxygen or fuel to sustain itself, it enters the long,
decay stage. There is a potential for new oxygen or fuels reaching the fire, these
will cause the fire to reignite.
Fire patterns
Fire patterns can give you information about the behaviour of fire, its point of origin,
the location where it started and how it was caused such as if it was deliberate or
