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Arson
& Fire
During the
beginning of the second world war the allies assumed that explosive weaponry
was the superior tactical weapon of choice, by the end of the war it was
proven that incendiary weapons (weapons of fire) were superior to explosives
several times over. It is ambigious therefore that such a weapon utilized
since the stone age receives a lot less media attention than explosives.
This article will attempt to prove that arson & fire are not the simple
subjects the media protrays.
Destruction
By Fire
Objectives of the Arsonist
Mechanism of Fire
Tools of Arson
Forensics & Arson Investigation
Destruction
By Fire
The worst place imaginable, Hell, is imagined by people to be a place
of fire, where people are burnt alive. And why not, fire can cause horrible
burns which are both very painful and horrible to look at. By a person's
instinct an open flame is known to be dangerous and a person would put
distance between him and the fire, however the majority of fires result
in death by the hot gasses given off. In a closed enviroment where a fire
is raging the gas given off by fire, mainly carbon monoxide, is extremely
poisonous. A naked flame can also be very destructive but more to the
structures and equipment of the arsonist's target rather than people/personnel.
Because fire feeds on it's target it can grow in size very quickly giving
way to a chain reaction.
Objectives
of the Arsonist
In a combat enviroment an arsonist has several tactical objectives by
his actions. To destroy enemy personnel and structures, To destroy military
equipment, to hamper the ability of the enemy to wage war, to force the
enemy to fight for survival and to implement a scorched earth to aid escape.
A fighting force cannot function properly if it is fighting fires on its
own ground, similarly a fighting force will have to fight for survival
if it's food supply is being destroyed by fire and the final example,
a retreat can be aided by scorching one's own property to hinder its use
by the advancing army. In a civilian scenario arsonists have been known
to set fires for purposes of revenge and profit.
Mechanism
of Fire
Fire needs three components to survive; Oxygen, Fuel and Heat. When oxygen
and a fuel are combined heat is applied to force a chemical reaction that
sustains itself further by the heat it generates. For a fire to burn in
flame the fuel evaporates combining with oxygen in an explosive volatile
reaction. If any one of these three is not present a fire will not survive.
With these basics and the knowledge of weather a fire can be engineered
for any purpose. E.g. Heat travels upwards so if a fire is started at
the base of a fuel it will propogate a lot quicker than if started at
the top of say a pile of wood or paper. Similarly, fires always move upwards
so a fire to be destructive is usually set at the basement of a structure
rather than on the roof. By this basic knowledge we know that fire 'eats'
oxygen at it's base and releases hot gases upwards leading us into an
insight on how wind and drafts in a structure play a part in the propagation
of fire.
Tools
of Arson
A naked flame is the basic tool of an arsonist, something which can be
purchased very cheaply in the form of matches or a cigarette lighter.
It is quite interesting to know that a cigarette lighter has the potential
to start many thousands of fires yet carried in a pocket is very inconspicuous.
The advanced arsonist would utilize special tools and techniques to control
when a fire is started and for this everything has been used from a mechanically
engineered 'booby trap' up to electronic-chemical initiators. The basic
improvised tool is usually in the form of a pad of matches and striker
modified in such a way that a pull to seperate the two would start a fire
that would further propagate with the aid of an accelerant fuel such as
diesel or petrol. Eg. a brick tied to the ceiling with string separated
on the brick side by a matchpad igniter placed on a flat board on the
edge of a table with a plastic container of petrol on the table side,
if a hole is poked in the base of the container petrol will spill out
on the ground and when it has become lighter than the brick the brick
will fall to the ground seperating and initiating the matchpad which in
turn explodes the fuel causing fire.
Forensics
& Arson investigation
In a civillian scenario the arsonist has to escape the fire and avoid
detection by the authorities. similarly if a fire is identified by the
forensics team to be non accidental that would probably come in the way
of the arsonist's financial incentive. A fire usually destroys everything
it touches and evidence can be disturbed by firefighters hindering the
efforts of the investigator. However, a lot of new equipment is available
to aid the forensics investigator in identifying foul play behind a fire;
the gas spectrometer. A gas spectrometer can analyze any substance into
its chemical constituents giving the investigator a clear few of chemicals
present in the ashes of a fire. The chemicals that investigators usually
look for are accelerants like petrol, diesel and other flamables, when
these fuels burn they leave a trace behind which is clearly identified.
The patterns of a fire are also tracked and compared to data of accidental
fires so as to conclude whether the fire was accidental or not. E.g. a
fire is thought to be more likely accidental if there are no accelerants
detected and the patterns indicate that the fire started at an electrical
socket. Chemcial engineers know very well that there are chemicals when
burnt do not leave any suspicious traces behind and when that is combined
with fire propagation patterns a perfect undetectable fire is possible.
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