University Of Nueva Caceres
Naga City
College Of Criminal Justice
Education
Products of
FIRE Combustion
TECHNOLOGY
AND ARSON
Dr. Lorlie B.Tanjay
INVESTIGATION Professor
Subject
COMBUSTION
or burning
is the sequence of between fuel
and an oxidant accompanied by
the production of heat and
conversion of chemical species.
The result of the heat can result in
the form of either glowing or flame.
Glowing combustion
occurs when solid fuels are
not capable of producing
sufficient quantities of
gas during pyrolysis to
sustain a flame. If access to
the oxidant (air) is limited,
glowing combustion may
result.
Flaming combustion
commonly recognized
type of fire and occurs with
gaseous fuel sources only.
The color of the flame can
give some indication of the
composition of the fuel.
Spontaneous combustion
the ignition of organic
matter with out apparent
cause, typically through
heat generated internally by
rapid oxidation. A process
whereby a material self
heats.
Explosive combustion
can occur when
vapors, dust of gases,
premixed with
appropriate amount
of air are ignited.
Some major products of
combustion
1. FIRE GASES
2. FLAME
3. HEAT
4. SMOKE
1. FIRE GASES
Referringto gases that remains
when the product of combustion
are cooled to normal temperatures.
Gases produced by fire depends
on many variables:
Chemical composition
Amount of oxygen
temperature
Fire gases:
Carbon monoxide
Carbon dioxide
Hydrogen sulfide
Sulfur dioxide
Ammonia
Hydrogen chloride
Hydrogen cyanide
2. FLAME
Itis the luminous body of burning
gas which gets hotter and less
luminous when mixed with more
oxygen.
Flame fades when carbon burns
completely.
Flame is a product of incomplete
combustion
Types of FLAME
Luminous flame-
reddish orange in color
It deposit soot' due to incomplete
combustion
It has lower temperature
Non-Luminous Flame-
Bluish in color
Product of complete combustion
Higher temperature
Types of FLAME
according to burning
Pre-mixed flame
Ex. bunsen burner
Diffusion Flame
Example oxyacetylene
torch , widely spread
Types of FLAME
according to smoothness
Laminar Flame
Smooth flame
Turbulent Flame
Rough flames, unsteady,
irregular swirls
3. HEAT
A product of combustion that
spread the fire.
It causes burns and other
injuries such dehydration, heat
exhaustion, and respiratory
tract injuries.
4. SMOKE
Avisible product of incomplete
combustion usually a mixture of
oxygen , nitrogen, carbon dioxide,
carbon monoxide, finely divided
particles of soot and carbon, and
miscellaneous assortment of
product released from the burning
material.
Transmission of fire (Fire
spread)
A fire will spread away from the point
of origin if sufficient fuel and oxygen
are present.
From the path of fire and the pattern it
leaves, the investigator can determine
on whether the fire spread naturally or
whether it was helped by an arsonist.
Methods of heat transfer
Convection
Conduction
Radiation
Convection
Isthe transfer of heat by
motion of a hot smoke,
gases, air and particles.
The hot smoke and
gases
• Three methods of heat
transfer…
Three Heat Transfer Methods
Conduction:
Transfer of heat from one molecule to another.
Example: touching your hand to a hot object
Conduction is the only means of transferring heat to the
interior of fuels (wood, litter, duff).
High-density fuels (green wood) vs. low-density fuels (litter, decayed wood)
High density fuels have greater conductivity – more heat
needed to raise temperature of surface layer
Radiation:
Transmission of heat by electromagnetic waves.
Examples of radiation: Heat from sun, fire place, stove
Contact between radiation source and affected body not necessary
Example: preheating of fuels ahead of fire front
Absorption of radiation by woody fuels
– only by thin layer at surface (rest by conduction)
Convection:
Transfer of heat by
movement of a gas
or liquid (air).
Hot air moves
vertically
(exceptions: winds,
slopes)
Examples: heating
a pot of water,
smoke from a fire.
What Factors
can Increase
Heat Transfer?
Factors that Increase Heat Transfer
Flames are brought
closer to the fuel
due to slope.
The wind pushes the
flames over...
Wind
...bringing the
flames closer
to the fuel.
Turn to your Partner (TYP)
FORMULATE an answer individually
SHARE your answer with your
partner
LISTEN carefully to your partner’s
answer
CREATE a new answer through
discussion
ACCOUNT for your discussion by
begin prepared to be called upon
