Fire Protection FundamentalsFPF 190
Learning Objectives
 Explain basic fire chemistry
 Explain the differences between the fire triangle and the
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fire tetrahedron
Understand fire chemistry and fire behavior terms
Explain the difference between heat and temperature
Describe the three methods of heat transfer
Understand ignition methods and sources
Explain the stages of fire and the products of combustion
Illustrate classifications of fire
Explain the ways to control, limit and suppress fires and
explosions
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Chemistry of Fire
Fire - a rapid oxidation process with the evolution
of light and heat in varying intensities.
Fire is an exothermic reaction (energy is released).
Flaming fire is always a gas phase (gas - gas) reaction
meaning one or more ignitable gases are combining
with a gaseous oxidizing agent in the flame zone
forming new compounds.
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Fire Triangle
 Fuel
 Oxygen
 Heat
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Fire Tetrahedron
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Fuel
Heat
Oxidizer
Uninhibited
(self-sustaining)
chemical chain
reaction
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Uninhibited Chemical
Chain Reaction
A chemical process yielding products able to act as
initiators for other reactants, leading to further
reactions of the same kind.
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Elements of Chemical Reactions
 Oxidation
Interaction between fuel and oxidizer
 Self-Sustaining Reaction
Provides enough energy to continue reaction
 Exothermic Reaction
Gives off more energy than is consumed
 Smoke-Producing Process
Smoke is broad term for all products of combustion
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Fire Terminology
 Heat Release Rate (HRR) - The amount of heat energy released by
combustion expressed in Btu/sec or kilowatts (kW). The HRR of a
combustible is related to its chemical makeup, physical form and the
quantity of oxidant present.
 Ignition temperature - The minimum temperature to which a
substance must be heated in air to ignite independently of the
heating source. This temperature is sometimes referred to as the
auto-ignition temperature. This temperature is derived from specific
laboratory testing of pure substances and serves to classify the
hazard presented by the ignitable liquid. The actual ignition
temperature of most substances may be somewhat higher than
those reported in laboratory tests.
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Fire Terminology
 Oxygen - A nonflammable (oxidizing), gaseous element that is
colorless, tasteless and odorless. It is found in a free state in the
atmosphere where it makes up 21% of atmospheric air. Oxygen
combines with virtually all the other elements except the inert gases.
Periodic Table symbol: O.
 Oxidation - Oxidation is generally considered any reaction in which
electrons are transferred. The substance that gains electrons in the
reaction is considered the oxidizing agent and the substance that
loses electrons is the reducing material. Oxidation and reduction
always occur simultaneously. Compounds containing oxygen,
chlorine, fluorine, etc. are common oxidizing agents. Compounds
such as potassium nitrate, potassium perchlorate, and calcium
hypochlorite are examples of oxidizers commonly encountered in
explosive and incendiary compositions.
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Fire Terminology
 Gas Chromatography - Flame Ionization Detector (GC - FID) - A
laboratory test method which vaporizes mixtures by heating and then
separates the individual components according to their boiling points
and molecular weights. For each component present in a sample, the
detector produces a signal proportional to the quantity of that
component. The resulting visual graph is called a chromatogram.
 Pyrolysis - Transformation of a compound into one or more
substances by heat alone. This process often precedes combustion.
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Characteristics and Behavior
of Fire
 Heat and Temperature are not the same…
 Heat- measure of the quantity of energy
contained by a material
 Temperature- indication of the level of
energy
Heat and Temperature Units
Temperature Units:
 Celsius
 Fahrenheit
 Kelvin
 Rankine
Heat Units:
• Joule
• Watt = 1 joule/sec.
(kilowatt kW = 1000 watts)
• Calorie
• British Thermal
Unit (BTU)
Heat Transfer
 Conduction
Through or within a material as result of
physical contact
 Convection
Due to movement of a fluid
 Radiation
By electromagnetic waves
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Conduction
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Convection
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Radiation
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Sources of Ignition
 Four types
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Chemical
Electrical
Mechanical
Nuclear
Explosions
 Detonations- propagate at the speed of sound
producing a shock wave
 Deflagrations- propagate at less than the speed of
sound
 Types of Explosions
 Chemical
 Mechanical
 Atomic
 Thermal
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Products of Combustion
 Fire Gases
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Carbon Monoxide (CO)
Carbon Dioxide (CO2)
Hydrogen Cyanide (HCN)
Hydrogen Chloride (HCl)
 Flame
 Heat
Flammability Properties of Fuels
 Gas phase fuels
 Liquid fuels
 Solid fuels
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Classification Based on Fuel Type
 Class A- ordinary combustibles- wood, paper, cloth,
rubber, etc.
 Class B- flammable and combustible liquidsgasoline, diesel fuel, solvents, lacquers, etc.
 Class C- energized electrical equipment- operating
saws, drills, transformers, etc.
 Class D- combustible metals- magnesium, titanium,
zirconium, sodium, lithium, potassium
 Class K – fire in cooking appliances that involve
cooking media
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Types of Fires
 Diffusion flame
 Candles, most natural fires
 Premixed flame
 gas furnace
 Smoldering fire
 Glowing embers
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Stages of Fire
Growth and Spread
 Preignition
 Ignition
(incipient)
 Growth (free
burning)
 Fully developed
 Decay (burnout)
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Incipient- ignition stage
 Instantaneous to
several hours
 Typically controlled
by fuel and heat source
 Still small enough
for fire extinguisher
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Growth
 Additional fuel ignites
 Series of ignitions
 How quickly flame
can heat additional
fuel-only limit
 Conditions become
life threatening
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Fire Growth-
2
t
curves
 Standard Time-Temperature Curves- t2 fires-
Fire Growth
Four Standard t2 Fires
1000
800
Heat Release
Rate (kW)
600
slow
400
medium
fast
200
ultra-fast
0
0
100
200
300
time (s)
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500
600
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Preflashover, flashover, post flashover, backdraft
 Preflashover
 Flashover
 Postflashover
 Backdraft
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Preflashover, flashover, post flashover,
backdraft
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Fire and Explosion Control
 Removal of heat
Examples
 Use of water
 Removal of fuel
 Turn off gas, remove
 Removal of oxygen
 Inhibit chemical chain
reaction
brush, trees, etc.
 Put lid on flame, use
CO2
 Use clean agents, dry
chemicals
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Effects of Fire
Products of Combustion:
 Products of complete combustion vs. products of
incomplete combustion
 Other products of combustion: soot or tar
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Conditions That Threaten Life Safety
 Thermal injury
 Toxicity
 Asphyxiation
 Obscuration
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Summary
 Explained basic fire chemistry
 Explained the differences between the fire triangle and







the fire tetrahedron
Described the effects of oxygen, fuel and heat on fire
Understood the many terms in fire behavior
Described the three methods of heat transfer
Understood ignition methods and sources
Explained the stages of fire and the products of
combustion
Illustrated classifications of fire
Explained the ways to control, limit and suppress fires
and explosions
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Association
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Review Questions
1.
2.
3.
4.
5.
6.
What three things are required for a fire?
What two elements provide the components for the
chemical reaction to occur?
How must the fuel and oxidizer be mixed?
When does piloted ignition occur?
What are the three methods of heat transfer?
List the five classifications of fire based on the type of
fuel burning.
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Answer Key to Review Questions
1.
2.
3.
4.
5.
6.
Fuel, oxygen, and heat
The fuel and the oxidizer
They must be intimately mixed.
Ignition that occurs in the presence of intense heat
source such as an arc, spark, or flame.
Conduction, convection, and radiation
The most common classification system depends on
type of fuel burning and gives a general indication of
the hazards involved. This system uses letters to
designate the fuel type: A, B, C, D, and K.
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Additional References
 NFPA’s Building Fire Safety Systems video
 NFPA’s Fire: Concepts and Behavior video
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