LESSON 4
Fire Behavior
OVERVIEW
Fire has played a major role in the development of society. Fire has been a friend as
well as an enemy. Burning is also known as combustion, which is a simple chemical
reaction. The American Heritage Dictionary defines burning as a rapid, persistent
chemical change that releases heat and light and is accompanied by flame, especially
the exothermic oxidation of a combustible substance. It is important to understand
the behavior of fire and what causes it to begin, grow, and spread.
LEARNING OBJECTIVES
After completing this lesson, the student should be able to:
4-1 Describe the properties of solid, liquid, and gas fuels associated with
structural fires.
4-2 Define combustion.
4-3 Name the parts of the fire tetrahedron.
4-4 Describe the methods for extinguishing a fire.
4-5 Describe hazardous conditions found on an emergency scene.
4-6 Name the parts of the fire tetrahedron. Explain how the effects of fire can
create a hazardous condition in a structure.
4-7 Explain the health and safety effects of prolonged exposure to the products of
combustion.
4-8 Explain the four sources of heat.
4-9 Identify the classes of fire (A, B, C, D, and K).
4-10 Explain the five classes of fire and the risks associated with each class.
4-11 Explain the effects of temperature on a fuel source.
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LESSON 4: FIRE BEHAVIOR
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4-12
4-13
4-14
4-15
4-16
4-17
4-18
4-19
4-20
4-21
Describe the effects of oxygen on fire.
List the three modes of heat transfer.
List the four phases of fires.
Discuss the chemistry and physics of fire through the stages of a fire in a
structure.
Describe the principles of thermal layering in a structure fire.
Identify products of combustion.
Describe the characteristics of each class of fire.
Describe the conditions leading to a boiling liquid expanding vapor explosion.
Describe hostile fire events including flashover and backdraft, and the
methods for preventing them from occurring.
Discuss the observations in reading smoke and the warning signs of hostile
fire events.
Note: The FF I and II levels, as defined by the NFPA 1001 Standards, are
identified in different colors:
FF I = black, FF II = red, additional information = blue.
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LESSON 4: FIRE BEHAVIOR
INSTRUCTIONAL DEVELOPMENT
Please take a moment to review the time frames, equipment needed, required
reading, and recommended reading (if listed).
TIME FRAME:
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Cognitive learning: 6 hours
Psychomotor learning: Not Applicable
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Instructional outline
Required references
Recommended references (if applicable)
PowerPoint presentation
Equipment required to run PowerPoint presentation
PowerPoint presenter
Chalkboard/whiteboard, or easel pad
Chalk or markers
EQUIPMENT:
REQUIRED REFERENCES:
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Read Chapter 4 in the Firefighter’s Handbook: Firefighting and Emergency
Response or the Firefighter’s Handbook: Essentials of Firefighting
RECOMMENDED REFERENCES:

NFPA 1001, Standard for Firefighter Professional Qualifications, National
Fire Protection Association, Quincy, MA, 2008
LESSON 4: FIRE BEHAVIOR
4
INSTRUCTIONAL OUTLINE
Slide 4.2
Slides 4.3–4.5
Slides 4.6–4.9
Slides 4.10–4.11
I.
INTRODUCTION (Estimated Time: 15 minutes)
Firefighter’s Handbook: Firefighting and Emergency Response, Pages 86–87
Firefighter’s Handbook: Essentials of Firefighting, Pages 86–87
A.
Since ancient times, fire has been one of the most important lifesustaining components
B.
Fire has played a major role as a tool in the development of society
C.
Sometimes an ally, sometimes an enemy
D.
Much has been learned about fire in the last thirty years
II.
FIRE DEFINED (Estimated Time: 20 minutes)
Firefighter’s Handbook: Firefighting and Emergency Response, Pages 87–96
Firefighter’s Handbook: Essentials of Firefighting, Pages 87–96
Objective: 4-1 Describe the properties of solid, liquid, and gas fuels associated with
structural fires.
Objective: 4-2 Define combustion.
Objective: 4-3 Name the parts of the fire tetrahedron.
Objective: 4-4 Describe the methods for extinguishing a fire.
Objective: 4-8 Explain the four sources of heat.
Objective: 4-9 Identify the classes of fire (A, B, C, D, and K).
Objective: 4-10 Explain the five classes of fire and the risks associated with each
class.
Objective: 4-11 Explain the effects of temperature on a fuel source.
Objective: 4-12 Describe the effects of oxygen on fire.
A.
Fire is burning
1.
Burning is combustion
2.
Combustion is a chemical reaction
B.
Deflagration is combustion at a rate below the speed of sound
C.
Detonation is combustion above the speed of sound
D.
Fire tetrahedron is the assembly of heat, fuel, oxygen, and a selfsustaining chemical reaction
E.
Heat
1.
For a fire to begin, fuels need to be heated
2.
Chemical heat: various chemicals react with each other
3.
Mechanical heat: friction of two materials rubbing against each
other
4.
Electricity most recognized source of heat
5.
Nuclear heat comes from unstable radioactive materials
F.
Fuel
1.
Material consumed by the combustion process
2.
Molecules in a solid are packed closely together
3.
Liquid’s ability to burn depends on substance’s ability to place
its molecules into suspension
4.
Gaseous fuels are in a state of suspension
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LESSON 4: FIRE BEHAVIOR
a)
Primed for combustion
Fuel must be at a certain temperature before combustion can
take place
Oxygen
1.
Acts as a catalyst for the combustion process
2.
Oxidation is the process of oxygen bonding to other elements
and compounds
3.
Oxidation affects the process of combustion
4.
Chemical reaction accelerated with an abundance of oxygen
Chemical chain reaction
1.
When heat, fuel, and oxygen combine to start combustion, a
chemical chain reaction forms
2.
Scientists discovered certain chemicals introduced into burning
process can stop flaming
3.
Foundation for understanding how fires begin is grounded in the
fire tetrahedron
5.
Slides 4.12–4.13
G.
Slide 4.14
H.
Slide 4.15
Slides 4.16–4.19
Slides 4.20–4.22
Slides 4.23–4.24
III. FIRE GROWTH (Estimated Time: 40 minutes)
Firefighter’s Handbook: Firefighting and Emergency Response, Pages 96–104
Firefighter’s Handbook: Essentials of Firefighting, Pages 96–104
Objective: 4-6 Explain how the effects of fire can create a hazardous condition in a
structure.
Objective: 4-7 Explain the health and safety effects of prolonged exposure to the
products of combustion.
Objective: 4-13 List the three modes of heat transfer.
Objective: 4-14 List the four phases of fires.
Objective: 4-15 Discuss the chemistry and physics of fire through the stages of a fire
in a structure.
Objective: 4-16 Describe the principles of thermal layering in a structure fire.
Objective: 4-17 Identify products of combustion.
A.
Once a fire begins, it will grow in a self-sustaining manner
B.
The heat being released will be transferred to other fuels
C.
The firefighter who understands fire growth can better predict fire
behavior
D.
Modes of heat transfer
1.
Heat is a by-product of combustion
2.
Conduction is the transfer of heat through a solid object
3.
Convection is the transfer of heat through air and liquid currents
4.
Radiation is the transfer of heat through invisible lightwaves
E.
Fire phases
1.
Burning occurs in clearly defined phases
2.
Ignition phase: substance begins to heat up, liberates gases that
can burn
3.
Growth phase: fire begins to grow from the point of ignition
4.
Fully developed phase: all contents within perimeter of fire's
boundaries are burning
5.
Decay stage: all fuel consumed and the fire diminishes in size
F.
Products of combustion
LESSON 4: FIRE BEHAVIOR
6
1.
2.
3.
4.
5.
Slide 4.25
Slides 4.26–4.27
Slide 4.28
Slide 4.29
Slide 4.30
IV.
Matter is neither lost nor gained; it changes form
By-products of burning process are heat, light, and smoke
Heat causes dehydration, heat exhaustion, and burns
Light can cause damage to eyesight
Smoke is the most dangerous product of combustion
SPECIFIC FIRE CHARACTERISTICS AND EVENTS (Estimated Time:
30 minutes)
Firefighter’s Handbook: Firefighting and Emergency Response, Pages 104–111
Firefighter’s Handbook: Essentials of Firefighting, Pages 104–111
Objective: 4-5 Describe hazardous conditions found on an emergency scene.
Objective: 4-18 Describe the characteristics of each class of fire.
Objective: 4-19 Describe the conditions leading to a boiling liquid expanding vapor
explosion.
Objective: 4-20 Describe hostile fire events including flashover and backdraft, and
the methods for preventing them from occurring.
Objective: 4-21 Discuss the observations of reading smoke and the warning signs of
hostile fire events.
A.
Liquid, electrical, and metal fires have certain characteristics
B.
Several unique fire events can occur within a compartment or structure
C.
Learning to “read smoke” can help predict fire behavior
D.
Liquid fires
1.
Liquid fuels must vaporize
2.
Vaporization is the process in which liquids are converted to
gas or vapor
3.
Most liquid fires do not mix well with water
a)
Typically extinguished by coating the liquid with an agent
such as foam
4.
Liquid heated to a high pressure in a closed vessel can explode
a)
BLEVE (boiling liquid expanding vapor explosion)
E.
Electrical fires
1.
Class C fire: electrical energy is creating heat
2.
Control of a Class C fire begins with control of electricity
3.
Fire control efforts are aimed toward Class A or B materials
4.
Use of water can present extreme shock hazards while fire is still
electrically energized
F.
Metal fires
1.
Class D metal fire is a chemical reaction fire
2.
In some cases, the presence of water will cause a violent reaction
3.
Control of Class D fires can be quite difficult or amazingly
simple
4.
Shape, size, amount, and type of metal burning will dictate the
best extinguishment method
G.
Hostile fire events
1.
Any uncontrolled fire in a building is a hostile fire event
2.
Hostile fire event: unique fire phenomenon
a)
Flashover
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LESSON 4: FIRE BEHAVIOR
Slides 4.31–4.34
Slide 4.35
H.
b)
Backdraft
c)
Rapid fire spread
Reading smoke at structural fires
1.
Firefighter applies understanding of basic fire behavior by
reading smoke
a)
Helps discover clues about the location of the fire
2.
Smoke volume is an indicator of the amount of fuels that are
“off-gassing”
3.
Smoke velocity is an indicator of pressure that has built up
within the building
4.
Smoke density is indicative of the amount of fuel that is laden
within the smoke
V.
LESSONS LEARNED (Estimated Time: 5 minutes)
Firefighter’s Handbook: Firefighting and Emergency Response, page 111
Firefighter’s Handbook: Essentials of Firefighting, page 111
A.
Firefighter survival and fire attack effectiveness is dependent on the
understanding of fire dynamics
1.
Ingredients needed for combustion
2.
Heat sources
3.
Fuels
4.
Fire phases
5.
Special considerations
6.
Reading smoke
LESSON 4: FIRE BEHAVIOR
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SUMMARY AND ASSIGNMENT
SUMMARY:
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Combustion results from the chemical reaction of heat, fuel, and oxygen.
With few exceptions, only organic materials will burn.
Heat sources can be chemical, mechanical, or nuclear.
The stages of the burning process are: ignition, growth, fully developed, and
decay.
Heat is transferred through conduction, convection, and radiation.
Fires are classified into different types and are extinguished differently.
ASSIGNMENT:
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Read Chapter 5 in the Firefighter’s Handbook: Firefighting and Emergency
Response or the Firefighter’s Handbook: Essentials of Firefighting
Optional: Complete Chapter 5 in the Firefighter’s Handbook Study Guide