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FIRE BEHAVIOR
FVCC Fire Rescue
OBJECTIVES2-2.1 Identify the following terms:
(3-3.10)2-2.1.1 Fire/combustion2-2.1.2 Heat2-2.1.3 Ignition temperature2-2.1.4 Flammable limits/flammable
range2-2.1.5 Vapor density2-2.1.6 Solubility
OBJECTIVES2-2.2 Identify the components of the
fire triangle and fire tetrahedron (3-3.10)2-2.3 Identify the relationship of the
concentration of oxygen to combustibility and life safety (3-3.1)
2-2.4 Identify four products of combustion commonly found in structural fires that create a life hazard. (3-3.1)
2-2.5 Identify the three methods of heat transfer (3-3.9, 3-3.11)
OBJECTIVES2-2.6 Identify the Law of Heat Flow2-2.7 Identify the three physical states of
matter in which fuels are commonly found. (3-3.9)
2-2.8 Identify the following conditions and explain their associated hazards and appropriate actions: (3-3.10)
OBJECTIVES2-2.8.1 Ignition/Incipient2-2.8.2 Growth/Freeburning2-2.8.3 Rollover/Flameover2-2.8.4 Flashover2-2.8.5 Fully developed2-2.8.6 Decay/Hot smoldering2-2.8.7 Backdraft
OBJECTIVES2-2.9 Identify the process of thermal
layering that occurs in structural fires. (3-3.11)
2-2.10 Identify how to avoid disturbing the normal layering of heat.
o IFSTA, Essentials, 4th ed, Chapter 2o Delmar, Firefighter’s Handbook, 2000, Chapter
4
FIRE TERMSFire/combustion
Fire: Self-sustaining process of rapid oxidation of a fuel which produces heat and light
Combustion: Self-sustaining chemical reaction yielding energy or products that cause further reactions
These terms are often used interchangeably; most often used in fire
FIRE TERMSHeat
The form of energy that raises temperatureThe energy transferred from one body to
another when the temperature of the bodies are different
Can be measured by the amount of work it does
Ignition temperature The minimum temperature to which a fuel, in
air, must be heated to start self-sustained combustion without a separate ignition source.
FIRE TERMSFlammable Limits/flammable range
Highest and lowest percentage of a flammable gas or vapor, in air, that will explode or ignite
Concentrations below the Lower Explosive (flammable) Limit are too “lean” to burn
Concentrations above the Upper Explosive (flammable) Limit are too “rich” to burn
Flammable (explosive) Range: The range between the Lower Explosive (flammable) Limit and the Upper Explosive (flammable) LimitThe word explosive and flammable are often used
interchangeably
FIRE TERMSVapor density:
Weight of a given volume of pure vapor or gas compared to the weight of an equal volume of dry air at the same temperature and pressure
Vapor density less than one indicates a vapor lighter than air
Vapor density greater than one indicates a vapor heavier than air
FIRE TERMSSolubility
Degree to which a solid, liquid, or gas dissolves in a solvent (usually water)
FIRE TRIANGLE & FIRE TETRAHEDRON
Fire triangle – heat, fuel, oxygenRepresentative of surface combustion
(smoldering fire)Fire tetrahedron
Chemical chain reaction is added to the fire triangle
Representative of the flaming mode of combustion
RELATIONSHIP OF OXYGEN TO LIFE SAFETY
Concentrations below twenty-one percent has some effect on life safetyAt nine percent, an individual becomes
unconsciousAt six percent, death will occur within a few
minutesIn concentrations below eighteen
percent, fire begins to decreaseGenerally concentrations below fifteen
percent will not support combustion
PRODUCTS OF COMBUSTIONHeat
Responsible for the spread of fireCause of burns and other injuries
SmokeMixture of carbon particles and fire gasesMakeup varies from fuel to fuel, all smoke is
considered toxicThe material burning has a direct influence
on the amount and color of smoke
PRODUCTS OF COMBUSTIONFire gases
Carbon monoxide (CO)Carbon Dioxide (CO2)Hydrogen CyanideSulfur DioxideNitrogenOther gases depending on fuel being burned
PRODUCTS OF COMBUSTIONFlame (light)
More complete the combustion, less luminous the flame
Flame absent in smoldering fire
HEAT TRANSFERConduction
Heat conducted from one body to another either by direct contact or by an intervening heat conducting medium
Depends on type of conductor: metal (good), drywall (poor)
Example: Metal plumbing components or electrical conduit
HEAT TRANSFERConvection
Transfer of heat energy by the movement of air or liquid
Heated gases rise: mushroomingExamples: Fire traveling through elevator
shafts, stairways, balloon frame wallsDirect flame contact is actually a form of
convection heat transfer
HEAT TRANSFERRadiation
Transfer by heat wavesTravels through space until it reaches an
opaque objectLight colors reflect radiant heat; dark colors
absorb radiant heatMajor source of fire spread to exposures
(important to protect exposures from radiant heat)
LAW OF HEAT FLOWHeat flows from a hot substance to a cold
substanceA colder substance will absorb heat until
temperatures are equal
3 PHYSICAL STATES OF MATTER
Solid fuelsHave a definite shape and size
Surface to mass ratioThe more surface areas exposed – the less energy is
required for ignitionPyrolysis
The chemical decomposition of a substance through the action of heat
The position of the fuel affects the way it burnsA solid fuel in a vertical position will allow fire spread
more rapidly than the same fuel in a horizontal position
3 PHYSICAL STATES OF MATTER
Liquid fuelsFuel gases are generated by a process called
vaporizationVaporization: The transformation of a liquid to its
vapor or gaseous stateEnergy input usually in the form of heatRequires less energy than said fuels
With liquids, the surface to volume ratio is important
3 PHYSICAL STATES OF MATTER
Gaseous fuelsCan be the most dangerous of all fuel types
because they are already in the natural state required for ignition
Must be mixed with air in the proper proportion to burn; i.e. flammable range
PHASES OF FIREIncipient/ignition 2-2.8.1
Occurs when the four elements of the fire tetrahedron come together and combustion begins
Can be caused by a spark or flameCan occur when a material reaches its ignition
temperature through self-heatingLimited to original materials ignitedSmall quantity of fire gases being generatedFlame temperature above 1000 degrees F. yet room
temperature is only slightly increasedEasiest to extinguish
PHASES OF FIREGrowth/freeburning 2-2.8.2
Fire plume begins to form above the burning fuel
Begins to draw air from the surrounding space into the plume
Hot gases rise, hit the ceiling and spread until they reach the walls
As fire grows, the overall temperature increases
PHASES OF FIRERollover/flameover 2-2.8.3
The ignition of combustible gases which have spread throughout the fire area
Differs from flashover in that only combustible gases are burning
One reason why firefighters stay low when entering a burning building
Controlled by extinguishing main body of fireFlame spread movement of flame away from
source of ignition
PHASES OF FIREFlashover
Transition between the growth stage and fully developed stage of a compartment fire
Occurs when flames flash over the entire surface of a room
Occurs as a result of all the materials in the room reaching their ignition temperatures
Involves all exposed combustible surfaces in the compartment
Temperatures range from 900 degrees F-1200 degrees F.
Survivability unlikely if caught in a flashover
PHASES OF FIREFully developed
All combustible materials in the compartment are involved
Releasing the maximum amount of heat and producing large amounts of fire gases
Hot unburned gases are flowing from the compartment and igniting when they enter a space with abundant air
PHASES OF FIREDecay/Hot smoldering fire 2-2.8.6
As fuel is consumed, the rate of heat decreases
Amount of fire diminishes and temperature begins to decline
Glowing embers can maintain moderately high temperatures
PHASES OF FIRE
Backdraft (smoke explosion) Explosion or rapid burning of heated gasesOccurs when oxygen is introduced into a smoldering
fireOften caused by improper ventilationWarning signs:
Pressurized smoke exiting small openingsDense gray-yellow smokeConfinement and excessive heatLittle or no visible flameSmoke leaving building in “puffs” (smoke puffing out and
then sucking back in)Smoke stained windowsMuffled sounds
PHASES OF FIREBackdraft cont.
Warning signsSudden rapid inward movement of air when an
opening is madeSituation can be made less dangerous by proper
ventilation. Open at highest point involved. Heated smoke and gases will be released, reducing the possibility of an explosion
THERMAL LAYERINGThe tendency of gases to form into layers
according to temperaturesSometimes referred to as heat stratification
or heat balanceHottest gases tend to be at the ceiling and
cooler gases towards the floorThermal layering is critical to firefighting
operations
HOW TO AVOID DISTURBING THE THERMAL LAYERING
Thermal layering can be disrupted if water is applied directly into the layer without proper ventilation
Results in higher temperatures at the floor level and decreased visibility.
Firefighters may suffer steam burns if thermal layering is disrupted
Match types and states of energy to their definitions. Write the correct letters on the blanks.
_____ 1. Energy developed when electrons flow through a
conductor _____ 2. Energy possessed by a moving object _____ 3. Energy released when atoms are split _____ 4. Visible radiation produced at the atomic level _____ 5. Energy an object possesses that can be released in the
futureA. Mechanical energy B. Fusion C. Potential energy
D. Light E. Electrical energy
Homework
Match heat and temperature terms to their definitions. Write the correct letters on the blanks.
_____ 6. The amount of heat required to raise the temperature of 1 pound of water 1 degree Fahrenheit
_____ 7. The amount of work done by a force of 1 newton through a distance of 1 meter
_____ 8. The relationship between the calorie and the joule _____ 9. The amount of heat required to raise the
temperature of 1 gram of water 1 degree Celsius _____ 10. The unit of temperature measurement in the
customary system A. Degrees Fahrenheit B. Mechanical equivalent of heat C. Joule D. British thermal unit E. Calorie
Homework
Distinguish among the three methods of heat transfer. Mark “A” for examples of conduction, “B” for examples of convection, and “C” for examples of radiation.
A = Conduction B = Convection C = Radiation _____ 11. A basement fire heats pipes enough to ignite
the wood inside walls several rooms away. _____ 12. Fire spreads from the first to the third floor up
a stairwell. _____ 13. The heat from a burning building ignites a
second building 20 feet away. _____ 14. Hot water heats a radiator. _____ 15. A firefighter testing hose on the ramp receives
a sunburn. _____ 16. The ventilation team opens the roof of a
burning building and smoke and flames issue from the opening.
Homework
Match properties of matter to their definitions. Write the correct letters on the blanks.
_____ 17. Mass, size, or volume _____ 18. How tightly the molecules of a solid substance are
packed together _____ 19. Solid, liquid, or gas _____ 20. The density of a gas in relation to air _____ 21. The ratio of the mass of a given volume of liquid to
the mass of an equal volume of watera. Density b. Specific gravity c. Physical property
d. Physical state e. Vapor density
Homework
Identify chemical reactions. Match the name of the described chemical reaction the letter provided.
___ 22. The formation of a chemical bond between oxygen and another element
___ 23. Alters the chemical makeup of a substance___ 24 . Does not alter the chemical makeup of a substance___ 25. Gives off energy as it occurs___ 26. Absorbs energy as it occurs
A. Physical change B. Chemical change C. Exothermic reaction
D. Endothermic reaction E. Oxidation
Match the name of the described types of oxidation the letter provided
___ 27. Rapid oxidation ___ 28. Slow oxidation___ 29. Instantaneous oxidation
a) Explosionb) Firec) Rust
Homework
HOMEWORKHOMEWORK
A.FuelB.Oxygen
C.Chemical ReactionD.Heat
30. ____
31. ____
32. ____
33. ____
Select facts about oxidizing agents. Write the appropriate letters on the blanks.
___ 34. Which of the following is not a likely characteristic of an oxygen-enriched atmosphere?
a. Materials burn more rapidly b. Ignition requires higher temperatures c. Some petroleum-based materials will autoignite d. Some materials will burn vigorously even though they do not
burn at normal oxygen levels___ 35. Which of the following fuels could burn in an oxygen-free
atmosphere? a. Methane b. Hydrocarbon liquid c. Alcohol d. Sodium
nitrate___ 36. Oxygen concentrations as low as ___ percent can support
combustion at room temperature. a. 21 b. 19 c. 18 d. 14___ 37. What percent oxygen does atmospheric air normally
contain? a. 17 b. 21 c. 28 d. 12
Homework
Identify a each false statement and mark with letter “B” and each true statement with the letter “A”.
___ 38. The shape and size of a fuel affects its ignitability.___ 39. As a fuel's surface-to-mass ratio decreases, its ignitability
increases.___ 40. When a solid fuel is in a vertical position, fire spread is
more rapid than when it is in a horizontal position.___ 41. Liquid fuels have physical properties that increase the difficulty of extinguishment and the hazard to personnel.___ 42. Volatility is the ease with which a liquid gives off vapor.___ 43. Flammable limits — how rich or how lean the fuel vapor
can be and still burn — are recorded in handbooks and are usually reported at ambient temperatures and
atmospheric pressures.
Homework
Identify stages of compartment fire development. Match the name of the stage described in the blank provided.
___ 44. The fire becomes fuel controlled, the amount of fire diminishes, and temperatures within the compartment begin to decline.
___ 45. The combustible materials in the compartment and the gases given off by pyrolysis ignite.
___ 46. Rising hot gases hit the ceiling and spread outward until they hit the compartment walls; the depth of the gas layer begins to increase and causes radiant heating of combustible materials.
___ 47. The four elements of the combustion tetrahedron come together; can be piloted or non-piloted.
___ 48. All combustible materials in the compartment are involved in fire, releasing the maximum amount of heat possible and producing large volumes of fire gases.
a. Ignition b. growth c. flashover d. fully developed e. decay
Homework
Select facts about the products of combustion. Write the appropriate letters on the blanks.
___ 49. Which of the following does not happen to a fuel when it burns during incomplete combustion?
A. It undergoes a chemical change B. It releases gases and liquidsC. The elements making up the fuel are destroyed D. Some of it is converted to energy___ 50. Which of the following products of combustion would not be
present in a smoldering fire? a. Fire gases b. Smoke c. Heat d. Flame___ 51. What happens to the flame as combustion becomes more
complete? a. It becomes cooler and less luminous b. It becomes cooler and more luminous c. It becomes hotter and less luminous d. It becomes hotter and more luminous___ 52. What is the most common of the hazardous substances
contained in smoke?a. Carbon monoxide b. Chlorine c. Hydrogen cyanide 4.
Carbon dioxide___ 53. What causes the most deaths in fires?a. Radiant heat b. Smoke c. Contact with heat conductive surfaces d. Direct flame contact
Homework
Select facts about fire extinguishment theory. (1 pt. each, 4/5)54. What type of extinguishment theory does flooding an area with
carbon dioxide illustrate?a. Fuel removal b. Chemical flame inhibition c. Oxygen dilution
d. Temperature reduction55. Which of the following illustrates extinguishment by fuel
removal?a. Flooding an area with an inert gas b. Establishing a negative
heat balancec. Blanketing with foam d. Allowing the fire to burn until all
fuel is consumed56. Which of the following is an example of an extinguishing agent
used to interrupt the chemical chain reaction and stop flaming?a. Carbon dioxide b. Halon c. Water d. Class A foam57. Which of the following fuels cannot be easily extinguished
through chemical flame inhibition?a. Low flash point liquids and flammable gases b. Solid flaming
fuelsc. High flash point liquids d. Solid
smoldering fuels58. Which of the following is a polar solvent?a. Alcohol b. Gasoline c. Petroleum jelly d. Motor oil
Homework
Match fire classes to their descriptions. Write the correct letters on the blanks.
_____ 59. Energized electrical equipment_____ 60. Ordinary combustibles_____ 61. Flammable and combustible
liquids and gases_____ 62. Combustible metalsA. Class AB. Class BC. Class CD. Class D
Homework
Match fire classes to their primary extinguishment methods. Write the correct numbers on the blanks.
_____ 63. The application of non-conducting extinguishing agents such as halon, dry chemicals, or carbon dioxide
_____ 64. Blanketing and smothering with fuel-specific extinguishing agents (usually dry powder agents)
_____ 65. Cooling or quenching with water or “wet water” foams
_____ 66. Smothering, blanketing, or oxygen exclusionwith various extinguishing agents
A. Class A B. Class B C. Class C D. Class D
Homework