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