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Lt. Study Material > Essentials Ch 5 > Flashcards

Essentials Ch 5 Flashcards

1
Q

Combustion:

A

A chemical process of oxidation that occurs at a rate fast enough to produce he and and usually light (glow or flame)
NFPA 921
Pg 208

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2
Q

Fire

A

Rapid oxidation process, which is a chemical reaction resulting in the evolution of light and heat
NFPA 921
Pg 208

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3
Q

Oxidizer:

A

Any material that readily yields oxygen or other oxidizing gas, or that readily reacts to promot or initiate combustion of combustible materials
NFPA 400
Pg 208

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4
Q

Heat:

A

From of energy characterized by vibration of molecules and capable of initiating and supporting chemical changes and changes of state.
Pg 208

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5
Q

All fires involve a _________ chemical reaction between some type of ___ and an _______, most commonly oxygen in the air.

A

Heat-producing, fuel, oxidizer

Pg 208

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6
Q

Physical science is the study of _____ and _____ and includes chemistry and physics.

A

Matter / energy

Pg 208

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7
Q

Matter:

A

Anything that occupies space and mass.

Pg 208

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8
Q

Chemical reaction is when a substance:

A

Changes from one type of matter onto another, uch as two or more substances combining to from compounds.

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9
Q

Energy is the _____ to ____ work.

A

Capacity / perform

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10
Q

The forms of energy are classified as either ____ or _____

A

Potential - store energy possessed by an object that can be released
Kinetic - the energy possessed by a body because of its motion
Pg 209

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11
Q

What are some types of energy?

A 
Chemical
Thermal
Mechanical
Electrical
Light
Nuclear
Sound
Pg 209
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12
Q

In terms of fire behavior, the potential chemical energy of a fuel is converted to:

A

Thermal energy and released as heat

Pg 209

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13
Q

How many joules are required to raise the temp of one gram of water one degree Celsius?

A

4.2 joules

Pg 210

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14
Q

The British thermal unit refers to the amount of heat required to raise the temperature of ____ of water ____.

A

1 pound of water 1 degree F; 1055 Joules = 1 Btu

Pg 209

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15
Q

Reactions the ‘emit’ energy are:

A

Exothermic reactions

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16
Q

Reactions that absorb energy:

A

Are endothermic reactions (converting water from liquid to steam)

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17
Q

Pyrolysis:

A

The chemical decomposition of a solid material by heating (often preceding combustion)
Pg 210

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18
Q

Ignition

A

The process of initiating self contained combustion

Pg 210

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19
Q

There are two forms of ignition:

A

Piloted Ignition: moment when a mixture of fuel and oxygen encounters an external heat (ignition) source with sufficient heat or thermal energy to start combustion process

Auto ignition- initiation of combustion by heat but without a spark or flame
Pg 212

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20
Q

Fire models:

A

Fire Triangle - Oxygen, heat, fuel
Fire Tetrahedron - oxidizing agent, heat, Reducing agent (fuel) and chemical reaction
Pg 212

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21
Q

Materials that absorb heat but do not participate actively in the combustion process are:

A

Passive agents (i.e. Gypsum board and green vegetation)

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22
Q

Smoke is an aerosol comprised of:

A

Gases, vapor, and solid particulates

Pg 215

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23
Q

Smoke is the product of:

A

Incomplete combustion

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24
Q

The most common product of incomplete combustion:

A

CO - toxic and flammable product, acts as a chemical asphyxiant binding with hemoglobin in the blood

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25
Q

Hydrogen Cyanide (HCN)

A

Colorless, toxic of products containing nitrogen, chemical asphyxiant

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26
Q

CO2 is a product of complete combustion of ________ materials. Displaces _______ and acts as a ________ _______.

A

Organic, oxygen, respiratory stimulant.

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27
Q

Common products of Combustion:

A

CO
Formaldehyde (colorless, pungent odor irritating to the nose)
Hydrogen Cyanide (colorless, asphyxiant)
Nitrogen Dioxide (Reddish-brown gas)
Particulates
Sulfur Dioxide (colorless gas with a choking ordor

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28
Q

Smoke that is thick, black and pressure can emit from a structure at a high rate. This is indicative of a potentially:

A

Under-ventilated structure or a ventilation-controlled fire.

Pg 207

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29
Q

T / F Flame is a product of combustion?

A

True

Pg 216

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30
Q

Thermal Energy

A

The kinetic energy associated with the random mentions of the molecules of a material or object; often interchangeably with the terms heat and heat energy (measured in joules or Btu)
Pg 216

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31
Q

______ is the _______ element of both the fire triangle and the fire tetrahedron. Heat is kinetic energy transferred from a __________ substance to a _________ substance.

A

Heat / kinetic / high-temperature / low-temperature

Pg 216

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32
Q

Temperature systems Fahrenheit and Celsius

A 
Conversion - C =F-32/1.8
F = C X 1.8 + 32
Boiling point - 100ºC or 212 ºF
Room Temperature 20ºC or 68 ºF
Freezing point 0ºC or 32ºF. All these for water
Pg 217
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33
Q

Measure of heat?

Measurement of the ________ ______ in the particles of a sample _______ is specifically heat.

A

Temperature / average kinetic energy / matter

Pg 217

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34
Q

Sources of thermal energy:

A

Chemical, mechanical, electrical, light, nuclear and sound

Pg 217

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35
Q

What are the common sources of heat that result in the ignition of a fuel?

A

Chemical, electrical and mechanical

Pg 217

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36
Q

What is the Most common source if heat in combustion reactions?

A

Chemical energy…the oxidation process almost always result in the production of thermal energy
Pg 217

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37
Q

What is a form of oxidation where a chemical reaction that increases the temperature of a material without the addition of external heat called?

A

Self-heating

Pg 217

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38
Q

What is it called when the material is heated to its autoignition temperature?

A

Spontaneous ignition
Common materials to spontaneous ignite: charcoal, linseed oil-soaked rags and straw/manure
Pg 218

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39
Q

List ways electrical energy can generate temperatures high enough to ignite any combustible material:

A

Resistance heating (incandescent lamps, ranges, ovens portable heaters)
Overcurren/overload (current flowing that exceeds limits)
Arcing (when a conductor is separated, high voltage, static electricity, lightning
Sparking (the spatter of a luminous electric discharge)
Pg 219

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40
Q

Mechanical energy is generated by ______ or _______.

A

Friction or compression (compression is generated when a gas is compressed - Diesel engine, SCBA cylinders recently filled will be warm as air is compressed)
Pg 219

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41
Q

The _____ of ____ from one point or object to another is basic to the study of _____ _____.

A

Transfer of heat / fire behavior

Pg 219

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42
Q

T / F Heat is transferred from warmer objects to cooler objects.

A

True

Pg 219

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43
Q

T / F Objects at the same temperature cannot transfer heat.

A

True

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44
Q

For any given substance, the ______ the temperature differences between the bodies, the _______ the transfer rate.

A

Greater/greater

Pg 219

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45
Q

Transfer of thermal energy is described as ____ _____ (energy transfer over time per unit of surface area) and is typically measured in kilowatts per meter squared. Three mechanisms of heat transfer is:

A

Heat flux / conduction, convention and radiation.

Pg 219

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46
Q

Heat transfers between solid objects is called:

A

Conduction

Pg 220

47
Q

Heat transfer due to conduction is dependent upon three factors:

A

Area being heated
Temp difference between the heat source and material being heated
Thermal conductivity of the heated material
Pg 220

48
Q

Heat transfer of thermal energy by the circulation or movement of a fluid, liquid or gas is called:

A

Convention

Pg 221

49
Q

When convection occurs the movement generally will be _______ because smoke and fire gases are heated and _______.

A

Upward / buoyant

Pg 221

50
Q

What makes convection currents move laterally?

A

The result of differences in pressure; moving from high pressure areas to low pressure areas
Pg 221

51
Q

Heat transfer by way of electromagnetic energy is:

A

Radiation (light waves, radio waves X-rays without an intervening medium)
Pg 222

52
Q

Some factors influence radian heat transfer such as:

A

Nature of the exposed surfaces (dark absorb greater heat, smooth surfaces reflect more heat)
Distance between the heat source and exposed surfaces
Temperature difference between the heat source and exposed surfaces - as the heat increases the radiant energy increases by a factor of FOUR.
Pg 223

53
Q

The fuel that is being oxidized or burning during combustion is known as:

A

The reducing agent.

Pg 223

54
Q

Heat of Combustion

Heat Release Rate

A

Heat of Combustion - total amount of thermal energy (heat) that could be generated by the combustion (oxidation) reaction if a fuel were completely burned (measured in Btus)

Heat Release Rate (HRR) - total amount of heat released per unit time (measured in kilowatts kW and megawatts of output)
Pg 223

55
Q

In terms of fire behavior, ______ is described as the HRR during _______.

A

Power / combustion

Pg 224

56
Q

For flaming combustion to occur:

A

Fuels must be in the gaseous state

Pg 225

57
Q

What gaseous fuels can be the most dangerous of all fuel types and why?

A

Methane, hydrogen, and acetylene
They are already in the physical state required for ignition
Pg 225

58
Q

The density of gases on relation to air is:

A

Vapor density; vapor density less than 1 is lighter than air, greater than 1 is heavier than air
Pg 226

59
Q

T / F Gases that expand are more dense when heated.

A

False - expand are less dense when heated, when cooled they contract and become more dense.
Pg 226

60
Q

Density of liquids compared with the density of water is:

A

Specific Gravity - mass or weight of a substance compared to the mass of an equal volume of water at a given temp. Water has a specific gravity of 1. (Gasoline is lighter and floats)
Pg 226

61
Q

Flash point less 100 ºF and a vapor pressure not exceeding 40 psi is:

A

Flammable Liquids

Pg 226

62
Q

When a liquid reaches the pressure to evaporate is called the liquid’s:

A

Vapor pressure - high vapor pressure presents a special hazard to FFs.
Pg 226

63
Q

Minimum temp at which a liquid gives off enough vapors to form an ignitable mixture with air near the liquid’s surface.

A

Flash point - liquid gives off enough to vapors to ignit, but not sustain combustion
Pg 227

64
Q

Them at which a liquid fuel produces sufficient vapors to support and sustain the combustion reaction.

A

Fire point - usually a few degrees above flash point

Pg 227

65
Q

Solubility describes the extent a substance with mix with _______. Materials that are _______ in water will mix in any proportion. Liquids such as _______ _____ are lighter than water and do not mix with water. ______ ______ will mix readily with water.

A

Water / miscible / Hydrocarbon fuels (gasoline, diesel and oils) / Polar Solvents (alcohols, methanol, ethanol)
Pg 227

66
Q

Do liquids that are less dense than water extinguish well with water?

A

No, should be extinguished using foam or chemical agent.

Pg 227

67
Q

Liquids having a flash point at or above 100 ºF and below 200 ºF is a

A

Combustible Liquid

Pg 228

68
Q

Pyrolysis occurs faster in wood products or plastics and why?

A

Plastics due to not having moisture content

Pg 228

69
Q

Will a solid substance ignite easier with a low or high surface to mass ratio?

A

The higher the surface to mass ratio, the higher the ability to ignite will occur. (Log-low ratio vs saw dust- high ratio)
Pg 229

70
Q

At normal temp (68 ºF) materials can ignite and burn at O2 concentrations as low as _____.

A

14% (normal air O2 concentration is 21%)

Pg 231

71
Q

At what concentration of oxygen is considered enriched?

A

23.5 percent where 19.5 percent is being oxygen deficient

Pg 231

72
Q

Common oxidizers:

A

Calcium Hypochlorite - granular solid (chlorine for swimming pools)
Chlorine - gas (water purification)
Ammonium Nitrate - granular solid (fertilizer)
Hydrogen Peroxide -liquid (industrial bleaching, pulp and paper)
Methyl Ehtyl Ketone Peroxide (catalyst in plastics manufacturing)
Pg 231

73
Q

What gaseous fuels can be the most dangerous of all fuel types and why?

A

Methane, hydrogen, and acetylene
They are already in the physical state required for ignition
Pg 225

74
Q

The density of gases on relation to air is:

A

Vapor density; vapor density less than 1 is lighter than air, greater than 1 is heavier than air
Pg 226

75
Q

T / F Gases that expand are more dense when heated.

A

False - expand are less dense when heated, when cooled they contract and become more dense.
Pg 226

76
Q

Density of liquids compared with the density of water is:

A

Specific Gravity - mass or weight of a substance compared to the mass of an equal volume of water at a given temp. Water has a specific gravity of 1. (Gasoline is lighter and floats)
Pg 226

77
Q

Flash point less 100 ºF and a vapor pressure not exceeding 40 psi is:

A

Flammable Liquids

Pg 226

78
Q

When a liquid reaches the pressure to evaporate is called the liquid’s:

A

Vapor pressure - high vapor pressure presents a special hazard to FFs.
Pg 226

79
Q

Minimum temp at which a liquid gives off enough vapors to form an ignitable mixture with air near the liquid’s surface.

A

Flash point - liquid gives off enough to vapors to ignit, but not sustain combustion
Pg 227

80
Q

Them at which a liquid fuel produces sufficient vapors to support and sustain the combustion reaction.

A

Fire point - usually a few degrees above flash point

Pg 227

81
Q

Solubility describes the extent a substance with mix with _______. Materials that are _______ in water will mix in any proportion. Liquids such as _______ _____ are lighter than water and do not mix with water. ______ ______ will mix readily with water.

A

Water / miscible / Hydrocarbon fuels (gasoline, diesel and oils) / Polar Solvents (alcohols, methanol, ethanol)
Pg 227

82
Q

Do liquids that are less dense than water extinguish well with water?

A

No, should be extinguished using foam or chemical agent.

Pg 227

83
Q

Liquids having a flash point at or above 100 ºF and below 200 ºF is a

A

Combustible Liquid

Pg 228

84
Q

Pyrolysis occurs faster in wood products or plastics and why?

A

Plastics due to not having moisture content

Pg 228

85
Q

Will a solid substance ignite easier with a low or high surface to mass ratio?

A

The higher the surface to mass ratio, the higher the ability to ignite will occur. (Log-low ratio vs saw dust- high ratio)
Pg 229

86
Q

At normal temp (68 ºF) materials can ignite and burn at O2 concentrations as low as _____.

A

14% (normal air O2 concentration is 21%)

Pg 231

87
Q

At what concentration of oxygen is considered enriched?

A

23.5 percent where 19.5 percent is being oxygen deficient

Pg 231

88
Q

Common oxidizers:

A

Calcium Hypochlorite - granular solid (chlorine for swimming pools)
Chlorine - gas (water purification)
Ammonium Nitrate - granular solid (fertilizer)
Hydrogen Peroxide -liquid (industrial bleaching, pulp and paper)
Methyl Ehtyl Ketone Peroxide (catalyst in plastics manufacturing)
Pg 231

89
Q

The range between the upper and lower flammable limit in which a substance can be ignited -

A

Flammable (explosive) range

Pg 232

90
Q

The range in which the gas or vapor is too rich to burn -

A

Upper flammable limit (UFL)

Pg 232

91
Q

The range where the the flammable gas or vapor is below the this limit is considered: (too lean)

A

Lower flammable limit (LFL)

92
Q

What are electrically charged and highly reactive parts of molecules?

A

Free Radicals and are highly reactive

Pg 233

93
Q

Stages of fire development:

A 
Incipient
Growth
Fully developed
Decay
Pg 234
94
Q

At a fire scene, the stages of fire development are a guid for what ______ occurs during the fire but are not a pattern of _____ occur every time.

A

Could / will

Pg 234

95
Q

In a compartment fire, what is one of the most fundamental Class A fuel characteristics influencing fire development?

A

Surface to mass ratio

Pg 235

96
Q

How can ventilation be influenced in a compartment?

A

Size, number denotes locations of openings as well as the velocity of the air being exchanged (ventilation occurs naturally during fire conditions - this is not to be confused with tactical ventilation)
Pg 238

97
Q

List the differences between fuel-controlled vs ventilation-controlled fires

A

Fuel-controlled is sufficient oxygen is available and the fuel controls the fire development
Ventilation-controlled is when the available air supply begins to limit fire development and the available air supply will determine the speed of fire development.
Pg 239

98
Q

High humidity and cold temperatures will slow or speed up the natural movement of smoke?

A

Slow

Pg 240

99
Q

Ceiling jet is referring also to:

A

Mushroom effect - collection of hot gasses at the ceiling spreading laterally
Pg 242

100
Q

Heat stratification and thermal balance refers to:

A

Thermal Layering - tendency of gases to form into layers according to temperature
Pg 244

101
Q

What is the level of an opening where hot gases and cooler air is exchanging called?

A

Neutral Plane - hot gases are leaving the topside and cooler air is incoming below - the pressure is neutral (hot gases higher than cooler air lower)
Pg 244

102
Q

When all the combustibles in a compartment are burning; the fire is considered in what stage?

A

Fully developed

Pg 246

103
Q

What terms are used for rapid fire development?

A

Flashover
Backdraft
Smoke explosion
Pg 247

104
Q

When conditions turn from two layer environment (hot on top and cooler on bottom) to a single layer environment (hot top to bottom), this is considered what type of conditions for rapid fire development?

A

Flash over conditions

Pg 247

105
Q

Four common elements of flashover:

A

Transition in fire development- growth to fully developed
Rapidity - flashover happens rapidly to spread complete fire involvement within the compartment
Compartment - must be an enclosed space such as single room
Ignition of ALL exposed surfaces - all combustible surfaces in an enclosed space become ignited
Pg 247

106
Q

Two interrelated factors determine whether a fire within a compartment will progress to flashover:

A

Sufficient fuel and heat release rate sufficient to support flashover
Ventilation - fire must have enough oxygen to support flashover (sealed room may not)
Go 248

107
Q

Usually the temperature which flashover occurs is:

A

1110 ºF

Pg 248

108
Q

One possible indicator for flashover is the condition of unburned gases on the upper layers produce flames

A

Also called as rollover

Pg 248

109
Q

What stage will a backdraft explosion occur?

A

Decay stage when it may be vent-controlled.

110
Q

Turbulent smoke with high velocity or with pulsing air movement are smoke indicators of what:

A

Flashover

111
Q

Dense smoke, light colored or black becoming dense gray-yellow are indicators of:

A

Backdraft

Pg 249

112
Q

How can firefighters influence fire behavior?

A 
Temperature reduction
Fuel removal
Oxygen exclusion
Chemical flame inhibition
Ventilation and fire behavior
Pg 250
113
Q

What are the effects of water on fire?

A

Absorbs significant heat, but it’s greatest effect is when water is vaporized into steam. When water reaches 212ºF, it expands 1700 times
Pg 251

114
Q

Control steam production by:

A

Use good nozzle technique
Apply the appropriate amount of water
Apply water using the most effective form of stream
Pg 251

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