Chap 1 Flashcards

Fire Dyamics

1
Q

__ __ describes the meeting point between fire science, materials science, fluid dynamics of gases, and heat transfer

A

Fire dynamics

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2
Q

All fires involve a heat producing chemical reaction between some type of __ and an __, most commonly __ in the air

A

Fuel
Oxidizer
Oxygen

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3
Q

Calcium hypochlorite, chlorine, ammonium nitrate, hydrogen peroxide, and methyl ethyl ketone peroxides are all..

A

Common oxidizers

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4
Q

A chemical process of oxidation that occurs at a rate fast enough to produce heat and usually light in the form of a glow or a flame

A

Combustion

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5
Q

A rapid oxidation process, which is a gas phase chemical reaction resulting in the evolution of light and heat

A

Fire

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6
Q

Form of energy associated with the motion of atoms or molecules in solids or liquids that is transferred from one body to another as a result of a temp difference between the bodies

A

Heat

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7
Q

Measure of a avg kinetic energy of the particles in a sample of matter, expressed in terms of units or degrees designated on a standard scale

A

Temperature

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8
Q

Physical science is the study of __ and __ and includes chemistry and physics

A

Matter
Energy

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9
Q

__ change occurs when a substance remains chemically the same but changes in size, shape, or appearance (water freezing (liquid to solid) and boiling (liquid to gas))

A

Physical

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10
Q

A __ __ occurs when a substance changes for one type of matter into another, such as two or more substances combining to form compounds

A

Chemical reaction

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11
Q

A material that will maintain combustion under specified environmental conditions

A

Fuel

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12
Q

Any material that readily yields oxygen or other oxidizing gas, or that readily reacts to promote or initiate combustion of combustible materials

A

Oxidizer

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13
Q

Anything that occupies space and has mass

A

Matter

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14
Q

Capacity to perform work; occurs when a force is applied to an object over a distance, or when a substance undergoes a chemical, biological, or physical transformation

A

Energy

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15
Q

Chemical process that occurs when a substance combines with an oxidizer

A

Oxidation

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16
Q

The rate at which fuel releases energy over time depends on many variables including:

A

Chemical composition
Arrangement
Density of fuel
Available oxygen for combustion

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17
Q

A fuels __ energy is the result of virbrations in molecules

A

Kinetic

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18
Q

Stored energy possessed buy and object that can be released in the future to perform work once released

A

Potential energy

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19
Q

Total amount of thermal energy (heat) that could be generated by the combustion (oxidation) reaction if a fuel were completely burned.

A

Heat of combustion

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20
Q

The heat of combustion is typically measured in..

A

Kj/g or MJ/kg

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21
Q

Energy possessed by a moving object because of its motion

A

Kinetic energy

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22
Q

Kinetic energy associated with the random motions of the molecules of a material or object; often used interchangeably with the terms heat and heat energy

A

Thermal energy

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23
Q

Types of energy:

A

Chemical
Thermal
Mechanical
Electrical
Light
Nuclear
Sound

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24
Q

Energy is measured in __ in the International System of Units (SI)

A

Joules (J)

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25
Q

The quantity of heat required to change the temp of 1 gram of water by 1 degree Celsius is..

A

4.2 joules

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26
Q

In the customary system, the unit of measurement for heat is the..

A

British thermal unit (Btu)

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27
Q

The amount of heat required to raise 1 pound of water 1 degree Fahrenheit is..

A

Btu

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28
Q

1055 J is equal to..

A

1 Btu

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29
Q

1 calorie is equal to..

A

4.19 J

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30
Q

Reactions that emit energy

A

Exothermic reactions

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31
Q

Reactions that absorb energy

A

Endothermic reactions

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32
Q

Unit of work or energy in the International System of Units (SI); the energy (or work) when a unit force (1 newton) moves a body through a unit distance (1 meter)

A

Joule ( J )

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33
Q

Chemical reaction between two or more materials that changes the materials and produces heat

A

Exothermic reaction

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34
Q

Chemical reaction in which a substance absorbs heat

A

Endothermic reaction

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35
Q

Chemical decomposition of a solid material by heating. Precedes combustion of a solid fuel

A

Pyrolysis

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36
Q

Physical process that changes a liquid into a gaseous state; the rate depends on the substance involved, heat, pressure, and exposed surface area

A

Vaporization

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37
Q

Moment when a mixture of fuel and oxygen encounters an external heat source with sufficient heat or thermal energy to start the combustion reaction

A

Piloted ignition

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38
Q

Initiation of combustion by heat but without spark or flame

A

Autoignition

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39
Q

The lowest temp at which a combustible material ignites in air without spark or flame

A

Auto ignition Temp (AIT)

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40
Q

The auto ignition temp of a substance is always __ than its piloted temp

A

Higher

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41
Q

Two modes of combustion

A

Flaming
Nonflaming

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42
Q

__ __ occurs more slowly and at a lower temp producing a smoldering glow in the materials surface

A

Nonflaming combustion

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43
Q

__ __ is commonly referred to as fire. Produces a visible flame above the materials surface

A

Flaming combustion

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44
Q

To draw in and transport solid particles or gases by the flow of a fluid

A

Entrain

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45
Q

Materials produced and released during burning

A

Products of combustion

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46
Q

Result of inefficient combustion of a fuel; the less efficient the combustion, the more products of combustion are produced rather than burned during the combustion process

A

Incomplete combustion

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47
Q

Fuels in which the energy of combustion derives principally from carbon

A

Carbon-based fuels

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48
Q

Petroleum based organic compound that contains only hydrogen and carbon; may also be used to describe those materials in a fuel load which were created using hydrocarbons such as plastics or synthetic fabrics

A

Hydrocarbon fuel

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49
Q

Heat and smoked are described as..

A

Products of combustion

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50
Q

Smoke is an aerosol comprised of gases, vapor, and..

A

Solid particulates

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51
Q

Smoke is a byproduct of..

A

Incomplete combustion

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52
Q

Examples of left over fuel from incomplete combustion..

A

Smoke and ash

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53
Q

Unburned fuel is smoke, and it has the potential to..

A

Burn

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54
Q

When the air supply is __, the level of incomplete combustion is __, which produces more smoke

A

Limited
Higher

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55
Q

__ is composed of a wide range of toxic and flammable gases and particulates

A

Smoke

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56
Q

Fatal condition caused by severe oxygen deficiency and an excess of carbon monoxide and/or other gases in the blood

A

Asphyxiation

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57
Q

Colorless, toxic, and flammable liquid until it reaches 79 degrees F. Above that it becomes a gas with a faint odor similar to bitter almonds

A

Hydrogen Cyanide (HCN)

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58
Q

Acts as a chemical asphyxiant. It’s molecules attach to hemoglobin, decreasing the bloods ability to carry oxygen

A

CO

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59
Q

CO combines with hemoglobin about __ times more effectively than oxygen

A

200

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60
Q

HCN is __ times more toxic than CO

A

35

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61
Q

HCN prevents the body from using __ at the cellular level

A

Oxygen

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62
Q

Colorless, odorless, heavier than air gas that neither supports combustion nor burns

A

CO2

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63
Q

Force per unit area exerted by a liquid or gas measured in psi or kPa

A

Pressure

64
Q

The tendency or capacity of a liquid or gas to remain afloat or rise

A

Buoyant

65
Q

Total amount of heat released per unit time. Typically measured in kW or MW

A

HRR

66
Q

The measure of the rate of heat transfer to or from a surface. Typically expressed in kW/m2

A

Heat flux

67
Q

Result of Exothermic reactions, occurring spontaneously in some materials under certain conditions, where heat is generated at a rate sufficient to raise the temp of the material

A

Self-Heating

68
Q

Initiation of combustion of a material by an internal chemical or biological reaction that has produced sufficient heat to ignite the material

A

Spontaneous ignition

69
Q

Gases always move from areas of __ pressure to __ pressure

A

Higher
Lower

70
Q

__ is the thermal kinetic energy needed to release the potential chemical energy in a fuel

A

Heat

71
Q

Temperature is the measurement of the avg __ __ in the particles of a sample of matter

A

Kinetic energy

72
Q

__ energy is the most common source of heat in combustion reactions

A

Chemical

73
Q

The oxidation process almost always results in the production of __ energy. The energy dissipates almost as quickly as it is generated.

A

Thermal

74
Q

Friction or compression generates __ energy

A

Mechanical

75
Q

__ is generated when a gas is compressed

A

Heat

76
Q

The transfer of heat from one point or object to another is part of the study of __

A

Thermodynamics

77
Q

Thermal equilibrium is where all areas of an object are a uniform..

A

Temperature

78
Q

The rate at which heat transfers is related to the temperature differential of the bodies and the __ __ of the materials involved

A

Thermal conductivity

79
Q

__ is the transfer of heat through and between solids

A

Conductivity

80
Q

Heat transfer due to conduction is dependent upon 3 factors:

A

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

81
Q

Insulating materials slow the __ of heat from one solid to another

A

Conduction

82
Q

__ is the transfer of thermal energy by the circulation or movement of a fluid (fluid or gas)

A

Convection

83
Q

The point at which 2 regions that are in thermal contact no longer transfer heat between them because they have reached the same temp

A

Thermal equilibrium

84
Q

The propensity of a material to conduct heat within its volume

A

Thermal conductivity

85
Q

Physical flow or transfer of heat energy from one body to another, through direct contact or an intervening medium, from the point where the heat is produced to another location, or from a region of high temp to a region of low temp

A

Conduction

86
Q

Transfer of heat by the movement of heated fluids or gases, usually in an upward direction

A

Convection

87
Q

Transmission or transfer of heat energy from one body to another body at a lower temp through intervening space by electromagnetic waves

A

Radiation

88
Q

Radiated heat energy travels in a straight line at the __ __ __

A

Speed of light

89
Q

Radiation is a common cause of..

A

Exposure fires

90
Q

A fire ignited in fuel packages or bldgs that are remote from the initial fuel package or bldg of origin

A

Exposure fire

91
Q

Fuel that is being oxidized or or burned during combustion

A

Reducing agent

92
Q

Amount of energy delivered over a given period of time. And the rate at which energy transfers.

A

Power

93
Q

The SI unit of power or rate of work equal to 1 joule per second (J/s)

A

Watt (W)

94
Q

A multiple of thousands

A

Kilo

95
Q

A multiple of millions

A

Mega

96
Q

__ describes the density of gases in relation to air.

A

Vapor density

97
Q

Air has a vapor density of..

A

1

98
Q

The vapor density of gas provides an indication of where a gas will __ at an incident

A

Collect

99
Q

__ __ is the ratio of the mass of a given volume of a liquid compared to the mass of an equal volume of water at the same temp.

A

Specific gravity

100
Q

Water is assigned a specific gravity of..

A

1

101
Q

The specific gravity of a liquid indicates whether the liquid will __ on the surface of water or __

A

Float
Sink

102
Q

__ __ is the min temp at which a liquid gives off sufficient vapors to ignite, but not sustain combustion, in the presence of a piloted ignition source

A

Flash point

103
Q

__ __ is the temp at which a piloted ignition of sufficient vapors will begin a sustained combustion reaction

A

Fire point

104
Q

Flammable liquids called polar solvents such as alcohols (methanol, ethanol) will readily..

A

Mix with water

105
Q

Materials that are __ in water will mix in any proportion

A

Miscible

106
Q

Pyrolysis of wood begins at temps below __

A

400*F

107
Q

The energy release in fire is directly proportional to the amount of __ available for combusiton

A

Oxygen

108
Q

At normal ambient temps (68*F), materials can ignite and burn in oxygen concentrations as low as __

A

15%

109
Q

Range between the upper and lower flammable limits in which a substance can ignite

A

Flammable (explosive) range

110
Q

As flaming combustion occurs, the molecules of a fuel gas and oxygen break apart to form..

A

Free radicals

111
Q

Electrically charged, highly reactive parts of molecules released during combustion

A

Free radicals

112
Q

Extinguishment of a fire by interruption of the chemical chain reaction. (Dry chemical, Halon, etc)

A

Chemical flame inhibition

113
Q

Compartment fire development depends on whether the fire is __ __ or __ __

A

Fuel limited
Vent limited

114
Q

All compartment fires begin in the incipient stage as __ __ fires

A

Fuel limited

115
Q

4 stages of fire development

A

Incipient
Growth
Fully developed
Decay

116
Q

Description of a fire burning in the open with no restrictions to its oxygen supply

A

Open burning (free burning)

117
Q

Transition from the incipient to the growth stage can occur in a matter of __ depending on the type and configuration of __

A

Seconds
Fuel

118
Q

Horizontal movement of a layer of hot gases and combustion by-products from the center point of the plume

A

Ceiling jet

119
Q

The drawing in and transporting of solid particles or gases by the flow of liquid

A

Entrainment

120
Q

A fire the enters vent limited decay __ __ indicate that the fire is in its final stage of development

A

Does not

121
Q

The __ of a fire in a compartment influences the entrainment of air into the fire

A

Location

122
Q

Area surrounding a heat source in which there is sufficient air available to feed a fire

A

Combustion zone

123
Q

__ __ is the tendency of gases to form into layers according to temp, gas density, and pressure

A

Thermal layering

124
Q

Changes in ventilation and flow path can significantly alter..

A

Thermal layering

125
Q

__ or __ flames may move through the hot gas layer

A

Isolated
Intermittent

126
Q

The appearance of isolated flames is sometimes an immediate indicator of ..

A

Flashover

127
Q

The interface between the hot gas layers and cooler layer of air is commonly referred to as the __ __ because the net pressure is zero, or __ where the layers meet

A

Neutral plane
Neutral

128
Q

Even if temps decrease, __ can continue where a large volume of flammable products of combustion can accumulate within the compartment. These gases are fuel that can ignite with new oxygen source.

A

Pyrolysis

129
Q

Warning: even coordinated tactical vent increases the combustion rate in __ __ fire

A

Vent limited

130
Q

Rapid transition from growth to fully developed stage

A

Flashover

131
Q

Rapid fire development has been responsible for numerous ff..

A

Deaths and injuries

132
Q

Instantaneous explosion or rapid burning of superheated gases that occurs when oxygen is introduced into an oxygen depleted confined space

A

Backdraft

133
Q

Flashover typically occurs during the fires __ stage

A

Growth

134
Q

As flashover occurs, the gas temps in the room reach __ or higher

A

1100*F

135
Q

4 common elements of flashover:

A

-Transition in fire development-growth to fully developed
-Rapidity-flashover happens rapidly, in a matter of seconds
-Compartment-must be an enclosed space
-Pyrolysis of all exposed surfaces

136
Q

The auto ignition temp of CO, the most abundant fuel gas created by most fires, is approx..

A

1100*F

137
Q

When a fire is in __ __ decay, the intro of new oxygen can trigger flashover quickly

A

Vent limited

138
Q

The available __ limits the peak heat release in a fuel limited, fully developed fire

A

Fuel

139
Q

Warning: additional ventilation will cause an already __ fire to grow

A

Ventilated

140
Q

It is not possible to make enough __ in a compartment to transition a fire from vent limited to fuel limited conditions

A

Openings

141
Q

__ __ occurs when a structural member fails-usually because of exposure to heat- and introduces a new source of oxygen to the fire

A

Unplanned ventilation

142
Q

Unplanned ventilation is often the result of:

A

Occupant action
Fire effects on bldg
Actions other than planned, systematic, and coordinated tactical ventilation

143
Q

Warning: wind speeds as low as __ mph can create wind driven fire conditions

A

10

144
Q

Caution: a __ __ can overpower the natural convective effect of a fire and drive the smoke and hot gases back into the bldg

A

Strong wind

145
Q

FF’s can influence fire dynamics in a number of ways:

A

Temp reduction
Fuel removal
Oxygen exclusion/flow path control
Chemical flame inhibition

146
Q

Form of gas ignition; the ignition of accumulated flammable products of combustion and air that are within their flammable range

A

Smoke explosion

147
Q

The total quantity of combustible contents of a bldg, space, or fire area, including finish and trim

A

Fuel load

148
Q

The orientation of fuels as well as their surface-to-mass ratio will also influence the __ and __ of fire spread

A

Rate
Intensity

149
Q

__ __ coverings may add carbon fuel (wooden siding) or petroleum fuels (vinyl siding) to the fuel load

A

Exterior wall

150
Q

Thermal properties of a bldg include:

A

Insulation
Heat reflectivity
Retention

151
Q

Unprotected engineered steel and wooden trusses can fail after __ to __ minutes of exposure to fire

A

5
10

152
Q

For steel trusses, __ is the critical temp of steel- the temp at which steel begins to weaken

A

1000*F

153
Q

Warning: entire pieces of decking may fall into the fire when __ __ fail. There may be no indications from the exterior that the trusses no longer support the roof decking.

A

Lightweight trusses

154
Q

The bowstring truss’ compressional forces within the top chord act to force the load bearing walls __ as well as __

A

Outward
Downward

155
Q

Web members in the bowstring truss transfer __ from the bottom chord and __ from the top chord onto load bearing walls

A

Tension
Compression