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Lieutenant 2022 > 1- Initial Response S&T- Fire Dynamics > Flashcards

1- Initial Response S&T- Fire Dynamics Flashcards

1
Q

All fires involve a heat-producing chemical reaction between some type of ___ and an ______, most commonly oxygen in the air.

A

Fuel ; Oxidizer

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2
Q

______ are not combustible but will support or enhance combustion.

A

Oxidizers

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3
Q

Energy is measured in joules (J). The quantity of heat required to change the temperature of 1 gram of water by 1 degree Celsius is ___ joules.

A

4.2

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4
Q

A _______ is the amount of heat required to raise the temperature of 1 pound of water by 1 degree Fahrenheit.

A

British Thermal Unit (Btu)

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5
Q

Reactions that emit energy as they occur are _____ reactions.

*Fire is a chemical one. It releases energy in the form of heat and sometimes light.

A

Exothermic

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6
Q

Reactions that absorb energy as they occur are _____ reactions.

*i.e. converting water from a liquid to a gas (steam) while extinguishing a fire

A

Endothermic

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7
Q

Fire Triangle = Fuel, Heat, Oxygen

Fire Tetrahedron = ?

A

Reducing Agent (fuel)
Heat
Oxidizing Agent
Chemical Chain Reaction

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8
Q

Fuels must be in a gaseous state to burn. In solids, off-gassing is a chemical change known as ______. In liquids, a physical change called _______.

A

solids = pyrolysis

liquids = vaporization

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9
Q

_____ _____ is the most common form of ignition and occurs when a mixture of fuel and oxygen encounter an external heat source with sufficient heat or thermal energy to start the combustion reaction.

A

Piloted Ignition

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10
Q

________ occurs without any external flame or spark to ignite the fuel gases or vapors.

A

Autoignition

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11
Q

The autoignition temperature of a substance is always ______ than its piloted ignition temperature.

A

HIGHER

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12
Q

________ is a fatal level of oxygen deficiency in the blood.

A

Asphyxiation

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13
Q

Carbon Monoxide (CO) combines with hemoglobin about ___ times more effectively than oxygen does.

A

200x

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14
Q

Hydrogen Cyanide (HCN) is __ times more toxic than Carbon Monoxide (CO).

A

35x

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15
Q

_____ _____ is a product of complete combustion of organic materials. It’s not toxic in the same manner as CO or HCN, but it displaces existing oxygen, which creates an oxygen deficient atmosphere. (it is also a respiratory stimulant)

A

Carbon Dioxide (CO2)

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16
Q

____ always move from areas of higher pressure to areas of lower pressure.

A

Gases

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17
Q

_____ energy is the most common source of heat in combustion reactions.

A

Chemical

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18
Q

Self-heating can lead to _____ _____.

A

Spontaneous Combustion

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19
Q

Electrical heating can occur in several ways, including _______, which is an electric current flowing through a conductor producing heat. Some electrical appliances make use of this. Other electrical equipment is designed to limit it.

A

Resistance Heating

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20
Q

Electrical heating can occur in several ways, including _______, when the current flowing through a conductor exceeds its design limits, and the conductor may overheat and present an ignition hazard.

A

Overcurrent (or overload)

*this is unintended resistance heating

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21
Q

Electrical heating can occur in several ways, including _______, which is a high-temperature luminous electric discharge across a gap or through a medium such as charred insulation.

A

Arcing

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22
Q

Electrical heating can occur in several ways, including _______. When an electric arc occurs, luminous (glowing) particles can form and splatter away from the point of arcing.

A

Sparking

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23
Q

Friction or compression generates ______ energy.

A

Mechanical

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24
Q

______ is the transfer of heat through and between solids. It occurs when a material is heated as a result of direct contact with a heat source.

A

Conduction

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25
Q

Heat transfer due to conduction is dependent upon THREE factors:

A

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

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26
Q

______ is the transfer of thermal energy by the circulation or movement of a fluid (liquid or gas). In the fire environment, it usually involves the transfer of heat through the movement of hot smoke and fire gases.

A

Convection

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27
Q

Heat transfer due to convection is dependent upon THREE factors:

A

-Area being heated
-Temp difference between the hot fluid/gas and the material being heated
-Turbulence and velocity of moving gases

28
Q

______ is the transmission of energy as electromagnetic waves, such as light waves, radio waves, or X-rays, without an intervening medium.

A

Radiation

29
Q

Numerous factors influence radiant heat transfer, including:

*3 answers

A

-Nature of the exposes surfaces
-Distance between heat source and exposed surfaces
-Temperature of the heat source

30
Q

_____ is a common cause of expose fires.

A

Radiation

31
Q

____ fuels, such as hydrogen or magnesium, DO NOT contain carbon.

____ fuels DO contain carbon.

A

Inorganic DO NOT
Organic DO

(most common fuels are organic)

32
Q

Power is the rate at which energy transfers. In terms of fire behavior, power is the ________ during combustion.

A

Heat Release Rate

33
Q

Air has a Vapor Density of 1. Gases with a vapor density of less than 1 will _____, while those having a vapor density of more than 1 will ______.

A

Less than 1 rises
More than 1 sinks

34
Q

Water has a Specific Gravity of 1. Liquids with a specific gravity of less than 1 will _____, while those with a specific gravity of more than 1 will ____.

A

Less than 1 will float on the surface of water (lighter)
More than 1 will sink (heavier)

35
Q

____ ____ is the minimum temperature at which a liquid gives off sufficient vapors to ignite, but not sustain combustion, in the presence of a piloted ignition.

____ ____ is the temperature at which a piloted ignition of sufficient vapors will begin a sustained combustion reaction

A

Flash Point ; Fire Point

36
Q

The ____ point is usually a few degrees above the ____ point.

A

Fire point above the flash point

37
Q

Flammable liquids called ____ ____ such as alcohols (methanol, ethanol) will mix readily with water. Firefighters should use alcohol-resistant fire fighting foam specifically designed for them.

A

Polar Solvents

38
Q

When wood first heats, it begins to pyrolize and decompose into its volatile components and carbon. These vapors are usually white in color. Pyrolysis of wood begins at temperatures below ___*F, which is lower than the temperature required for ignition of the released vapors.

A

Below 400* F

39
Q

As fuel particles become more finely divided (like wood shavings or sawdust), their ability to ignite _____ tremendously.

A

Increases

40
Q

Normally, air consists of about __% oxygen.

A

21%

41
Q

At normal ambient temperatures (68*F), materials can ignite and burn at oxygen concentrations as low as ___%.

A

15%

42
Q

Fires develop through four stages:

A

-Incipient
-Growth
-Fully Developed
-Decay

43
Q

There are three key factors that control how a fire develops:

A

-The fuel properties
-The ventilation available
-Heat conservation

44
Q

The ____ stage of fire development starts with ignition when the three elements of the fire triangle come together and the combustion process begins. At this point, the fire is small and confined to a small portion of the fuel first ignited.

A

Incipient

45
Q

In the ____ stage, more of the initial fuel package becomes involved and the production of heat and smoke increases. Radiant heat may begin to pyrolize nearby fuels. The fire may continue to grow or may enter an early state of decay depending upon available oxygen.

A

Growth

46
Q

The ____ stage occurs when all combustible materials in the compartment are burning at their peak heat release rate based on available oxygen. The fire is consuming the maximum amount of oxygen that it can.

A

Fully Developed

47
Q

As the fire consumes the available fuel or oxygen and the heat release rate begins to decline, the fire enters the ____ stage.

A

Decay

48
Q

A visual indicator that a fire is leaving the incipient stage is ____ ____.

A

Flame Height

49
Q

When flames reach ___ feet high, radiated heat begins to transfer more heat than convection. The fire will then enter the growth stage.

A

2.5 feet

50
Q

The ____ ____ is defined as the space between the air intake and the exhaust outlet.

A

Flow Path

51
Q

Isolated flames (intermittent flames) may move through the hot gas layer (highest layer in thermal layering). The appearance of isolated flames is sometimes an immediate indicator of ______.

A

Flashover

*isolated flames = rollover

52
Q

Rapid development from the growth stage to the fully developed stage is known as _____. The combustible materials and fuel gases ignite almost simultaneously. This typically occurs during the GROWTH stage, but may occur during the fully developed stage due to a change in ventilation.

A

Flashover

53
Q

As flashover occurs, the gas temperatures in the room reach ____*F or higher.

A

1,100*F

54
Q

There are four common elements of flashover:

A

-Transition in fire development (growth stage to fully developed stage)
-Rapidity
-Compartment (must be an enclosed space)
-Pyrolysis of all exposed fuel surfaces

55
Q

The autoignition temperature of CO, the most abundant fuel gas created by most fire, is approximately ____*F.

A

1,100*F

56
Q

SCBA face pieces begin to fail after __ minutes of exposure to a heat flux of 15kW/m2.

A

5

57
Q

A HIGH neutral plane observed from the exterior of a structure can indicate:

*2 answers

A

-That the fire is in the early stages of development
-A fire above your level

58
Q

A MID-LEVEL neutral plane observed from the exterior of a structure can indicate:

A

That the compartment has not yet ventilated or that flashover is approaching.

59
Q
  1. A very LOW-LEVEL neutral plane observed from the exterior of a structure may indicate:
  2. It could also mean that the fire:
A
  1. That the fire is reaching backdraft conditions.
  2. Is below you (basement fire or lower story)
60
Q

A ventilation-limited compartment fire can produce a large volume of flammable smoke and other gases due to incomplete combustion. An increase in ventilation can result in an explosively rapid combustion of flammable gases, called a _____.

_____ occurs in a space containing a high concentration of heated flammable gases that lack sufficient oxygen for flaming combustion.

A

Backdraft

61
Q

There are two main types of fully developed fires:

A

Ventilation-Limited and Fuel-Limited

62
Q

Technically speaking, most fully developed compartment fires are _____ limited.

A

Ventilation

63
Q

A fire is said to be in the ____ stage when it runs out of either fuel or oxygen.

A

Decay

64
Q

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

A

5 to 10 minutes

65
Q

For steel trusses, _____*F is the critical temperature of steel- the temperature at which steel begins to weaken.

A

1,000*F

Lieutenant 2022 (49 decks)

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