Chapter 4 Fire Dynamics
Observed from the exterior, a high neutral plane may indicate that the fire is in the early stages of development, or could indicate: Select one: a.a fire above your level. b.that the fire is reaching backdraft conditions. c.that the compartment has not yet ventilated. d.a fire in decay stage.
a
Sawdust ignites more easily than a log because the sawdust has a higher: Select one: a.surface-to-mass ratio. b.pyrolysis point. c.flammable (explosive) range. d.fuel thickness proportion.
a
The use of engineered or lightweight construction and trussed support systems pose a danger to firefighters because engineered trusses: Select one: a.can fail after 5 to 10 minutes of exposure to fire. b.add more to the fuel load of a fire than natural building materials do. c.are not required to meet any special building code requirements. d.obstruct the ability to identify dangerous building conditions from the exterior.
a
To ensure that the decay stage of a ventilation-limited fire is the fire's final stage, firefighters must provide a controlled transition of a fire in the decay stage from ventilation-limited to fuel-limited, by: Select one: a.cooling the hot fire gases before further ventilation occurs. b.protecting exposures until the fire consumes all available fuel. c.restricting ventilation until the heat transfers out of the compartment. d.carrying unburned fuel away from the compartment.
a
What is the likely result if additional air is allowed into an already-ventilated compartment fire? Select one: a.Higher peak heat release rate b.Higher ratio of complete to incomplete combustion c.Reduced vapor pressure at the seat of the fire d.Lower neutral plane
a
What occurs during flashover? Select one: a.The volume of burning gases can increase to fill the room's entire volume and extend out of any openings from the room. b.The heat release rate of the fire will reach its peak. c.Flames propagate through the hot gas layer or across the ceiling. d.The compartment will fill with black smoke and slowly cooling fuel gases; the compartment will show no visible flames. Feedback
a
What provides the best indicators of structural integrity? Select one: a.Information gathered at the scene b.Year and method of construction c.Occupancy classification d.Occupant interview during the preincident survey
a
What will establish new flow paths between the fire compartment and exterior vents of the building? Select one: a.Firefighters advancing a hoseline through an open door or ventilating windows to make entry into a building b.Firefighters applying water from the exterior through an existing opening in the structure c.Rapid fire development from the growth stage into the fully developed stage d.Fire gases pushing into compartments adjacent to the burning compartment
a
When a substance changes from one type of matter into another, such as two or more substances combining to form compounds, the substance undergoes a: Select one: a.chemical reaction. b.metamorphosis. c.physiological change. d.dissolution.
a
A compartment is any: Select one: a.enclosed space within a building. b.open space with no complete fire barrier dividing it. c.bay, cell, chamber, vault, or cubicle within a building. d.space divided into separate areas.
b
Gaseous fuels can be the most dangerous of all fuel types because they: Select one: a.are the most commonly encountered form of fuel. b.are already in the physical state required for ignition. c.will sink and collect in low areas. d.can quickly change into a liquid or a solid fuel.
b
Most building codes rate construction types according to: Select one: a.the size of each compartment relative to the total square footage of the structure. b.how long each construction type maintains its structural integrity over a certain period of time. c.the ratio of the typical number of occupants to the number of egress points. d.the size, type, and capability of fire suppression systems.
b
The _____ stage of fire development occurs when the heat release rate of the fire has reached its peak. Select one: a.decay b.fully-developed c.incipient d.growth
b
Which type of phenomenon occurs when the fire rapidly transitions from the growth stage to the fully developed stage? Select one: a.Entrainment b.Flashover c.Flame propagation d.Spontaneous ignition
b
Fires involve a heat producing chemical reaction between fuel and: Select one: a.free radicals. b.a catalyst. c.an oxidizer. d.a reducing agent.
c
What will occur if firefighters begin an attack on a ventilation-limited structure fire with ventilation alone? Select one: a.The fire's heat release rate will decrease temporarily until the introduced air is heated to the fuel's ignition temperature. b.Visibility will improve, clearing path to the seat of the fire. c.The fire's heat release rate and spread will progressively increase as additional vents are made. d.Hot gases will be pushed inward, toward the seat of the fire.
c
Where might firefighters be MOST likely to encounter inoperative standpipes and sprinkler systems? Select one: a.Open-plan commercial structures b.Structures at the wildland/urban interface c.Buildings under demolition d.Residential structures built prior to 1990
c
Which element of the fire tetrahedron is included to explain flaming (gas-phase) combustion? Select one: a.Oxygen b.Fuel c.Chemical chain reaction d.Heat
c
A fire is said to be in the _____ stage when it runs out of either available fuel or available oxygen. Select one: a.decay b.incipient c.fully-developed d.growth
a
An extinguishing agent, such as dry chemical or Halon-replacement agent, terminates the combustion reaction by: Select one: a.cooling the fuel below the ignition temperature. b.cutting off the oxygen supply to the fuel. c.reacting with the fuel to create a fire-resistant layer. d.interfering with the chemical chain reaction.
d
Heat that is radiated to the insulating air layer between PPE and your body: Select one: a.dissipates at a much quicker rate than convected heat. b.may cause spontaneous ignition of the PPE materials. c.is less dangerous than heat conducted to the outside of the PPE. d.can cause heat stress and failure of the PPE.
d
How does a compartment fire affect pressure in and around gases in the compartment? Select one: a.At standard temperature and atmospheric pressure, gases circulate at a steady, uniform rate. b.Gases move from areas of lower pressure to areas of higher pressure. c.Significant differences in pressure, typically 10 kPa or greater, are required to cause movement of gases in a compartment. d.Heat from a fire increases the pressure of the surrounding gases.
d
In a ventilation-limited compartment fire that has a large volume of flammable gases, opening a door or window could result in: Select one: a.piloted ignition. b.flashover. c.spontaneous ignition. d.backdraft.
d
In addition to structural members, what can be a significant factor influencing fire spread and loss of lives in fires? Select one: a.Free radicals released during combustion b.Gases heavier than air that collect in the lower levels c.Combustible exterior wall coverings d.Combustible interior finishes and furnishings
d
Which statement BEST describes a fire in a large compartment or a compartment with a high ceiling? Select one: a.Lack of ventilation becomes the limiting factor more quickly in a large compartment than it would in a smaller compartment. b.The fire will normally develop more rapidly than one in a small compartment. c.Open plan commercial structures have limited fuel loads and numerous physical barriers to prevent the spread of fire and smoke in the space. d.In structures with high ceilings, a large volume of hot smoke and fire gases can accumulate at the ceiling level, while conditions at floor level remain relatively unchanged.
d
Which statement describes the factor that MOST influences compartment fire development? Select one: a.Whether the fuel is cellulose-based or petroleum-based b.Ambient temperature and wind speed outside the compartment c.Ratio of square footage to ceiling height of the compartment d.Whether the fire is fuel-limited or ventilation-limited
d
Which type of electrical heating occurs when the current flowing through a conductor exceeds its design limits? Select one: a.Friction heating b.Arcing c.Sparking d.Overcurrent or overload
d
A fuel's chemical content influences its heat release rate and its: Select one: a.heat of combustion. b.physical attributes. c.organic compounds d.convective flow.
a
Fire spreading from a wall to a nearby couch due to radiant heat transfer is an example of: Select one: a.heat reflectivity. b.insulation. c.heat conductivity. d.conduction. Feedback
a
Fires develop through four stages: incipient, growth, _____, and decay. Select one: a.fully-developed b.radiant c.ventilation-limited d.rollover
a
In most compartment fires, the energy release in fire is directly proportional to the: Select one: a.amount of oxygen available for combustion. b.ambient temperature of the environment. c.thermal conductivity of the fuel. d.amount of fuel available for combustion. Feedback
a
What occurs when a gas is compressed? Select one: a.Heat is generated b.Heat is absorbed c.Gas becomes more buoyant d.Gas becomes less conductive
a
What occurs when a mixture of unburned fuel gases and oxygen come in contact with an ignition source? Select one: a.Smoke explosion b.Radiant combustion c.Spontaneous ignition d.Flashover
a
The transfer of heat through and between solids is known as: Select one: a.radiation. b.conduction. c.convection. d.self-heating.
b
What construction features tend to contain fires for a longer period of time, thus creating fuel-rich, ventilation-limited environments? Select one: a.High ceilings and atriums b.Energy-efficient designs c.Tile, stone, and concrete flooring d.Heat-reflective wall treatments
b
What factor helps determine the flow path in a structure fire? Select one: a.The nature and arrangement of the fuel b.The floor plan and openings within the structure c.The stage of development of the fire d.The temperature reactions of the structure and its contents
b
What is often the most readily available fuel source and significantly influences fire development in a compartment fire? Select one: a.Exterior wall coverings b.Contents within the structure c.Window, wall, and floor coverings d.Combustible roof materials
b
What may occur in an oxidation reaction when the heat generated exceeds the heat being lost? Select one: a.Piloted ignition b.Spontaneous ignition c.Backdraft/flashover d.Arcing/sparking
b
Which action will transition a compartment fire in a modern structure from ventilation-limited to fuel-limited? Select one: a.Making additional openings in the compartment b.Extinguishing some of the fuel c.Altering the flow paths within the structure d.Cooling the exterior of the compartment
b
Which heat transfer mechanism is dependent on several factors including the turbulence and velocity of moving gases? Select one: a.Radiation b.Convection c.Reflection d.Conduction
b
Which is an indicator for potential backdraft? Select one: a.Light, white smoke rising from the roof b.Pulsing smoke movement around small openings in the building c.Heavy black smoke from numerous open windows d.Turbulent, dark smoke coming from the open front door
b
Which measurement is often used to measure how long PPE will protect a firefighter in an interior fire environment? Select one: a.Rate of rise in temperature b.Heat flux to the PPE c.Pressure of convective flow d.Temperature in the structure
b
Which statement about energy and combustion is accurate? Select one: a.A fuel's chemical energy is the result of rapid vibrations in the molecules. b.A fuel's potential energy releases during combustion and converts to kinetic energy. c.Chemical changes involve an exchange of energy; physical changes involve no energy exchange. d.Chemical and physical changes almost never involve an exchange of energy.
b
Which statement about the dangers of products of combustion is accurate? Select one: a.Visible smoke presents the greatest inhalation danger. b.Low oxygen concentrations alone can result in hypoxia or death. c.The toxic effects of smoke inhalation are the result of the interaction between carbon monoxide and heat. d.Toxic products of combustion are released only during the combustion reaction.
b
Which type of buildings are subject to rapid fire spread because many of the protective features such as gypsum wallboard and automatic fire suppression systems are not in place? Select one: a.Buildings with a bowstring truss roof design b.Buildings under construction c.Commercial buildings constructed prior to 1990 d.Buildings at the wildland/urban interface
b
Why must firefighters use tactics that control the oxygen available to the fire when they advance a hoseline through a door or ventilate windows? Select one: a.To transition the fire to a ventilation-limited environment b.To prevent unwanted fire spread c.To maintain structural integrity d.To increase the pressure inside the compartment
b
A collapsed storage shed that is fully involved in flames would be an example of a: Select one: a.fire in the decay stage. b.fire in the growth stage. c.fully-developed fuel-limited fire. d.fully-developed ventilation-limited fire.
c
By which mechanism of heat transfer does heat travel in a straight line at the speed of light, allowing heat to travel through vacuums and air spaces? Select one: a.Convection b.Conduction c.Radiation d.Reflection
c
Combustion can occur within a range of concentration of fuel vapor and air; this range is referred to as the: Select one: a.vapor pressure range. b.oxidation (combustion) range. c.flammable (explosive) range. d.surface to mass range.
c
During the _____ stage of fire development, the three elements of the fire triangle come together and the combustion process begins. Select one: a.decay b.growth c.incipient d.rollover
c
Firefighters working in the exhaust portion of the flow path will: Select one: a.see visibility improve as turbidity and airflow increase. b.feel a decrease in temperature as air is entrained by the fire. c.feel the increase in temperature as the velocity and/or turbulence increases. d.see waves of radiant heat emitting from the walls or ceiling.
c
How does the self-sustained chemical reaction influence the oxidation reaction in flaming combustion? Select one: a.Increases the ratio of complete to incomplete combustion of fuel b.Decreases the temperature required for the oxidation reaction c.Increases the speed of the oxidation reaction d.Decreases the types of products of combustion released
c
Hydrogen cyanide (HCN) is a product of combustion that: Select one: a.is equally as toxic as carbon monoxide (CO). b.acts as a respiratory stimulant, increasing respiratory rate and increasing oxygen to blood cells. c.targets the brain after being inhaled, ingested, or absorbed into the body. d.is released when wood and other natural materials are burned.
c
In a compartment fire, smoke flashover indicators include rapidly increasing volume, turbulence, optical density, and: Select one: a.fuel load. b.ventilation. c.darkening color. d.thermal properties.
c
In a compartment fire, the interface between the hot gas layers and cooler layer of air is commonly referred to as the: Select one: a.no pressure zone. b.neutral pressure interface. c.neutral plane. d.zero balance plane.
c
Materials that burn at normal oxygen levels will burn more intensely in _____ atmospheres. Select one: a.flaming b.oxygen-deficient c.oxygen-enriched d.nonflaming
c
What causes flaming combustion to occur? Select one: a.A solid fuel mixes with an adequate amount of liquid fuel to be able to sustain an open burning flame. b.A gaseous fuel encounters an external heat source and experiences piloted ignition. c.A gaseous fuel mixes with an adequate amount of oxygen and heats to ignition temperature. d.A solid fuel encounters an open flame and entrains enough air to ignite.
c
What is the cause of most fire deaths? Select one: a.Exposure to extreme heat and/or contact with flames and hot surfaces b.Accidental injuries sustained during escape and/or evacuation procedures c.Exposure to toxic gases found in smoke and/or lack of oxygen d.Injuries caused by falling materials or structural collapse
c
What occurs when a mixture of fuel and oxygen encounters an external heat source with sufficient heat or thermal energy to start the combustion reaction? Select one: a.Autoignition b.Sustained ignition c.Piloted ignition d.Kinetic ignition
c
Which means of influencing fire dynamics is typically a tactic in wildland fires or liquid and gas fires? Select one: a.Chemical flame inhibition b.Oxygen exclusion c.Fuel removal d.Temperature reduction
c
Which product of combustion acts as a chemical asphyxiant by excluding oxygen from the blood, leading to hypoxia of the brain and tissues? Select one: a.Aerosolized fuel particles b.Carbon dioxide (CO2) c.Carbon monoxide (CO) d.Hydrogen cyanide (HCN)
c
Which statement about ventilation and wind considerations is MOST accurate? Select one: a.Unplanned ventilation is most likely to occur in structures undergoing construction or renovation. b.The source of new oxygen always originates from outside the building. c.Wind can increase the pressure inside the structure, driving smoke and flames into unburned portions of the structure and onto advancing firefighters. d.Unplanned ventilation occurs when an occupant or bystander interferes with coordinated fireground activities and introduces a new source of oxygen to the fire. Feedback
c
Which statement describes a fire in the incipient stage? Select one: a.The fire consumes the available fuel and the heat release rate begins to decline. b.The heat release rate of the fire has reached its peak because of lack of fuel or oxygen. c.The temperature is only slightly above ambient in areas that the fire, plume, and ceiling jet directly affect. d.The fire has grown large enough for compartment configuration and amount of ventilation to influence it.
c
In the fire environment, convection usually involves the transfer of heat through: Select one: a.direct contact with a heat source. b.intermittent contact with a heat source. c.electromagnetic energy waves. d.the movement of hot smoke and fire gases.
d
The flow path of a structure fire is comprised of two regions: the ambient air flow in and the: Select one: a.cool air subsidence. b.ambient air flow out. c.ceiling jet. d.hot exhaust flow out.
d
The minimum temperature at which a fuel in the air must be heated in order to start self-sustained combustion is known as the: Select one: a.piloted ignition temperature (PIT). b.lower explosive (flammable) limit (LEL). c.upper explosive (flammable) limit (UEL). d.autoignition temperature (AIT).
d
The minimum temperature at which a liquid gives off sufficient vapors to ignite, but not sustain combustion, is its: Select one: a.specific gravity. b.degree of solubility. c.vapor pressure. d.flash point.
d
Using extinguishing agents other than water and foam to interrupt the combustion reaction is referred to as: Select one: a.temperature reduction. b.oxygen exclusion. c.fuel removal. d.chemical flame inhibition.
d
What is the MOST common source of heat in combustion reactions? Select one: a.Convective flow b.Electrical energy c.Thermal equilibrium d.Chemical energy
d
What is the measurement of the average kinetic energy in the particles of a sample of matter? Select one: a.Heat b.Candlepower c.Wattage d.Temperature
d
What is the most effective means of establishing awareness of hazards in commercial, industrial, and storage facilities with large fuel loads? Select one: a.Accessing code enforcement databases b.Studying plat maps and building plans c.Contacting the facilities manager during the incident d.Performing and updating preincident surveys
d
What may occur if water is added to a burning liquid that is less dense than water? Select one: a.The fuel's rate of vaporization will decrease due to the increased water pressure. b.The water will mix with the burning liquid and become less effective at extinguishing the fire. c.The liquid fuel may vaporize much more rapidly as it draws thermal energy from the water. d.The water may disperse the burning liquid instead of extinguishing it.
d
What will a liquid with a specific gravity of less than one do when combined with water? Select one: a.Easily mix b.Sink c.Vaporize d.Float
d
When a structural member such as a window, roof, or doorway fails, introducing a new source of oxygen to a fire, _____ ventilation has occurred. Select one: a.passive b.natural c.elemental d.unplanned
d
When solid fuels are heated, they begin to _____ and release fuel gases and vapors. Select one: a.evaporate b.melt c.hypoxilize d.pyrolize
d
