ifsta chapter 4

A fuel's \_____ is the total amount of thermal energy released when a specific amount of that fuel burns.

heat of combustion

Heat that is radiated to the insulating air layer between PPE and your body:

can cause heat stress and failure of the PPE.

Which statement about smoke is accurate?

Smoke has the potential to burn.

How does the self-sustained chemical reaction influence the oxidation reaction in flaming combustion?

Increases the speed of the oxidation reaction

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?

Buildings under construction

Which is a measure of heat energy transfer rate?

Heat flux

Which type of phenomenon occurs when the fire rapidly transitions from the growth stage to the fully developed stage?

Flashover

Which is an example of a self-sustaining chemical reaction?

Flaming combustion

The total quantity of combustible contents of a building, space, or fire area is referred to as the:

fuel load.

Which element is included in the fire tetrahedron that is not part of the fire triangle model?

Chemical chain reaction

Which statement about flow paths and ventilation in a structure is accurate?

When firefighters make entry into a building, they establish new flow paths between the fire compartment and exterior vents of the building.

The four stages of fire development are:

incipient, growth, fully developed, and decay.

Which is an indicator for potential backdraft?

Pulsing smoke movement around small openings in the building

What is the primary consideration affecting how easily solid fuels ignite?

Surface-to-mass ratio

If there are no openings for lateral movement during the growth stage of a fire, the hot gases released during combustion will fill the compartment:

starting at the ceiling and filling down.

In order to burn, fuel must be in a \_____ state.

gaseous

Development of a fire in the incipient stage depends largely upon the:

characteristics and configuration of the fuel involved.

Slower fire development in large compartments is due to the \_____ and the increased distance that radiated heat must travel from the fire to the contents that must be heated.

greater volume of air

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:

cooling the hot fire gases before further ventilation occurs.

When a compartment fire is in ventilation-limited decay, \_____ can trigger flashover quickly.

introduction of new oxygen

Which type of fuel is difficult to extinguish using water as the only extinguishing agent?

Liquids that are less dense (lighter) than water

Heat transfers from one body to another by three mechanisms: conduction, radiation, and:

convection

What is the likely result if additional air is allowed into an already-ventilated compartment fire?

Higher peak heat release rate

Which stage of fire occurs when all combustible materials in the compartment are burning at their peak heat release rate based on the available oxygen?

Fully developed

What is the MOST common source of heat in combustion reactions?

Chemical energy

The minimum temperature at which a liquid gives off sufficient vapors to ignite, but not sustain combustion, is its:

flash point.

Most residential fires that develop beyond the incipient state become:

ventilation limited.

What is the primary oxidizing agent in most fires?

Oxygen in the air

Combustion can occur within a range of concentration of fuel vapor and air; this range is referred to as the:

flammable (explosive) range.

The range of concentrations of fuel vapor and air within which combustion can occur is the:

flammable (explosive) range.

What occurs during flashover?

The volume of burning gases can increase to fill the room's entire volume and extend out of any openings from the room.

Which heat transfer mechanism is dependent on several factors including the turbulence and velocity of moving gases?

Convection

What may occur in an oxidation reaction when the heat generated exceeds the heat being lost?

Spontaneous ignition

During the \_____ stage of fire development, the three elements of the fire triangle come together and the combustion process begins.

incipient

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

decay

A collapsed storage shed that is fully involved in flames would be an example of a:

fully-developed fuel-limited fire.

Which statement about energy and combustion is accurate?

A fuel's potential energy releases during combustion and converts to kinetic energy.

In the fire environment, convection usually involves the transfer of heat through:

the movement of hot smoke and fire gases.

What will establish new flow paths between the fire compartment and exterior vents of the building?

Firefighters advancing a hoseline through an open door or ventilating windows to make entry into a building

A fuel's chemical content influences its heat release rate and its:

heat of combustion.

Fires develop through four stages: incipient, growth, \_____, and decay.

fully-developed

Why must firefighters use tactics that control the oxygen available to the fire when they advance a hoseline through a door or ventilate windows?

To prevent unwanted fire spread

What construction features tend to contain fires for a longer period of time, thus creating fuel-rich, ventilation-limited environments?

Energy-efficient designs

The minimum temperature at which a fuel in the air must be heated in order to start self-sustained combustion is known as the:

autoignition temperature (AIT).

What factor helps determine the flow path in a structure fire?

The floor plan and openings within the structure

An extinguishing agent, such as dry chemical or Halon-replacement agent, terminates the combustion reaction by:

interfering with the chemical chain reaction.

Sawdust ignites more easily than a log because the sawdust has a higher:

surface-to-mass ratio.

What occurs when a mixture of unburned fuel gases and oxygen come in contact with an ignition source?

Smoke explosion

Gaseous fuels can be the most dangerous of all fuel types because they:

are already in the physical state required for ignition.

Where might firefighters be MOST likely to encounter inoperative standpipes and sprinkler systems?

Buildings under demolition

What will a liquid with a specific gravity of less than one do when combined with water?

Float

Which statement describes a fire in the incipient stage?

The temperature is only slightly above ambient in areas that the fire, plume, and ceiling jet directly affect.

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?

Piloted ignition

The \_____ stage of fire development occurs when the heat release rate of the fire has reached its peak.

fully-developed

In a compartment fire, smoke flashover indicators include rapidly increasing volume, turbulence, optical density, and:

darkening color.

What is often the most readily available fuel source and significantly influences fire development in a compartment fire?

Contents within the structure

Fires involve a heat producing chemical reaction between fuel and:

an oxidizer.

The flow path of a structure fire is comprised of two regions: the ambient air flow in and the:

hot exhaust flow out.

The use of engineered or lightweight construction and trussed support systems pose a danger to firefighters because engineered trusses:

can fail after 5 to 10 minutes of exposure to fire.

Most building codes rate construction types according to:

how long each construction type maintains its structural integrity over a certain period of time.

In most compartment fires, the energy release in fire is directly proportional to the:

amount of oxygen available for combustion.

What is the cause of most fire deaths?

Exposure to toxic gases found in smoke and/or lack of oxygen

Observed from the exterior, a high neutral plane may indicate that the fire is in the early stages of development, or could indicate:

a fire above your level.

Hydrogen cyanide (HCN) is a product of combustion that:

targets the brain after being inhaled, ingested, or absorbed into the body.

In addition to structural members, what can be a significant factor influencing fire spread and loss of lives in fires?

Combustible interior finishes and furnishings

Which product of combustion acts as a chemical asphyxiant by excluding oxygen from the blood, leading to hypoxia of the brain and tissues?

Carbon monoxide (CO)

In a compartment fire, the interface between the hot gas layers and cooler layer of air is commonly referred to as the:

neutral plane.

What will occur if firefighters begin an attack on a ventilation-limited structure fire with ventilation alone?

The fire's heat release rate and spread will progressively increase as additional vents are made.

Materials that burn at normal oxygen levels will burn more intensely in \_____ atmospheres.

oxygen-enriched

When a structural member such as a window, roof, or doorway fails, introducing a new source of oxygen to a fire, \_____ ventilation has occurred.

unplanned

Which measurement is often used to measure how long PPE will protect a firefighter in an interior fire environment?

Heat flux to the PPE

What may occur if water is added to a burning liquid that is less dense than water?

The water may disperse the burning liquid instead of extinguishing it.

Which type of electrical heating occurs when the current flowing through a conductor exceeds its design limits?

Overcurrent or overload

Which statement about the dangers of products of combustion is accurate?

Low oxygen concentrations alone can result in hypoxia or death.

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:

chemical reaction.

What causes flaming combustion to occur?

A gaseous fuel mixes with an adequate amount of oxygen and heats to ignition temperature.

What provides the best indicators of structural integrity?

Information gathered at the scene

Which statement BEST describes a fire in a large compartment or a compartment with a high ceiling?

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.

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?

Radiation

What is the measurement of the average kinetic energy in the particles of a sample of matter?

Temperature

A compartment is any:

open space with no complete fire barrier dividing it.

Which action will transition a compartment fire in a modern structure from ventilation-limited to fuel-limited?

Extinguishing some of the fuel

Which statement describes the factor that MOST influences compartment fire development?

Whether the fire is fuel-limited or ventilation-limited

What occurs when a gas is compressed?

Heat is generated

Using extinguishing agents other than water and foam to interrupt the combustion reaction is referred to as:

chemical flame inhibition.

What is the most effective means of establishing awareness of hazards in commercial, industrial, and storage facilities with large fuel loads?

Performing and updating preincident surveys

When solid fuels are heated, they begin to \_____ and release fuel gases and vapors.

pyrolize

Which element of the fire tetrahedron is included to explain flaming (gas-phase) combustion?

Chemical chain reaction

Which statement about ventilation and wind considerations is MOST accurate?

Wind can increase the pressure inside the structure, driving smoke and flames into unburned portions of the structure and onto advancing firefighters.

In a ventilation-limited compartment fire that has a large volume of flammable gases, opening a door or window could result in:

backdraft

The transfer of heat through and between solids is known as:

conduction

Fire spreading from a wall to a nearby couch due to radiant heat transfer is an example of:

heat reflectivity.

How does a compartment fire affect pressure in and around gases in the compartment?

Heat from a fire increases the pressure of the surrounding gases.

Firefighters working in the exhaust portion of the flow path will:

feel the increase in temperature as the velocity and/or turbulence increases.

Which means of influencing fire dynamics is typically a tactic in wildland fires or liquid and gas fires?

Fuel removal