IFSTA 8 Chapter 5 - Fire Dynamics (Test)

What factor determines the type of fully developed fire?

Select one:

a. Whether the fire is entering decay or a stage of regrowth

b. Whether it is a lack of fuel or oxygen that is limiting the peak heat release rate

c. Whether the fire can no longer grow or has just grown as much as it can

d. Whether it is flashover or backdraft that makes the fire fully developed

B

As heat begins to vibrate the molecules in a fuel, the fuel begins a physical change from a:

Select one:

a. solid or gas to a liquid.

b. solid to a liquid or gas.

c. liquid or gas to a solid.

d. solid or liquid to a gas.

D

What is one of the indicators of backdraft?

Select one:

a. Pyrolysis of contents or fuel packages located some distance from the fire

b. Pulsing smoke movement around small openings in the building

c. Rapidly increasing volume of darkening smoke

d. Isolated flames or rollover in the hot gas layers or near the ceiling

B

What is the main difference between a fuel-limited fire and a ventilation-limited fire?

Select one:

a. A fuel-limited fire will enter an early stage of decay in the growth stage; a ventilation-limited fire will usually progress through the stages of fire development in order.

b. A ventilation-limited fire begins at the beginning of the incipient stage; a fuel-limited fire may begin during the growth stage.

c. A ventilation-limited fire has sufficient oxygen for combustion; a fuel-limited fire does not have enough oxygen to continue to burn or spread.

d. A fuel-limited fire has sufficient oxygen for combustion; a ventilation-limited fire does not have enough oxygen to continue to burn or spread.

D

Firefighters can establish new flow paths for structure fires when they:

Question 5Select one:

a.

decrease the fuel load by extinguishing flammable contents.

b.

add more fuel gases to a compartment fire.

c.

advance a hoseline or ventilate windows to make entry.

d.

extinguish flames in the hot gas layer.

C

What determines the available flow path in a structure fire?

Select one:

a. Temperature and pressure differences

b. Construction materials and occupancy types

c. The floor plan and openings in the structure

d. Thermal gas layers

C

When a fire becomes ventilation-limited in a compartment,:

Select one:

a. the heat release rate increases rapidly.

b. the pyrolysis process is stopped.

c. the environment is tenable for firefighters with full PPE and SCBA.

d. it can still reignite if more oxygen is introduced into the compartment.

D

The energy released in fire is proportional to the:

Select one:

a. vapor density in the air.

b. heat release rate of the materials.

c. amount of fuel available to burn.

d. amount of oxygen available.

D

During flaming combustion, what is "pumped in" and mixed with fuel gases?

Select one:

a. Combustion products

b. Fresh oxygen

c. Carbon dioxide

d. Thermal energy

B

Firefighters should have a knowledge of building construction and occupancy types when fighting structural fires in order to:

Select one:

a. prioritize resources to use at an incident.

b. determine approximate costs of an incident.

c. determine the fuel load of a structure.

d. distinguish between low-value and high-value properties.

C

Which type of materials are likely to produce toxic levels of hydrogen cyanide when under burning conditions?

Select one:

a. Brick and concrete

b. Wood

c. Metal

d. Upholstered furniture and carpets

D

A rapid transition from the growth stage to the fully developed stage is known as:

Select one:

a. thermal layering.

b. smoke explosion.

c. pyrolysis.

d. flashover.

D

To ensure the decay stage of a ventilation-limited fire is its final stage, firefighters must:

Select one:

a. cool the hot fire gases before any further ventilation occurs.

b. wait for the heat release rate to decrease to the point the heat can transfer outside the compartment.

c. create multiple ventilation points in the compartment.

d. cool any furnishings or materials in the compartment.

A

In thermal layering, the hottest gases typically form the:

Select one:

a. neutral layer.

b. middle layer.

c. highest layer.

d. lowest layer.

C

When planning for potential fires in commercial, industrial, and storage facilities with large fuel loads, remember that:

Select one:

a. fire suppression systems should be sufficient for extinguishment.

b. firefighters should not attempt fire suppression operations without consent from facility supervisors.

c. firefighters should perform and update preincident surveys to establish awareness of fuel load hazards.

d. more than one fire department or response unit will be required.

C

The main difference between flash point and fire point is that a:

Select one:

a. fire point temperature will not actually lead to ignition, while ignition will begin at a flash point temperature.

b. fire point temperature will not sustain combustion, while a flash point temperature can begin a sustained combustion reaction.

c. flash point temperature will not sustain combustion, while a fire point temperature can begin a sustained combustion reaction.

d. flash point temperature will not actually lead to ignition, while ignition will begin at a fire point temperature.

C

New sources of fuel introduced after a fire is fully developed will:

Select one:

a. speed up the decay of the fire.

b. allow fuel-limited fires to grow.

c. decrease the heat release rate.

d. allow ventilation-limited fires to grow.

B

How can firefighters help prevent backdraft from occurring?

Select one:

a. By controlling or limiting ventilation openings

b. By confining the fuel/air mixture in the compartment

c. By creating multiple ventilation openings in the compartment

d. By protecting the surrounding exposures

A

Spontaneous ignition through self-heating is an oxidation process produced by:

Select one:

a. chemical energy.

b. electrical energy.

c. radiant energy.

d. mechanical energy.

A

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

Select one:

a. the transmission of energy as electromagnetic waves.

b. insulating materials.

c. spontaneous combustion.

d. the movement of hot smoke and fire gases.

D

Carbon monoxide is released when an organic material burns in an atmosphere with a _____ and exposure can result in hypoxia or death.

Select one:

a. low-carbon concentration

b. low-oxygen concentration

c. high-carbon concentration

d. high-oxygen concentration

B

What is one way firefighters can influence fire dynamics at a structure fire?

Select one:

a. Using dry chemicals and halogenated agents to cool hot fire gases and surfaces

b. Using doors to control the amount of air available to the fire

c. Using flashover or backdraft to control the fire

d. Using water and foam for chemical flame inhibition

B

In the intake flow of a structure fire, the ambient air (higher pressure):

Select one:

a. flows toward the seat of the fire and reacts with the fuel.

b. does not flow unidirectionally.

c. causes the fire to enter the decay stage.

d. flows away from the fire toward the low pressure outlet.

A

As the efficiency of combustion decreases in a hot gas layer, the heat release rate ____ and the amount of unburned fuel within the hot gas layer ____.

Select one:

a. increases; decreases

b. decreases; increases

c. stays the same; decreases

d. stays the same; increases

B

The self-sustained chemical reaction process:

Select one:

a. does not affect the oxidation reaction.

b. increases the speed of the oxidation reaction.

c. decreases the speed of the oxidation reaction.

d. pauses the oxidation reaction.

B

Assuming there is available oxygen, the higher the fuel load and the longer the fire burns, the:

Select one:

a. more fire spread accelerates.

b. lower the heat release rate.

c. slower the fire will spread.

d. less likely it is for the fire to reignite.

A

Friction and compression generate:

Select one:

a. radiant energy.

b. electrical energy.

c. chemical energy.

d. mechanical energy.

D

In solids, off-gassing is a chemical change known as pyrolysis; in liquids, it is a physical change called:

Select one:

a. oxidation.

b. hydrolization.

c. vaporization.

d. convection.

C

Why should firefighters working in the exhaust portion of the flow path limit their time there?

Select one:

a. Smoke explosions will likely occur in the exhaust portion of the flow path.

b. Increased convective heat transfer can make conditions unsurvivable even in PPE.

c. Visibility is lessened in these areas of heavy smoke.

d. Firefighter SCBA is more likely to fail in these areas of heavy smoke.

B

Most flammable liquids, such as gasoline, have a specific gravity less than 1, which means they are:

Select one:

a. lighter than water and will float.

b. heavier than water and will sink.

c. heavier than air and will sink.

d. lighter than air and will rise.

A

How can firefighters use doors to their advantage during interior operations?

Select one:

a. By closing them to control available oxygen sources

b. By removing them from their hinges to create a permanent flow path

c. By wetting them down with extinguishing agents

d. By opening them to slow the effect of fire in one room

A

The primary consideration for how easily a solid fuel ignites is its:

Select one:

a. flash point.

b. vapor density.

c. surface-to-mass ratio.

d. heat release rate.

C

What is an indicator of rollover?

Select one:

a. An increase of ventilation in the compartment

b. A mid-level neutral plane

c. Little or no visible flame in the compartment

d. Flames spread through the hot gas layer

D

What are the three elements of the fire triangle?

Select one:

a. Fuel, oxygen, and heat

b. Incipient, growth, and decay

c. Incipient, fully-developed, and decay

d. Fuel, carbon, and heat

A

Buildings under construction, renovation, or demolition:

Select one:

a. have increased fire risk.

b. are less susceptible to structural collapse under fire conditions.

c. have decreased fire risk.

d. are easier to control and extinguish under fire conditions.

A

To protect combustible roofs on structures adjacent to a fire building or wildland fire:

Select one:

a. use wind conditions to help blow smoke and hot gases back into the burning structure, if possible.

b. perform exposure protection tactics on the burning structure.

c. avoid creating a flow path that goes in the direction of the neighboring structures.

d. perform exposure protection tactics on those structures' roofs.

D

For piloted ignition to occur, the mixture of fuel and oxygen:

Select one:

a. must encounter an external heat source to start the combustion reaction.

b. must off-gas before ignition.

c. cannot have an autoignition temperature higher than the piloted ignition temperature.

d. does not need an external flame or spark to ignite.

A

Unprotected engineered-steel and wooden trusses used in construction:

Select one:

a. are designed to remain intact under fire conditions.

b. can withstand heat exposure, but not flame contact.

c. are less popular in modern construction.

d. can fail after five to ten minutes of exposure to fire.

D

The autoignition temperature (AIT) of a substance is:

Select one:

a. the same as its piloted ignition temperature.

b. always higher than its piloted ignition temperature.

c. always lower than its piloted ignition temperature.

d. the maximum temperature at which a fuel must be heated to start combustion.

B

How does a fire in a large compartment compare to a fire in a small compartment?

Select one:

a. A fire in a large compartment will normally develop more quickly than one in a small compartment.

b. A fire in a large compartment will develop at the same rate as one in a small compartment but will have less intensity.

c. A fire in a large compartment will normally develop more slowly than one in a small compartment.

d. A fire in a large compartment tends to be smaller than a fire in a small compartment because more air is entrained.

C

Liquids that are less dense than water are:

Select one:

a. are easily extinguished with water.

b. miscible.

c. more difficult to extinguish with water.

d. completely soluble.

C

During combustion, the potential chemical energy of a fuel converts into:

Select one:

a. mechanical energy.

b. heat and light.

c. oxygen.

d. carbon and hydrogen.

B

Heat transfer rate is best measured by:

Select one:

a. oxygen concentrations.

b. temperature.

c. pressure differences.

d. heat flux.

D

During a fire, heat transfer methods tend to:

Select one:

a. involve conduction.

b. involve radiation.

c. occur individually.

d. occur together.

D

Unplanned ventilation occurs when:

Select one:

a. contents are extinguished.

b. extinguishing agents are applied on hot fire gases.

c. a door in the exhaust flow path is left open.

d. a window or roof fails.

D

A situation that might cause a fire to enter fuel-limited decay would be a compartment:

Select one:

a. that has failed and burned to the ground.

b. fire with a new source of ventilation.

c. that has additional fuel added.

d. fire with an increasing heat release rate.

A

The cause of most fire deaths is due to lack of oxygen and/or:

Select one:

a. the heat from a fire.

b. exposure to toxic gases found in smoke.

c. nonflaming combustion.

d. internal and external burns from the flames.

B

The movement of gases during a fire occurs because gases move:

Select one:

a. to low-lying areas of high pressure.

b. from areas of lower pressure to areas of higher pressure.

c. from areas of higher pressure to areas of lower pressure.

d. to the center of the structure.

C

In simple terms, products of combustion are:

Select one:

a. fire and ash.

b. flaming and nonflaming.

c. carbon dioxide and methane.

d. heat and smoke.

D

The two primary types of dangerous building conditions are those that contribute to the spread and intensity of the fire and those that:

Select one:

a. carry smoke and fire gas away from the building.

b. reduce the fuel load in the building.

c. make the building susceptible to collapse.

d. reduce the amount of oxygen flowing into the building.

C

Rapid fire development usually occurs during the ____ stage.

Select one:

a. fully-developed

b. decay

c. incipient

d. growth

D

Oxygen concentrations above the upper explosive limit (UEL) are said to be too _____ to burn.

Select one:

a. lean

b. dense

c. rich

d. heavy

C

When all available oxygen is consumed and not replenished, the heat release rate:

Select one:

a. increases.

b. becomes extremely variable.

c. becomes stagnant.

d. decreases.

D

Why do structure fires tend to have a lot of smoke?

Select one:

a. The lack of carbon in the environment creates smoke.

b. Combustion is incomplete in a structure fire.

c. The high amount of air supply in the structure produces smoke.

d. All of the fuel burns out, leaving smoke behind.

B

The rate of heat transfer depends on the _____ differences between the objects and the thermal conductivity of their materials.

Select one:

a. temperature

b. physical

c. pressure

d. oxidation

A

Most fuels are organic, meaning they contain _____ and other elements.

Select one:

a. oxygen

b. nitrogen

c. carbon

d. methane

C

What is a good visual indicator that a fire is leaving the incipient stage?

Select one:

a. Sparks

b. Flame height

c. Smoke density

d. Flame color

B

When does a fire leave the growth stage?

Select one:

a. When it begins to reach rapid fire development

b. When air begins to entrain onto the fuel package and fire

c. When a flame's radiated heat begins to transfer more heat than convection

d. When it cannot grow without the introduction of a new fuel or oxygen source

D

Conduction occurs when a material is heated as a result of:

Select one:

a. turbulence and the velocity of moving gases.

b. direct contact with a heat source.

c. the circulation or movement of a fluid.

d. the transmission of energy as electromagnetic waves.

B

What might a very low-level neutral plane indicate about a fire's behavior?

Select one:

a. The compartment has not yet been ventilated.

b. Flashover is approaching.

c. The fire is reaching backdraft conditions.

d. The fire is in the early stages of development.

C

Which product of complete combustion can displace oxygen, creating an oxygen-deficient atmosphere?

Select one:

a. Heat

b. Vapor

c. Nitrogen

d. Carbon dioxide

D

What is an example of an exothermic reaction?

Select one:

a. Evaporation

b. Fire

c. Melting

d. Steam

B

Once ignition occurs and the combustion process begins, development in the ____ stage depends largely on the characteristics and configuration of the fuel involved.

Select one:

a. fully-developed

b. decay

c. growth

d. incipient

D

What is one indicator that a fire is approaching flashover?

Select one:

a. Large volumes of darkening smoke

b. High heat, crackling, or breaking sounds

c. Little or no visible flame

d. Pulsing smoke movement around small openings in the building

A

Thermal layering can be significantly altered by:

Select one:

a. products of combustion.

b. isolated or intermittent flames.

c. ventilation and flow paths.

d. backdrafts.

C

The neutral plane can be found at openings where:

Select one:

a. cool air exits and hotter gases enter the compartment.

b. cool gases exit and hotter air enters the compartment.

c. hot air exits and cooler gases enter the compartment.

d. hot gases exit and cooler air enters the compartment.

D

Which method of heat transfer can have a significant effect on the ignition of objects located some distance from a fire?

Select one:

a. Conduction

b. Convection

c. Combustion

d. Radiation

D

The fire triangle illustrates the conditions required for ____ while the fire tetrahedron illustrates the conditions required for ____ .

Select one:

a. flaming combustion; nonflaming combustion

b. piloted ignition; autoignition

c. autoignition; piloted ignition

d. nonflaming combustion; flaming combustion

D

Why can gaseous fuels be the most dangerous fuel type?

Select one:

a. They have a vapor density of 1.

b. They have a low surface-to-mass ratio.

c. They are already in the physical state required for ignition.

d. They have a specific gravity of 1.

C

When engineered roof joists fail quickly under fire conditions,:

Select one:

a. the roof decking will fall directly into the fire.

b. firefighters will only be able to tell by "sounding" or standing on the roof.

c. the roof will immediately start to sag.

d. there may not be any indicator to firefighters that the roof is failing.

D

Heated gases expand and become ____ ; when cooled they contract and become_____.

Select one:

a. convective; conductive

b. less dense; denser

c. conductive; convective

d. denser; less dense

B

How can a fire's location within a building influence fire development?

Select one:

a. Fuels in the lower level of a structure will pyrolize more quickly because of heat radiating from the hot gas layer.

b. Fuels in the upper level of a structure will pyrolize more slowly because of heat radiating from the hot gas layer.

c. Convected heat currents in the lower levels of a building will cause horizontal extension.

d. Fires in the upper level will generally extend downward much more slowly.

D

To reduce the risk of unpredictable window failure, firefighters must transition a fully developed fire from:

Select one:

a. preflashover to postflashover.

b. ventilation-limited to fuel-limited.

c. fully developed to incipient.

d. fuel-limited to ventilation-limited.

B

What causes backdraft in a ventilation-limited compartment fire?

Select one:

a. A decrease in temperature

b. A high neutral plane

c. An increase in fuel

d. An increase in ventilation

D

Open plan commercial structures, such as warehouse-style stores, have:

Select one:

a. low fuel loads and many physical barriers to help prevent the spread of fire and smoke.

b. high fuel loads but many physical barriers to help prevent the spread of fire and smoke.

c. high fuel loads and no physical barriers to prevent the spread of fire and smoke.

d. low fuel loads and no physical barriers to prevent the spread of fire and smoke.

C