Fire Behavior and Combustion Quiz

Chapters 8-10

How many different categories are available for flame classification?

A) 5

B) 8

C) 12

D) 16

D) 16

An upholstered chair in a bedroom is ignited from an improperly discarded cigarette. In the incipient phases, the fire plume grows and the flame streamlines are smooth. Which type of flame is present in this scenario?

A) Stationary

B) Propagating

C) Laminar

D) Turbulent

C) Laminar

The generation of species so highly reactive that they can destabilize a fuel molecule is the first step of:

A) combustion

B) the ignition process

C) detonation

D) the containment of fire

B) the ignition process

Which type of ignition is represented by a person lighting a candle with a match?

A) Piloted

B) Non-piloted

C) Thermal

D) Auto

A) Piloted

Which gas has the highest thermal ignition temperature?

A) Methane

B) Propane

C) Ethane

D) Acetylene

A) Methane

Which type of mixture is typically found to be the easiest to ignite?

A) Lean

B) Rich

C) Diffused

D) Stoichiometric

D) Stoichiometric

What defines the boundaries of combustible mixtures?

A) Molecular weight

B) Flammability limits

C) Ignition temperature

D) Atomic structure

B) Flammability limits

An active propane leak has ignited and is burning violently. A firefighter is able to turn off the main supply valve, and the flames begin to decrease in size and velocity. What is occurring to the flammable mixture?

A) It is becoming oversaturated with oxygen, reaching its ventilation limit.

B) It is becoming fuel lean, reaching the lean flammability limit.

C) It is burning so cleanly that the flames are becoming invisible.

D) It reaches a stoichiometric mixture, which is not flammable

B) It is becoming fuel lean, reaching the lean flammability limit.

What happens when nitrogen is introduced to a stoichiometric methane–air mixture?

A) Regardless of the percentage of nitrogen added, the mixture immediately becomes more flammable.

B) Regardless of the percentage of nitrogen added, the mixture immediately becomes less flammable.

C) If nitrogen at more than 35 percent by volume is added, the mixture becomes nonflammable.

D) If nitrogen at more than 35 percent by volume is added, the mixture becomes highly flammable

C) If nitrogen at more than 35 percent by volume is added, the mixture becomes nonflammable.

When does the leading edge of burning move fastest?

A) When the released heat is absorbed into surrounding combustibles

B) When the released heat preheats the approaching fuel–air mixtures

C) When the released heat is entrained in the plume flow

D) When the released heat is confined to a small area

B) When the released heat preheats the approaching fuel–air mixtures

The rapid release of enthalpy and an increase in pressure when a premixed flame propagates in a confined space is referred to as a(n):

A) enthalpy force.

B) deflagration.

C) conflagration.

D) explosion

D) explosion

What are the primary differences between a deflagration and a detonation?

A) A deflagration is supersonic while a detonation is subsonic.

B) A deflagration is characterized by a Mach number, and a detonation is characterized by meters per second.

C) A deflagration is subsonic, and a detonation is supersonic.

D) There are no differences between a deflagration and a detonation

C) A deflagration is subsonic, and a detonation is supersonic.

A natural gas appliance in a residential household is leaking. How is the leaking gas most likely to behave?

A) The gas will rapidly sink to the floor and lower areas of the house.

B) The gas will spread latently at the same level of its release.

C) The gas will slowly rise and begin filling the room from the ceiling downward.

D) The gas will quickly mix and dissipate when in contact with ambient air nitrogen

C) The gas will slowly rise and begin filling the room from the ceiling downward.

Which two substances react violently with water to form hydrogen gas?

A) Magnesium and copper

B) Ammonia and chlorine

C) Sodium and potassium

D) Methane and petroleum

C) Sodium and potassium

What principal characteristic of a liquid contributes most to its ignition?

A) The viscosity of the liquid

B) The flash point of the liquid

C) The fire point of the liquid

D) The temperature at which the liquid forms a fuel–air mixture that is within its flammable limits

D) The temperature at which the liquid forms a fuel–air mixture that is within its flammable limits

When a flammable liquid is ignited, and flame moves across the surface momentarily without sustained ignition, what temperature has most likely been obtained?

A) Ignition temperature

B) Fire point

C) Flash point

D) Combustion point

C) Flash point

At what temperature is combustion of a liquid fuel sustained after removal of an ignition source from a flammable liquid?

A) Ignition temperature

B) Fire point

C) Flash point

D) Combustion temperature

B) Fire point

Which classification of liquids would gasoline be categorized into?

A) Class I

B) Class II

C) Class III

D) Class IV

A) Class I

Diesel fuel has a flash point between 40 °C (104 °F) and 55 °C (131 °F). Which classification of liquids does it fall into?

A) Class I

B) Class II

C) Class III

D) Class IV

B) Class II

Which description most accurately represents Class I liquids?

A) Liquids with flash points below 93 ° (200 °F), an indoor temperature that could be reached only during summer months

B) Liquids with flash points at or above 38 °C (100 °F) but below 60 °C (140 °F), an ambient temperature that could be reached with a modest degree of heating

C) Liquids with flash points below 38 °C (100 °F), an indoor temperature that could be reached during the year if there is no climate control system

D) Liquids with flash points at or above 60 °C (140 °F), an ambient temperature that would require considerable heating

C) Liquids with flash points below 38 °C (100 °F), an indoor temperature that could be reached during the year if there is no climate control system

What temperature has been reached when the vapor pressure of a liquid equals the lower flammability limit?

A) Flash point

B) Fire point

C) Ignition temperature

D) Combustion temperature

A) Flash point

How does atmospheric pressure affect flash point?

A) Flash points are higher than normal at pressures below atmospheric pressure and lower than normal at pressures above atmospheric pressure.

B) Flash points are lower than normal at pressures below atmospheric pressure and higher than normal at pressures above atmospheric pressure.

C) Flash points are lower than normal at pressures below atmospheric pressure and unaffected by pressures above atmospheric pressure.

D) Flash points are higher than normal at pressures below atmospheric pressure and unaffected by pressures above atmospheric pressure

B) Flash points are lower than normal at pressures below atmospheric pressure and higher than normal at pressures above atmospheric pressure.

Once a fluid has been heated to the point that produces molecular vibration intense enough to break molecular bonds and produce free radicals that collide with oxygen molecules, what event may occur?

A) Combustion

B) Piloted ignition

C) Flame propagation from flash point

D) Autoignition

D) Autoignition

Why is more heat required to reach the lean limit fuel concentration of a higher-density liquid?

A) Less heat is initially available to heat the slowly vaporizing fuel.

B) More mass is present that must be heated to raise the fuel temperature.

C) More air is entrained into the fuel–air mixture, requiring more heat.

D) Less air is entrained into the fuel–air mixture, requiring more heat

B) More mass is present that must be heated to raise the fuel temperature.

How does flame typically spread over a liquid whose initial temperature is well below its flash point?

A) The liquid must be ignited through piloted ignition and create radiative heat that will cause adjacent liquid to autoignite.

B) The liquid must be heated by an ignition source to a temperature greater than its flash point, then radiative heat transfer must be sufficient to heat adjacent cold liquid to its fire point.

C) The liquid must be heated to a point of molecular autoignition so that simultaneous flaming can occur across the surface of the liquid.

D) The liquid must be heated throughout so that all points reach flash point simultaneously

B) The liquid must be heated by an ignition source to a temperature greater than its flash point, then radiative heat transfer must be sufficient to heat adjacent cold liquid to its fire point.

What occurs when a flame or spark contacts a liquid whose initial temperature is above its flash point?

A) A combustible vapor concentration in excess of the lower flammability limit exists over the surface; therefore, flame contact will ignite the entire surface.

B) A combustible vapor concentration exists near the surface but has not yet reached lower flammability limits; therefore, flame contact will not result in ignition.

C) A combustible vapor concentration exists near the surface in excess of upper flammability limits and is too rich to burn when in contact with a flame or spark.

D) A combustible vapor concentration has not yet formed; therefore, no ignition will occur when in contact with a flame or spark.

A) A combustible vapor concentration in excess of the lower flammability limit exists over the surface; therefore, flame contact will ignite the entire surface.

What type of lithium-ion battery is most commonly used in electric vehicles?

A) Magnesium oxide blended with copper

B) Cobalt oxide with a cathode of magnesium oxide blended with nickel oxide

C) Magnesium oxide cathode blended with silver and 24K gold

D) Cobalt oxide with a cathode of copper and nickel oxide

B) Cobalt oxide with a cathode of magnesium oxide blended with nickel oxide

What typically occurs as a burning liquid’s depth becomes sufficiently thinner as it flows from its container?

A) Flame growth is intensified because of the lower fuel mass.

B) Flame growth is halted because of the lower fuel mass and resulting lean flammability limit.

C) Flames are limited due to heat losses to the ground underneath the flowing liquid.

D) Flames are further propagated due to the radiative heat from the closer ground surface

C) Flames are limited due to heat losses to the ground underneath the flowing liquid.

Which special hazard associated with liquid fuel fires involves a container failure caused by rapidly expanding vaporized fuel?

A) Boilovers

B) Cooking oil fires

C) UCVEs

D) BLEVEs

D) BLEVEs

What is the result of ignition of a large airborne mass of a flammable vapor, resulting in a flame speed that may accelerate to high velocities and produce significant blast overpressure?

A) Boiling liquid expanding vapor overpressure

B) Boiling liquid expanding vapor explosion

C) Unconfined vapor cloud overpressure

D) Unconfined vapor cloud explosion

D) Unconfined vapor cloud explosion

In what ways does the burning of a solid fuel differ from the burning of gaseous and liquid fuels?

A) There is often no change in the fuel chemistry of solid fuels during combustion.

B) The fuel composition of a burning solid remains identical throughout the burning process.

C) Significant chemical and physical change generally occurs within the solid during burning.

D) The emitted volatiles have the same chemistry as the original solid

C) Significant chemical and physical change generally occurs within the solid during burning.

What considerations are required for the heat transfer to, from, and within a burning solid?

A) Changes at the fuel surface and chemical changes below the surface

B) Fuel-to-air mixture of emitted volatiles and heat of release rate

C) Ignition temperature of the solid and flame height

D) Vaporization of the solid and direct flame contact

A) Changes at the fuel surface and chemical changes below the surface

How does the involvement of a solid fuel in fire generally begin?

A) With direct heat contact to the fuel surface, creating conductive heat across the surface, decomposing the solid into gas particles

B) With radiative, convective, and/or conductive heat decomposing the solid into smaller fragments

C) With direct heat contact to the fuel surface, resulting in immediate flame and radiative heat

D) With radiative, convective, and/or conductive heat changing the internal chemical properties of the solid

B) With radiative, convective, and/or conductive heat decomposing the solid into smaller fragments

The decomposition process for a solid fuel, where volatile compounds are released is referred to as:

A) degradation.

B) pyrolysis.

C) combustion.

D) decay

B) pyrolysis.

How would an oxygen-depleted atmosphere affect the process of pyrolysis?

A) Pyrolysis would proceed at an increased rate.

B) Pyrolysis would proceed at a decreased rate.

C) Pyrolysis would begin to create oxygen.

D) Pyrolysis would cease progress

B) Pyrolysis would proceed at a decreased rate.

How does the pyrolyzate of a solid differ from the vapor from a pure liquid?

A) Pyrolyzate is typically uniform while gaseous vapors contain a mixture of compounds.

B) Pyrolyzate is typically a mixture of many decomposition products while the vapors from a pure liquid are a single molecule.

C) Vapors tend to ignite less readily than pyrolyzate.

D) Pyrolyzate contains very few flammable components

B) Pyrolyzate is typically a mixture of many decomposition products while the vapors from a pure liquid are a single molecule.

Why does the risk of fire from cigarettes increase with individuals using supplemental medical oxygen?

A) The supplemental oxygen could cause the cigarette to spontaneously ignite as the individual is smoking.

B) The enriched-oxygen environment could contribute to extensive smoldering of the cigarette should it be dropped onto nearby combustibles, resulting in a potential fire.

C) The use of oxygen increases the likelihood of explosion from a lit cigarette.

D) The enriched-oxygen environment causes cigarettes in particular to release flammable vapors that can self-ignite.

B) The enriched-oxygen environment could contribute to extensive smoldering of the cigarette should it be dropped onto nearby combustibles, resulting in a potential fire.

Which action could result in a quick transition from smoldering to flaming?

A) Soaking the smoldering item with water and transporting it outdoors

B) Opening a door or window to vent the gases and odors from smoldering

C) Closing doors and windows to a room where contents have been smoldering

D) Applying carbon dioxide extinguishing agent to a smoldering item

B) Opening a door or window to vent the gases and odors from smoldering

What is developed or adopted by governments to guide features such as construction materials, fire endurance of structure members, and means of egress?

A) Test methods

B) Fire codes

C) Building codes

D) Moral codes

C) Building codes

Which synthetic polymer is classified based on the nature of the chemical synthesis?

A) Homopolymers

B) Copolymers

C) Linear polymers

D) Condensation polymers

D) Condensation polymers

How do fire barriers modify the ignition and burning behavior of soft furnishings?

A) Restraining the carbon containing pyrolyzate, providing more time for char to form

B) Allowing oxygen in the surrounding air to reach the fuel side of the barrier and create an oxygen-rich layer

C) Conducting heat away from the area of flame impingement

D) Insulating pyrolyzate from oxygen-rich ambient air

A) Restraining the carbon containing pyrolyzate, providing more time for char to form

Once a flame has progressed a short distance from its source, which of the following variables determine its rate of spread?

A) Thermal conductivity of the solid

B) Heat of combustion of the solid

C) Degree of preheating of the solid

D) Radiative heat flux underneath the solid

C) Degree of preheating of the solid

Why do noncharring materials typically present a greater fire hazard than charring materials?

A) Charring combustibles produce more carbon particles, which inhibit flaming.

B) Charring combustibles allow more pyrolyzate to reach flaming areas, creating a fuel-rich layer that cannot burn.

C) Charring combustibles produce a char layer that hinders the flow of pyrolyzate to the flame and insulates the solid, reducing pyrolysis.

D) Charring combustibles generally melt and burn clean, producing less overall heat

C) Charring combustibles produce a char layer that hinders the flow of pyrolyzate to the flame and insulates the solid, reducing pyrolysis.