Fire Behavior and Combustion FINAL

Chapters 8-13

How much thermal radiation typically comes from the soot contained in a flame?

A) 80 percent

B) 75 percent

C) 60 percent

D) 55 percent

A) 80 percent

Smoke exiting a burning building appears very light in color. Which of the following aerosols are responsible for this appearance?

A) Carbonaceous solid particles

B) Hydrogen particles

C) Liquid droplets

D) Carbon dioxide droplets

C) Liquid droplets

Why is understanding the formation of soot and sooting tendency of fuels of particular importance to the aviation industry?

A) Higher-sooting fuels may lead to poor fuel economy and can foul aircraft engines.

B) Higher-sooting fuels may contribute to environmental pollution.

C) Lower-sooting fuels may lead to less available engine power.

D) Lower-sooting fuels may not have enough vapor pressure to provide needed lift for an aircraft

A) Higher-sooting fuels may lead to poor fuel economy and can foul aircraft engines.

Why does methanol burn with practically no particulate production?

A) Because it is a flaming fuel that contains oxygen

B) Because it is a nonflaming fuel that contains oxygen

C) Because it is a flaming fuel that does not contain oxygen

D) Because it is a nonflaming fuel that does not contain oxygen

A) Because it is a flaming fuel that contains oxygen

How does ventilation impact smoke yield?

A) Smoke yields decrease significantly as the fire proceeds from well-ventilated to underventilated.

B) Smoke yields from underventilated fires are approximately double those from well-ventilated flaming of the same materials.

C) Smoke yields from well-ventilated fires are approximately double those from underventilated fires of the same materials.

D) Smoke yields increase significantly as higher amounts of ventilation are introduced into the fire plume

B) Smoke yields from underventilated fires are approximately double those from well-ventilated flaming of the same materials.

How do infrared-sensitive video cameras increase the ability of firefighters to “see” through smoke?

A) The infrared radiation wavelengths emitted from heated objects have longer wavelengths than visible light, which prevents particle scattering.

B) The infrared radiation wavelengths emitted from heated objects have shorter wavelengths than visible light, which prevents particle scattering.

C) The infrared radiation wavelengths emitted from heated objects have longer wavelengths than visible light, which causes smoke particles to scatter.

D) The infrared radiation wavelengths emitted from heated objects have shorter wavelengths than visible light, which causes smoke particles to scatter

A) The infrared radiation wavelengths emitted from heated objects have longer wavelengths than visible light, which prevents particle scattering.

In smoldering fires, why is the oxidation zone very thin and cool relative to flaming fires?

A) Because heat-generated buoyancy lifts heat away from the point of pyrolysis

B) Because effluent temperatures have lifted away from the smoldering material

C) Because ventilation in the room has dispersed oxygen toward warmer areas

D) Because no flames are present

D) Because no flames are present

Which type of smoke alarm employs voltage across a sensing chamber in order to detect smoke particles?

A) Non-ionizing smoke alarm

B) Ionization smoke alarm

C) Photoelectric smoke alarm

D) Calorimetric smoke alarm

B) Ionization smoke alarm

Which CO detection device is advantageous for residential use because its output is proportional to CO concentration and it is operated at room temperature?

A) Electrochemical CO sensor

B) Semiconductor Electrical Resistance Detector

C) Photoionization alarm

D) Ionizing CO detector

A) Electrochemical CO sensor

A light emitting diode (LED) would be found in which type of smoke alarm?

A) Polarizing smoke alarm

B) Photoelectric smoke alarm

C) Ionization smoke alarm

D) Electrochemical smoke alarm

B) Photoelectric smoke alarm

Why should homeowners be advised to place smoke alarms high on the wall or on the ceiling of each bedroom?

A) Because the natural flow of warm fire effluent travels upward and will reach high levels of walls and ceilings prior to lower areas of the room

B) Because alarms placed in other areas of the home may not be audible to bedroom occupants due to dense smoke

C) Because an open bedroom door could increase fire growth that destroys an alarm installed at a lower level

D) Because alarms installed at lower levels are difficult for occupants to see

A) Because the natural flow of warm fire effluent travels upward and will reach high levels of walls and ceilings prior to lower areas of the room

When HF, HBr, or HCl is present in smoke, what atoms are likely to be present?

A) Oxygen, fluorine, or chlorine

B) Hydrogen, oxygen, or nitrogen

C) Fluorine, bromine, or chlorine

D) Phosgene, chlorine, or carbon

C) Fluorine, bromine, or chlorine

What is the available safe escape time?

A) The calculated time interval between flashover and total room involvement, preventing occupant escape

B) The calculated time interval between the time of ignition and the time that fire conditions would incapacitate an occupant

C) The calculated time interval between an occupant’s recognition of fire and their attempt to extinguish it

D) The calculated time interval between an occupant’s exposure to fire products and their ability to escape

B) The calculated time interval between the time of ignition and the time that fire conditions would incapacitate an occupant

Impaired mobility and reduced clarity of thinking are examples of which type of smoke exposure effects?

A) Chronic effects

B) Toxic effects

C) Postfire effects

D) Acute effects

D) Acute effects

What molecule is formed when a CO molecule bonds to the hemoglobin in red blood cells?

A) Hydroxyhemoglobin

B) Carboxyhemoglobin

C) Hydrogen oxide

D) Carbon dioxide

B) Carboxyhemoglobin

What was the major significant finding of the Maryland forensic study on fire victims?

A) That 80 percent of victims died from second- and third-degree burns

B) That 80 percent of victims could have died as a result of carbon dioxide inhalation

C) That 80 percent of victims could have died as a result of carbon monoxide inhalation

D) That 60 percent of victims suffered from hydrogen cyanide poisoning

C) That 80 percent of victims could have died as a result of carbon monoxide inhalation

Based on laboratory studies with test animals, how is fire-generated CO toxic?

A) It is an irritant upon contact.

B) It is an asphyxiant.

C) It is a corrosive gas.

D) It is a hallucinogen

B) It is an asphyxiant.

What symptoms might a person experience when the percentage of carboxyhemoglobin increases to 20 percent in the blood stream?

A) Death within an hour

B) Severe headache, vomiting

C) Coma, collapse

D) Slight headache, dizziness

D) Slight headache, dizziness

What percentage of hemoglobin converted to carboxyhemoglobin can result in death with an hour?

A) 10 to 20 percent

B) 30 to 40 percent

C) 40 to 50 percent

D) 80 to 90 percent

D) 80 to 90 percent

Which gas has a lethal toxic potency that is approximately 20 times that of CO?

A) Carbon dioxide

B) Hydrogen cyanide

C) Phosgene

D) Aromatic hydrocarbon

B) Hydrogen cyanide

What type of materials can produce smoke containing hydrogen cyanide?

A) Highly oxygen-rich materials

B) Materials containing nitrogen

C) Carbon neutral materials

D) Hydrocarbon materials

B) Materials containing nitrogen

How does hydrogen cyanide harm the body?

A) It displaces oxygen in the blood stream, preventing circulation.

B) It prevents blood from reaching the brain, impairing motor skills and cognition.

C) It combines with body and brain cell enzymes and inactivates them so the cells can no longer accept oxygen.

D) It forms carboxyhemoglobin in the blood stream

C) It combines with body and brain cell enzymes and inactivates them so the cells can no longer accept oxygen.

How can faster and more accurate fire alarms reduce firefighter and public exposure to smoke?

A) Alerting firefighters more quickly so that they can avoid making entry during the most toxic phases of fire

B) Alerting occupants when fires are smaller and generating less smoke so that early notification to firefighters can be made

C) Alerting and automatically activating sprinkler systems so that firefighters do not have to engage

D) Alerting occupants by notifying their cellular devices of a possible fire

B) Alerting occupants when fires are smaller and generating less smoke so that early notification to firefighters can be made

Why have authorities begun banning or restricting the use of certain fire retardant chemicals?

A) Because they have been shown some indication of significant health risk

B) Because they have been shown to accelerate fire growth in certain synthetic materials

C) Because they have been proven to be ineffective

D) Because they have been proven to produce second-degree burns even at low temperatures

A) Because they have been shown some indication of significant health risk

What interior building components are most susceptible to nonthermal smoke damage?

A) Electronics

B) Wood components

C) Drywall

D) Concrete

A) Electronics

Why is understanding of limiting hazards important?

A) So firefighters can pre-plan response activities

B) So occupants and firefighters are aware of their own performance limitations

C) So mitigation activities can be focused on the most effective improvements in the safety for occupants and fire personnel

D) So structural engineers can design fireproof buildings

C) So mitigation activities can be focused on the most effective improvements in the safety for occupants and fire personnel

Which term describes the fire stage where no flames are visible and the combustible item no longer generates heat or combustion products?

A) Fire extinguishment

B) Fire control

C) Fire containment

D) Fire inerting

A) Fire extinguishment

Which items would be found in a Class A fire?

A) Cooking oil and grease

B) Electrical equipment

C) Gasoline

D) Cloth and paper

D) Cloth and paper

Which items would be found in a Class B fire?

A) Cloth and paper

B) Electrical equipment

C) Methanol

D) Magnesium

C) Methanol

Which items would be found in a Class C fire?

A) Electrical equipment

B) Wood and paper

C) Magnesium

D) Cooking oil

A) Electrical equipment

Which items would be found in a Class D fire?

A) Wood and paper

B) Magnesium

C) Cooking grease

D) Polypropylene

B) Magnesium

At what temperature range are residential sprinklers typically designed to actuate?

A) 100 °F to 175 °F

B) 135 °F to 170 °F

C) 200 °F to 250 °F

D) 300 °F to 350 °F

B) 135 °F to 170 °F

Which extinguishing agent is most desirable for use on solid combustibles because of its high heat of vaporization?

A) Carbon dioxide

B) Dry chemical

C) Water

D) Protein foam

C) Water

By what action does aqueous foam work to suppress flames from burning hydrocarbons?

A) It sinks beneath the fuel’s surface to cool heated fuels and prevent further creation of flammable gases.

B) It forms a continuous layer on top of burning fuel, cooling the surface and separating fuel vapors from air.

C) It forms small pockets of chemical layers on top of burning fuel, reducing the amount of oxygen that reacts with flammable vapors.

D) It immediately cools the entire body of fuel, reducing flammable vapor creation

B) It forms a continuous layer on top of burning fuel, cooling the surface and separating fuel vapors from air.

Which of the following liquids are nonflammable and could be considered as fire suppressants?

A) Bromine

B) Helium

C) Chlorine

D) Hydrogen

A) Bromine

Which gas is considered to be a noble gas?

A) Argon

B) Hydrogen

C) Chlorine

D) Nitrogen

A) Argon

Why is it important to evacuate any personnel not wearing SCBA from an environment where noble gas mixtures are to be applied for fire suppression?

A) Noble gases are an irritant and will cause respiratory distress.

B) Noble gases are toxic and will cause respiratory infection.

C) Noble gases dilute ambient air to the point where a person isn’t inhaling enough oxygen.

D) Noble gases are poisonous and will cause organ failure upon absorption into the respiratory tract

C) Noble gases dilute ambient air to the point where a person isn’t inhaling enough oxygen.

Why have halon 1301, 1211, and 2402 been phased out of use in many parts of the world?

A) Because of their high corrosively when exposed to fire

B) Because of their asphyxiant nature

C) Because they are among the highest ozone-depletion-potential chemicals

D) Because they are expensive to produce and use

C) Because they are among the highest ozone-depletion-potential chemicals

13. Applied with a stream or widely dispersed, which agent is mainly used to extinguish Class B and Class C fires?

A) Halon 1301

B) Carbon dioxide

C) Protein foam

D) Dry chemical powders

D) Dry chemical powders

What popular name is used for the dry chemical agent KCl?

A) Super K

B) Purple K

C) Baking soda

D) ABC

B) Purple K

What is the best tactic for extinguishment of flowing gas flames?

A) Introduce large volumes of water to keep the gas from producing flammable vapors.

B) Apply AFFF to the gas container and surroundings to prevent ignition.

C) Increase fresh air supply to the area so that oxygen concentrations are too saturated for flaming to occur.

D) Shut off the flow of gas

D) Shut off the flow of gas

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.