64 Questions
What is the primary role of the incident safety officer (ISO) on the fire ground?
To assess smoke conditions and evaluate their hazards
What does brown smoke under pressure pushing from the eaves and soffit area below the roof indicate?
The fire is ventilation-limited and burning in an oxygen-restricted environment
What term is often used for the process of surfaces releasing a mix of particulates, aerosols, and gases while smoking?
Off-gassing
Why do materials begin to degrade and produce smoke when exposed to heat?
To release a mix of particulates, aerosols, and gases
What should the ISO consider when reading smoke coming from a structure?
All of the above options
In what situation does brown smoke under pressure pushing from the eaves and soffit area below the roof indicate?
Fire is ventilation-limited and burning in an oxygen-restricted environment
What is the primary reason for the volatility of smoke?
High surface-to-mass materials collect heat but have no mass to sink heat.
How does soot differ from ash in terms of supporting flame?
Soot is carbon and can support flaming, whereas ash is depleted salts that can no longer support flame.
What is the role of particulates in smoke in relation to fire behavior?
They displace air, which can cause a fire to become ventilation-limited.
What is the primary component of aerosols in smoke at a structure fire?
Hydrocarbons (oil and tar)
What color does flaming plastics release due to the hydrocarbons in smoke?
Satin (wet) black
What makes smoke at a typical house fire amazingly explosive?
The very common hydrocarbons in smoke.
Which gases of significant quantity affect fire behavior due to their flammable nature?
Carbon monoxide (CO), benzene (C6 H6 ), acrolein (C3 H4 O)
What should an ISO always wear when conducting fire suppression activities due to the toxicity of modern structure fire smoke?
Self-contained breathing apparatus (SCBA) and personal protective equipment (PPE)
"Open flaming" is considered beneficial because:
The products of combustion are minimized.
What triggers may cause accumulated smoke to ignite?
The right temperature and the right mixture
What is the key factor that determines if smoke gases below their ignition temperature will ignite?
Proper air mix
What happens when smoke gases reach ignition temperature?
They ignite with the right mixture in the air
What change occurs in fire spread dynamics when accumulated smoke ignites?
The fire spreads with the smoke flow instead of across surfaces of contents
According to John Mittendorf, what does smoke represent in relation to the fire?
"Smoke is the fire talking to you—it’s telling you the future."
Why does the ISO who pays attention to smoke make better decisions than the one focused on flaming?
Because smoke indicates how intense the fire is about to become
Why has the traditional four-phase growth model for building fires become outdated?
Due to overwhelming quantities of smoke from low-mass fuels
What are some factors that can lead to a six-phased growth model for compartmentalized fires?
The size of individual compartments, type of fire load, presence of smoke and fire control systems, and available flow paths
What do flow paths in compartmentalized fires refer to?
Avenues that heat, smoke, flames, and combustion air follow
What is likely to occur if overwhelming quantities of smoke exceed available flow paths in compartmentalized fires?
A ventilation-controlled event
What does the incipient phase of a ventilation-controlled fire involve?
The event that brings together heat, fuel, and oxygen to start combustion
Why has the growth phase been labeled as 'initial growth phase' in ventilation-controlled fires?
To emphasize its role in determining subsequent fire behavior
What role do flow paths play in ventilation-controlled fires?
They provide avenues for heat, smoke, flames, and combustion air movement
What prompted NIST and UL to secure federal grant money for researching modern fire behavior?
All of the above
According to the text, what is the primary difference between the four-phase fire growth model and the new ventilation controlled fire growth model?
The four-phase model is for a 'fuel-controlled' fire event while the new model is for a 'ventilation-controlled' fire event
What phase is characterized by smoke production displacing and limiting available combustion air, leading to a dangerously explosive condition?
Explosive growth phase
What is the proactive solution recommended to prevent the explosive growth phase?
Application of water to ceilings and walls to help quench and cool moving smoke
What effect can occur when firefighters advance toward the seat of the fire in zero-visibility conditions during the explosive growth phase?
They can be totally engulfed in flames
What can cause an explosive growth event during a compartmentalized fire?
Reintroduction of combustion air into a ventilation-controlled fire
What does the decay phase signify in the context of modern fire behavior?
'Fuel-limited' phase as available fuels become consumed and the fire begins to wane
According to the text, what can cause an air track flow path to reform back to the fire?
'Volume shift delay' after opening a door or window
What is the primary reason for considering an explosive growth event different from a backdraft event?
'Hot smoldering' backdraft event can be delayed as a volume shift takes place after opening a door or window
In which phase does room visibility remain good at lower levels, but smoke from the flames begins to accumulate at the ceiling?
Initial growth phase
What does room visibility indicate in the context of modern fire behavior?
Good room visibility indicates an abundance of air and prompt heating up of other fuels in the area
What is one detrimental effect of an explosive growth phase on firefighting efforts according to the text?
Firefighters may be totally engulfed in flames while advancing toward the seat of the fire in zero-visibility conditions
What is ghosting?
Intermittent ignition of small pockets of smoke, usually seen as fingers of flame that dance through the upper smoke layer
What is flame-over as described in the text?
The sustained burning of the overhead smoke layer within a room and/or hallway
What is a smoke explosion according to the text?
A hostile fire event that occurs when a spark or flame is introduced into a pocket of smoke that is below ignition temperature but above some aggregate flashpoint
What warning sign indicates backdraft?
Yellowish-gray smoke emitting from cracks and seams
What occurs during the explosive growth phase of a fire?
The development of an air track below the smoke when an opening is made
What characterizes ghosting as described in the text?
Intermittent ignition of small pockets of smoke, usually seen as fingers of flame that dance through the upper smoke layer
What warning sign indicates flashover?
Rapid change in smoke volume and velocity (getting worse in seconds)
What is backdraft as described in the text?
Occurs when oxygen is introduced into a closed, pressurized space where fire products are above their ignition temperature
"What action typically originates at the seat of the fire and travels along the heat flow paths during a flame-over?"
The flames start near the ventilation opening and burn back to the fire seat where they can trigger a flashover of the room (ignition of all surfaces and contents)
"What does explosive growth phase include?"
Smoke flame-over upon the breaking of windows or opening of doors (late sign)
"What occurs during explosive growth phase?"
Slow but steady smoke flowing from closed doors or windows
"What serves as a warning sign for impending flashover or flame-over according to the text?"
Ghosting
What is a flashover?
A sudden hostile fire event that occurs when all the surfaces and contents of a space reach their ignition temperature nearly simultaneously
What is a backdraft?
An explosive event that occurs when air is suddenly reintroduced into a closed space filled with pressurized, ignition-temperature, and oxygen-deprived products of combustion and pyrolysis
What does smoke velocity indicate?
The pressure that has built up in the building
What is the primary cause of a flashover?
Room surfaces and contents reaching their ignition temperature nearly simultaneously
How does a backdraft differ from an explosive growth event?
A backdraft involves instantaneous ignition upon the introduction of air, while an explosive growth event spreads like a detonation burning above the speed of sound
What is smoke volume an indicator of?
The amount of fuels that are off-gassing in a given space
What does smoke density contribute to understanding?
The story behind fire behavior
What does smoke color indicate?
The substances burning and stages of combustion
How does smoke velocity relate to smoke volume?
Smoke volume is one of the generators of smoke velocity
What are some reactive warning signs for hostile fire events that most firefighters list?
Sudden heat buildup that forces them to the floor
What does low-ignition-temperature gases/aerosols being already ignitable when firefighters feel heat indicate?
The room has been heated to the point of flashover, but ignition can't occur due to lack of combustion air availability
How does an explosive growth event differ from a backdraft in terms of air introduction?
The explosive growth event spreads like a detonation upon instantaneous air introduction, while a backdraft is triggered by a volume shift between smoke and air over a 10- to 90-second time span
Explore the history and development of scientific research on fire behavior, including the contributions of NIST and UL in the late 1990s. Discover the impact of federal grant funding on advancing knowledge in fire science.
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