Chapter 6 Reading Smoke Flashcards
Define Backdraft
AN explosive event that occurs when air is suddenly reintroduced into a closed space that is filled with pressurized, ignition-tempature, and oxygen deprived products of combustion and pyrolysis
Define Black fire
A slang term for smoke that is high-volume, has turbulent velocity, is ultra-dense, and is dep black; a sign of impending autoignition and flashover
Define explosive growth phase
A rapid fire growth phenomenon that occurs when combustion air is reintroduced into a ventilation-controlled fire, leading to smoke flame-over and room and/or hallway
Define flashover
A sudden hostile fire event that occurs when all the surfaces and contents of a space reach their ignition temperature nearly simultaneously, resulting in a full-room fire involvement
Define flow path
An avenue that heat, smoke, flames, and combustion air follow
Define ghosting
A hostile fire event warning sign that is characterized as the intermittent ignition of small pockets of smoke; usually seen as fingers of flame that dance through the upper smoke layer
Define hostile fire event
A fire behavior phenomenon that can suddenly harm firefighters; events include explosive growth phase, flashover, backdraft, smoke explosion, and flame-over
Define pyrolysis
Also referred to as pyrolytic decomposition, the chemical breakdown of compounds into other substances by heat alone
Define smoke
The products of incomplete combustion and pyrolysis; it includes an aggregate of particles, aerosols, and fire gases that are toxic, flammable, and volatile
Define smoke explosion
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. The result is a split-second ignition and rapid expansion of that pocket with no sustained burning
What are the four key attributes of smoke?
volume, velocity, density, color
What two sources is smoke developed?
incomplete combustion, pyrolitic decomposition
Define aerosols
suspended or propelled liquid
Define off-aggregating
releasing a mix of particulates and aerosols as well as gases
slang term is off gassing
3 things smoke is made up of
particulates, aerosols, gases
Carbon that can support flaming
Soot
Define Ash
Trace metals and minerals (depleated salts) that can no longer support flame
Related to reading smoke define colors of carbon (soot) in smoke vs Ash in smoke
carbon adds flat dry black color
ash adds dirty white color
What are the primary liquids in smoke?
moisture and hydrocarbons
What gives smoke a satin wet color?
Hydrocarbons
List the gases that are present in smoke that affect fire behavior?
CO, Hydrogen cyanide, benzene, acrolein, hydrogen sulfide
Smoke is ignitable as low as ___ degrees and flammable range of ___ to ____
450F, 1 to 74% in air
Define piloted ignition
smoke gases below ignition temp but above flashpoint needing only a proper air mix and sudden spark or flame to complete ignition
What can tell the ISO what is about to happen in a structure fire?
Smoke flow
What are the factors of a six-phased growth model (vent controlled model)
size of individual compartments
type, quantity, and continuity of fire load
presence or lack of smoke and fire control systems
available flow paths through adjoining compartments and the exterior of the building
size and status of exterior openings
What are the phases of ventilation-controlled fire?
ignition phase initial growth phase ventilation-limited phase explosive growth phase fully developed phase decay phase
Event that brings together heat, fuel, and oxygen to start the self-sustaining process of combustion
Ignition phase
fire growth phase controlled by the proximity of burning fuels to other burnable fuels. pyrolysis begins and smoke production become abundant
initial growth phase
Phase of compartmentalized fire condition where open flaming decreases due to smoke displacing available combustion air
Ventilation-limited phase
Phase of rapid fire growth that occurs when combustion air is reintroduced into a ventilation-controlled fire leading to smoke flame over and flashover
Explosive growth phase
Phase of total flame involvement of the interior flow paths
Fully developed phase
Phase of available fuels consumed and fire begins to wane
Decay phase
What are the hostile fire events?
flashover, backdraft, smoke explosion, and flame over
Define flame over
ignition and sustained burning of the overhead smoke layer within a room and/or hallway
What typically originates at the seat of the fire and travels along the heat flow path
Flame over
Which direction does flames travel in a ventilation limited flame over?
Toward the seat of the fire along the heat flow path
Event that typically occurs in an area away from the fire such as a dead-end hallway, top of a stairwell, an uninvolved room above the fire or a void space
Smoke explosion
Difference between a explosive growth event and backdraft?
backdraft is instantaneous and explosive growth event occurs over 10 - 90 seconds
What are the warning signs of flashover?
turbulent smoke flow that has filled a compartment
Ghosting
Vent-point ignition (exterior autoignition)
Rapid change in smoke volume and velocity
What are the warning signs of Backdraft
yellowish gray smoke emitting from cracks and seams
bowing, black stained windows
closed pressurized box with signs of extreme heat
puffing from the cracks and seams of a closed box
What are the warning signs of a smoke explosion
Smoke that is being trapped in a separate space above the fire
signs of a growing fire
signs of smoke starting to pressurize
What are the warning signs of a flame over?
Increase in smoke speed
Ghosting
Laminar flow of smoke that is becoming turbulent
Smoke flowing from hallways and stairways faster than a ff can move
What are the four distinctive characteristics for smoke?
Volume, velocity, density, and color (VVDC)
What are the two forces that cause smoke to pressurize
convection heat, smoke volume
Volume pushed smoke does what outside the fire building?
it will immediately slow down and balance with outside airflow
