Art of Reading Smoke Flashcards
What has led to a more volatile fire environment?
Low mass synthetics and big box trends
What are the four attributes of smoke leaving a structure?
volume, velocity, density, and color
A comparative analysis of the 4 attributes can help an officer
determine the size and location of the fire and hostile fire conditions such as flashover
Smoke leaving a structure needs to be interpreted as an aggregate of
solids, aerosols, and fire gases that were toxic, flammable, and volatile
The solids suspended in smoke are
carbon (soot), dust, and airborne fibers
The aerosols in smoke are
hydrocarbons (oils/tar)
Fire gases in smoke contain
carbon monoxide, hydrogen cyanide, acrolein, hydrogen sulfide, and benzene
What ultimately dictates fire behavior?
Hot flammable smoke
What are the products of fire limited to during open flame
Carbon, carbon dioxide, and water vapor
Where does smoke flammability begin?
FIre inside a compartment when heat is absorbed into the materials such as contents and walls/ceilings
What two triggers cause smoke to ignite
right temp and right mixture
What is an underventilated fire
when off-gassed smoke displaces air leading to increased levels of CO
What changes basic fire spread dynamics
accumulated smoke. Flame follows smoke flow
Which attribute by itself tells you very little about a fire
Volume
What emits very little smoke
a hot clean burning fire
A hot fast-moving fire in an under ventilated building will create
a tremendous volume of smoke
What kind of smoke will dampened materials create?
it’ll burn slowly and create lots of smoke that’s light in color
What changes in today’s contents create large volumes of smoke with little flame?
low-mass
What does the volume of smoke in a structure tell you
size of the fire based on the size of the occupancy (small fire can fill a small restaurant with smoke but a large fire would be needed to fill a warehouse)
What is velocity
the speed at which smoke leaves the structure
What does smoke velocity indicate?
The pressure that has built up in the structure
From a fire behavior standpoint, what two things cause velocity
heat and volume
Velocity caused by heat will
rise and slow gradually after it leaves the structure
Velocity caused by volume will
immediately slow and balance with outside airflow
Turbulent smoke leaving a structure indicates
flashover is likely to occur
How is turbulent flow created?
rapid molecular expansion of the gasses within the smoke restricted by the container
The expansion is caused by radiant heat feedback from the container that can’t absorb any more heat
A box that is still absorbing heat from smoke will create smoke that’s
more laminar
What is the most important smoke observation?
Turbulent vs laminar
Comparing smoke velocity at different openings can help
locate the seat of the fire - faster moving smoke will be closer to the fire
What is the smoke velocity outside the fire determined by
the exhaust opening
What happens to smoke as the distance from the fire increases
smoke follows the path of least resistance and will lose velocity
what must happen when attempting to locate the fire when comparing openings
you must only compare like size openings
What does smoke density tell you?
how bad things are going to be - Density refers to the smoke “thickness” which tells you how much laden fuel is in the smoke
What will thicker smoke indicate?
how far fire will spread during flashover. Thicker smoke will spread fire farther than thinner smoke
What does Thick black smoke do?
reduces the chance of survivability for victims
Thick laminar smoke can be a sign of
flashover
What does smoke color tell first-arriving companies
stage of heating and location of fire
What color smoke will all solid materials emit when first heated?
white smoke which is mostly moisture
What happens to the smoke of solids as they break down when heated
wood turns tan/brown and plastics turn grey
as materials are heated the smoke will turn all black
What happens when flame touches a surface
the smoke will turn black almost immediately
Black smoke that is high velocity and very thin indicates
flame pushed smoke and that the fire is nearby
What does brown smoke indicate
that wood is reaching ignition temperature which signals the fire is transitioning from a contents fire to a structure fire
White and grey smoke can indicate what depending on the velocity
that the smoke has traveled some distance away from the fire
White smoke that has its own pressure indicates______ while lazy white smoke indicates ______
Distance traveled from the fire
early stage heating
Brown smoke from structural spaces containing OSB or LVL indicates
critical strength has been lost and collapse is impending
Smoke that is uniform from multiple openings indicates
the fire is in a concealed space or deep seated
Black fire is indicative of
impending autoignition or flashover
black fire smoke can reach temps of 1000 degrees
Treat black fire like actual flames. Heat and cool
What changes the appearance of smoke
Wind, thermal balance, ventilation openings, water streams, and sprinkler systems
