Reading Smoke Flashcards
Where did this reading smoke class come from?
This class adapted from: “The Art of Reading Smoke” by Dave Dodson (Retired Battalion Chief) and “Reading Smoke” by Gary Ells (Battalion Chief)
Why do we read smoke?
- To help determine what we have
- To help determine where it’s at
- To help us predict where it is going
- To help us predict what is going to happen
- To help us better plan to deal with it
Evaluating smoke allows us to determine and plan for:
o Size and extent of the incident
o Speed and direction of fire spread
o Degree of heat release and stage of the fire
o Possible adverse fire events
o Appropriate prioritization of strategies and tactics
What is smoke?
a. The visible vapor and gases given off by a burning or smoldering substance, esp. the gray, brown, or blackish mixture or gases and suspended carbon particles resulting from combustion of wood, peat, coal or other organic matter
Smoke Composition
a. Gases
b. Aerosols
c. Particulates
d. The bottom line is SMOKE is unburned fuel
What has changed with fuels mass?
i. Today’s structures exhibit materials with considerably less mass than yesterday’s
1. This is due to the increased use of engineered materials such as trusses
2. In terms of a structure fire….MASS = TIME
What has changed with fuels composition?
i. More synthetic materials such as plastics
ii. Plastics put off twice the BTU’s as normal Class A fuels
iii. Plastics also produce thick black clouds of smoke with more flammable gases than normal Class A fuels
iv. This means….More heat within the structure and more flammable smoke
What has changed with regards to structures?
i. More synthetic materials such as plastics
ii. Plastics put off twice the BTU’s as normal Class A fuels
iii. Plastics also produce thick black clouds of smoke with more flammable gases than normal Class A fuels
iv. This means….More heat within the structure and more flammable smoke
What has changed with regards to our equipment?
i. Better turnouts than in the past
ii. Use of SCBA is prevalent
iii. Faster notification systems leading to faster response times
iv. Equipment changes allow us…
1. To go farther into, and stay longer in hotter environments
2. To arrive on-scene prior to flashover
e. It all adds up to an increased exposure to extreme fire behavior events for today’s firefighters
f. The ability to read the smoke will allow us to avoid these events and deal with them safely
Smoke as fuel
a. Smoke has trigger points
i. Flash point
ii. Fire point
iii. Ignition temp
b. How does Flammable range factor in?
Predicting fire events
a. Need to be able to determine…
i. What stage the fire is in
ii. Is the “box” absorbing heat
1. Laminar vs. Turbulent smoke flow
b. What fire events do we want to predict
i. Flashover
ii. Backdraft
iii. Smoke explosion
iv. Rapid fire spread
Reading smoke definition of flashover and warning signs
Transition between the growth and fully developed fire stages
i. Interior warning signs:
1. Heavy interior smoke conditions
2. Rollover occurring
3. High heat banking down suddenly
ii. Exterior warning signs:
1. Heavy, Dark, Turbulent smoke exiting
2. Auto ignition in the exiting smoke column
3. Advanced stage of burning
Reading smoke definition of backdraft and warning signs
An explosion caused by the sudden introduction of oxygen to a smoldering oxygen deprived fire
i. Warning Signs
1. Yellowish-grey smoke
2. Whistling
3. Bowing windows
4. Sealed container
5. Pressurized smoke form small cracks
6. Little or no visible flame from exterior
7. Smoke stained, crazed windows
Smoke explosions
Explosion in adjoining compartments where the smoke is below ignition temperature
i. Warning Signs:
1. Large amounts of relatively cool smoke in rooms or areas adjacent to the fire room
a. Upstairs from fire?
2. Growing fire
3. Increasing smoke density
4. Air intake overtaking smoke exiting
Reading smoke rapid fire spread
i. Usually “Container” influenced
1. Look for fast moving smoke in high pressure zones (stairs and hallways)
ii. Fuel for spread is smoke driven vs. contents surface flaming
Putting it (reading smoke) all together
a. Read it
b. Predict it
c. Reading the smoke and other factors to predict what is happening or going to happen is…
i. A four step process
1: evaluate the smoke
2: weigh all the factors
3: judge the rate of change
4: predict the event
What are we evaluating in smoke?
i. Volume
ii. Velocity (Pressure)
iii. Density
iv. Color
v. Volume
Volume of smoke
- The amount of smoke visible
a. Relative to the “box”
b. Tells us how much fuel has off-gassed
c. Typically described as light or heavy
Velocity of smoke
- The speed of the smoke exiting
a. Velocity of the smoke leaving the building is indicative of the amount of pressure within the building
b. Indicates either volume or heat
c. Helps us locate the actual fire
Rule of thumb regarding smoke
The hotter the fire, the faster and more turbulent the smoke
Density of smoke
- How thick the smoke is
a. This is the most important factor
b. Changes in density can indicate sudden change in conditions or spread of fire to other areas
c. Quality of burning
d. Chances of an adverse event - Density tells us how bad things are going to be
Color of smoke
- Off-white through dense black
a. Odd colors may indicate hazmats - Tells us the stage of heating
- Helps us determine location of fire
What would an incipient fire look like?
- Volume: Light
- Velocity: Lazy and slow
- Density: Thin and transparent to translucent
- Color: Off white to gray
What would an pre-flashover fire look like?
- Volume: Heavy
- Velocity: Moderate speed and very turbulent
- Density: Very opaque
- Color: Dark gray to black
What would an air controlled fire look like?
- Volume: Heavy
- Velocity: Moderate speed and heavy turbulence
- Density: Opaque to very opaque
- Color: Dark grey, Brown, Yellowish
What would an high-back-draft potential fire look like?
- Volume: Large amount of light smoke, no smoke, puffing out of cracks
- Velocity: Puffing
- Density: Translucent to opaque
- Color: Light grey to grey, Yellowish grey
What would a freeburning (fuel fed) fire look like?
- Volume: Heavy
- Velocity: Rapid and turbulent
- Density: Translucent to opaque
- Color: Grey to dark grey
Reading smoke step 2: weighing the factors
i. Container
ii. Thermal balance
iii. Weather
iv. Firefighting efforts and effect
Reading smoke step 3: judge the rate of change
How fast are the smoke conditions getting better or worse?
Reading smoke step 4: predict the event
i. One hostile event can lead to another
ii. Communicate your observations
iii. Warning signs are not always visual…trust your instincts
What is the most important factor to look for in the smoke?
Density
Tips to reading smoke (11 of them)
a. Sealed buildings “Filter” the smoke
b. Prior to entering, allow smoke to exit for a few seconds—determine if it looks the same?
i. Determine if your opening is going to cause an event and let it happen without you inside—It’s called burping the building
c. The higher the hydrocarbon content of the fuel
i. More energy (BTU’s) released
ii. Higher temperature
iii. Greater expansion and pressure created
d. Hot smoke moves faster near the seat of the fire
i. You can hold your hand light vertical to observe this
e. Grey-Black smoke with velocity and turbulence suddenly clearing
i. Flashover in seconds
f. Dense black smoke
i. Flammable liquids, plastics or hydrocarbons saturated materials
g. Dirty white-grey smoke, virtually no pressure, smoke hangs in the air
i. Mattress fire or food on the stove likely
h. Large volume of white smoke and no heat, smoke is translucent or transparent
i. Void space fire
i. Operating sprinklers show grey smoke outside with cool, dense smoke inside
i. Prime for smoke explosion
j. Fires in unventilated void spaces will backdraft or have a smoke explosion
i. Recognize and address voids early
1. The bigger the void space the more dangerous
2. Knee walls, bowstring truss attics, etc.
k. When dealing with these void spaces, either ventilate them vertically or apply water prior to opening
i. Piercing nozzles or small access hole for nozzle
Or just use an “Attic Sticker” [patent pending for TerrazasTech]
