Firefighter - 2020 - 21

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Photo courtesy of Sheldon Levi ©2019

2020 FLORIDA FIREFIGHTER

higher temperatures and release higher
concentrations of toxic gasses and
smoke. It should be noted that smoke is
also flammable. However, it has a much
higher ignition temperature because it's
already been through the process of
pyrolysis (combustion/fire) once before.
As a fire burns, it consumes copious
amounts of oxygen in and around the
area/room of origin. This use of oxygen
causes a fire to start to decay and burn
slower. The fire is not out though. Until
the heat is removed or ignition source
extinguished, the fire is still very much
active and holds a great threat. 
Let's put ourselves in the officer's
seat for a moment. We have arrived on
scene of a typical single-family home. As
the engine pulls up to the scene, we see
that there is moderate smoke pushing
from the roofline. No one is home, and
the house appears to be sealed (doors
and windows closed). You perform a
walk around the house, secure power
and gas, and confirm that the fire is in
the bedroom in the back of the house,
and the fire appears to be contained to
that room. Our firefighter pulls a hand
line and prepares to force the front door
open to gain access to the fire. We are
at the front door and are ready to make
entry with them. Our driver has the hose
line charged and is packing out to assist
until the second due unit arrives. Up to
this point, this call is basic and is what
is known as an offensive attack. We are
taking the fight or water to the seat of
the fire in order to put it out quickly. It
is here that we have to consider proper
ventilation. Proper ventilation is achieved
through using an appropriate method,
joined with the proper timing; this is
accomplished through communication
with interior crews, ventilation crews,
and the Incident Commander. If we vent

too soon, we are taking a small fire and
allowing it to become bigger. If we vent
too late, we are slowing the progress
of heat removal and therefore the
extinguishment of the fire. 
There are several techniques in
ventilation and each has its purpose.
The most famous is vertical venting,
or firefighters getting on the roof and
cutting a hole. This hole is generally
required to be approximately 4 feet by
4 feet and at the highest point that's
closest to the seat of the fire. The goal
is to create a chimney effect that will
allow heat and smoke to flow up and out
and improve overall interior conditions.
We also have to take into consideration
the integrity of the roof. If the fire has
been burning for an extended amount
of time, the support structure that holds
the roof up may be compromised
and unable to support the weight of a
team of firefighters. The next technique
is negative pressure, or sucking the
smoke out of the structure. In order to
facilitate this, you take a fog nozzle, open
it to a narrow pattern, and flow water
through a window. This flow of water
creates the negative pressure that pulls
smoke out. The downside is it increases
water damage and ties up a hand line.
The third method is positive pressure
ventilation (PPV). This method takes a
gas or electric powered fan or series
of fans and forces air into the structure,
thereby increasing the pressure and
forcing the smoke/gasses out. A
concern with this method is if you are
using a gas-powered fan, you're blowing
carbon monoxide (CO) into the building.
All interior crews need to be careful and
should use a Self-contained Breathing
Apparatus (SCBA) or air pack while
working inside to prevent CO poisoning.
The final method and by far the easiest

is natural lateral ventilation. It is important
to note that this is performed any time
the structure is opened up. whether it
be a window opening or a door. This
method allows the heat and gas from
the fire to escape without any further
facilitation by fire crews.
Because of the training firefighters
receive, they able to read the smoke
that's being produced and understand
the flow dynamics, as well as how the
fire reacts to ventilation. This ability
to recognize, communicate, and act
accordingly has allowed them to have a
positive outcome and save much of the
homeowners property, while keeping the
crew as safe as possible. 
SO WHY IS ALL OF THIS
EVEN IMPORTANT?
The primary mission of a fire
department is the preservation of life
and property, and ventilation plays a
huge role in that. If heat and smoke are
released, the chances a firefighter can
save the structure, find victims, and get
out safely are dramatically increased.
Ventilation can also slow and even stop
heat and smoke damage to other areas
of the structure. As textiles become
more synthetic, ventilation becomes
more and more important. It is true that
a house is just four walls and a roof, but
a home is made up of everything else
inside and that is really what we are
protecting. FSFA
ABOUT THE AUTHOR: Christopher
Burris is a 17-year veteran of Fire and
EMS services. He is currently working
as a Firefighter/Paramedic for Sumter
County Fire and EMS. Christopher can
be reached at Christopher.Burris@
sumtercountyfl.gov.
Firefighter - 2020

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