Tactical PPV

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Tactical PPV
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Tactical PPV

• This powerpoint was created using information
  provided to us by Chief Bob Nicks of the Austin
  Fire Department and Professor O.A. Ezekoye of the
  University of Texas.

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Objectives

• The Firefighter should be able to
• Describe why coordinated ventilation provides the
  context for the development of fireground
  tactics
• Describe how fan positioning, building size and
  configuration, wind, and vent size affect
  ventilation
• Describe how under-ventilation or improper
  ventilation can create an unsafe interior
• Perform PPV during Investigative Mode to assist
  in fire location

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Objectives

• The Firefighter should be able to
• Perform PPV during Offensive Mode fire attack,
  coordinating search, ventilation and fire attack.
• Perform PPV outside the fire corridor to reduce
  hazards to Firefighters and decrease damage to
  structure and contents (adjacent structures and
  attics).
• Perform PPV post-knockdown to assist in overhaul
  without increasing risk of rekindle.

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Tactics and Fire Ventilation

• Venting for fire situations is often misapplied
  and careful thought should be given to the
  objective at hand. The main objective must be to
  improve interior conditions for firefighters by
  reducing heat levels and improving visibility -
  Paul Grimwood, British Fire Service
• An analysis of the last 8 years of NIOSH
  Firefighter fatality reports show that in every
  fatality where fire behavior was a causal factor
  in the Firefighter death, ventilation was not
  performed or performed incorrectly.
• Coordinated PPV will make the fireground safer
  uncoordinated PPV or PPV employed by improperly
  training Firefighters can be dangerous!

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Tactics and Fire Ventilation

• Ventilation is the most complex tactic to perform
  correctly because proper ventilation requires
• Knowledge of proper ventilation
• As an industry, information on the subject varies
  widely.
• All companies working on scene must work together
  to coordinate their efforts
• To coordinate on-scene efforts, all Firefighters
  must know their role and how their role affects
  others on the fireground.

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Tactics and Fire Ventilation
Tactics determine how the fire fighting operation
is structured, put together, and creates an
entirety of parts. If smoke is the primary
hazard, the coordination of ventilation
activities should become the context for all
fireground tactical activities. Explained later
in detail during the tactical portion
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What is Proper Ventilation?

• Coordinated Fire Attack
• 360
• Locate Fire Determine Risk of PPV
• Determine Vent Opening Location
• Determine when to make vent Coordinate Do not
  vent until attack crew is ready to move
• Fire Attack
• Employ PPV before entry,
• Observe effects
• Make Fire Attack
• Other Tactical Functions
• Must ensure Vent for Life, Laddering, and/or
  Additional Forcible Entry do not negatively
  affect ventilation
• Backup Team stands down until entry of Fire
  Attack Team

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AFD Close Calls

• Between 1998 and 2003 the Austin Fire Department
  experienced FIVE near death fire related events
  at three incidents
• 903 E. Riverside Drive (Two Firefighters)
• 2213 S. Lakeshore Drive (Two Firefighters)
• 837 E. Oltorf Street

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Common Incident Factors

• All Firefighters were hospitalized with thermal
  and/or smoke related injuries
• All were minutes or possibly seconds from death
• Proper ventilation could have prevented these
  injuries

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Common Fire Characteristics

• All fires were in a ventilation controlled state
  at the time of the event (A fire where the fire
  growth is determined by the amount of air
  available. A ventilation-controlled fire occurs
  when there is not enough air to burn all the
  materials being pyrolyzed)
• All were located in residential structures
• All fires were located on the second floor
• All were either unventilated or ventilated
  improperly

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2213 S. Lakeshore Drive
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INITIAL DISPATCH0426 HOURS

• ENGINE COMPANY 22
• HEAVY BOX ALARM COMPLEMENT

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RESPONDING UNITS

• UNIT
• ENGINE 22
• ENGINE 1
• ENGINE 50
• ENGINE 6
• TRUCK 1
• TRUCK 35
• RESCUE 14
• BATTALION 6
• BATTALION 4

• PERSONNEL
• 3
• 4
• 3
• 4
• 4
• 3
• 2
• 1
• 1

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1st floor door open
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2nd floor looking toward fire apartment
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CRITICAL FACTORS

• FIRE KNOCKED DOWN
• VENTILATION-CONTROLLED FIRE
• FUEL RICH
• OXYGEN STARVED
• RAPID FIRE PROGRESSION
• HEAVY BLACK SMOKE TO THE FLOOR
• NO DOOR CONTROL
• ATTACK LINE IS SHORT
• ENGINE 22 OFFICER AND TRUCK 35 OFFICER NEVER MEET
• TRUCK 35 OFFICER CONDUCTING SEARCH

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CRITICAL FACTORS

• STILL VENTILATION CONTROLLED FIRE
• FUEL RICH
• OXYGEN STARVED
• RAPID FIRE PROGRESSION
• HEAVY SMOKE CONDITION PERSISTS
• PERSONNEL IN THE INTERIOR OF THE STRUCTURE
  WITHOUT A CHARGED LINE
• ENGINE 22
• TRUCK 35
• 2ND ALARM SOUNDED 0444 HOURS

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HEAVY BLACK SMOKE SHOWING FROM THE EAVES OF THE
ENTIRE BUILDING FIRE APARTMENT VENTS AT THE
SLIDING GLASS DOOR
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2213 S. Lakeshore Drive
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AFD Recommendations from 2213 S. Lakeshore

• Formal Investigations indicated that AFD needed
• Change from a policy based system to a
  guideline based system
• The need to develop and review new fireground
  tactics
• Additional fire ground training with an emphasis
  on ventilation tactics and procedures

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837 E. Oltorf Incident
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Investigative Results from the 837 E. Oltorf
Incident

• On August 22, 2003 at 0241 Engine 6 responded to
  a Heavy Box Alarm at 837 East Oltorf Street.
  Engine 6.
• All occupants were out of the structure.
• The second floor fire was in a ventilation-control
  led state with no visibility and moderate to high
  heat (at least 500-600? F at waist level at the
  doorway of fire room).

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Investigative Results from the Dan Dillon
Incident

• The fire attack team became separated for
  approximately 45 seconds, the Lieutenant
  advancing into the bedroom on the right and the
  Firefighter 1 proceeding down to the end of the
  hall.
• During this time of separation, the Engine 6
  Lieutenant experienced a sudden and complete loss
  of air.
• The Engine 6 Lieutenant tried troubleshooting the
  air pack, unsuccessfully attempted to communicate
  a Firefighter Down and attempted to exit the
  building. The Lieutenant lost consciousness
  during the escape attempt and was unable to exit
  on his own.
• The other fire attack team member (Engine 6
  Firefighter 1) and Ladder 17 crew located and
  removed the Lieutenant from the structure.

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2nd floor
1
2
3
1- location of dropped axe. 2 -location of voice
enunciator. 3- Lt. Dillon found. 4- Fire Origin
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Stairway Engine 6 ascended to make fire
attackOpen door where Engine 6 LT removed
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Looking up attack stairwell.
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Looking up attack stairwell.
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Fire room, first door to the left (cannot see in
this photo). Door at end of hall is where Engine
6 Firefighter advanced. Engine 6 LT advanced into
room on the right.
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Where Engine 6 LT ran into closet door. Engine 6
LT lost consciousness inside closet for 5 to 30
seconds, then regained consciousness and
collapsed in hall at end of rug in doorway. Fire
room directly across hall, stairway through the
door just to the left.
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837 E. Oltorf
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Point of Origin
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Fire room. Window vented from the outside with
pike pole
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Investigative Results from the Oltorf Incident

• The Engine 6 Lieutenant was transported to the
  hospital and treated for smoke inhalation.
• Doctor providing treatment stated that the
  Lieutenant was within 30 seconds of the injuries
  being fatal.
• The Engine 6 Lieutenant was treated and released
  the next day. Several days later the Engine 6
  Lieutenant was readmitted to the hospital and
  treated for chemical burns to the lungs.
• The Engine 6 Lieutenant was released back to
  active duty after three weeks and has made a full
  recovery.

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Issues Relevant to this Incident

• Engine 6 Lieutenant experienced a sudden and
  complete loss of air.
• Ventilation was not coordinated with fire attack.
  Engine 6 fire attack team, along with all other
  crews operating on the interior, entered a fire
  building in a ventilation-controlled state before
  the structure was effectively ventilated.
• The Engine 6 fire attack team became separated in
  an IDLH atmosphere while attempting to locate the
  fire.
• Both hose team members tried to communicate via
  radio to announce a Firefighter Down and could
  not locate their radio collar mics.

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Formal Investigations of the Dan Dillon incident
indicated that the department needed

• Continue to seek information that would assist in
  determining why the Engine 6 Lieutenant
  experienced a lost of air.
• Determine a better way of carrying the collar
  mics.
• Improve interior fire fighting communications
• Train Firefighters to solicit important
  information from occupants and witnesses.
• Share important size-up information with the
  entire crew.
• Conduct Department Wide Ventilation Training.

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Why Ventilate?

• Smoke is Fuel
• Smoke is Fuel
• Smoke is Fuel
• Smoke is Fuel
• Smoke is Fuel
• Smoke is Fuel
• Smoke is Fuel

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Would you fight a fire in a house filled with
Propane?
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Propane vs. SmokeSmoke is Fuel

• Propane
• Flammable Range 2.1-9.6
• Ignition Temperature 920-1120 F

• Smoke / CO
• Flammable Range 12.5-74
• Ignition Temperature 1128 F

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WARNING!!!When firefighters arrive, most fires
will be in a ventilation-controlled state.
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Ventilation Controlled FiresCreate Smoke that is
Fuel!

• Most fires are ventilation controlled on arrival.
• Firefighter vent practices (or lack of) can
  change a ventilation controlled fire to a rapid
  fire progression (flashover,backdraft, etc.).
• PPV can reduce the risks of ventilation
  controlled fires when properly performed.

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Ventilation-ControlledWhat does this mean?

• A fire where the fire growth is determined by the
  amount of air available. A ventilation-controlled
  fire occurs when there is not enough air to burn
  all the materials being pyrolyzed.
• Less than 21 oxygen oxygen deprived combustion
  process produces 2 to 5 times the amount of
  carbon monoxide than in a balanced reaction.
• Less than 13 oxygen under-ventilated fire
  conditions, flaming ceases, smoldering combustion
  occurs

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Ventilation-Controlled Compartment Fires Facts

• High production of flammable gases
• Containment of heat
• Containment of flammable gases
• Only needs more air for the fire to rapidly
  progress into flashover conditions
• Fire poised for a rapid change

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Ventilation Controlled Case Studies

• This is an Emerging National Problem!
• Washington DC under-ventilated fire flashover
  kills two firefighters
• Ohio flashover kills a firefighter
• Illinois backdraft kills two firefighters

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UT/AFD Research

• Using PPV to mitigate ventilation controlled fire
  dangers in single family dwellings.

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What Did We Know About PPV?

• PPV has been in existence for over 30 years.
• Marketed as a tool to increase FF/Victim Safety
• Large difference of opinions across the Fire
  Service as to its benefits
• Untested. Very few studies conducted on the
  cost/benefit of this tactic.
• It is claimed that PPV could help reduce the
  chance of extreme fire behavior caused by fires
  in a ventilation controlled state.
• If misunderstood and used improperly, PPV can be
  harmful.

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AFD/UT Fire Tactics Research Group

• Recognized a lack of scientific based research in
  ventilation tactics particularly positive
  pressure
• Most tactics have been based on anecdotal
  evidence
• There is a great variance in opinion as to how
  positive pressure impacts a ventilation
  controlled fire
• Firefighter safety
• Victim tenability
• Impact on fire spread/growth
• Very few research studies have been performed on
  the effects of positive pressure ventilation

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Existing Studies

• Svensson (Swedish Rescue Services, 2001 2002)
• PPV increases mass burning rates
• Temperatures increase downstream of fire and
  decrease upstream
• Delays in attack of fire after application of PPV
  may induce fire spread
• Application of Positive Pressure without
  Ventilation created worse conditions
• Ingason Fallberg (Swedish Natl Testing
  Research Inst., 2002)
• Overpressures of 1-6 Pascals.
• Flow patterns in rooms were mapped and showed
  jetting flows
• Ziesler, Gunnerson, Williams (Univ. of Central
  Florida, 1992-1994)
• Primary show positive benefits of PPV (reduced
  temperatures, improved visibility, no spread of
  heat)
• National Research Council of Canada (2002,
  high-rise buildings)
• Technical Research Center of Finland (VTT) (2000)
• Walton and Kerber (NIST/BFRL)
• PPV fan flows have been characterized Effects on
  heat release rate are documented.
• UT/AFD (2002-present)
• Effects of vent location cold flows in multiple
  story buildings effects of leakages

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• Current Positive Pressure Studies

• Context of the Study
• What type of building are we testing?
• Single family dwellings (Hot Tests)
• Multi-story structure (Cold Flow Tests)
• Burn structure cold and hot tests
• Test Variables
• Vent opening location
• PPV fan configuration (CFM rating)
• Natural vs. PPV ventilation
• Balloon frame flows
• What are the effects of Positive Pressure on
• Victim survivability in relation to the
  ventilation/attack corridor
• Fireground conditions

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Single Story House Layout
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Fire Room

• Fire room hardened by adding more sheet rock

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Fire Room Exterior

• Cut ports for video
• Install vent opening system Articulated Flying
  Buttress.

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Victim Room

• Cut holes for cameras
• Remove windows and replace with plywood
• Cover closet to simplify modeling
• Insert Dummy

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Temperature
Multiple burns damage gypsum

• 40 channels of type K thermocouples were used.
• All signals taken from exterior of house to data
  shed.

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Data Acquisition

• Data acquired by computer.
• Video and Infrared movies

Rocket Scientist
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Fuel

• 12 Polyurethane foam pads.
• Fuel load approximates total heat release of
  heavily loaded room contents fire (2.4 MW).

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Air Flow

• Two Fans used
• an 18 and a 24
• 18 6500 CFM
• 24 9130 CFM
• Fan placed at attack entrance typically placed
  at the front door of the house

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Live Fire Video
Hallway
Victim Room (video camera)
Victim Room (TIC)
Vent Window
PPV Victim Room Vent
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Live Fire Video
Victim Room (video camera)
Hallway
Staging Room (TIC)
Vent Window
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Scientific Principles and Results of the Research

• Not Tactics!

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Physics of PPV How does PPV work?

• The heat layer affects rapid fire progression
• Pressure created by PPV
• (Is "positive pressure a correct term?)
• Fan characteristics (Fan is a Pump)
• Typical house flow resistances (Friction Loss)
• Trade-offs in applying PPV

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How heat layer effects rapid fire progression.
There is a competition between heat release rate
and heat losses. Heat release rate is tied to
the heat feedback. Heat losses can be tied to
the convection of the hot upper layer out of the
compartment.
To prevent rapid fire progression, take away the
heat feedback and increase the heat losses by
blowing the products out of a vent.
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Fire Dynamics 101
Fires are generally modeled as having three
distinctive phases growth phase, fully
developed phase and decay phase.
Natural venting
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PPV pushes the heat layer out and decreases the
average temperature even when the burning rate
increases
PPV
Burn Rate
Avg. Temp.
time
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Review 1When Fire is Ventilation Controlled

• This is when firefighters normally arrive.
• Heavy smoke is produced creating limited
  visibility.
• The heat layer increases off gassing (CO) faster
  than the fire itself.
• Conditions poised to change rapidly.
• Venting the hot products makes entry safer.

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How Does PPV Work?

• PPV uses a fan (positive pressure source) to
  exhaust smoke, flammable gases, and high
  temperature gases from a structure fire.
• The fan characteristics (pump) and the resistance
  network (friction loss) will determine the flow
  characteristics.
• The flow at the fire compartment determines if
  PPV is a net positive or negative.
• Big flow good, small flow could be bad.

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Swedish Studies

• Swedish study of Ingason and Fallberg measured
  static pressures and flow patterns
• PPV produces pressures less than 1/100th of 1
  PSI
• Flow velocities and patterns show jet like
  regions (Jet Stream) with secondary flows
  (recirculation regions).
• Velocities are typically in 2.2 mph to 8.8 mph
  range.

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Computer Modeling of Fire

• The newest way to understand fire physics is
  through the use of computer simulations.
• A powerful modeling tool is Fire Dynamics
  Simulator (FDS) developed by NIST.
• Great care must be taken in the use of computer
  models to understand fire since we all know that
  garbage in garbage out!

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Cold Flow Contours of Air Speed Fire Room Vented
CLOSED
OPEN
CLOSED
OPEN
OPEN
CLOSED

• PPV does not pressurize the entire structure
• PPV develops a Jet Stream from the entrance to
  the exit opening.

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Cold Flow Contours of Air Speed Fire Room Vented
CLOSED
OPEN
CLOSED
OPEN
OPEN
CLOSED

• PPV does not pressurize the entire structure
• PPV develops a Jet Stream from the entrance to
  the exit opening.
• Fire corridor- All of the compartments that
  contain fire or are connected to the fire room
  though open doorways.

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House Layout Friction Loss
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House Layout Friction Loss

• PPV uses a fan (positive pressure source) to
  exhaust smoke, flammable gases, and high
  temperature gases from a structure fire.

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House Layout Friction Loss

• PPV uses a fan (positive pressure source) to
  exhaust smoke, flammable gases, and high
  temperature gases from a structure fire.
• The fan characteristics (pump) and the resistance
  network (friction loss) will determine the flow
  characteristics.
• The windows can be thought of as the nozzles

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House Layout Friction Loss

• PPV uses a fan (positive pressure source) to
  exhaust smoke, flammable gases, and high
  temperature gases from a structure fire.
• The fan characteristics (pump) and the resistance
  network (friction loss) will determine the flow
  characteristics.
• The flow rate at the fire compartment determines
  if PPV is a net positive or negative.
• Big flow good, small flow could be bad.

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House Layout Friction Loss

• PPV uses a fan (positive pressure source) to
  exhaust smoke, flammable gases, and high
  temperature gases from a structure fire.
• The fan characteristics (pump) and the resistance
  network (friction loss) will determine the flow
  characteristics.
• The flow rate at the fire compartment determines
  if PPV is a net positive or negative.
• Big flow good, small flow could be bad.

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Review 2

• PPV creates very little pressure, normally just a
  fraction of a PSI.
• Instead of pressurizing the entire building, the
  fan creates a Jet Stream from entrance to exit.
• A fan is like a pump - A fire is like a pump.
• Opening too many windows can cause small flow.
• Big flow is good, small flow could be bad.
• PPV overcoming winds Vendors say 35 MPH, but
  Tests show 8.8 MPH.

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Trade-offs in Applying PPV

• Benefits
• Clears attack corridor of smoke, gases, and high
  temperatures
• Less likely extreme fire behavior
• Faster path to fire compartment
• Safer attack scenarios
• Costs
• Possible spread of fire to non-connected areas.
• Possible increase in burning rate of fire
• Possible hazard to victims downstream of
  ventilation path

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PPV in House
Detailed simulations were performed for the
entire house to examine the effect of ventilation
on a victim room.
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Natural Burn Fire Room Slices
Temperature and velocity vector plots in the fire
room without venting
Roll-up vortices are clearly identifiable
No visible mixing in victim room
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Effects of fire room venting and positive
pressure on velocity vectors is clearly seen
in Figure (a) prior to venting (40
seconds) Figure (b) at initiation of venting (80
seconds) Figure (c) during PPV (120
seconds)
(a)
(b)
(c)
Notice the increased mixing in the fire room
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Effects of fire room venting and positive
pressure on velocity vectors is clearly seen
in Figure (a) prior to venting (40
seconds) Figure (b) at initiation of venting (80
seconds) Figure (c) during PPV (120
seconds)
(a)
(b)
(c)
No visible mixing in victim room
Notice the increased mixing in the fire room
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Effects of victim room venting and positive
pressure on velocity vectors is clearly seen
in Figure (a) prior to venting (40
seconds) Figure (b) at initiation of venting (80
seconds) Figure (c) during PPV (120
seconds)
(a)
 
(b)
(c)
Notice the increased mixing in the victim room
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Effects of victim room venting and positive
pressure on velocity vectors is clearly seen
in Figure (a) prior to venting (40
seconds) Figure (b) at initiation of venting (80
seconds) Figure (c) during PPV (120
seconds)
(a)
 
(b)
(c)
Visible Mixing is victim room
Notice the increased mixing in the victim room
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FDS Models of Platt Road House

• Examining Temperature in the hallway for a vented
  fire room versus a vented fire room with PPV

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Hallway Temperature 20s
Natural Vent (Top) PPV (Bottom)
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Hallway Temperature 30s
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Attack direction
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Hallway Temperature 60s
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Hallway Temperature 80s
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Hallway Temperature 100s
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Hallway Temperature 105s
PPV Fan turned on.
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Hallway Temperature 120s
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Hallway Temperature 150s
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Hallway Temperature 180s
Note cooler attack path for PPV case (bottom)
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Review

• Correctly Venting Fire Room
• Vent as close to the fire as possible
• PPV is more effective than natural horizontal
  ventilation
• Temperature slightly increases with natural
  ventilation at victim level
• Temperatures reduce with PPV at victim level
• Incorrectly Venting Victim Room
• Victims downwind of the PPV do experience an
  increase in temperature but the increase is
  small, survivable and temporary

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Tactical Application of Scientific Results
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Ventilation can be Confusing

• Positive Pressure Ventilation
• Negative Pressure Ventilation
• Horizontal Ventilation
• Vertical Ventilation
• Mechanical Ventilation
• Natural Ventilation
• Hydraulic Ventilation
• Vent for Life, Vent for Fire

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Vertical Ventilation is the Most Effective Form
of Ventilation If

• It can be performed safely
• It can be performed in a timely manner
• Vertical Ventilation should be strongly
  considered on
• Heavily smoke charged, larger, commercial
  structures
• Heavily involved balloon framed structures

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If Vertical Ventilation is Not Performed

• UT/AFD have conducted 3 full scale tests on PPV
  and has conducted continuous PPV research for the
  last 5 years.
• UT/AFD studies prove that horizontal ventilation
  with PPV at single family dwelling fires is
  effective
• Firefighters must know how and why to employ
  horizontal PPV tactics correctly

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Ventilation Reasons

• Vent for Fire Venting to assist the fire attack
  effort
• Vent For Life Venting as you search improves
  Firefighter safety and reduces thermal and toxic
  damage to victims.
• How can we perform both of these ventilation
  tactics with PPV?

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Vent for Fire, Vent for Life

• Think of the fire building as a series of
  compartments that can be separated or connected
  by the existing doors.
• Fire corridor- All of the compartments that
  either contain fire or are connected to the fire
  room though open doorways.

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Fire Corridor
CLOSED
OPEN
OPEN
CLOSED
OPEN
CLOSED
Outside of Fire Corridor
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Properly Venting for Fire

• Coordinated Fire Attack SOG (90/10 rule)
• Hot Lap and Ventilation
• Locate Fire Determine Risk
• Determine Vent Opening Location, close to fire
• Determine when to make vent Coordinate Do not
  vent until attack crew is ready to enter
• Fire Attack
• Employ PPV before entry
• Observe effects
• Make Fire Attack

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Properly Venting for Fire

• Other Tactical Functions
• Must ensure Vent for Life, Laddering and/or
  Additional Forcible Entry do not negatively
  affect ventilation
• The coordination of ventilation activities should
  becomes the context for all fireground tactical
  activities.

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Ventilation Context for Tactics

• 1st in Engine Officer
• Locate fire room, Coordinate opening vents with
  attack team readiness
• Open up all possible fire room vents.
• Outside Team Monitor
• During the Officer hot lap, look under smoke/heat
  layer in first room for victims.
• Place fan correct distance from door (6-10 feet).
• Ensure fan is at correct position and angle.
• Stay out of jet Stream as much as practical
• Monitor vent exit to ensure ventilation
  effectiveness.

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Ventilation Context for Tactics

• Backup Team
• Close doors
• Stay out of jet Stream as much as practical
• Inside Truck
• Maintain fire corridor integrity by shutting
  doors
• Ensure that search for fire extension activates
  have minimum impact on fire corridor integrity
• Outside Truck
• Coordinate VES (if used).
• Ensure forcible entry does not negatively effect
  fire corridor integrity
• Check soffit for exposure near fire room vent
  opening
• Laddering

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Vent or Search?

• Many times, first arriving crews are faced with
  competing priorities.
• Knowing what to start first and what to leave out
  is an extremely difficult choice, especially when
  a victims life may be at stake.
• Which choice gives the victim the best chance for
  survival?

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Vent or Search?

• There is no possible right answer that will fit
  every situation.
• How close the next crew is to arriving may affect
  this decision
• If a very reliable source is giving you victim
  location from, it may be best to search before
  ventilation.
• If you are less sure of victim location, venting
  may increase your overall search speed

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Vent or Search?

• Vent 1st
• Advantages
• Time used venting can be made up quickly after
  ventilation begins
• Once victim is found, environment may be better
  for survival
• Disadvantages
• Search may be delayed 30-60 seconds while
  ventilation is being set up

• Search 1st
• Advantages
• Could locate victim faster if victim located very
  early on
• Disadvantages
• If victim is not located early, overall search
  speed is reduced
• Increased risk to FFs

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Vent or Search Comparison
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All Fire Tactics Should Be Selected, Assessed
and, if necessary, Altered.

• A tactic should not be selected routinely, rather
  should be selected to solve the problems the fire
  is presenting.
• After selected, the tactic should be assessed for
  effectiveness.
• The tactic should be changed if it proves to be
  ineffective.

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How Can The Effectiveness Of PPV Be Assessed?

• After PPV is applied to the entrance of the
  attack corridor, observe the direction of the
  smoke flow.
• If the smoke flow is toward the fire room vent
  opening, PPV is effective.
• Prevailing winds are not overcoming fan.
• Added oxygen is not increasing burning rate
  enough to create ceiling jet.
• There is a clear path from entrance to vent exit.
  
• Continually observe smoke flows as you advance
  down the attack corridor.

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How Can The Effectiveness Of PPV Be Assessed?

• If the smoke and fire gases are still moving
  towards you
• Prevailing winds may be overcoming the fan,
  possibly making the entrance corridor unsafe for
  entry.
• Fire behavior may have rapidly increased, making
  entry risky.
• A change of tactics may be required.

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Rules for Effective PPV

• Must have an exit before positive pressure is
  applied
• Must have attack corridor integrity. Too many
  vent exits can adversely effect PPV effectiveness
• Should know the fire location and make the exit
  vent as close to the fire as possible
• Must account for wind direction and speed
• Must assess direction of smoke flow in the fire
  attack corridor to assess effectiveness of PPV.
• Never direct a hose stream into the exit vent

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Benefits of Effective PPV

• Heat and smoke are removed before the
  firefighters enter the area
• The chance of rapid fire progression due to
  ventilation-controlled fire is reduced
• The officer knows the location of the fire and
  the layout of the building
• Visibility is improved
• Search can be performed faster and more safely
• In general, Firefighter safety is enhanced.

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FAN
123
WRONG!
FAN
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FAN
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WRONG!
FAN
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Coordinated Ventilation
FAN
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Venting for Life

• Breaking windows in the fire corridor will affect
  (either positively and negatively) ventilation
  conditions.
• Research from the UT/AFD PPV studies indicates
  that, all things being equal, small pressure
  differences caused by breaking a window in a fire
  corridor causes the smoke and heat to start
  moving in that direction.

133
Venting for Life

• Therefore, if while searching you remove a window
  in the fire corridor to release heat and smoke to
  improve your conditions (Vent for Life), the
  opposite effect may be realized.
• Many Firefighters that were killed or injured in
  extreme fire behavior were killed in an event
  that was caused by their own ventilation
  practices!

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CLOSED
OPEN
OPEN
CLOSED
OPEN
CLOSED
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Fire Corridor
CLOSED
OPEN
OPEN
CLOSED
OPEN
CLOSED
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Fire Corridor
CLOSED
OPEN
OPEN
CLOSED
OPEN
CLOSED
Outside of Fire Corridor
Tenable Victim Locations
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Properly Venting for Life

• Separate a compartment from the fire corridor by
  closing a door (door control).
• Now the heat layer is no longer racing into the
  room and windows can be safely removed, if
  necessary
• All crews operating inside should close doors as
  they go (if possible) to ensure fire corridor
  integrity.

138
Properly Venting for Life

• Break or open windows If you cannot see your
  exit, break the window! Your life is more
  valuable than a window.
• When leaving the room, the door should remain
  shut.
• This will ensure that vent for life actions do
  not effect ventilation efforts in the fire
  corridor.

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Coordinated Ventilation
FAN
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WRONG! Door Open
FAN
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Coordinated Ventilation
FAN
Door Closed
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Benefits of Venting for Life

• Creates an environment safer for both the victims
  and searchers.
• Increases visibility and improves victim
  tenability
• Allows for secondary egress
• By looking out the window, searches can re-orient
  themselves
• Indicates to the Outside Truck / RIC their
  location

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Wind considerations?

• Will prevailing winds affect your ability to
  ventilate a building using Positive Pressure
  Ventilation?

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Wind considerations?

• If you cannot vent because of prevailing wind
  conditions
• Use another window
• or
• Do not vent
• or
• Vent for position

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Importance of starting PPV before making entry

• When performed properly, PPV can have a dramatic
  effect on the fire
• Basically, PPV rapidly forces a ventilation
  controlled fire back to a free burning (fuel
  controlled) fire.
• The behavior of a free-burning fire is much more
  predictable

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Importance of starting PPV before making entry

• You do not want Firefighters inside during this
  transition! If something is to go wrong, now is
  the most likely time.

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Importance of starting PPV before making entry
Ventilation at 2 seconds, The green region shows
an area of danger as fire gases mix with incoming
air to form a flammable layer
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Importance of starting PPV before making entry
Just 10 seconds after the venting action
occurs, a clear flammable layer (green) exists
near the ceiling. This situation could possibly
lead to a rollover, if there is an ignition
source available
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Other PPV Uses

• We have discussed PPV used during an offensive
  fire attack to mitigate the effects of
  ventilation controlled fires.
• Other Possible Uses for PPV
• Use during investigative mode to assist in
  locating the fire
• Use PPV to assist in overhaul, post fire
  knock-down
• Venting for tactical position
• Use of PPV outside the fire corridor for
• Attic Fires
• Uninvolved adjacent structures

155
PPV Use During Investigative Mode to Assist in
Locating Fire

• Situation Structure filled with smoke. The smoke
  is moving slowly (low pressure/ velocity). Fire
  location is not evident. Fire could be in void
  spaces. In the occupied area of the building, the
  fire is not in a ventilation controlled state.

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PPV Use During Investigative Mode to Assist in
Locating Fire

• Possible Tactical Considerations
• Do not want to spread fire by running fan
  unregulated
• If available, consider selecting an opening that
  could be later shut (window, sliding glass door)
• Run fan long enough to remove smoke and then
  remove fan (turn to the side and throttle down).
• If fire location is not now evident, look for
  smoke seepage. Smoke seepage can be hard to
  recognize when fan is running.
• Open up as necessary.

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PPV Use During Investigative Mode to Assist in
Locating Fire

• If visibility becomes poor again, run fan long
  enough to remove smoke and then remove fan (turn
  to the side and throttle down).
• Repeat as necessary
• This starting and stopping of the fan allows you
  to clear the smoke making it easier to locate
  fire but reduces the change of increasing fire
  spread in the void spaces.
• Important If fan is started with no vent
  opening, void spaces will become pressurized and
  fire located in the void spaces may be increased.

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Use of PPV to Assist in Overhaul, Post Fire
Knock-Down

• Very similar in principal to PPV use during
  investigative mode to assist in locating the fire
  
• There have been many cases nationally of a fan
  being left running after fire knockdown and a
  rekindle then destroying the structure.
• Although these cases are caused by improper use
  of the fan, some firefighters will use it as a
  justification for never using PPV.

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Use of PPV to Assist in Overhaul, Post Fire
Knock-Down

• Possible Tactical Considerations
• Use same vent opening used to vent fire room when
  possible
• Run fan long enough to remove smoke and then
  remove fan (turn to the side and throttle down).
• Look for smoke seepage. Smoke seepage can be hard
  to recognize when fan is running.
• Open up as necessary.

160
Use of PPV to Assist in Overhaul, Post Fire
Knock-Down

• If visibility become poor again, run fan long
  enough to remove smoke and then remove fan (turn
  to the side and throttle down).
• Repeat as necessary
• This starting and stopping of the fan allows you
  to clear the smoke making it easier to locate
  hidden fire during overhaul but reduces the
  change of increasing fire spread in the void
  spaces.
• Important If fan is started with no vent
  opening, void spaces will become pressurized and
  fire located in the void spaces may be increased.

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Venting for Tactical Position

• Sometimes, even if you know fire location,
  ventilation of the fire room may not be possible.
• In multi-story structures, window(s) for venting
  may be out of reach
• Obstacles such as fences, dogs, or anything else
  may prevent ventilation
• The building may have solids walls with no
  windows or other opening in the fire area.
• Wind direction/velocity may prevent venting

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Venting for Tactical Position

• Possible Tactical Considerations
• If you have a high confidence of fire location
  but cannot vent the fire room
• Locate vent opening between fire and entrance
• Start PPV, jet stream should clear smoke path
  between entrance and exit making entry safer than
  attacking under heated, smoky conditions
• Advance closer to the fire area trying to stay
  within the fan jet stream as much as possible

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Venting for Tactical Position
164
PPV use Outside the Fire Corridor

• The fire compartment is pressurized by the fire
  itself and can start seeping to other
  compartments outside the fire corridor
• Compartments outside the fire corridor can become
  charged with smoke through seepage.
• This can happen in
• Attic Fires (smoke seeping from attic to occupied
  space)
• Uninvolved adjacent structures or compartments

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PPV use Outside the Fire Corridor

• Attic Fires
• Possible Tactical Considerations
• If fire is contained to attic on arrival, smoke
  conditions in occupied spaces will be from
  seepage. This should be easily recognizable by
  lower temperatures and smoke character (speed,
  density).
• If attack crews pull ceiling to attack fire
  BEFORE pressurizing structure, the fire products
  from the attic will enter the occupied space .

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PPV use Outside the Fire Corridor

• Attic Fires
• Possible Tactical Considerations
• If time allows, before pulling ceiling to attack
  fire, create additional ventilation opens in
  attic.
• This can usually be quickly accomplished by
  opening up eve vents or gable vents where smoke
  is exiting (if available) or possibly by
  performing vertical ventilation.
• Structure can be pressurized while the attic exit
  opening is being made. This may prevent
  additional seepage into the occupied areas.
• Place salvage covers if time allows
• After the attic is effectively ventilated, ensure
  fan is properly placed and running at the
  entrance area before pulling ceiling to attack
  fire.

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PPV use Outside the Fire Corridor

• Pressurization of adjacent spaces
• Much like the attic fire described before, areas
  outside the fire corridor, such as adjacent
  occupancies in strip malls, can begin to fill
  with smoke through seepage.
• If your crew is assigned to protect an adjacent
  occupancy, pressurizing the adjacent occupancy
  could help to reduce the seepage into this area
  thus increasing your visibility and possibly
  reducing smoke damage.

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Pressurization of adjacent spaces
Purpose to prevent the spread of smoke and hot
gases to adjacent spaces
Space on fire
Adjacent space
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PPV use Outside the Fire Corridor

• Pressurization of adjacent spaces
• Possible Tactical Considerations
• If filled with smoke, initially start fan and
  open vent opposite the fan side of the adjacent
  property which you are trying to protect.
• After smoke is clear, close vent. This should
  pressurize the structure and help to prevent
  further seeping of smoke into the adjacent
  structure.
• Closely monitor the effects of your ventilation
  efforts and make adjustments as necessary.

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Final Review
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Final Review

• Understand the dangers of Ventilation Controlled
  Fires.
• A ventilation controlled fire creates smoke that
  is fuel
• This smoke can cause rapid fire progression
• This smoke can cause zero visibility
• Rapid fire progression and zero visibility can
  kill firefighters

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Final Review

• Given the coordination of all company actions on
  the fireground needed to ventilate effectively
  and safety, ventilation becomes the context for
  the development of tactical decisions and
  on-scene actions.

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Final Review

• Understand the importance of proper ventilation.
• Proper ventilation can reduce the risk of rapid
  fire progression
• Proper ventilation can increase visibility
• Proper ventilation can save firefighter lives

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Final Review

• Understand how to perform proper ventilation.
• Venting for Fire makes fire attack safer
• Venting for Life makes searching safer
• UT/AFD research has shown that PPV is effective
  in single family dwelling fires
• UT/AFD studies recommend using a coordinated PPV
  fire attack in single family dwelling fires
• Coordinated PPV fire attack makes firefighters
  safer in single family dwelling fires