Newfoundland and Labrador Association of Fire Chiefs and Firefighters

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Newfoundland and Labrador Association of Fire
Chiefs and Firefighters
Founded 1964
Incorporated 1979
Serving Our Province for the Betterment of Fire
protection
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NLAFCFF. Basic Firefighting Course

• Ventilation
• Lesson Four

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OverviewIn this lesson, you will look at

• What ventilation is and its advantages.
• How to decide if you should ventilate.
• Vertical ventilation.
• Horizontal ventilation.
• Forced ventilation.
• Building ventilation systems.

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ObjectivesBy end of this lesson, you should be
able to

• 4.1 Define ventilation.
• 4.2 Identify the advantages of ventilation.
• 4.3 Identify situations where ventilation is
  needed.
• 4.4 Identify vertical ventilation and its
  characteristics
• 4.5 Demonstrate skills required for vertical
  ventilation

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ObjectivesBy end of this lesson, you should be
able to

• 4.6 Identify horizontal ventilation
• 4.7 Demonstrate the skills required for
  horizontal ventilation.
• 4.8 Identify forced ventilation
• 4.9 Identify the effects of building ventilation
  systems in fire situations.

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Ventilation

• Is the systematic removal and replacement of
  heated air, smoke, and gases from a structure
  with cooler air.

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Advantages of Ventilation

• Aids rescue operation
• Increases breathable air, improves visibility
• Speeds attack and extinguishment
• Removal of heat increased visibility
• Property Conservation
• Fire can be confined to an area
• Reduces heat and smoke damage
• Controls Fire Spread
• Reduces mushrooming
• Reduces danger of Flashover and backdraft
• Removal of heat

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99Ventilation

• Before ventilating, the need for ventilation must
  be established, as well as, where ventilation is
  needed, the type of ventilation to use, and
  whether or not the building is structurally safe
  for specific ventilation operations.

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Ventilation Considerations

• Life safety
• Occupants
• Disoriented or overcome by smoke and gases
• Rescuers
• Reduced visibility, unsafe structure,
  gas/backdraft/flashover potential
• Visible smoke conditions
• Developing or decaying stage of fire

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Ventilation Considerations

• Building type and design
• Walls/roof opening, number of stories, exterior
  fire escapes, exposures
• High-rises
• May have to use mechanical horizontal ventilation
  due to stack effect top ventilation through
  stairwells or elevator
• Basements and windowless Buildings- limited
  access also impedes natural ventilation

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Ventilation Considerations

• Location and extent of fire.
• Opening for ventilation before fire is located
  may spread fire throughout areas of the building.

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Selecting where to Ventilate

• Ventilate as directly over the fire as possible.
• Consider availability of natural openings
• building construction
• wind direction
• building condition
• effect of ventilation.

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Vertical Ventilation

• Vertical ventilation normally refers to opening
  the roof or roof openings to remove heated gases
  and smoke. It is therefore essential for
  firefighters to understand roof construction.

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Vertical Ventilation

• Roof shapes
• Prevalent types include
• Flat
• Pitched
• Arched

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Vertical Ventilation

• Consider ventilating through existing roof
  opening.
• Scuttle hatches
• Skylights
• Monitors
• Ventilation shafts
• Stairway doors

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Vertical Ventilation Ventilating through the roof

• Advantages
• Speed entry
• Easy to perform
• Removes heat and fire gases
• Reduces chance of backdraft
• Disadvantages
• May increase fire spread and rate of burn

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Vertical VentilationVentilating through the roof

• Create one large opening, at least 4 x 4 ft (1.2
  x 1.2 m)
• Use tools such as rotary saws, carbide-tipped
  chain saws, ventilation saws and axes.
• Flat roofs, found on commercial industrial and
  apartment buildings, are constructed similar to
  floors.

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Vertical VentilationVentilating through the roof

• Pitched roof construction involves rafters or
  trusses sheathed with wood or gypsum slabs and
  covered with shingles and roofing tar
• Use sledge hammers to open pitched slate or tile
  roof
• Pitched tin roof can be sliced open and peeled
  back.

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Vertical VentilationVentilating through the roof

• Arched roof may be of either trussed or trussless
  construction.
• Cutting procedures are the same as for flat or
  pitched roofs.
• High collapse potential exists.
• Concrete roofs are difficult to break through
  natural roof openings or horizontal openings
  should be used.
• Light-weight concrete can be opened with a
  penetrating tool
• Metal roofs can be opened with metal cutting
  tools.

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Concrete and Metal Roofs
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Vertical Ventilation Trench or strip ventilation

• Used to stop the spread of fire in long, narrow
  structures by cutting a trench that is at least 4
  ft (1.2 m) wide extending from one exterior wall
  to the opposite exterior wall.
• Advantages
• Allows for defensive attack
• Saves large property loss.
• Disadvantages
• Takes time to perform
• Causes extensive damage to property

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Vertical VentilationBasement Ventilation

• Direct ventilate with horizontal ventilation
  through ground level or below ground-level
  windows.
• If no windows, ventilate through stairwells or
  cut a hole in the floor near a ground level door
  or windows.

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Vertical VentilationPrecautions

• Do not upset thermal column.
• Do not project streams downward through
  ventilation opening.
• Project streams above ventilation opening,
  slightly above the horizontal plane.

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Vertical VentilationPrecautions

• Other safety precautions
• Wind direction, presence of obstructions or extra
  weight
• Need for secondary escape route
• Use of team approach, full protective equipment,
  lifelines, roof ladders as well as tool safety

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Vertical Ventilation

• Students will demonstrate skills for vertical
  ventilation on the fire ground.

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Horizontal Ventilation

• Horizontal ventilation refers to venting heat,
  smoke and fire gases through wall openings.

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Horizontal Ventilation

• Structures that can be horizontally ventilated.
• Residential buildings, attic uninvolved.
• Involved floors of a multi-storied structures
  below top floor or attic.
• Structures with large, unsupported open spaces
  under the roof that have been weakened by fire

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Horizontal Ventilation

• Advantages
• Uses natural openings
• Easy to perform
• Minimal damage to property
• Wind may be an advantage
• Disadvantages
• Restricted to size of natural opening.
• Openings may be wrong location.
• Wind direction may be wrong.

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Horizontal Ventilation

• Influenced by location and extent of fire.
• Consider wind direction.
• Internal as well as external exposures must be
  considered.

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Horizontal VentilationPrecautions

• Do not upset thermal layering
• Create opening on leeward side before opening
  windward side.
• Avoid creating openings between advancing crews
  and the established ventilation exit point.
• Do not obstruct ventilation openings

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Horizontal Ventilation

• Students will demonstrate skills for horizontal
  ventilation on the fire ground.

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Forced Ventilation

• Forced ventilation refers to ventilation done
  mechanically or hydraulically. Forced ventilation
  can be accomplished using either negative or
  positive ventilation.

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Forced Ventilation

• Advantages
• More control of fire
• Supplements natural ventilation
• Speeds removal of smoke
• Reduces smoke damage
• Promotes good public relations

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Forced Ventilation

• Disadvantages
• May cause fire to intensify/spread
• Requires special equipment
• Requires a power source

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Positive-Pressure Ventilation

• By using fans, higher pressure is developed
  inside the structure than out, and in turn smoke
  and gases flow from a structure

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Forced VentilationNegative vs positive pressure

• Negative pressure pulls smoke out
• Place fans to exhaust in same direction as wind
• Positive pressure ventilation creates a higher
  pressure inside the building than outside,
  forcing smoke out.
• Place fans several feet outside the door to allow
  cone of air from the fan to cover the entire door
  opening

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Forced VentilationNegative vs positive pressure

• Exhaust opening is the same size as the entry
  opening.
• Take advantage of wind direction.
• Speed up smoke removal by closing interior doors
  and pressurizing one room at a time.
• Start at the lowest point when removing smoke
  from a multi-storey building struture. Use cros
  ventilation or direct smoke via stairwell to
  rooftop opening.

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Hydraulic Ventilation

• This technique takes advantage of the air that is
  drawn into a fog stream to help push the products
  of combustion out of the structure

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Hydraulic Ventilation

• Performed by hose teams making an interior
  attack.
• Procedure
• Set a wide angle to cover 80-90 of the opening
  from which the smoke will be forced out.
• Nozzle tip should be 2 ft (.6m) back from the
  opening.

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Buildings own Ventilation

• A building own ventilation system can greatly
  impact on how fire spreads through a structure.
  The only way to remedy this is for the fire
  fighter to perform pre-incident planning and be
  able to manually shut down a buildings
  ventilation system if required.

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Buildings own Ventilation

• Fire fighter considerations regarding ventilation
  systems.
• Identify smoke control systems during
  pre-incident planning
• Check ductwork for fire extension during overhaul.

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TEST

• 1. An advantage of horizontal ventilation is
  that?
• A. It releases heat and smoke directly above the
  fire
• B. Fire fighters do not have to worry about
  internal exposures
• C. There is no danger of igniting higher portions
  of the fire building
• D. It uses natural openings
• 2. In order to avoid upsetting the normal process
  of thermal layering, an opening of a door or
  window should be first made on the building
• A. Windward side B. Leeward side
• C. North Side D. Lowest side

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• 3. When using a positive pressure fan, the fans
  cone of air must cover
• A. 75 of the entire opening
• B. 85 of the entire opening
• C. 90 of the entire opening
• D. 100 of the entire opening
• 4. When using positive pressure to remove smoke
  from multiple floors of a building it is best to
  start
• A. On the floor where the fire is situated.
• B. At lowest level
• C. At the highest level
• D. Where the greatest amount of smoke is
  situated.

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• 5. In order to adequately perform hydraulic
  ventilation, a fire fighter should
• A. Use a fog stream set on a pattern that will
  cover 50 of the opening from which the smoke
  will be pushed out
• B. Place nozzle tip at least 2 ft (.6m) back from
  the opening
• C. Place the nozzle tip even with the opening
• D. Place a fan so that the cone of air covers 50
  of the opening
• 6. Which of the following would be a warning sign
  of sn unsafe roof condition?
• A. Trussless arched roof construction.
• B. Smoke coming from the top storey window
• C. Melting asphalt
• D. A roof with two 4 X 4 ft (1.2X1.2m) openings
  cut into it.

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• 7. One of the advantages of trench ventilation
  is
• A. It sets up a defensive line to stop the fire
  progress
• B. It causes minimal damages to the property
• C. It takes minimal time to perform
• D. It allows wind to be used as an advantage
• 8. when opening a pitched roof, a fire fighter
  should make the first cut
• A. On the side closest to the ladder
• B. On the side furthest from the ladder
• C. Through the rafters
• D. Horizontally across the bottom of the planned
  opening

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• 9. In order to maintain thermal balance when
  ventilating a roof, fire fighters should
• A. Project hose streams downward through the
  ventilation opening.
• B. Never use hose streams near a ventilation
  opening
• C. Project hose streams slightly above the
  horizontal place of the ventilation opening
• D. Project one hose stream downward through the
  opening and one above the opening
• 10. If backdraft conditions exist in a building,
  the probability of explosion may be reduced by
• A. Opening a window on the windward side and then
  opening a window on the leeward side.
• B. Opening a window at the lowest level of the
  building
• C. Ventilating the building at its highest level
• D. Opening a door and directing a fog stream
  into the building

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• 11.When opening a roof, the fire fighter should
  position him/herself on the side of the
  roof
• A. Leeward
• B. Windward
• C. Right
• D. Left
• 12. Which of the following statements is true
• A. Power tools should be started on the ground
  and kept running while hoisting them to the roof.
• B. A solid roof will spring back when walked upon
• C. Conduction causes heat and smoke to travel
  upward to the highest point
• D. Smoke-stained windows is a sign of potential
  backdraft

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Answers

• 1. An advantage of horizontal ventilation is
  that?
• D. It uses natural openings
• 2. In order to avoid upsetting the normal process
  of thermal layering, an opening of a door or
  window should be first made on the building
• B. Leeward side

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• 3. When using a positive pressure fan, the fans
  cone of air must cover
• C. 90 of the entire opening
• 4. When using positive pressure to remove smoke
  from multiple floors of a building it is best to
  start
• B. At lowest level

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• 5. In order to adequately perform hydraulic
  ventilation, a fire fighter should
• B. Place nozzle tip at least 2 ft (.6m) back from
  the opening
• 6. Which of the following would be a warning sign
  of sn unsafe roof condition?
• C. Melting asphalt

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• 7. One of the advantages of trench ventilation
  is
• A. It sets up a defensive line to stop the fire
  progress
• 8. when opening a pitched roof, a fire fighter
  should make the first cut
• B. On the side furthest from the ladder

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• 9. In order to maintain thermal balance when
  ventilating a roof, fire fighters should
• C. Project hose streams slightly above the
  horizontal place of the ventilation opening
• 10. If backdraft conditions exist in a building,
  the probability of explosion may be reduced by
• C. Ventilating the building at its highest level

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• 11.When opening a roof, the fire fighter should
  position him/herself on the side of the
  roof
• B. Windward
• 12. Which of the following statements is true
• D. Smoke-stained windows is a sign of potential
  backdraft