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FVCC Fire Rescue Ventilation Part B. Types of Ventilation Horizontal Ventilation: Use of doors and windows to ventilate across the floor of a building

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Text of FVCC Fire Rescue Ventilation Part B. Types of Ventilation Horizontal Ventilation: Use of doors and...

  • FVCC Fire RescueVentilationPart B

  • Types of VentilationHorizontal Ventilation: Use of doors and windows to ventilate across the floor of a building. Especially, when there is not a roof directly above fire floor. Opening doors/windows between advancing firefighting crews and established ventilation points, reduces intake of fresh air from opening behind firefighters

  • Types of VentilationHorizontal AdvantagesUses openingsUses natural air currentsDisadvantagesDepends on natural air currentsRouting may expose other parts of the buildingSame routes used by ventilation may be used by occupants escaping.Danger of released gases igniting higher portions of the building.

  • Types of VentilationHorizontal Ventilation: Open leeward side windows first at top. If windward side is opened first, may pressurize building upsetting the normal thermal layering.Open windward side windows next at bottom. Keep ventilation openings clear from obstructions.Performed on floor(s) above fire floor.Used mostly on multi-storied buildings.When would you use horizontal vent on a ranch house?Hint: (house has a basement)

  • Horizontal Open building on leeward sideRemove any obstructionsOpen building on windward sideRemove any obstructions

  • Types of VentilationVertical Ventilation: Opening made above the fire to relieve heat and gases due to mushrooming Mushrooming: when heat, smoke & other gases accumulateTo the state in which they bank down & begin to spread laterallyTo involve other parts of the structure. Caused by convection!!!

  • Types of VentilationVertical Ventilation: Ventilation opening should be made directly over the fire and at the highest point.

  • Types of VentilationVertical Ventilation: Utilize any natural openings already in place, such as: skylights, scuttle holes, exhaust fans, etc. These openings are faster to open than cutting a hole .

    When attempting ventilation through a roof monitor, if the monitor is Not removable, 2 sides should be opened to create required draft.

  • Types of VentilationNote the existence of obstructions or excessive weight on the roof.

  • Types of VentilationVertical Ventilation: Ventilation openings should be large enough (minimum of 4 x 4 ).4 ft4 ftSquare openings help facilitate roof repairs (Customer Service) *Kerf cuts are small cuts (normally thewidth of the saw blade) sometimesUsed to determine fire direction.*Inspection hole is done by cutting a Small triangle in the roof.*Louvered cuts are made in between the Rafters rather than beside the raftersCausing the panels to be hinged.

  • Types of VentilationVertical Ventilation: Openings cut on pitched roofs should be on the leeward side and as high as possible. WindObserve wind direction in relation to exposure.Work with wind at your back or side.

  • Types of VentilationVertical Ventilation: Make sure opening is clear from any material or obstruction.Guard the opening to prevent personnel from falling into the building.Last step in roof ventilation is to open up the ceiling below theVentilation hole, with a pike pole or plaster hook.Be aware that excessive glass breakage including skylights, Explosions, additional openings between attack team & upper Opening, improper use of forced ventilation, & burn through roofCan destroy effectiveness of vertical ventilation.

  • Types of VentilationTrench Ventilation (strip ventilation): Used in buildings with large attic areas to stop horizontal spread of fire. Identify escape routes. Consider location, duration & extent of fire.Good for venting small strip malls

  • Types of VentilationTrench or strip AdvantagesAids in stopping the horizontal spread of fireDisadvantagesMust be cut well ahead of the advancing fireMust be a minimum of four foot wide and is time-manpower consuming

  • Types of VentilationTrench Ventilation: 4 wide opening cut in roof from outside wall to outside wall.

  • Type of VentilationTrench Ventilation: Opening must be far enough away from fire to allow it to be completed before fire reaches there.

  • Type of VentilationTrench Ventilation: Tactic used to save rest of structure by cutting fire break in roof.

  • Type of VentilationHydraulic Ventilation: Use of interior fog stream to move smoke and gases through window or door.Pressurized ventilation

  • Type of VentilationHydraulic AdvantagesMay be used in situations other types are notTakes advantage of the air drawn into the fog stream.DisadvantagesMay increase the amount of water damage inside the structureDrain on the available water supplyIncrease in the ice problem during freezing weatherFirefighters operating the nozzle must remain in the heated, contaminated areaRemain aware of conditions around you; can intensify fire in surrounding areaOperation may be interrupted when crew goes for fresh SCBA bottles

  • Type of VentilationHydraulic Ventilation: Wide fog pattern utilized approximately 2 from the opening.

    2 ft.Hydraulic Ventilation: Fog pattern must cover 85%-90% opening for maximum effect.

  • Type of VentilationMechanical VentilationForcedPrevents smoke from churning in the opening.Avoid blockage of the intake side of the ejector.Mechanical (forced) AdvantagesEnsures positive controlSupplements natural ventilationSpeeds the removal of contaminantsFacilitates a more rapid rescue under safer conditionsReduces smoke damagePromotes good public relationsDisadvantagesIntroduction of air can cause the fire to intensify and spreadDependent upon a power sourceRequires special equipment

  • Type of VentilationNegative Pressure: (Use of smoke ejectors)Placement of ejector for maximum effect (highest point in the opening and on leeward side of building if possible). Place to exhaust is in same direction as the natural wind.Keep airflow in as straight a line as possible

  • PROCEDURESMechanical/mechanical pressurization (forced ventilation) Negative pressurePlace ejector in opening to exhaust in the same way as the wind directionCover the area around the ejector to prevent churningEstablish and maintain desired draft pathRemove all obstaclesAvoid blockage of the intake side of the ejector

  • PROCEDURESNegative pressurePlace ejector in opening to exhaust in the same way as the wind direction.Cover the area around the ejector to prevent churningEstablish and maintain desired draft pathRemove all obstaclesAvoid blockage of the intake side of the ejector

  • Type of VentilationReduce churning (cover area around the fan with a salvage cover)Remove items such as: drapes, blinds, screens, etc. which might block air flow.Provide and maintain unobstructed replacement air opening. Supplements natural ventilationSpeeds up removal of contaminants, assisting in creating a safer environmentPromotes good public relations

  • Type of VentilationMechanical Ventilation:Positive Pressure: (PPV Fans)Placement of PPV fan for maximum effect (outside ground level on windward side of building). Placed a few feet outside the door.Produce a cone of air to completely cover door opening. Have exit area same size as opening.More efficient removal of smoke & heat.Caution: Improper application of positive pressure ventilation may increase fire spread and the safety hazards.

  • Type of VentilationMechanical Ventilation:Positive Pressure: (PPV Fans)Eject smoke from opening on opposite side of building (leeward side). May pressurize one room at a time by closing interior doors.Speed up process by reducing size of area being ventilated by systematically opening/closing doors. A window screen could reduce effectiveness by as much as 50%.Multiple story buildings point of entry is at the lowest point, point of exit is at highest point. Do not block openings.For greatest efficiency, exhaust opening should be 75% to 150% intake opening.Equally effective with Vertical or Horizontal Ventilation.Set without firefighters entering a smoke filled environment.

  • PROCEDURESPositive Pressure Place blower several feet outside the point of entryCheck to make sure air cone completely covers the openingOpen the exit opening (75% to 150% of the entrance opening)Systematically open and close doors within the structure to exhaust the products of combustion.

  • Type of VentilationMechanical pressurization (positive pressure) Cleaning and maintenance of blowers usually reduced.System applicable to all types of structures.Heat and smoke may be directed away from unburned areas or paths of exitDisadvantagesMay intensify and spread hidden fire.Gas power may increase CO2 levels in building.Noise affects communications.Control of openings and pressure leaks.

    Caution: Prior to using PPV, firefighters must be property trained and aware that if used improperly, it can intensify and spread fire conditions. Refer to the PPV fan manufacturer;s training program.