ventilation methods and techniques
TRANSCRIPT
Ventilation Methods and
Techniques
Ventilation Methods and
Techniques
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AcknowledgementsThe following presentation was developed from the review, practice, and emergency ground experience utilizing principles and techniques which have been documented in “Ventilation Methods and Techniques” written by John Mittendorf.
Retired Battalion Chief John Mittendorf has an extensive background as a national lecturer and seminar leader, and is a recognized authority on building construction, truck company operations, and ventilation methods. He has authored numerous ventilation articles that have appeared in American Fire Journal, Fire Engineering, and Firehouse magazines.
Chief Mittendorf is a member of 5 college fire science advisory boards and lectures for the Fire Protection Administration and Technology program at California University at Los Angeles.
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Objectives
Increase Knowledge of Building ConstructionUnderstand the Principles of VentilationReview Ventilation RulesReview Pressurized Ventilation TechniquesDiscuss the Anatomy of a Ventilation OpeningReview Conventional Ventilation MethodsReview Lightweight Ventilation Methods
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Introduction
Definitions:Ventilation:
Procedures necessary to effect the planned and systematic direction and removal of smoke, heat, and fire gases from a structure.
Size Up:A mental evaluation that assists in determining a course of action and the methods necessary to accomplish a desired goal.
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IntroductionSize Up
1) Analyze the situationVentilation Yes/NoOffensive vs. DefensiveTime factor
2) Decide on a plan2 Man vs. 4 Man TeamsVertical vs. HorizontalNatural vs. Mechanical
3) Put the plan into operationLadder placementTool assignmentsType of opening
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Introduction
Visually “size up” construction methods and styles.
Undress the building in your mind!
Look past the exterior of the building and visualize what is inside.
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Table of Contents
1. Building Construction2. Ventilation Principles3. Ventilation Rules4. Pressurized Ventilation5. Ventilation: Anatomy 1016. Conventional Ventilation7. Lightweight Ventilation
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Chapter 1 Building ConstructionChapter Contents:
Construction StylesRoof StylesConstruction MethodsAge of the Building
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Chapter 1 Building Construction
Construction Styles
Conventionalsize = strengthdepends on the structural members size to be strong.the greater the span, the larger the material.characteristics; 8x8, 2x6, mill timber.
Lightweightcompression and tension = strengthdepends on multiple members.length does not change the size.characteristics; 2x4, 2x3, mgp
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Chapter 1 Building Construction
Roof Styles
GableHipBridge TrussArchSaw ToothCorrugatedFlat
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Chapter 1 Building Construction
Roof Styles
Flatconventionalwooden I-beamopen webopen web bar joistmetal gusset platepanelizedlightweight concrete
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Chapter 1 Building Construction
Construction Methods
MetalConcreteMasonryFrame/StuccoFrame/WoodCurtain
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Chapter 1 Building Construction
Age of the Building
Pre - 19331933 - 1950’s1950’s - 1970’s1970’s - Today
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Chapter 2 Ventilation PrinciplesChapter Contents:
Key TermsVentilation as a ToolStructural Considerations
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Chapter 2 Ventilation Principles
Key Terms
VentilationProcedures necessary to effect the planned and systematic direction and removal of smoke, heat, and fire gases from a structure.
BackdraftThe introduction of oxygen to a confined area that is pressurized with heated flammable gases, that are deficient in oxygen, that results in an explosive force of significant intensity.
FlashoverThe sudden ingition of exposed combustible surfaces and/or combustible gases in an involved area that results in a sudden and intense rise in temperature.
Note: Vertical Ventilation prevents Backdraft and Flashover!!!
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Chapter 2 Ventilation Principles
Ventilation as a Tool
RescueExposure ProtectionConfinementExtinguishmentOverhaul and Salvage
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Chapter 2 Ventilation Principles
Structural Considerations
BasementsHabitationCommercialHigh Rise
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Chapter 3 Ventilation RulesChapter Contents:
Efficient and timely ventilation operations should be governed by a set of characteristic standard operational procedures whose values will determine the behavior of a ventilation operation.
The following ventilation rules should be an integral part of each ventilation team members standard operating procedures.
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Chapter 3 Ventilation Rules
Standard Operating Procedures
Pre-Plan Standard OperationsSize UpMinimum of 2 Team MembersMinimum of 2 LaddersBasic EquipmentLadder the Strong Areas of the RoofUninvolved to the Involved
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Chapter 3 Ventilation Rules
Standard Operating Procedures
PrioritiesRead the roofLocation and extension of the fireSound your path of travelKeep the wind at your backUtilize natural ventilation aids
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Chapter 3 Ventilation Rules
Standard Operating Procedures
Use construction to your advantageWork towards the means of egressOnly cut as deep as necessarySize of the openingCoordinationCommunicationPower tool safety
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Chapter 4 Pressurized VentilationChapter Contents:
Key TermsNegative PressurePositive PressureOperational ConsiderationsStructural Considerations
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Chapter 4 Pressurized Ventilation
Key Terms
2 Basic Methods of VentilationNatural Ventilation
natural currents directing flow of air through buildings openingspositive pressure
Pressurized Ventilationmechanically forcing the flow of air through buildings openings
negative pressurepositive pressure
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Chapter 4 Pressurized Ventilation
Negative PressureRequires personnel to be exposed to contaminantsContaminates the blowersMay require special equipment to hang blowersAdded noise and confusion inside structure
ImplementationBlower is placed inside of opening and startedMust have another opening to draw fresh air fromContaminated air is drawn to and through the blower and outside
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Chapter 4 Pressurized Ventilation
Positive PressurePersonnel are not exposed to contaminantsContaminants are not drawn through the blowerDoorways and hallways are not blockedNo additional noise inside the structureEfficient at removing contaminants from all parts of room/buildingTwice as efficient as negative pressure
ImplementationEntrance opening – “the cone”Control the travel of air through the building – “compartmentalize”Exhaust opening – ¾ to 1 ¾ the size of the entrance
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Chapter 4 Pressurized Ventilation
Operational ConsiderationsBlower exhaust odor in building
Exhaust opening is too small
Multiple blowersMaximum efficiency = in-line#1 blower directed into opening#2 blower covers the opening (“the cone”)Large entrance opening = side by side
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Chapter 4 Pressurized Ventilation
Structural ConsiderationsBasements
#1 blower into lower portion of opening#2 blower blowing from the side, and above the #1
High RiseHVAC/StairwellPressurized systemsCross ventilationExhaust features
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Chapter 5 Anatomy of an OpeningChapter Contents:
Key TermsTypes of OpeningsSize of Openings
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Chapter 5 Anatomy of an Opening
Key TermsVentilation Opening
Specific openings that are utilized to reduce and/or remove concentration of heat, smoke, and fire gases from a structure, and/or to channel and redirect the travel of fire.
Center RafterA section of roof decking that has been cut for ventilation purposes of the section to be removed is nailed to a single rafter.
DeckingMade up of a base (lightweight concrete, wood sheathing, plywood, corrugated metal), and a covering (tile, shingles, comp).
DicingA series of cuts between and parallel to rafters. Ventilation is then accomplished by “J” hooking roof material off of its structural members.
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Chapter 5 Anatomy of an Opening
Key TermsHead cut
A cut through the decking that is perpendicular to the direction of the rafters and involves rolling the rafters.
“J” HookRemoval of sheathing enhanced by using a “J” Hook motion which brings the tool under and up to the decking to be removed.
LouveringA cut section of roof decking that is hinged vertically on a single rafter to open a ventilation opening.
Parallel CutCuts through the decking that are parallel to the direction of the rafters. Utilized when dicing.
Pull BackA cut section of roof that is removed from its structural support by pulling up and back with an appropriate tool to open the ventilation opening.
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Chapter 5 Anatomy of an Opening
Key TermsRolling Rafters
When cutting through roof decking with a power saw and a rafter is encountered, the saw is lifted over the rafter and the cut is resumed. (Note: mark the rafters).
Score CutA light cut of the decking covering (usually composition) only.
StripA long and narrow section of roof decking that is removed ahead of a horizontally extending fire to minimize extension of the fire. A defensive cut.
Inspection CutA cut through the roof decking only and at 45 degrees to any exterior wall. When contact is made with a structural member, roll the member and continue the cut for approximately one foot. Complete the cut by making two small cuts over the structure which will allow the removal of a small triangular portion of decking directly over the rafter. This will assist in determining the type of roof, decking, and rafter direction.
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Chapter 5 Anatomy of an Opening
Key TermsIndicator Hole
A small hole which indicates the conditions of smoke or fire within a structure.Heat Hole
Heat openings are opened over (or in close proximity to) a fire and are specifically designed to vertically vent the fire, heat, and smoke.
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Chapter 5 Anatomy of an Opening
Types of OpeningsNatural Openings –utilized/created by a fire to “self ventilate”
Fire burning through the roofVentilatorsSkylights that fail/burn throughAutomatic smoke vents
Heat OpeningsOpened over a fireDesigned to vertically vent the fire
Directional OpeningsCut ahead of the fireDirects horizontal/extension travel
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Chapter 5 Anatomy of an Opening
Size of OpeningsType of Opening
Heat Hole vs. Strip Cut
Ease of RemovalLouvering vs. DicingMultiple rafter sections
Location of OpeningType of constructionStyle of opening (heat vs. strip)Strength of work area (conventional vs. lightweight)
Note:As long as contaminants are venting under pressure, keep enlarging the opening!
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Chapter 6 Conventional VentilationChapter Contents:
IdentificationTeamworkLadder PlacementLocation of FireStructural IntegrityMethod of TravelVentilation Openings
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Chapter 6 Conventional Ventilation
Identification
Objective: “Identify the type of roof”Dwellings
Older stylesWood sidedPre-1970’s2x6 rafter tailsTrue shake roof material
CommercialEarthquake retroPre-1950’sUn-reinforced masonry
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Chapter 6 Conventional Ventilation
Teamwork2 Man Team
Verbal communicationNon-verbal communication1 Saw man1 Sounder/Safety
4 Man TeamVerbal communicationNon-verbal communication2 Saw men1 Sounder/Lead1 Sounder/Safety
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Chapter 6 Conventional Ventilation
Ladder PlacementLadder and approach the involved area from the uninvolvedMinimum of 2 laddersDetermine the location and extension of the fireWindward side of objectiveLadder the strong areas of the building
Beams, Ridges, Valleys, Hips, CornersAvoid windows and doorsExtend far enough to be readily visibleOnce climbed – DO NOT MOVE!
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Chapter 6 Conventional Ventilation
Location of FireWhat is the location and extent of the fire?Read the Roof
Smoke IndicatorsIndicator holesRadio trafficWindowsVentilatorsVent Pipes
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Chapter 6 Conventional Ventilation
Structural IntegrityWhat is the structural integrity of the area to be ventilated?Dwellings
PerimeterRidgesValleysRafters
CommercialPerimeterBeamsPerlinsRafters
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Chapter 6 Conventional Ventilation
Method of TravelDwellings
PerimeterRidgesValleysRafters
CommercialPerimeterBeamsRafters
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Chapter 6 Conventional Ventilation
Ventilation OpeningsDicing
Not possible with plywood decking
LouveringMandatory with plywood decking
StripTime consuming18-24 inch widthLouver – sheathing, plywood, metal decking (4-6 ft)“J” Hook – sheathing (not plywood)
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Chapter 7 Lightweight VentilationChapter Contents:
IdentificationTeamworkLadder PlacementLocation of FireStructural IntegrityMethod of TravelVentilation Openings
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Chapter 7 Lightweight Ventilation
IdentificationObjective: “Identify the type of roof”Dwellings
Newer stylesLast 20-30 years2x4 rafter tails
CommercialConcrete “tilt-up” wallsNewer style with fasciasFlat roofsLast 20-30 years
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Chapter 7 Lightweight Ventilation
Teamwork2 Man Team
Verbal communicationNon-verbal communication1 Saw man1 Sounder/Safety
4 Man TeamVerbal communicationNon-verbal communication2 Saw men1 Sounder/Lead1 Sounder/Safety
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Chapter 7 Lightweight Ventilation
Ladder PlacementLadder and approach the involved area from the uninvolvedMinimum of 2 laddersDetermine the location and extension of the fireWindward side of objectiveLadder the strong areas of the building
Beams, Pilasters, CornersAvoid windows and doorsExtend far enough to be readily visibleOnce climbed – DO NOT MOVE!
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Chapter 7 Lightweight Ventilation
Location of FireWhat is the location and extent of the fire?Read the Roof
Smoke IndicatorsIndicator holesRadio trafficWindowsVentilatorsVent PipesSky lights (4x8)
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Chapter 7 Lightweight Ventilation
Structural IntegrityWhat is the structural integrity of the area to be ventilated?Dwellings
PerimeterTrussesValleys
CommercialPerimeterBeamsTrussesPerlins
Note:Do not ventilate over the fire - Go as close as possible on an uninvolved part of the roof!
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Chapter 7 Lightweight Ventilation
Method of TravelDwellings
PerimeterRidgesHips
CommercialPerimeterTrussesBeamsPerlins
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Chapter 7 Lightweight Ventilation
Ventilation OpeningsLouvering
Plywood deckingPanelizedOpen WebMetal Gusset PlateWooden I-BeamOpen Web Bar Joist
Removing SkylightsPanelized4x8 = roof structure
Drop PanelPanelizedDangerous for those below
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Chapter 7 Lightweight Ventilation
Ventilation OpeningsStrip
Time consuming18-24 inch widthLouver - plywood, metal decking (4-6 ft)
Pull BackPanelizedDemands timing and teamwork
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