Ventilation Methods and Techniques

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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Roof Styles

GableHipBridge TrussArchSaw ToothCorrugatedFlat

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Roof Styles

Flatconventionalwooden I-beamopen webopen web bar joistmetal gusset platepanelizedlightweight concrete

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Construction Methods

MetalConcreteMasonryFrame/StuccoFrame/WoodCurtain

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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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Ventilation as a Tool

RescueExposure ProtectionConfinementExtinguishmentOverhaul and Salvage

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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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PrioritiesRead the roofLocation and extension of the fireSound your path of travelKeep the wind at your backUtilize natural ventilation aids

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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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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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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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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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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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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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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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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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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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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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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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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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Location of FireWhat is the location and extent of the fire?Read the Roof

Smoke IndicatorsIndicator holesRadio trafficWindowsVentilatorsVent Pipes

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Structural IntegrityWhat is the structural integrity of the area to be ventilated?Dwellings

PerimeterRidgesValleysRafters

CommercialPerimeterBeamsPerlinsRafters

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Method of TravelDwellings

PerimeterRidgesValleysRafters

CommercialPerimeterBeamsRafters

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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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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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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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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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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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Method of TravelDwellings

PerimeterRidgesHips

CommercialPerimeterTrussesBeamsPerlins

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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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Ventilation OpeningsStrip

Time consuming18-24 inch widthLouver - plywood, metal decking (4-6 ft)

Pull BackPanelizedDemands timing and teamwork

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Documents

Ventilation Methods and Techniques