Docstoc

Ventilation Practices

Document Sample
Ventilation Practices Powered By Docstoc
					1
2
   8-1.1 Define the principles of ventilation, and identify the
    advantages and effects of ventilation.
   8-1.2 Identify the dangers present, and the precautions to
    be taken in performing ventilation.
   8-1.3 Demonstrate opening various types of windows
    from inside and outside, with and without fire department
    tools.
   8-1.4 Demonstrate breaking window or door glass, and
    removing obstructions.
   8-1.5 Using an axe, demonstrate the ventilation of a roof
    and a floor.
   8-1.6 Demonstrate ventilation using a water fog.
   8-1.7 Define the theory of a back draft explosion.
   8-1.8 Identify the signs of a potential flashover.

                                                                   3
   8-2.1 Demonstrate the use of different types of
    power saws and jack hammers.
   8-2.2 Identify the different types of roofs,
    demonstrate the techniques used to ventilate each
    type, and identify the necessary precautions.
   8-2.3 Identify the size and location of an opening
    for ventilation, and the precautions to be taken
    during ventilation.
   8-2.4 Demonstrate the removal of skylights,
    scuttle covers, and other covers on roof tops.
   8-2.5 Demonstrate the types of equipment used
    for forced mechanical ventilation.




                                                         4
   8-3.1 Identify and demonstrate natural and
    mechanical methods for horizontal
    ventilation of a structure.
   8-3.2 Identify and demonstrate natural and
    mechanical methods for vertical ventilation
    of a structure.
   8-3.3 Identify the location of the opening,
    the methods to be used, and the
    precautions to be taken when ventilating a
    basement.

                                                  5
   Ventilation is the systematic removal and
    replacement of heated air, smoke, and gases
    from a structure, with cooler air
   Ventilation facilitates entry by firefighters and
    improves life safety for rescue and other
    firefighting operations
   Ventilation increases visibility, decreases
    danger to trapped occupants by channeling
    away hot, toxic gases, and it reduces the
    chance of flashover or backdraft



                                                        6
   Because the increased use of plastics and other
    synthetics have greatly increased the fuel load
    in all occupancies, modern technology requires
    a greater emphasis on ventilation
   The products of combustion are becoming
    more dangerous and are in larger quantities
    than ever before
   Prompt ventilation for the saving of lives,
    suppression of fire, and reduction of damage is
    just as important, if not more so, than it ever
    has been


                                                      7
   Today’s energy conserving houses create
    additional ventilation issues
   Energy saving glass, steel entry doors, and
    building vapor barriers make heat
    retention much greater
   This means when there is a fire, the heat is
    retained better, and flashover can occur
    faster than in a less insulated structure




                                                   8
   A roof covering is the exposed part of the
    roof {the part we see every day} and its
    purpose is to protect against the weather
   It can be wood shingles, composition
    shingles, composition roofing paper, tile,
    slate, synthetic membrane, or built up tar and
    gravel
   This is important to us because it may be
    subjected to sparks or blazing embers from
    another source
   Insulation over the covering retains heat and
    may reduce fire rating drastically, causing
                                                     9
   All the preceding mean that the need for
    ventilation is increased and it must be
    accomplished much sooner than in the past
   We must know how the roofs in our area are
    constructed
   Pre Incident plans need to note roof
    construction and any areas of a roof over or
    added insulation
   Not any light weight building materials as
    they can be a serious collapse hazard



                                                   10
   When the officer decides ventilation is needed,
    they must consider the precaution necessary
    to control the fire and assure the safety of
    teams performing the task
   The team must wear full PPE, including SCBA
    and have a charge hose line available
   Before, during , and following the operation it
    is important to consider the possibility of fire
    spreading through out a building and the
    danger of exposure fires



                                                       11
   All PPE
   Charged Hose Line
   Forcible Entry
    Tools
   Chain Saw
   Rotary Saw
   Ladders



                        12
13
   Proper Ventilation simplifies and expedites
    rescue by removing smoke and gases that
    endanger trapped or unconscious occupants
   Replacement of heat, smoke, and gases with
    cooler, fresh air helps victims breathe better
   This will also make condition safer for
    firefighters and improve visibility so that we
    may more easily locate the victims



                                                     14
15
   Vent team and fire attack must coordinate
    closely
   When the hole is cut, a chimney effect is created
    in the structure
   If this hole is cut directly over a fire, it tends to
    localize the fire – If it is made on the other side
    of the structure, it may well contribute to the
    spread of the fire into unburned areas
   Good ventilation will lessen the chances of
    steam burns to firefighters and increase
    visibility
                                                            16
17
   Property conservation will occur through
    good ventilation because the attack team
    will be able to find and extinguish the fire
    quicker
   It will allow the water fog, smoke, heat, and
    gases to escape into the environment rather
    than remain in the structure
   All of this will allow better salvage
    operations while the extinguishment is in
    process

                                                    18
19
   Convection will cause the heat, smoke, and
    gases to travel up to the highest point until they
    are trapped by a roof or ceiling
   As they accumulate, they bank down and spread
    laterally to involve other areas
   This process is called Mushrooming
   Ventilation will reduce this effect
   Fire must be put out quickly though or the extra
    air coming in will allow the fire to expand


                                                         20
21
   Rollover is sudden ignition superheated
    unburned gases across the ceiling space
   Unburned gases gather across the ceiling
    and when fresh air is supplied the ignite
   Proper ventilation on the side of the fire
    opposite the firefighters will reduce
    chances of a rollover



                                                 22
23
   Flashover is the transition between growth and
    fully developed fires
   As original seat of the fire burns, everything
    else in a room is heated to its ignition
    temperature
   Once reached, the entire room can burst into
    flames simultaneously with severe
    consequences to anyone in the room at this
    time
   Ventilation can relieve this as it lets the heat
    escape before ignition temperatures are
    reached                                            24
   High heat is available in a structure, but
    oxygen levels are too low to support
    combustion
   A very dangerous condition exists because
    the sudden admission of oxygen can cause a
    sudden ignition called a backdraft
   To prevent this, we need to provide vertical
    ventilation to release trapped heat and
    flammable products of combustion


                                                   25
   We need to be aware of this potential and proceed
    cautiously if conditions are ripe for backdraft
   Signs of potential backdraft include:
   Smoke stained windows
   Smoke puffing from the building {breathing}
   Pressurized smoke from cracks in the building
   Very little flame visible from the exterior
   Black smoke becoming dense gray yellow
   Confinement and excessive heat
   IF ANY are seen, wait on vertical ventilation to be
    completed before you try to enter the building

                                                          26
   We must understand our overall plan of
    attack before we direct or order ventilation
    to be started

   We must make a series of decisions that
    pertain to ventilation needs

   These decisions should fall into the
    following order




                                                   27
   This must be based on the
    amount of heat, smoke,
    and gas conditions within
    the structure, structural
    conditions, and the life
    hazards

                                28
29
   This involves knowing
    construction features of the
    building, contents, exposures,
    wind direction, extent of the
    fire, location of the fire,
    location of top or vertical
    openings, and location of cross
    or horizontal openings




                                      30
   Horizontal?
   Natural or Mechanical?

   Vertical?
   Natural or Mechanical?




                             31
32
   Must use all information available to you to
    answer this question
   Will need input from the people in the structure
    and those going to the roof
   To answer the questions, we have to evaluate
    several pieces of information and take into
    account many factors which are covered in the
    next several slides

                                                       33
   The danger to human life is our utmost concern
   Our first consideration is the safety of
    firefighters and occupants
   Proper ventilation will be needed in conjunction
    with rescue operations
   Dependant on the fire, ventilation may need to
    happen before rescue operations, or if
    conditions warrant, fire attack may need to
    come first – in some cases, both will have to be
    done at the same time


                                                       34
   There are also hazards to us as firefighters

   The type of building, whether natural
    openings are adequate, the need to cut
    through roofs, walls, or floors of varying
    types, all make the decision process more
    difficult



                                                   35
   Some of the expected hazards due to an
    accumulation of smoke and gases can be:

   Obscurity caused by dense smoke
   Presence of poisonous gases
   Lack of oxygen
   Presence of flammable gases
   Backdraft
   Flashover




                                              36
   We can make some ventilation and tactical
    decisions as we arrive at the scene based
    on what visible smoke conditions we have
   The density of the smoke is in direct ratio
    to the amount of suspended particles
   The conditions vary according to how
    burning has progressed
   A developing fire and a decaying fire are
    two totally different fires and must be
    treated as such


                                                  37
   An early stage fire will usually give off
    smoke that is of not much density

   If large quantities of carbon particles are
    present, the smoke may become denser

   As the building becomes more involved with
    fire, the smoke will become denser




                                                  38
   Building type and design are the initial factors
    to consider in determining whether to use
    horizontal or vertical ventilation
   Some other factors to consider:

   Number and size of wall openings
   Number of stories, staircases, shafts, ducts,
    and roof openings
   Availability and involvement of exterior fire
    escapes and exposures


                                                       39
   Get in good with the building department so
    they can let you know when buildings are
    altered or subdivided
   Building permits can reveal information about
    the heating, ventilating, and HVAC systems
    and avenues of escape for smoke, heat, and
    fire gases
   Adjoining buildings and how they are
    attached has a bearing on ventilation
   Pre plans can provide valuable information
    and familiarity with the buildings in your
    area


                                                    40
   Basement fires are among the most challenging
    a firefighter will face
   We basically have to descend through the
    chimney to get to the fire
   Access can be by interior or exterior stairs,
    exterior windows, or hoist ways
   Outside entrances may be blocked or secured
    by iron gratings, steel shutters, wooden doors,
    or combinations of these for protection from
    weather and burglars


                                                      41
   Many buildings have windowless wall areas
   While they may not be a desirable means of
    escape, they are important considerations for
    ventilation
   Windowless buildings create and adverse effect
    on firefighting and ventilation operations
   Ventilation in windowless buildings may be
    delayed for a long time, allowing the fire to
    gain headway or to create backdraft conditions



                                                     42
   Problems in ventilating these building vary
    depending on the size, occupancy,
    configurations, and type of material from which
    the building is constructed
   They usually require mechanical ventilation for
    the removal of smoke
   The HVAC system can sometimes clear the
    smoke by itself
   The drawback to this is that it can also spread
    the fire and it requires electricity to work



                                                      43
   Depending on time from ignition until
    firefighters arrive, the fire may have traveled
    some distance
   We must consider the location and extent of the
    fire when deciding on ventilation
   Ventilation before fire location is know may
    spread the fire into unburned areas
   Severity and extent of the fire usually depend on
    the type of fuel and amount of time it has been
    burning, installed early warning and fire
    protection devices, and degree of confinement
    of the fire
   Phase of the fire is a primary consideration

                                                        44
   Some means of vertical fire extension:
   Through stairwells, elevators, and shafts by
    direct flame contact or by convected air
    currents
   Through partitions and walls and upward
    between the walls by flame contact and
    convected air currents
   Through windows or other outside openings
    where flame extends to other exterior
    openings and enters upper floors {lapping}


                                                   45
   Some means of vertical fire extension:

   Through ceilings and floors by conduction or
    heat through beams, pipes, or other objects
    that extend from floor to floor
   Through floor and ceiling openings where
    sparks and burning material fall through to
    lower floors
   By the collapse of floors and roofs


                                                   46
   The ideal situation is one in which we have
    prior knowledge of the building and its
    contents
   There is no exact rule except to open the roof
    “as directly over the fire as possible”
   Some of the may factors that will have a
    bearing on where to ventilate include:
   Availability of natural openings such as
    skylights, ventilator shafts, monitors, and
    hatches
   Location of fire and direction in which the IC
    wants it to be drawn

                                                     47
   Some of the many factors that will have a
    bearing on where to ventilate include:
   Type of building construction
   Wind direction
   Extent of progress of the fire and the condition
    of the building and its contents
   Bubbles or melting of roof tar
   Indications of lessening structural integrity of
    the roof



                                                       48
   Some of the many factors that will have a
    bearing on where to ventilate include:
   Effect that ventilation will have on the fire
   Effect that ventilation will have on exposures
   Attack crew’s state of readiness
   Ability to protect exposures prior to actually
    opening the building




                                                     49
   Before ventilating, adequate personnel and fire
    control equipment must be ready because the
    fire may increase in intensity once the building
    is opened
   Resources for the involved building and
    exposures need to be in place
   Try to attack the seat of the fire {if safe}
    immediately after ventilation
   Entrance should be made as close to the fire as
    possible, with charged hoses in place in case of
    flare up and at critical points of exposure



                                                       50
   Means opening the roof or existing roof
    openings for the purpose of allowing heated
    gases and smoke to escape to the
    atmosphere
   In order to properly ventilate, we must
    understand the basic types and designs of
    roofs
   Study local roof types and the manner of
    construction to develop effective vertical
    ventilation policies and procedures


                                                  51
   We should be concerned with 3
    prevalent types of roof shapes: Flat,
    Pitched, and Arched
   Buildings may be constructed with a
    combination of roof designs
   Some of the more common styles are
    the: flat, gable, gambrel, shed, hip,
    mansard, dome, lantern, and butterfly




                                            52
53
   We can undertake vertical ventilation after we
    have considered the following:

   Type of building involved
   Location, duration, and extent of the fire
   Observed safety precautions
   Identified escape routes
   Selected the place to ventilate
   Moved personnel and tools to the roof



                                                     54
   Roof team should be in constant communication
    with the IC
   Responsibilities of the Roof Team Leader:

   Ensure that only the required openings are made
   Direct efforts to minimize secondary damage
   Coordinating the crew’s efforts with those of the
    firefighters inside the building
   Ensuring the safety of all personnel who are
    assisting in the opening of the building



                                                   55
   Observe the wind direction with relation to
    exposures
   Work with the wind at your back or side to
    provide protection while cutting the roof
    opening
   Note the existence of obstructions or excess
    weight on the roof. These may make
    operations more difficult or reduce the
    amount of time before a roof flails.
   Provide a secondary means of escape for
    crews on the roof


                                                   56
   Exercise care in making the opening so that
    main structural supports are not cut
   Guard the opening to prevent personnel from
    falling into the building
   Evacuate the roof promptly when ventilation
    work is complete
   Use lifelines, roof ladders, or other means to
    protect personnel from sliding and falling off
    the roof
   Make sure that a roof ladder is firmly secured
    over the peak of the roof before using it



                                                     57
   Exercise caution in working around electric
    wires and guy wires
   Ensure that all personnel on the roof are
    wearing full personal protective equipment
    including SCBA
   Keep other firefighters out of the range of
    those handling axes and operating power saws
   Caution axe users to beware of overhead
    obstructions within the range of their axe
   Make sure that the angle of the cut is not
    toward the body



                                                   58
   Start power tools on the ground to ensure
    operation; however, it is important that the
    tools be shut off before hoisting or carrying
    them to the roof
   Extend ladders at least five rungs above the
    roof line and secure the ladder. When using
    elevating platforms, the floor of the platform
    should be even with or slightly above roof level
   Check the roof for structural integrity before
    stepping on it; do not jump onto a roof without
    checking it first


                                                       59
   Use pre plans and surveys to identify
    buildings that have roofs supported by
    lightweight or wooden trusses. Realize that
    these roofs may fail early into a fire and are
    extremely dangerous to be on or under

   Work in groups of at least two, but not
    more people than absolutely necessary to
    get the job done



                                                     60
   Beware of the following warning signs of an
    unsafe roof condition:

   Melting Asphalt
   Spongy Roof {a normally solid roof that springs
    back when walked upon}
   Smoke coming from the roof
   Fire coming from the roof {if it has already
    vented itself, we probably do not need to}



                                                      61
62
   May be found on various types of roofs
   Almost all of them will be locked or secured in
    some manner
   Scuttle hatches are normally square and large
    enough to permit a person to climb onto the
    roof
   They may be metal or wood and generally do
    not provide an adequate opening for
    ventilation
   Skylights with ordinary glass can be easily
    shatter, but if they contain wired glass,
    Plexiglas, or Lexan, they will difficult to shatter
    and you will do better to attack the framing

                                                          63
   The sides of a monitor may contain glass or
    louvers made of wood or metal
   Usually have hinged sides that are easily forced
    at the top
   If you cannot remover the top, open at least
    two sides to create the required draft
   Force open stairway doors like you would any
    door of the same type
   It is usually quicker to use one of these
    openings than to cut a hole in the roof
   Drawbacks are their placement and size



                                                       64
   Pre planning is the best way to learn about the
    types and construction of roofs in your area
   When cutting a roof, one large opening is
    better than many small ones
   Also, try to cut a square or rectangular hole in
    order to make repairs to the building easier
   Power saws are the best equipment for
    opening roofs, making the work a lot quicker
   Safety of the operator and crew are paramount
   Pre plans can clue us in as to what equipment
    we will need to open a specific roof


                                                       65
66
   Several types of cuts may be used on a roof:

   Kerf Cut: Basically you just put the saw blade
    through the roof to look for fire and determine
    direction of spread
   Inspection Opening: Make a triangular hole by
    placing the blade into the roof three times – This
    can be done when you first get on the roof and
    as you move away from your point of egress –
    You are checking for fire under you



                                                    67
68
   Several types of cuts may be used on a roof:

   Louvered Cuts: May be used when cutting
    through plywood
   The cuts are made in between the rafters rather
    than beside them.
   The panels are then hinged on the rafters




                                                      69
70
   Most commonly found on commercial, industrial,
    and apartment buildings, {and older homes in
    Florida}
   May or may not have a slight slope for drainage
   Frequently pierced by chimneys, vent pipes,
    shafts, scuttles, and skylights.
   May be surrounded and/or divided by parapets,
    and it may support water tanks, air-conditioning
    equipment, antennas, and other obstructions to
    ventilation operations



                                                   71
   Structurally, they are generally similar to a
    floor that consists of wooden, concrete, or
    metal joists covered with sheathing
   The sheathing is covered with a layer of
    waterproofing material and an insulating
    material
   Sometimes, these roofs can be poured
    reinforced concrete or lightweight concrete,
    pre-cast gypsum, or concrete slabs se in
    metal joists
   Pre plans, again, will tell us what type of roof
    it is and what we need to open it


                                                       72
   These are elevated in the center and form a
    pitch to the edges
   They involve rafters or trusses that run from
    the ridge to a wall plate on top of the outer
    wall at the eaves level
   The rafters or trusses can be made out of
    various materials
   Sheathing is applied over these, then roofing
    paper, then shingles or other roof covering
   Shingles may be wood, metal, composition,
    asbestos, slate, or tile


                                                    73
   On barns, churches, supermarkets, or
    industrial buildings, you may have roll felt over
    the sheathing
   This can be mopped on with asphalt roofing
    tar
   Instead of wood sheathing, you may find
    gypsum slabs approximately 2” thick
   The incline on these roofs can be very gradual
    or very steep
   Personnel safety is still the main prerogative
    when venting, take extra precautions as
    needed
                                                        74
   Some of these may be easier to get into:

   If the roofing material is slate or tile, you may
    be able to open it with a sledgehammer

   Smash the slate or tile, and also the thin lath
    strips or 1x4’s that they are held up by

   Tin roofs can be sliced open and peeled back
    with tin snips or a large device similar to a can
    opener


                                                        75
   One form of this is constructed with
    bowstring trusses for supporting members
   They conceal large un-vented spaces which
    create dangerous ventilation problems and
    contribute to the spread of fire and early
    failure of the roof
   WARNING:
   Many firefighters have lost their lives while a
    trussed roof has failed. A good rule to follow
    is that when a significant amount of fire
    exists in the truss area of a roof structure,
    firefighters should not be on or under a truss    76
   Trussless arched roofs are made of
    relatively short timers of uniform length
   This network forms an arch of mutually
    braced and stiffened timbers
   Because it is not a truss, a hole of
    considerable size may be cut or burned
    through the sheathing and roofing without
    causing collapse of the roof structure
   Vent them the same as you would other
    roofs, with safety being an issue because
    you will not be able to use a roof ladder –
    Use a ladder truck! ~Mutual Aid~
                                                  77
   Precast roof slabs are available in many
    shapes, sizes, and designs
   Can be trucked in or built on site
   These are very difficult to break through and
    opening them should be avoided whenever
    possible
   Us natural roof openings and horizontal
    openings
   Popular lightweight materials made of gypsum
    plaster and Portland cement mixed with
    aggregates, such as perlite, vermiculite, or
    sand provided a lightweight floor and roof
    assembly often referred to as lightweight
    concrete
                                                    78
   Lightweight precast planks and slabs are
    reinforced with steel mesh or rods
   The roof is usually finished with roofing felt
    and a mopping or hot tar to seal it
   These roof decks can be poured over
    permanent form boards, steel roof decking,
    paper-backed mesh, or metal rib lath
   They are relatively easy to ventilate with a
    hammer head pick, power saw with concrete
    blade, jackhammer, or other penetrating tool


                                                     79
   Can be made from several different kinds of
    metal and constructed in many styles
   Light gauge steel roof decks can either be
    supported on steel frameworks or they can
    span wider spaces
   Corrugated roofing sheets can be made from
    light gauge cold formed steel, galvanized
    sheet metal, or aluminum
   Light gauge cold formed steel is used
    primarily for roofs of industrial buildings
   These are seldom covered and can be pried
    from their supports


                                                  80
   Metal cutting tools or power saws with
    metal cutting blades must be used
   Industrial building usually have adequate
    natural roof openings, skylights, or hatches
   Older buildings may have roofs that are
    made of large, fairly thin sheets of tin over
    lath strips
   They can be opened by cutting with a power
    saw, axe, or large sheet metal cutter



                                                    81
   This is used a little differently than
    standard ventilation techniques
   Trench ventilation is used to stop the
    spread of fire in a long, narrow structure
   It is performed by cutting a large hole
    {trench} that is at least 4 feet wide and
    extends from one exterior wall to the
    opposite one
   Usually cut well ahead of the advancing
    fire for the purpose of setting up a
    defensive line where the fire’s progress
    will be halted
   Rest of the building is written off
                                                 82
   Without built in vents, the heat and smoke
    from these fires will quickly spread up into
    the building
   Especially true of balloon frame construction
   In balloon frame, fire may go from the
    basement to the attic without showing
    anywhere in between
   Ventilation of a basement can be
    accomplished in several ways
   If windows are present, horizontal
    ventilation can be used                         83
   If no windows are present, you will have to
    use interior vertical ventilation with natural
    paths from the basemen, such as stair wells
    and hoist way shafts
   Try to direct this smoke outside on the first
    floor without spreading it to other portions
    of the building
   The last resort would be to cut a hole in the
    floor near a first floor window or door to vent
    the basement, and put a fan in the window /
    door to draw the smoke out of the building



                                                      84
   Once vertical ventilation is done, the
    convection of heated gases creates upward
    currents that draw the fire and heat toward
    the opening
   Team inside will have better visibility and
    less contaminates in the air to make their
    attack easier
   You can direct hose streams over the
    opening to lessen sparks and flying embers
   DO NOT direct the stream downward
    through a ventilation opening as this will
    upset the orderly movement of gases
                                                  85
   If the gas movement is upset, it can force super
    heated air and gases back down on the interior
    crews causing serious injury or death
   It can also contribute to the spread of fire
   Project your ventilation streams just above the
    opening and slightly above the horizontal plane
    of the roof
   They will help cool the thermal column and
    extinguish sparks and maybe speed the rate of
    ventilation


                                                   86
   Factors that can destroy vertical ventilation:
   Improper use of forced ventilation
   Excess breakage of glass
   Fire streams directed into ventilation holes
   Breakage of skylights
   Explosions
   Burn through of the roof, a floor, or a wall
   Additional opening between the attack team and
    the upper opening



                                                 87
   WARNING:
   Never operate any type of fire stream through
    a ventilation hole during offensive operations.
    This stops the ventilation process and places
    interior crews in serious danger
   Vertical ventilation is not the solution to all
    ventilation problems because it is sometimes
    impractical or impossible
   You must be able to use all types of ventilation
    to be effective



                                                       88
   Venting of heat, smoke, and gases through
    wall openings such as windows or doors
   Structures that lend themselves to
    horizontal ventilation include:
   Residential building where fire has not
    involved the attic
   Involved floors of multistoried buildings
    below the top floor, or the top floor if attic
    is uninvolved
   Buildings with large, unsupported spaces
    under the roof where the structure has been
    weakened by the effects of burning

                                                     89
   Different procedures are used to
    horizontally ventilate a room , floor,
    cockloft, attic, or basement

   Procedures will be influenced by the
    location and extent of the fire




                                             90
   Some of the ways of horizontal extension
    are:
    ◦ Through wall openings by direct flame contact
      or by convected air
    ◦ Through corridors, halls, or passage ways by
      convected air, radiation, and flame contact
    ◦ Through open space by radiated heat or
      convected air currents
    ◦ In all directions by explosion or flash burning of
      fire gases, flammable vapors, or dust
    ◦ Through walls and interior partitions by direct
      flame contact
    ◦ Through walls by conduction across pipes,
      beams or other objects that extend through
      them
                                                           91
   This is always an issue in deciding the
    horizontal ventilation procedure
   Wind is an important factor
   Direction may be designated as windward
    {side wind is hitting} or leeward {opposite
    or downwind side}
   If there is no wind, natural horizontal
    ventilation is less effective because there
    is not force to remove the smoke
   In other cases, exposures on the leeward
    side can be in severe danger
                                                  92
   Routing of smoke and heat becomes an issue
    in horizontal ventilation
   We should be aware of internal and external
    exposures
   The routes we use to move the smoke and
    heated gases can be the same corridors
    occupants and firefighters will be using
   First consideration of horizontal ventilation
    needs to be the escape routes of the
    occupants and rescue routes of the firefighters



                                                      93
   Horizontal ventilation is not accomplished at
    the highest point in a building, therefore there
    is the danger that when the rising heated gases
    are released, they will ignite highest portions of
    the building
   This could be the eaves of this building or an
    adjacent building, or they may enter a window
    above the ventilation point
   Building should not be opened {unless
    immediate rescue is needed} until charge lines
    are in place to attack @ the point where fire
    might be expected to spread


                                                         94
   Opening a door or breaking a window on the
    windward side before the leeward side may
    pressurize the building and upset the thermal
    layering
   Opening doors and windows between the entry
    team and the established ventilation exit reduces
    the intake of fresh air from the opening behind
    the entry team




                                                   95
96
   This is accomplished mechanically {fans} or
    hydraulically {fog streams}
   The principal is to move large quantities of
    smoke and air
   Forced ventilation equipment is difficult to
    classify by a a particular type
   Fans can be powered by electric motors,
    gasoline engines, or water pressure from
    hose lines



                                                   97
   Some of the reasons for employing forced
    ventilation include the following
   Ensures more positive control of the fire
   Supplement natural ventilation
   Speeds the removal of contaminants,
    facilitating a more rapid rescue under safer
    conditions
   Reduces Smoke damage
   Promotes better public relations




                                                   98
   Misapplied or improperly controlled forced
    ventilation can cause a great deal of harm
   It requires supervision because of the
    mechanical force behind it
   Some disadvantages are:
   Introduces air in such great volumes that it can
    cause the fire to intensify and spread
   Depends upon a power source
   Requires special equipment


                                                   99
   Oldest of mechanical forced ventilation
    techniques: uses fans to develop artificial
    circulation and pull smoke out of a structure
   Fan is placed in a window, door, or roof vent
    hole and they pull the smoke, heat, and gases
    from inside the building and eject them to the
    exterior
   The fan should be set up to exhaust in the same
    direction as the wind flow
   This will help the wind, speed up the process
    and supply fresh air to replace what is being
    removed
                                                  10
                                                   0
   If natural wind is too light to be effective, you
    can place fans blowing in on one side and
    exhausting on the other side
   Recirculating air around the fan can be an issue
   This can cause a churning effect that reduces
    efficiency
   To prevent this, cover the area around the fan
    with salvage covers or other materials
   Select your desired path and keep it in as
    straight a line as possible


                                                        10
                                                         1
   Every corner will cause turbulence and
    decrease efficiency
   Do not open doors or windows near the
    exhaust fan unless it definitely increases
    circulation
   Remove items such as curtains, drapes,
    blinds or anything that can reduce airflow
   The fans should have explosion proof
    motors and power cords / connectors
   They should be turned off with they are
    moved
   When starting, clear the area of people &
    loose items                                  10
                                                  2
   Ventilation technique that uses the principle
    of creating pressure differentials
   A higher pressure is created in the build than
    that outside by using high volume fans
   Due to the high pressure inside the building
    the smoke will seek and outlet to a lower
    pressure zone through openings controlled
    by the firefighters
   The location where the fan blows in, usually
    an exterior doorway, is called the point of
    entry
   Place the fan several feet outside the door so
    that a cone of air covers the entire door
    opening                                          10
                                                      3
   Smoke is ejected from exhaust openings
    the same size or smaller than the entry
    opening
   Do not open other openings while positive
    pressure is in use, except the point of
    exhaust
   We can now close doors and windows,
    pressurizing one room or at a time, in order
    to speed up ventilation
   Additional fans can be placed @ the point of
    entry to increase the CFM flow and thus the
    interior pressure
                                                   10
                                                    4
   If you do not systematically control the
    exhaust points, the ventilation will work,
    but it will take a lot longer
   When using on multiple floor buildings,
    the point entry should be at the lowest
    point.
   Smoke can then be systematically removed
    starting at the floor most charged with
    smoke {straight out of the book}
   It is best to start exhausting at the lowest
    point and work your way up {experience –
    if you start in the middle, you will have to
    do that floor again as smoke from the
    lower floors will drift up there}
                                                   10
                                                    5
   PPV requires good fire ground discipline,
    coordination, and tactics
   The main probable is coordinating the opening
    and closing of doors is stairwells
   People may stand with doors to the stairwell or
    their door open and redirect the PPV away from
    where you want it
   Place a person in charge of the pressurizing
    process, use radios to make sure it is working
    properly


                                                 10
                                                  6
   Take advantage of existing wind conditions
   Make certain that the cone of air from the
    fan covers the entire entry opening
   Reduce the size of the area being
    pressurized to speed up the process by
    systematically opening and closing doors or
    by increasing the number of fans
   Keep the size of the exit opening in
    proportion to the entry opening



                                                  10
                                                   7
   Firefighters can set up PPV without entering
    the smoke filled environment
   PPV is equally effective with horizontal or
    vertical ventilation because it merely
    supplements natural ventilation currents
   More efficient removal of smoke and heat from
    a structure or vessel is allowed
   The velocity of air currents in a building is
    minimal and has little, if any, effects that
    disturb the building contents or smoldering
    debris. Yet the total exchange of air within the
    building is faster than using NPV


                                                       10
                                                        8
   Fan powered by internal combustion engines
    operate more efficiently in clean, oxygen
    rich atmospheres
   The placement of fans does not interfere
    with ingress or egress
   The cleaning and maintenance of fans used
    for positive pressure ventilation is greatly
    reduced compared to that of those used in
    negative pressure ventilation


                                                   10
                                                    9
   This is applicable to all types of structures
    or vessels and is particularly effective at
    removing smoke from large, high ceiling
    areas where NPV is ineffective



   Heat and smoke may be directed away
    from unburned areas or paths of exit




                                                    11
                                                     0
   An intact structure is required

   Interior carbon monoxide levels may be
    increased during use

   Hidden fires may {will} be extended




                                             11
                                              1
   May be used where other types of forced
    ventilation are not being used
   It is performed by hose teams inside the fire
    building
   It is used to clear the room or building of smoke,
    heat, steam, and gases following the initial
    knockdown of the fire
   It takes advantage of the air that is drawn into a
    fog stream to help pus the products of
    combustion out of the structure


                                                     11
                                                      2
   To perform, set a fog stream to wide pattern
    that will cover 85 to 90 percent of the window
    or door opening from which the smoke will be
    pushed out
   Nozzle tip should be at least 2 feet from the
    opening
   The larger the opening, the faster the
    ventilation
   There are some drawbacks to using fog
    streams to perform forced ventilation


                                                     11
                                                      3
   There may be an increase in the amount of
    water damage within the structure
   There will be a drain on the available water
    supply. This is particularly crucial in rural
    firefighting operations where water shuttles
    are being used
   In climates subject to freezing temperatures,
    there will be an increase in the problem of ice
    in the are surrounding the building



                                                      11
                                                       4
   The firefighters operating nozzle must
    remain in the heated, contaminated space
    during the operations

   The operation may have to be interrupted
    when the nozzle team has to leave the area
    for some reason {SCBA, Rehab, Etc.}




                                                 11
                                                  5
   Most modern building have HVAC systems
   These systems can contribute to fire and
    smoke spread throughout a building
   Pre plans should include information on
    the systems design and use along with
    diagrams of the duct system and fire
    protection within
   We should know the location and operation
    of the controls that will manually shut
    down the system when so desired
   System may draw heat and smoke in, so
    always check the duct work and areas
    around it for extension
                                                11
                                                 6
   Remember, this system will need to be
    ventilated before it is restarted
   In large buildings or where large numbers of
    people are present, the building may have a
    smoke control system
   They involve the mechanical systems, doors,
    partitions, windows, shafts, ducts, fan dampers,
    wire controls, and pipes
   We should know about these in our pre plans
   We should not try to operate them due to their
    differences and complexity. Call the occupants.



                                                       11
                                                        7
   Typical high rise occupancies are hospitals,
    hotels, apartments, and office buildings
   All these equal a lot of people in danger in a fire
   Fire and smoke may spread rapidly through pipe
    shafts, stairways, elevator shafts, air-handling
    systems, and other vertical openings
   These openings cause a stack effect {natural,
    vertical heat and smoke movement throughout a
    building} creating an upward draft and
    interfering with evacuation and ventilation


                                                          11
                                                           8
   Layering of smoke and gases on floors below
    the top floor of un-vented multi-story
    buildings is possible
   These gases travel up until their temperature
    is reduced to the same as the surrounding air
   When this happens, the smoke and gases will
    mushroom on this floor or in this area
   The layering of smoke at an area of
    temperature equalization is called
    stratification
   Pre plans should include tactics and
    strategies to deal with this problem in tall
    buildings
                                                    11
                                                     9
   High rise ventilation must be carefully
    coordinated to ensure the effective use of
    personnel, equipment, and extinguishing
    agents
   Personnel demand will be approximately 4
    to 6 times what it is for a normal house
    fire
   Consider using horizontal ventilation @
    stratification level
   SCBA and extra bottles will be in great
    demand
   Communication and coordination among
    teams will become more difficult due to
    the number of people on the scene            12
                                                  0
   Top ventilation must be considered during pre
    planning
   Often, in these buildings, only one stairwell
    goes to the roof
   We must know which one so we can use this as
    a chimney to ventilate the building
   Block this door open or take it off its hinges
    before you begin opening the interior stairwell
    doors



                                                      12
                                                       1
   Failure to open / secure this door can
    result in the stairwell becoming filled with
    superheated fire gases and smoke
   Elevator shafts may also penetrate the
    roof line and may be used for ventilation
   Using stairwells or elevator shafts for
    evacuations and ventilation
    simultaneously is potentially life-
    threatening




                                                   12
                                                    2
   Failure to open / secure this door can
    result in the stairwell becoming filled with
    superheated fire gases and smoke
   Elevator shafts may also penetrate the
    roof line and may be used for ventilation
   Using stairwells or elevator shafts for
    evacuations and ventilation
    simultaneously is potentially life-
    threatening



                                                   12
                                                    3
   8-1.3 Demonstrate opening various
    types of windows from inside and
    outside, with and without fire department
    tools.
   8-1.4 Demonstrate breaking windows or
    door glass, and removing obstructions.
   8-1.5 Demonstrate ventilation of a floor
    or roof using an axe.
   8-1.6 Demonstrate ventilation using a
    water fog stream.
                                                12
                                                 4
   8-2.1 Demonstrate the use of different type
    of power saws and jack hammers.
   8-2. Demonstrate the techniques for
    ventilating different types of roofs.
   8-2.4 Demonstrate the removal of existing
    roof opening. I.e.: skylights, scuttle covers,
    and other roof openings.
   8-2.5 Demonstrate the different types of
    equipment used for forced ventilation.



                                                     12
                                                      5
   8-3.1 Demonstrate natural and mechanical
    methods for horizontal ventilation.
   8-3.2 Demonstrate natural and mechanical
    methods for vertical ventilation.




                                               12
                                                6
THE END
      12
       7

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:7
posted:9/26/2012
language:Unknown
pages:127