VENTILATION.

VENTILATION

Ventilation Practices

Basic Objectives Ventilation Practices
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.

Intermediate Objectives Ventilation Practices
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.

Advanced Objectives Ventilation Practices
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.

Introduction 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

Introduction 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

Introduction 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

Introduction 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 premature roof failure

Introduction 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

Introduction 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

Introduction Ventilation Tools
All PPE Charged Hose Line Forcible Entry Tools Chain Saw Rotary Saw Ladders

Ventilation and Rescue

Advantages of Ventilation Rescue Operations
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

Ventilation and Fire Attack or Extinguishment

Advantages of Ventilation Fire Attack & Extinguishment
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

Ventilation and Salvage

Advantages of Ventilation Property Conservation
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

Mushrooming What Type of Ventilation is Needed?

Advantages of Ventilation Fire Spread Control
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

Advantages of Ventilation Reduction of Rollover Potential ~Firefighters should always stay as low as possible~

Advantages of Ventilation Reduction of Rollover Potential
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

Advantages of Ventilation Reduction of Flashover Potential

Advantages of Ventilation Reduction of Flashover Potential
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

Advantages of Ventilation Reduction of Backdraft Potential
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

Advantages of Ventilation Reduction of Backdraft Potential
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

Considerations for Ventilation
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

Is There a Need for Ventilation at This Time?
This must be based on the amount of heat, smoke, and gas conditions within the structure, structural conditions, and the life hazards

What Type of Structure? Any Exposures? Where is Fire Located?

Where is Ventilation Needed?
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

What Type of Ventilation Should Be Used?
Horizontal? Natural or Mechanical? Vertical?

Natural or Mechanical?

Do Fire and Structural Conditions Allow for Safe Roof Operations?
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

Life Safety Hazard 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

Life Safety Hazard 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

Life Safety Hazard 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

Visible Smoke Conditions
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

Visible Smoke Conditions
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

The Building Involved 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

The Building Involved 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

Basements and Windowless Buildings
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

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

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

Location and Extent of the Fire
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

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}

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

Selecting the Place to Ventilate
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

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

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

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

Vertical Ventilation 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

Vertical Ventilation 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

Main Roof Types

Vertical Ventilation 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

Vertical Ventilation 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

Safety Precautions 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

Safety Precautions 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

Safety Precautions 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

Safety Precautions 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

Safety Precautions 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

Safety Precautions 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}

Existing Roof Openings

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

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

Roofs 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

Inspection Opening

Roof Cuts 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

Louvered Cut

Roof Cuts 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

Typical Flat Roof Construction

Flat Roofs 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

Flat Roofs 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

Pitched Roofs 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

Pitched Roofs 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

Pitched Roofs 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

Arched Roofs 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 roof.

Arched Roofs 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~

Concrete Roofs 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

Concrete Roofs 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

Metal Roofs 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

Metal Roofs 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

Trench or Strip Ventilation
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

Basement Fires 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

Basement Fires 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

Ventilation Problem Precautions
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

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

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

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

Horizontal Ventilation
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

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

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

Weather Conditions 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

Exposures 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

Exposures 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 the point where fire might be expected to spread

Upsetting Horizontal Ventilation
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

Cross Ventilation

Forced Ventilation 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

Forced Ventilation - Advantages
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

Forced Ventilation - Disadvantages
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

Negative Pressure Ventilation
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

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

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

Positive Pressure Ventilation
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

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 the point of entry to increase the CFM flow and thus the interior pressure

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}

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

Key Points for Effective PPV
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

Advantages of PPV over NPV
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

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

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

Disadvantages of PPV An intact structure is required
Interior carbon monoxide levels may be increased during use Hidden fires may {will} be extended

Hydraulic Ventilation
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

Hydraulic Ventilation
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

Hydraulic Ventilation - Drawbacks
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

Hydraulic Ventilation - Drawbacks
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.}

Building Ventilation Systems
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

Building Ventilation Systems
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.

High Rise Buildings 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

High Rise Buildings 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

High Rise Buildings 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 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

High Rise Buildings 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

High Rise Buildings 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

Hand on Objectives Basic 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 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.

Hands on Objective Intermediate Ventilation
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.

Hands on Objectives Advanced Ventilation
8-3.1 Demonstrate natural and mechanical methods for horizontal ventilation. 8-3.2 Demonstrate natural and mechanical methods for vertical ventilation.

THE END

VENTILATION.

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