Fire Service Ventilation (7th Edition)-All Chapter Test ...



Fire Service Ventilation (7th Edition)

Chapter 1-Fire Behavior/Airflow Characteristics

Test Review

▪ The three phases of fire are: Incipient, Steady-state, and Hot-smoldering.

▪ The incipient phase begins with the actual ignition and is usually limited to the original products of ignition.

▪ The supply of oxygen has been depleted in the hot-smoldering phase.

▪ Opening a window may be all that is required to ventilate during the incipient phase.

▪ Ventilation on the side opposite the fire attack can reduce rollover potential.

▪ Directing water toward the ceiling and room contents along with aggressive ventilation can reduce flashover potential.

▪ Opening a door or window late in the hot-smoldering phase can cause a backdraft.

▪ Warning signs of backdraft include:  Smoke exiting small openings under pressure, black smoke becoming dense, grayish-yellow, confinement, excessive heat, little or no visible flame, smoke leaving structure at intervals, muffled sounds, or sudden rapid movement of air inward when an opening is made.

▪ Warning signs of backdraft from inside the structure include:  windows rattling, flames becoming sickly yellow or less lively, muffled noises, and fire diminishing before water is applied.

▪ If backdraft conditions are developing, leave as quickly as possible, if not possible, stay low and away from ventilation openings.

▪ Carbon monoxide is present in every fire.

▪ Temperature is an indicator of heat.

▪ The greater the molecular activity, the more intense the heat and the higher the temperature.

▪ The Law of Heat Flow states that "heat tends to flow from a warmer to a colder substance" and "the colder of the two bodies will absorb heat until both objects are the same temperature".

▪ Asbestos is a carcinogen and is extremely dangerous when airborne.

▪ Nitrogen oxides are liberated in the combustion of pyroxylin plastics.

▪ Phosgene is a strong lung irritant.

▪ Carbon monoxide is an asphyxiates by combining with hemoglobin 200 times more readily than does oxygen.

▪ Particulates in smoke include:  carbon, tar, dust, and fire gases.

▪ Most gases emitted by fire have a vapor density greater than 1.0.

▪ Fire gases return to ground level after a fire, making it important to wear SCBA during overhaul.

▪ The factors that determine the fire gases given off are:  nature of the combustible, rate of heating, temperature of evolved gases, and oxygen concentration.

▪ Acrolein is a strong respiratory irritant produced when polyethylene, wood, and natural materials smolder.

▪ Acrolein is used in the manufacture of pharmaceuticals, herbicides, and tear gas.

▪ Carbon dioxide is a colorless, odorless, nonflammable gas produces in free-burning fires.

▪ Carbon dioxide can asphyxiate by excluding oxygen from a space as well as increase inhalation of toxic gases by increasing respirations.

▪ Carbon monoxide is a colorless, tasteless, odorless gas present in every fire.

▪ The darker smoke is, the more carbon monoxide being produced.

▪ Carbon monoxide combines 200 times more readily than oxygen to hemoglobin, resulting in inadequate oxygen perfusion.

▪ Hydrogen chloride is a colorless, very pungent, irritating gas produces when plastics, containing chlorine, burn.

▪ Hydrogen cyanide is a colorless gas with an almond odor that is 20 times more toxic than carbon monoxide.

▪ Hydrogen cyanide is an asphyxiant that is skin absorbable.

▪ Wool, silk, and nitrogen-containing products give off hydrogen cyanide when they burn.

▪ Nitric oxides, which are reddish brown or copper color, are liberated from burning pyroxylin plastics.

▪ Nitric oxides convert to nitrogen dioxide in the presence of oxygen, which is a pulmonary irritant.

▪ Phosgene is a highly toxic, colorless gas with a odor of musty hay.

▪ When freon contacts flame, it produces phosgene gas that is a strong lung irritant.

▪ The process of gases rising until they reach the top of a space, spreading out laterally, then banking down is termed mushrooming.

▪ A pressure differential is a low pressure area at the bottom of a space created by the upflow of fire gases.

▪ Horizontal layers of different temperature levels within a space is termed thermal layering.

▪ An inversion is when smoke rises until the temperature of the air equals the smoke temperature, then spreads out laterally in a horizontal layer.

▪ Sulfur dioxide, large quantities of carbon dioxide, and oxygen-deficient atmospheres are hazardous non-fire gases found in most communities.

▪ Methane, hydrogen, and acetylene are lighter-than-air gases.

▪ Chlorine, and carbon dioxide are heavier-than-air gases.

▪ Pressure transfers from an area of higher pressure to areas of lower pressure until pressures equalize.

▪ Neutral pressure planes are points within structures, usually midpoint vertically, in which the pressure of internal and external spaces are equal.

▪ The stack effect is the inward pull of air at the bottom of a space due to negative pressure which is created by convected smoke and heat to upper portions which creates a positive pressure at the top of the space.

▪ Dilution rate is affected by volume of air moved, placement of fan (if used), size of openings, and availability of replacement air.

Fire Service Ventilation (7th Edition)

Chapter 2-Ventilation Size Up

Test Review

▪ Ventilation size-up includes determining location/extent of fire, assessing life hazards, and identifying building construction features.

▪ Infrared detection equipment can detect hot spot without entering structure and detect people when used inside a structure.

▪ Hydrocarbons are products containing hydrogen and carbon.

▪ Ventilating as close to the seat of the fire as possible is considered offensive ventilation.

▪ Cutting a trench/strip ventilation ahead of a fires path is considered defensive ventilation.

▪ When assessing life hazards, get data on number and location of occupants, obtain the structure's use/processes, and identify hazardous materials present.

▪ Fire crews must coordinate with ventilation groups since ventilation often increases the intensity of fire.

▪ Directing a fire stream into a vent opening does not permit smoke and heat to exit and can cause steam burns to crews inside.

▪ Severity of fire can be determined by the type of fuel burning, fire protection devices present, degree of confinement, and the time elapsed since the fire began.

▪ Creating ventilation openings other than over the seat of the fire can spread fire to uninvolved portions.

▪ Fire involving ordinary combustibles will initially produce an off-gray white or blue-white smoke of little density.

▪ Dense black smoke indicates burning hydrocarbons (rubber, tar, oil, some plastics).

▪ Brown or copper color smoke indicates nitrogen oxide presence.

▪ Gray-yellow smoke exiting under pressure through small cracks indicates possible backdraft conditions.

▪ Fire intensity/location can be determined by feeling structural components for heat.

▪ Discolored/blistering paint indicate high heat.

▪ Hot spots on floors above the fire floor can indicate fire location.

▪ Attic fires may be revealed by areas of melted snow on roofs.

▪ Readiness of rescue, fire attack, and exposure protection crews determines when to ventilate.

▪ Fire location, occupant location, interior/exterior exposures, construction type, occupancy purpose, fire progression, building condition, existing openings, wind direction, and availability of personnel/equipment determine where to ventilate.

▪ Horizontal ventilation might be useful with small fires, wall openings are close to seat of fire, fire involves top floor, or when fire has not entered structural voids.

▪ Vertical ventilation might be useful when fire is in attic or on top floor, in windowless buildings, in buildings with large vertical shafts, or when fire has entered structural voids.

▪ Natural ventilation is fast and efficient, however, may need to be supplemented with forced ventilation for facilitate rescue/fire attack.

▪ Forced ventilation is appropriate when location/extent of fire has been determined, natural ventilation will not be sufficient, when fire is below grade, or when non-fire contaminated atmospheres are present.

▪ Horizontal ventilation may threaten internal exposures due to the path of smoke and fire gases being the same as those used by occupant to escape or due to smoke reentering structure through air drawn in by HVAC units.

▪ Horizontal ventilation may threaten external exposures by lapping up to upper parts of the structure or by igniting exposure buildings through radiant heat.

▪ External exposure threats due to vertical ventilation include hot embers carried by convection to the roofs of nearby structures or to dry vegetation or igniting structures taller than the fire structure through radiant heat.

▪ The side of a building that the wind strikes is the windward side.

▪ The side of a building that the wind blows away from is the leeward side.

▪ Wind can affect ventilation by blowing fire toward external exposures, feeding oxygen to the fire, or by blowing fire into uninvolved portions of the structure.

▪ High humidity can keep products of combustion from rising into the atmosphere.

▪ Snow and ice can increase loads on roofs, conceal roof features, and delay operations.

Fire Service Ventilation (7th Edition)

Chapter 3-Horizontal Ventilation

Test Review

It is advised that you review IFSTA Building Construction before completing this chapter

as there are many terms which are presented in the text.

▪ A blower is any device positioned outside a space to blow fresh air in.

▪ An ejector is any device positioned inside a space to blow contaminated air out of a space.

▪ A fan is a term used to describe either a blower or ejector.

▪ Flexible ducts can be used to draw contaminants out of a space by attaching an ejector outside the space to the duct which is positioned inside the space such as in confined spaces.

▪ Forced ventilation is use of fans, blowers, nozzles, and other mechanical devices to create or redirect flow of air in a space.

▪ A hasp is a locking mechanism found on many metal doors.

▪ HVAC stands for Heating, Ventilation, & Air Conditioning.

▪ Natural ventilation utilizes natural wind currents and building openings to rid structures of contaminants.

▪ A teepee cut is a cut made in metal components by making two cuts in the shape of a triangle, leaving the bottom uncut, then rolling it down for access.

▪ Thermoplastic is a type of extremely resilient plastic used in place of glass in many commercial windows.

▪ Fire walls reduce the likelihood of horizontal fire spread.

▪ Masonry brick walls are made of reinforced concrete, concrete block, brick, or stone.

▪ Veneers are decorative exterior wall finishes made of brick, stone, stucco, plastic paneling, or foam.

▪ Masonry is best breached by jackhammers.

▪ Veneer over frame is best breached by regular forcible entry tools, sledgehammers, or battering rams.

▪ Metal is best breached by making a "teepee" cut with hand or power tools.

▪ Fixed windows are usually flanked by double-hung or casement windows which are more accessible for ventilation.

▪ The entire window area of casement windows are available for ventilation use.

▪ Jalousie windows are very difficult to open without breaking the panes.

▪ Only the openable portion of single/double-hung, horizontal-sliding, awning, projected, jalousie, and hopper windows are available for ventilation without breaking glazings.

▪ Thermoplastic/energy-efficient windows tend to hold in more heat, accelerate development of flashover conditions, and increase chances of backdraft.

▪ Swinging doors are the most common type of door.

▪ Sliding exterior doors are common on storage, commercial, and industrial buildings.

▪ Sliding interior fire doors are metal clad, fire resistance rated doors suspended on slanting tracks attached to the surface of fire walls.

▪ The primary use of sliding interior pocket doors is for a visual privacy barrier.

▪ There is always a mechanism present on revolving doors to collapse the wings.

▪ Most roll-up doors have a more convenient swinging door next to them.

▪ A teepee cut can be made in roll-up doors when immediate access is needed.

▪ Air flow through a structure can be interrupted by partitions, the arrangement of rooms, and stacks of high-piled storage.

▪ It is a good practice to close doors once a room has been searched.

▪ Ejectors or fog streams used for ventilation are put on the leeward side of buildings.

▪ Blowers are placed on the windward side of buildings.

▪ Top windows on the leeward side of a building should be opened first to allow heated gases to escape.

▪ Screens, curtains, and blinds will hinder air circulation.

▪ In the absence of a blower, windward side windows should not be opened until initial knockdown of the fire.

▪ When breaking a window, use the flat side of an axe, with the handle held higher than the blade.

▪ Circular saws with carbide-tipped, medium tooth blades, can be used to open thermoplastic glazings.

▪ Striking a thermoplastic glazing with a sledgehammer will not break the pane, however, it will bow the pane enough to slip it out of the frame in most cases.

▪ Scoring a thermoplastic pane with an "X" will usually allow the pane to break along the scoring when struck.

▪ Thermoplastic glazings can be frozen with a CO2 extinguisher, then struck in the middle with a pick head axe.

▪ If a thermoplastic pane has been heated by fire, striking methods may not be successful.

▪ Smoke ejectors must have explosion-proof motors.

▪ When using a smoke ejector, the open area around the ejectors should be sealed to prevent churning.

▪ The cone of air from a blower should cover the entire opening.

▪ Hydraulic ventilation may increase water damage and drain the available water supply.

▪ Hydraulic ventilation is limited to negative pressure ventilation.

▪ Operations involving hydraulic ventilation must be interrupted each time the operator runs out of breathing air.

Fire Service Ventilation (7th Edition)

Chapter 4-Vertical Ventilation

Test Review

▪ Ventilation at the highest point of a building through existing or created openings and channeling the contaminated atmosphere vertically within the structure and out the top is termed vertical ventilation.

▪ Vertical ventilation reduces property damage, increases visibility, decreases heat and fire gases, and reduces flashover/backdraft conditions.

▪ A second means of egress from roofs should always be provided.

▪ Enlarging existing openings should always be chosen over making new ones.

▪ Snow, ice, and personnel are examples of live loads.

▪ Permanent structures, such as HVAC units, are examples of dead loads.

▪ Vertical ventilation hazards include, fire-weakened roofs, live/dead loads increased, poor footing on steep roofs, parapet walls, products of combustion exiting ventilation openings.

▪ Observing the condition of roofs and any hazards present is termed "reading the roof".

▪ A hollow sound when sounding a roof indicates an area of the roof is between structural supports.

▪ A solid sound when sounding a roof indicates an area of roof the contains structural supports underneath it.

▪ Hoselines may be needed on roofs to cool thermal columns, protect the vent team, and extinguish attic fires.

▪ Pick head axes can be used to open roofs, mark where cuts with power saws are to be made, and scraping away gravel.

▪ Rotary saws should be placed flat on the surface, revved to cutting speed and rocked forward to start the cut.

▪ To clear rafters with a rotary saw, simply rock it backward to decrease the depth of the cut.

▪ Chains saws should only use the last few inches of the cutting bar.

▪ Burning bars can cut through materials that cannot be cut with oxyacetylene torches.

▪ Pike poles and rubbish hooks can be used to strip away roofing materials.

▪ Sledge hammers can be used to break tile/slate roof coverings to allow for cutting.

▪ Scuttle hatches provide entrance to and exit from the top floor.

▪ Bulkheads enclose the top of stairways that terminate on the roof and are usually fitted with a standard size metal clad door.

▪ Skylights may be used for ventilation by removing three sides and using the fourth as a hinge.

▪ Skylights containing wired glass must be removed for ventilation.

▪ Monitors penetrate roofs to provide additional lighting/ventilation and may have metal, glass, wired glass, or louvered sides.

▪ Monitors with solid walls should have at least two opposite sides hinged at the bottom and held closed by fusible link.

▪ Light and ventilation shafts do not require opening or enlarging for ventilation purposes.

▪ Bridge trusses, also known as Howe or Pratt trusses, are similar to mansard roofs and are in constant tension and compression.

▪ Early failure of bridge truss tie rods affect stability of the trusses.

▪ Firefighters should NOT walk diagonally across a roof, but should only walk over main roof support members.

▪ Butterfly roofs have a peak that is inverted.

▪ The most common style of roof on residential structures is gable type.

▪ On gable roofs, the point where the rafters meet the outside bearing walls and the ridge beam provides the most support.

▪ Valley rafters are used on gable roofs where two roof lines intersect.

▪ Gambrel roofs are found on barns or outbuildings.

▪ Large attic spaces of gambrel roofs make them susceptible to premature failure, making aerial ladders the method of choice for vertical ventilation.

▪ Gambrel roofs are a gable roof with two slopes on each side with the lower slope being steeper.

▪ Hip roofs slope down to meet every outside wall.

▪ The strongest part of hip roofs are the valley rafters, hip rafters, ridge beam, and points where rafters cross outside bearing walls.

▪ Lantern roofs are difficult to vertically ventilate without an aerial device.

▪ A high-gabled roof with a vertical wall above a downward-pitched shed roof section on either side is called a lantern roof.

▪ Mansard roofs have a double slope on each of the four sides and forms a hipped peak.

▪ Modern mansard possesses characteristics of flat and pitched roofs with four steeply sloped sides that rise to meet a flat top called a "deck".

▪ Modern mansard roofs may utilize bridge trusses or K-trusses as supporting members.

▪ A void space between ceiling and roof in modern mansard roofs create a potential for early collapse.

▪ Sawtooth roofs are used on industrial buildings to maximize light and ventilation.

▪ Vertical walls of sawtooth roofs include openable windows with wired glass along the entire length.

▪ Shed roofs are a flat roof sloping only to one side and may utilize a mono-pitched truss which may be prone to early collapse.

▪ The two most common types of concrete roofs are lightweight concrete poured over metal decking or precast "Double-T" panels.

▪ Opening concrete roofs may require special tools such as jackhammers, core drills, or burning bars.

▪ Lightweight concrete roofs may be cut with a rotary saw with a masonry blade.

▪ Concrete roofs may be designed with access panels that can be lifted out in an emergency.

▪ Using existing openings on concrete roofs such as bulkheads, ventilators, or scuttles, are the fastest access.

▪ Sheathing is nailed to the framework and weatherproofing is applied over the sheathing in inverted roof construction.

▪ Inverted roof surfaces usually feel "spongy" or "springy".

▪ Inverted roofs contain a concealed space that exists between the roof deck and ceiling.

▪ The structural members within the concealed space of inverted roofs are exposed on all four sides and can be weakened if fire enters the space.

▪ Metal deck roofs consist of metal bar joists, usually running across the narrow dimension of the building, and metal decking laid perpendicular to the joists.

▪ Metal decking is usually spot welded to the joists.

▪ Large-area metal deck roofs consist of large supporting beams that run across the narrow dimension of the building and bar joists that run perpendicular to the beams and parallel to the long dimension of the building.

▪ Metal decks can be expected to fail within a few minutes of flame impingement.

▪ Metal decking around vents and other openings heated by fire will not support the weight of a firefighter.

▪ Panelized roofs are supported at their ends by pilasters, wooden or steel posts, or saddles.

▪ The strongest part of a panelized roof structure are the beams, purlins, and perimeter where the building meets the exterior walls.

▪ A three-layer laminated, insulated paper is used on the underside of a panelized decking made of a tar-impregnated layer covered on either side by a layer of thin aluminum foil.

▪ With panelized roofs, the foil on insulation paper peels off under fire condition allowing joists and decking to be exposed to fire.

▪ Poured gypsum roofs consist of bar joists or I-beams with bulb tees tack-welded to the joists.

▪ Poured gypsum roofs are sealed with a weatherproof covering.

▪ The weatherproof covering of poured gypsum roofs is easily cut with a power saw using a metal-cutting blade, then rolled back to open the hole.

▪ Rain roofs are most common with flat or arched roofs.

▪ Rain roofs are commonly built over an existing roof that has become so porous that it cannot keep rain out or sags and collects water.

▪ Voids between an old roof and a rain roof can delay detection of a fire.

▪ Rain roof assemblies may be more susceptible to collapse since the underlying roof was not designed to support the additional weight.

▪ Some brands of fire-resistant plywood used in wooden deck roofs can delaminate and cause firefighters to be able to step through the plywood that has not been damaged by fire.

▪ Hazard signals of ventilating flat roofs include sagging and hot spots (melting, soft, or bubbling tar).

▪ Overhangs added to give the appearance of a mansard roof form concealed spaces which a fire may spread undetectably and quick.

▪ Inverted flat roofs create a concealed space several feet high that contain many unprotected structural members which can weaken the structure under fire conditions.

▪ Security measures such as razor wire and guard dogs may hinder roof access.

▪ High parapet walls may present a fall hazard to the roof below and low parapet walls may present a trip hazard.

▪ Ventilation should occur as directly over the fire as possible.

▪ Removing roof vents, cutting a large square or rectangular hole, cutting a strip or trench opening (defensive), or a combination of methods can be used on flat roofs.

▪ If smoke is exiting a roof ventilator under pressure, enlarge the opening by cutting the shroud down to the flashing and fold back.

▪ At least two sides of roof monitors should be removed.

▪ Bubble skylights should be removed from their frames.

▪ Panes in wired-glass skylights should be broken or removed.

▪ If breaking more than one pane, pause after breaking the first pane to allow those below that did not hear the initial warning to move or alert the vent crew to delay breaking further panes.

▪ Thick tar coverings tend to gum up chain saws, so rotary saws may be a better choice.

▪ Holes in flat roofs should be cut parallel to the rafters and perpendicular to the sides of the building.

▪ Start cuts on the leeward side followed by parallel side cuts approximately 4 feet apart between the rafters, then roof should be pulled back using pick-head axes, pike poles, or rubbish hooks.

▪ Bowstring roofs are commonly found on bowling alleys and supermarkets.

▪ Bowstring roofs use tie rods for lateral support and turnbuckles to maintain proper tension.

▪ The perimeter and arch members of bowstring roofs are the strongest points.

▪ Bowstring roofs have an early collapse hazard when tie rods are exposed to fire.

▪ Time into the incident should be closely monitored with bowstring roofs due to the possibility of early collapse.

▪ It is recommended to only work from aerial devices when vertically ventilating a bowstring roof.

▪ Lamella roofs consist of a geometric, egg-crate or diamond pattern framework on which plank sheathing is laid.

▪ Support for lamella roofs is provided by exterior buttresses or interior tie rods and turnbuckles.

▪ The perimeter of lamella roofs is the strongest area.

▪ Lamella roofs are just as prone to early collapse as bowstring construction.

▪ Ribbed roofs are similar to bridge-trussed roof except top chord is curved instead of straight.

▪ Ribbed roofs are found on older commercial buildings.

▪ Arched roof hazards can be estimated by the size of the lumber and span of the arches.

▪ Concealed spaces formed by the lower chord of the truss covered by the ceiling may contribute to fire spread and delay detection of fire in arched roof types.

▪ Arched roofs may have a sudden and total collapse without warning.

▪ Arched roofs should be vented at the top of the arch directly over the fire or by a long, narrow strip vent along the centerline of the roof.

▪ Another method of arched roof ventilation is to cut a conventional square opening cut perpendicular to the main arch support of a louver vent. 

▪ A series of louver vents may be most effective on arched roofs.

▪ It is recommended that all ventilation of arched roofs be made from aerial devices.

▪ Open web trusses are prefabricated systems that consist of wooden top and bottom chords that are cross-connected by steel tube web members.

▪ The bridge effect of an open web truss system causes the top chord to be under compression while the bottom is under tension.

▪ Flattened ends of open web trusses are inserted into slots in the chords and steel pins are inserted through the flattened tube ends.

▪ The open configuration of open web trusses creates large open spaces where fire can spread rapidly.

▪ The area on open web trusses where the roof meets the exterior wall is the strongest point.

▪ Metal gusset plate trusses are used in residential and light commercial applications.

▪ Area where metal gusset plate trusses cross the outside bearing walls is the strongest points.

▪ Interior partition walls are essentially free-standing walls that do not actually support the trusses, however, truss clips may be nailed to the bottom chord and top plate of the wall to provide lateral support of the truss.

▪ Gusset plates often distort and pull out during a fire.

▪ Roof failure on metal gusset plate trusses can occur if the bottom chord or webbing fails.

▪ Wooden I-beams are used in both roof and floor systems.

▪ Chipboard stem is joined to the top and bottom chord by a continuous glued joint on wooden I-beam trusses.

▪ The strongest point on wooden I-beam trusses construction is where the roof or floor meets the exterior walls.

▪ Stems of wooden I-beam trusses can burn quickly and cause the floor or roof to collapse quickly.

▪ Wooden shingles/shakes are most commonly made of Cedar and Redwood because of durability and appearance.

▪ Wooden shingles/shakes are highly combustible when dehydrated by age and weather.

▪ Wood shingles are sawn from large rectangular blocks of wood and tend to be uniform in shape and thickness.

▪ Wooden shakes are much thicker than shingles and are split from blocks of wood making them less susceptible to ignition.

▪ There is usually a single layer of tar paper between sheathing and wooden shingles/shakes.

▪ Wooden shingles and shakes can easily be stripped away by inserting a pick-head axe between the planks and pulling the axe laterally with quick short strokes.

▪ Composition roofing consist of and asphaltic base and granular mineral coating.

▪ The mineral coating on composition roofing provides weather and fire resistance.

▪ Composition roofing is usually installed over a layer of tar paper.

▪ Composition roof coverings are nailed through tar paper and into solid plywood sheathing or butted plank sheathing.

▪ Composition roof covering will burn and may be stripped with a flat shovel when necessary.

▪ Many roofs have more than one layer of composition roofing material and can hinder removal and will often gum up blades of power saws.

▪ Tar and gravel roofs, also called "built-up roofs", are found on flat to nearly flat roofs and on residential to large commercial buildings.

▪ Tar and gravel roofs consist of melted roof tar that is "hot-mopped" on to one or more layers of tar paper substrate over plywood or butted plank sheathing.

▪ Pea-sized gravel or crushed slag is added to the melted tar surface of tar and gravel roofs for durability and weather resistance.

▪ The mineral covering on tar and gravel roofs should be removed before cutting takes place.

▪ Because the tar on tar and gravel roofs is thermoplastic, it will melt or bubble during exposure to fire which also indicate structural instability.

▪ Urethane/Isocyanate foam is covered by one or more layers of a weather resistant covering.

▪ Thick, heavily insulated roofs tend to hold in heat and increase flashover and backdraft conditions.

▪ Foam products, such as urethane/isocyanate, release toxic products when they burn.

▪ A liquid elastomer sealed with a flexible, water-resistant synthetic membrane known as "single-ply roofs".

▪ Synthetic membranes are usually made of neoprene, polyvinyl chloride, chlorinated polyethylene, or bituminous sheets reinforced with polyester or fiberglass.

▪ Sheets in synthetic membrane coverings are sealed to the substrate with an adhesive or by heating the underside of the sheet with an electric heat gun or LPG torch.

▪ Synthetic membranes are easily cut, however, they liberate toxic products when they burn.

▪ Tile/Slate roofs are common on Spanish-type architecture.

▪ Tile roofs are made of curved tiles that are "nested" on the roof, usually over a layer of tar paper or wooden sheathing.

▪ Concrete or ceramic tile roofs are made of tiles that are flat, interlocking pieces.

▪ Slate roofs are most common on churches and older residences.

▪ Slate/tile roofs are extremely fragile and cannot usually be walked on without breaking them.

▪ Ventilation of tile/slate roofs should be accomplished from roof ladders.

▪ Ventilation of tile/slate roofs involves shattering the tile or slate over the appropriate area with a sledgehammer or pick-head axe and then ventilating in the normal fashion.

▪ Tile/slate roofs carry more weight per surface area than any roof type so early collapse may occur.

▪ Lightweight metal/fiberglass panels may be corrugated, ribbed, or shaped to simulate tiles or shakes.

▪ Corrugated metal roofs often use plastic or fiberglass panels as skylights in shed or gable roof configurations.

▪ The strongest parts of lightweight metal/fiberglass roofs are the ridge and area where the roof crosses bearing outside walls.

▪ Little fire resistance and early collapse are possible with lightweight metal/fiberglass roofs due the fact that they usually cover lightweight substructures.

▪ Lightweight metal/fiberglass roofs can be opened with an axe, "can opener", or by a power saw with a metal cutting blade.

▪ Smoke and heat retention with steel clad roofs is extreme and ventilation is difficult.

▪ The extreme weight of steel clad roofs can cause early failure.

▪ Steel clad roofs are used to protect many high-value buildings.

▪ Do not make the opening between a crew member and the escape route.

▪ Cut roof covering and decking, not the structural members.

▪ Begin opening on the leeward side and work against the wind when possible.

▪ Remove ceiling below ventilation openings to ensure ventilation.

▪ One 8x8 foot hole is equal to four 4x4 holes.

▪ Square/rectangular openings should be at right angles to the bearing walls.

▪ A rectangular hole cut over a rafter can be used to make a louver vent.

▪ Louver vents are the fastest, most efficient way to open a roof.

▪ With a louver vent there is always a rafter in the center of the piece being cut.

▪ Cutting parallel to the rafters is sometimes called "cutting the rafters".

▪ Trench ventilation is a defensive form of ventilation, also known as strip ventilation.

▪ A strip vent in some jurisdictions may indicate a louver vent.

▪ Trench ventilation confines the fire to one section of the building by reducing horizontal fire spread beyond the trench cut.

▪ Trench cuts must be made far enough ahead of the fire to allow time to complete the cuts.

Fire Service Ventilation (7th Edition)

Chapter 5-Forced Ventilation

Test Review

▪ Forced ventilation eliminates or reduces the effects of unstable and erratic winds.

▪ Forced ventilation provides greater control of the fire situation by providing dependable, controllable airflow.

▪ Forced ventilation allows flames, heat, and smoke to be directed away from occupants and uninvolved portions of the structure.

▪ Forced ventilation can be utilized to channel products of combustion using the most efficient and least destructive path.

▪ Forced ventilation allows fresh air to be introduced into the space.

▪ Forced ventilation allows a tenable atmosphere to be obtained quicker.

▪ Forced ventilation increases visibility and reduces fire and smoke damage.

▪ Forced ventilation reduces interior heat levels and supplements natural air flow.

▪ Forced ventilation improves survivability of occupants still inside.

▪ Forced ventilation can greatly intensify the fire or fire spread.

▪ Forced ventilation when misapplied, it can obscure vision, fail to reduce interior temperatures, and channel contaminants into exit passageways.

▪ Ventilation equipment is sometimes dependant on a power source.

▪ Gasoline blowers must be shut down to be refueled, interrupting the ventilation process.

▪ Using hydraulic (fog stream) forced ventilation requires that a firefighter stay inside the atmosphere and ventilation must be stopped if their SCBA runs out.

▪ Smoke ejectors are ducted fans of various sizes, usually in box-like housings.

▪ Air-moving capacity is measured in cubic feet per minute.

▪ Most smoke ejectors are electric, however, gasoline powered models exist.

▪ Smoke ejectors must have explosion proof motors.

▪ Smoke ejectors are sometimes fitted with flexible ducting to reach hard to access (confined) spaces.

▪ Blowers are ducted and non-ducted fans that are used to blow fresh air into a space from outside the space.

▪ Blowers are larger in size and rated capacity than smoke ejectors.

▪ The majority of blowers are gasoline-powered, however, electric and hydraulically-powered units are available.

▪ Some blowers are equipped with spray nozzles to inject water into the air stream, however, it has been found to be of little use in suppressing fires.

▪ Hydraulic ventilation is most often used with handlines, however, adjustable master stream nozzles can be used.

▪ Fire streams can be used to direct and control the airflow much as a smoke ejector by pointing the nozzle or portable adjustable master stream nozzle through a window or doorway.

▪ Fog streams draw large amounts of smoke and heat out of the opening in the direction of the stream.

▪ If a HVAC system is designed to draw air from the outside, it can aid in diluting and displacing cold smoke.

▪ HVAC systems most often create a need for forced ventilation due to the fact that they circulate smoke throughout the structure.

▪ Commercial climate control systems are normally just larger versions of residential systems.

▪ Some commercial climate systems are equipped with basic fire-control features such as fire dampers in the ducts activated by fusible links.

▪ Heavy-duty HVAC systems found in major mercantile occupancies, enclosed shopping malls, high-rise apartments and office buildings, and some heavy industrial occupancies are designed with features that will limit fire spread.

▪ Some HVAC system include heat/smoke-activated dampers in the ducting, heat/smoke detection systems integrated into the alarm system, and automatic sprinkler protection.

▪ Most important feature on some HVAC systems is that there may be a manual control for exhausting cold smoke.

▪ Positive pressure ventilation counteracts the pressure being generated by the combustion process and/or by adverse winds.

▪ Positive pressure ventilation is far more effective than negative pressure ventilation and much safer.

▪ Positive pressure ventilation keeps interior temperatures cooler by introducing fresh air and improves visibility.

▪ Blowers set up at ground level can force smoke out of high-rise structures more than 20 floors above.

▪ When continued into the overhaul phase, positive pressure ventilation can aid in the detection of hot spots by supplying additional air which produces visible smoke sooner.

▪ Attack crews must be ready before performing positive pressure ventilation.

▪ Negative pressure ventilation draws cool, fresh replacement air into the space as contaminants are ejected.

▪ With negative pressure ventilation, personnel and equipment usually must stay in the space being ventilated.

▪ When natural ventilation does not effectively clear the space, forced ventilation may be needed.

▪ Forced ventilation may be needed for below-grade fires.

▪ With large spaces that natural ventilation would not work or be to time-consuming, forced ventilation is a better choice.

▪ Windowless buildings or situations where access to fire is limited may benefit from forced ventilation.

▪ Hydraulic ventilation moves 2 to 4 times more contaminants than ejectors when applied properly.

▪ Hydraulic ventilation increases water damage to the structure and requires a substantial supply of water.

▪ With freezing temperatures, icing may be a problem when using hydraulic ventilation.

▪ Hydraulic ventilation operations must be halted when airpacks run out.

Fire Service Ventilation (7th Edition)

Chapter 6-High Rise Structures & Special Situations

Test Review

▪ Limited access, multiple compartments, masses of occupants, falling glass/debris, smoke/fire spread through vertical shafts, locked interior doors, low water pressure to upper floors, and crew fatigue are challenges of high-rise fires.

▪ Low rise elevators access lower floors and must not serve the fire floor to be considered low rise.

▪ High rise elevators provide access to upper floors.

▪ Express elevators run non-stop from ground floor to top floor.

▪ Freight elevators are designed to carry large, heavy loads.

▪ Elevator car may be automatically called to the fire floor due to a control malfunction.

▪ Power failure may strand an elevator above the fire or between floors.

▪ Products of combustion rise through vertical openings until they encounter an obstruction or until their temperature is reduced to the temperature of the surrounding air.  

▪ Equalization of the pressure of rising smoke vertically to a point where it is equal with pressures outside the space causes the combustion products to lose their buoyancy, cease to rise and "stratify".

▪ The three most common ventilation techniques for high-rise structures are vertical ventilation, horizontal ventilation of the fire floor, and horizontal ventilation of the floor above and below the fire floor.

▪ Vertical ventilation in high-rises can prevent or reduce the chance of mushrooming.

▪ Vertical ventilation in high-rises does not promote lapping.

▪ Automatic smoke vents may eliminate the need for additional top ventilation.

▪ Getting the vent group and equipment needed to the roof, roofs are out of reach of aerial devices, and intensity of the stack effect are common problems associated with high-rise ventilation.

▪ Use of aerial apparatus is the fastest, safest, most direct method of ventilating high-rises.

▪ Most roofs are out of reach of aerial ladders.

▪ Interior stairways may be congested with escaping occupants. 

▪ Not all stairwells penetrate the roof, so pre-incident inspection is a must.

▪ Use of helicopters is the most direct way of moving the vent team and equipment to the roof and removing occupants from the roof.

▪ Level of coordination with the use of helicopters is extremely high and dependent on training,  pre-incident planning, and smoke/weather conditions.

▪ Stairwell bulkheads on the roof must be blocked open or removed from hinges.

▪ Ventilation must be delayed until occupants above the fire floor are either evacuated or moved to an area of refuge.

▪ Stairwells used for ventilation should not be used for fire attack.

▪ The greater the distance between upper and lower openings and the greater the difference in temperature, the more intense the stack effect.

▪ If it is hotter inside than it is outside, the airflow will be inward at the bottom and outward at the top.

▪ If it is hotter outside than it is inside, the airflow will be outward at the bottom and inward at the top.

▪ If temperatures are equal inside and outside, no natural airflow will take place.

▪ Wind produces a positive pressure on the windward side which tends to raise the neutral pressure plane.

▪ Negative pressure exists on the leeward side of a building, which lowers the neutral pressure plane.

▪ Ventilating on the windward side can work against effective ventilation and spread fire into uninvolved areas.

▪ Ventilating horizontally, below the neutral pressure plane will cause air to be drawn inward.  Ventilating horizontally, above the neutral pressure plane will cause air to escape.

▪ The closer ventilation is to the neutral pressure plane, the less the effect of negative or positive pressure.

▪ Ventilating below the fire floor is useful when smoke has spread to floors below the fire floor due to negative stack conditions or mushrooming.  

▪ The most common technique for ventilating below the fire floor is to vent these floors horizontally which can be enhanced by pressurizing the entire building.

▪ Ventilating below the fire floor is not a common practice.

▪ Ventilation of the fire floor is difficult, time-consuming, and potentially dangerous to those on the street below due to falling glass that must be broke to effect horizontal ventilation.

▪ Ventilating above the fire floor is the most effective method if the process is started at the top of the building.

▪ The addition of controllable dampers to HVAC systems which can be selectively opened and closed can serve as smoke-control systems.

▪ HVAC systems can limit spread of smoke/fire, improve operating conditions, and increase survivability of occupants.

▪ HVAC systems used to control smoke movements should be operated by a qualified building engineer.

▪ HVAC systems may be used to assist in locating the origin of the fire.

▪ HVAC systems should be used to limit the extension of the fire and smoke to the smallest possible area.

▪ HVAC systems should NOT promote the growth or extension of fire or smoke beyond the area of origin.

▪ HVAC systems should provide fresh, uncontaminated air to any occupants who may still be trapped or located in a safe refuge area.

▪ HVAC systems can be shut down automatically by smoke detectors in the ducts in the event smoke enters the ducts.

▪ HVAC systems can be manual shut down by the building engineer.  

▪ Contact with the building engineer should be made as soon as units arrive at the incident to avoid delay in shutting down HVAC systems.

▪ Automatic roof vents, which take advantage of convection, eliminate the need for additional ventilation by the fire department.

▪ Automatic roof vent fusible links may fail, locking mechanisms may fail, sprinkler heads near them may prevent heat which activates them, and they create a large open space that firefighters may fall into while on the roof.

▪ Atrium vents lend themselves to the stack effect and are usually accompanied by automatic vents to further rid contaminants.

▪ Sprinklers may cool the surrounding air around atrium vents so that they do not open.

▪ Monitors utilize a fusible link to open automatically to effect ventilation, but may be manually opened by removing the metal, glass, wired glass, or louvered sides.

▪ Fusible links on monitors may fail and glass designed to break may not.

▪ Skylights can open automatically in fires due to the glass breaking or thermoplastic cover melting.  

▪ Skylights with panes which have not been broken can be easily used for ventilation by breaking out the pane.

▪ Skylight panes made of wired glass must be removed and cannot be effectively broken for ventilation purposes.

▪ Curtain boards usually confine a fire to a relatively small area and may accelerate the activation of automatic sprinklers.

▪ Curtain boards may slow or prevent the activation of roof vents.

▪ If an opening of adequate size can be made opposite the point of entry in an underground structure, the fastest way to ventilate is to set up positive pressure blowers at the point of entry which allows the vent group to stay out of the underground area and still ventilate.

▪ While ventilating an underground structure, the rest of the structure should constantly be monitored for signs of fire extension though walls or vertical channels.

▪ The absence of exterior windows severely limits horizontal ventilation opportunities and increases the chances of backdraft and flashover conditions.

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