TRAINING DIVISION VENTILATION TRAINING MANUAL

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GLENDALE FIRE DEPARTMENT – VENTILATION TRAINING MANUAL

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GLENDALE FIRE DEPARTMENT

VENTILATION TRAINING MANUAL

UTABLE OF CONTENTS

VENTILATION – TERMINOLOGY 3 BUILDING CONSTRUCTION - STYLES 10 BUILDING CONSTRUCTION - METHODS 12 VENTILATION – CUTTING TECHNIQUES 20 SMOKE REMOVAL 48


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UVENTILATION TERMINOLOGY

Center Rafter Cut A technique used when cutting plywood sheathing (4 cuts). Center Rafter provides the largest hole possible with the minimum amount of cuts. Sheathing removal (louvering) requires a minimal effort. Center Rafter can also be used for cutting strip ventilation on 1” x 4” or 1’ x 6” sheathed roofs. 0BDecking Decking is the material used to comprise the base and exterior covering for the roof. The base is the material attached to the roof rafters. The base material can consist of solid wood sheathing, plywood-type materials, corrugated metal and other materials. 1BDiaphragm Nailing Plywood sheathing is installed so the 8’ dimension of the plywood crosses the rafters or joists and the 4’ dimension parallels the rafters or joists. The sheets of plywood are then staggered much like a brick or block wall. 2BDicing A technique used to cut 1’ x 4” or 1” x 6” solid, spaced or diagonally sheathed roofs. Dice cuts are made parallel to rafters with no concern to locating rafters. 3B“H” Clips Metal clips used to hold the butted ends of plywood together. “H” Clips are common on pitched roofs. 4BHead Cut A cut through the roof decking that is made perpendicular to rafters. UA head cut is used to locate raftersU. This cut involves rolling rafters. A head cut must be done on roofs covered with plywood and diagonal sheathing. A head cut is usually the first cut made on a center rafter cut. 5BHeat Hole “OFFENSIVE VENTILATION” A hole placed directly over the fire or as close to the fire that safety will allow. A properly placed heat hole saves lives and will allow firefighter access by reducing heat and smoke conditions inside the structure. A heat hole will also reduce the possibility of backdraft and flashover, and will slow down the horizontal spread of fire.


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6B“J” Hook The removal of sheathing is enhanced by a “J” Hook motion with an appropriate tool (pick head axe). The “J” Hook motion brings the pulling tool under and up to the decking in a smooth, forceful motion that will separate the decking materials from the rafters. This is simplified if the pulling tool is used near the rafters. 7BKerf Cut A Kerf Cut is a single cut made through the roof decking the same width as the chain saw blade. Although not as effective, the Kerf Cut can be used as an alternative to using the Smoke Indicator Hole. Laddering Ground ladders should be thrown to the uninvolved corners of the structure. The exception to the rule is when using a roof ladder. You must ladder the base of the roof ladder. It is preferable to have the wind to your back. For roof ventilation, A “MINIMUM” of two ladders should be thrown to the involved structure. 8BLouver It is not practical in most cases to remove cut plywood from a roof due to the method in which the plywood is nailed to the roof rafters. The best alternative is to louver the plywood. UOnce all 4 cuts are completeU, use a rubbish hook and push down on the near side (the side closest to your ladder) and pull on the far side. This method is used with the center rafter louver technique. 9BNailing Blocks Usually a 2” x 4” laid flat between rafters to provide a nailing surface for the edge of the plywood sheathing. Since the plywood normally used is 4’ x 8’ in size, a nailing block will usually be found every 4’. Parallel Cut. A cut through the roof decking made parallel to the roof rafters. Penthouse A door leading from the interior stairwell to the roof. Opening the Penthouse door can be a quick way to clear smoke out of the stairwell and any hallway that is open to the stairwell.


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10BPlug Cut A small triangular piece of roof covering (composition) that is removed from the roof to expose the roof sheathing. A plug cut is used to determine sheathing type and roof composition thickness. Plywood Type Sheathing Plywood, chip board, (OSB) oriented strand board are all materials used for floor and roof decking. The normal and most common size for plywood is 4’ x 8’. Under fire conditions, plywood burns at a quicker rate than solid wood sheathing and Uplywood delaminates U. 11BRolling Rafters Rolling rafters is used when making a head cut. When a rafter is felt with the chain saw, the saw is backed off and lifted or rolled over the rafter and then re-inserted into the sheathing and the cut is resumed. 12BScore Cut A light cut of the roof covering, usually composition only. A score cut is used to facilitate the removal of multiple layers of roofing material (composition). 13BSkim Cut A light cut made with the chain saw, cutting through the roof covering and plywood sheathing. The saw is not inserted deep enough to cut through the rafters. You “skim” over the top of the rafters. The skim cut is used on a Panelized roof when you are performing the cutting technique known as, “Louver off a Purlin”. Skylights Skylights are usually constructed from glass or plastic. On apartment buildings, skylights will be placed over hallways and stairwells. On commercial buildings they will be placed over manufacturing areas. When using skylights in conjunction with roof ventilation it is imperative that you systemically remove skylights. Remove skylights just as you would a ventilation hole. 14BSmoke Indicator Hole A small triangular hole cut through the roof decking (sheathing and roofing material) made with the chain saw or an axe. A smoke indicator hole is used to indicate smoke and fire conditions directly below the indicator hole. Smoke indicator holes should be placed along the path of access or egress every few yards. When placed directly in an area where a roof crew is working, they give a good indication of changing conditions, which may be vital for the safety of


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the roof ventilation team. Placing smoke indicator holes in the path of the fire can monitor fire spread. Smoke indicator holes can be placed on roofs of buildings attached to fire buildings to indicate interior exposure. 15BSounding A technique used to safely walk on a roof. Sounding utilizes a long handled tool (rubbish hook / pike pole) used to hit the roof. Sounding the roof will allow you to determine the condition of the roof. On some roofs (panelized) sounding can be used to locate main beams (Lam-Beams (Girders), Purlins). 16BStrip Ventilation “Defensive Ventilation” A long narrow section of roofing material that has been removed well ahead of the fire. The strip acts as a firebreak. Strip ventilation is usually preformed across the width of the roof, from parapet to parapet. Strip ventilation is sometimes called “Trenching”. Ventilators Ventilators are placed on roofs to ventilate attics and building interiors. Ventilators can be used to assess the progression of a fire. If ventilators are working correctly, leave them alone. A turbine style ventilator is about 30% more effective when the turbine is spinning. Ventilators are designed to ventilate, let them do their job. Vent Pipes Plumbing that extends from inside the structure through the roof line. Vent pipes can be constructed from ABS Plastic, Cast Iron, and Steel Pipe. Vent pipes travel vertically through a structure (pipe alleys) and can become an avenue for fire to travel. If vent pipes appear to be growing out of the roof, this should be an indication that the roof has sagged or dropped. This condition is known as “growing vent pipes”. 17B45 Degree Cut UA series of two cuts used to identify rafter direction “ONLY”. U The first 45-degree angle cut is made towards any exterior wall. A 45-degree cut will ensure the saw will intersect a structural member. When you hit a rafter “STOP”. Make a second cut parallel or perpendicular to the exterior wall.


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18B45 Degree Cut

19BSecond Cut Parallel to Exterior Wall

Second Cut Perpendicular to Exterior Wall

U45 Degree “Inspection” Cut A 45-degree inspection cut is accomplished by cutting through the roof decking at a 45-degree angle towards any exterior wall. A 45-degree cut will ensure the saw will intersect a structural member. When the saw makes contact with a rafter, roll over the rafter and continue for approximately 6 to 10 inches. Complete the cut by removing a small triangle of decking directly over the structural member. UA 45-degree inspection cut will tell you rafter type and direction, sheathing type, thickness of tarpaper and when complete, it can act as a smoke indicator hole.


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45 degree cut towards exterior wall.

Roll rafter.

Continue cut about 6 to 10 inches.


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Cut perpendicular to exterior.

Complete cut by making a triangle.

Remove triangle


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UBUILDING CONSTRUCTION - STYLES UCONVENTIONAL CONSTRUCTION

Conventional construction utilizes structural members that depend on size for strength. The greater the span for a structural member, the larger it has to be to support a given load. Additionally, conventional construction does not usually depend on the sum total of all structural parts or members for its strength. Structural members depend on their size for strength.

This can be easily demonstrated by considering mill/timber construction. The size of structural members dictates the time necessary for failure when exposed to heat or fire. ULIGHTWEIGHT CONSTRUCTION

Unlike conventional construction, lightweight truss construction does not derive strength from size. Strength is obtained from multiple members that are in compression and tension. The strength of the individual structural member is dependent on the total sum of the other members; therefore, if one member fails, others may fail.


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A single lightweight truss structural member can span 70-feet and may be comprised of 2 x 4's in compression and tension to form an integral unit. Although this structural member is strong, the size of the individual members are relatively small, requiring less time for structural collapse when exposed to heat or fire. Let's briefly compare some of the major differences between conventional and lightweight construction and what can be expected when they are exposed to fire: As previously mentioned, conventional construction does not rely on a sum total of members for strength. A simple example is a gable roof in a dwelling. The ridge board and rafters are an integral unit. However, they are separate and distinct from the ceiling joists. Therefore, when the attic is exposed to fire, the rafters and roof may collapse on the ceiling joists, thereby preventing collapse onto firefighting personnel below. Lightweight construction is vastly different due to truss construction that depends on the sum total of members for strength. When a truss gable roof in a dwelling is exposed to sufficient fire, expect the rafters (top chord of the truss), the roof decking and ceiling joists (bottom chord of the truss) to collapse as a unit into the structure, exposing firefighting personnel to falling, burning debris. There is no comparison between the size of the wood in conventional and lightweight construction. With few exceptions, 2” x 3”s and 2” x 4”s are the standard for lightweight construction, while conventional construction will utilize a minimum of 2” x 4”s (and up to mill/timber construction).

This translates into time that must be considered when deploying personnel and evaluating an offensive or defensive operation. Remember, the ability to accurately estimate the amount of time that a structure can be considered structurally strong is dependent on the following factors:

• Type of Construction.

• How long the fire has been burning.

• Fire Intensity.


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UBUILDING CONSTRUCTION - METHODS METAL CONSTRUCTION METHODS

Buildings that are primarily constructed of metal can be categorized as follows:

UCORRUGATED

These buildings utilize a sub-structure of wood or steel, covered with corrugated steel, aluminum or fiberglass. They are easily erected, can be utilized in various types of applications, and are easily identified by their characteristic "corrugated" appearance.

UHazards

The corrugated portions of these buildings will quickly fail when subjected to sufficient heat or fire. Remember, steel loses its tensile strength at 1000 degrees F, and aluminum or fiberglass offers little resistance to fire. Roof ventilation operations on these buildings should be considered extremely dangerous.

UMETAL BEAM

These buildings have a sub-structure of steel beams, usually coated with a sprayed on fire retardant material.

This skeleton is then finished with an exterior of concrete, masonry, glass or similar materials.

This type of building will vary from two stories to the tallest high rise. Modern High Rise buildings and multi-story office buildings typify this type of building. Although structurally strong, consideration must be given to the type of fire, intensity of fire, and the type of building materials exposed to fire.

UHazards

Vertical extension of fire and smoke to upper floors is enhanced in buildings with multiple floors.

Falling panels of glass or other building materials.

What you see is "not what you get." Brick buildings that consist of brick construction offer both structural integrity and the lack of vertical extension through the walls. However, newer buildings that appear to be of brick construction covered with brick veneer can be attached to lightweight construction. Pre-fire planning your area and being familiar with construction and specific buildings is key to determining the building construction materials used.

Note:

When exposed to sufficient heat, metal beams can expand 9" per 100' which can push out walls, etc.


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CONCRETE CONSTRUCTION METHODS

UTILT UP

These buildings are made of concrete slabs that have been "tilted up" into place to form exterior walls of a structure. These buildings are easily identified by their exterior appearance and can be up to five stories in height.

UHazards

• Expect to find lightweight construction in the interior walls, floors (if multiple story) and roof. Lightweight roof construction may be comprised of 2” x 4”s or 2” x 3”s in tension and compression and extensive use of 1/2 inch plywood. These contribute to rapid spread of fire and early roof collapse. Ventilation operations on this type of roof are dangerous unless personnel are properly trained.

• The modern "tilt up" with its characteristic flat roof has increased the popularity of the facade. The style of construction allows increased areas of fire spread and collapse potential that may threaten personnel close to the exterior of a structure.

MASONRY CONSTRUCTION METHODS

Buildings that have masonry as the prime material can be categorized as follows:

UBRICK

One of the more popular building materials used in various types of buildings, old and new, is the common brick. Unfortunately, brick buildings that were constructed prior to the 1930's are significantly different, both in appearance and structural integrity than brick buildings built today. It is safe to assume that the masonry portion of brick buildings constructed before the 1930's are "an accident looking for a place to happen," while the masonry portion of brick buildings built after the 1930's are very stable and are constructed as follows:

UPre-1933

Brick buildings constructed up until the 1930's are commonly classified as unreinforced masonry buildings. These buildings, built prior to 1933, are of ordinary brick construction and present extreme hazards to firefighting personnel under fire or earthquake conditions. Masonry buildings constructed prior to 1933 have the following characteristics.


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• Mortar consisting of sand and lime only, no cement.

• Lack of steel reinforcing rods ("rebar").

• Brick exterior walls about 13 inches thick.

• Parapet walls around the perimeter of a roof. Parapet walls can be three feet above the roof line, and five feet or more if used as a facade on the front of a building.

• Floor and roof joists that are "let" (penetrated or resting in a cavity) into the inside of the exterior walls.

• Straight roof sheathing.

• Roof and floor joists that are "fire cut" (ends were cut with an angle) so they would pull loose from the exterior walls during a fire and collapse into the interior of the building without pulling down the exterior walls.

Post 1933

After the disastrous Long Beach Earthquake of 1933, building codes were revised to provide better earthquake safety for new masonry buildings. The following revisions characterize the masonry buildings that were built after 1933:

• Exterior walls are required to be at least nine inches thick.

• Masonry walls are required to be reinforced with steel "rebar."

• All joists and rafters are required to be anchored to exterior walls. This is usually


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accomplished by bolting a "ledger board" to a masonry wall and attaching the joist and rafters to the ledger board with metal hangers.

• Cement utilized in the mortar.

• Diagonal roof sheathing.

Post 1959

After the Tehachapi Earthquake of 1959, building codes were modified to require the following retroactive correction on existing buildings masonry construction:

• A four to six inch concrete bond-beam cap to be laid on top of lowered parapet walls along public ways and exits.

• Parapet walls should not be higher than 16 inches including the bond-beam cap, and most importantly;

• Exterior walls drilled at the roof rafter level and a steel anchor bar/rod installed every four feet and attached to the existing roof rafter. This modification rendered the fire cut of the roof rafter ineffective. The steel anchor bar/rods are secured to the exterior of the building by a plate/nut combination that is known as "rafter tie plates."

Post 1971

The Sylmar Earthquake of 1971 provided the impetus to further modify existing buildings of unreinforced masonry construction. A Committee was formed to evaluate these buildings and review current building codes. That review was instrumental in additional retroactive corrections (EARTHQUAKE ORDINANCE) designed to prevent exterior walls from collapsing outward by stabilizing the building by:

• Anchoring walls to floor and roof systems.

• Strengthening roof construction (plywood, metal straps, etc.) Brick Identification

Unreinforced masonry buildings will share all or a portion of the following trademarks:

• Rafter tie-plates on the exterior of a building (rafter tie-plates can be found on remodeled "new" appearing buildings). These exterior plates on a masonry building indicate that the joists and rafters of the building are anchored to the exterior walls.

• A bond-beam cap of concrete on top of parapet walls. Concrete bond-beams may also have been added for strength over the windows and between the second floors of multi-story buildings. This is a common technique used for additional strength for exterior walls.

• Deeply recessed window frames. Window frames are "set" to the inside of the wall, thereby exposing about eight-inches of brick return on the exterior of a building. Remember, these walls are at least 13 inches thick.

• Windows may have arched or straight lintels.


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• The lime mortar between the bricks is white, porous, sandy, and may be easily rubbed away by a fingernail, knife, etc. In some cases, the bricks have not been uniformly laid and the workmanship appears sloppy.

• In every fourth to seventh row of bricks, one row will have been laid "on-end." This row of bricks is referred to as the "king row" and is for additional strength.

Some unreinforced masonry buildings have a fancy or better quality brick on the front of the building to improve the appearance. However, utilizing the preceding trademarks, the following indicators can be easily identified:

• Recessed windows • Bond-beams over the windows • Rafter tie plates

Additionally unreinforced masonry buildings are required to be reinforced to comply with the Earthquake Ordinance. Modifications may include the following:

• Add steel bracing from parapet walls to roof structural members.

• Metal straps across the width of the roof and attached to opposing walls. The straps are usually 1/3 of the length of the building back from the front and rear walls.

• Remove the layers of composition and cover the sheathing with 1/2 inch plywood. This decking is then recovered with composition.

HAZARDS

The primary hazards with this type of construction is as follows:

Wall, roof, and floor collapse. Unreinforced masonry construction that is held together with lime, mortar, and sand creates a weak wall, particularly after the lime mortar has deteriorated with age and/or is subjected to heat from a fire. These buildings were originally designed so that floor and roof joists would pull out from the walls during a fire, thereby preventing wall collapse. When rafters or joists are anchored to the walls, collapse is enhanced during fire conditions.

RAFTERS

SHEATING (ORIGINAL)


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An additional collapse hazard can result from arch type roofs (bowstring, tied truss and lamella) on unreinforced masonry construction. When arch roofs (particularly the bowstring and tied truss) are modified as per the Earthquake Ordinance, the additional roof stability provided by plywood and metal straps can increase the potential for collapse of front/rear walls.

A collapsing truss (A) that is connected to the "HIP" rafters at the ends of these buildings will push the hip rafter outward (B), also pushing the corresponding wall outward (C) with considerable force.

Personnel and apparatus placement. Due to the presence of arch roofs that have been modified as per the Earthquake Ordinance and floor/joists rafters that have been anchored to the walls, exterior walls may suddenly collapse (during fire conditions) outward a distance that is equal to at least the height of the wall. The primary dangers from collapse are the front and rear walls of a building. The secondary danger from collapse is the side walls of a building. The safe areas are as follows: 1. The corners of a building. 2. A distance at least equal to the height of the walls away from the building. Placement of personnel and apparatus should be a primary concern when confronted with this type of construction.

During retrofit modifications, consider:


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• Vertical openings.

• Holes in floors and ceilings.

• Building materials in hallways.

• Stairs removed.

• Metal straps across the width of the building and three to four feet from walls are hard on power saws.

• Decking comprised of sheathing, plywood, and composition. The extra "thickness" of the decking will not enhance "feeling" the rafters with a power saw.

BLOCK

These buildings are primarily concrete block that form the exterior walls. This type of construction is strong and extensively utilized.

Hazards

It is common to find this type of construction supporting lightweight floor joists and roofs (depending on the age of the building). Facades are also common on this type of construction.

FRAME / STUCCO CONSTRUCTION METHODS

These buildings are used in a wide variety of applications, old and new. Although they are structurally sound, the stucco exterior walls can support extensive remodel additions and/or conventional or lightweight construction. The difference in construction can be detected by a prior knowledge of the building (pre-planning) or recognizing the difference between an "old or new" style of building.

Hazards

• Vertical spread of fire through the walls is a possibility (if balloon construction is present). However, this is controlled by horizontal fire blocking, if present.

• Lightweight construction. The age of the building is a key factor in identification of this construction.

Facades

A facade can be defined as an "identifiable style of construction on the exterior of a building that will conceal and spread the travel (extension) of fire." To summarize, facades are external attics.

Style

Currently, this style of construction is enjoying widespread popularity across the country.

Facades are utilized to conceal equipment and machinery on flat roofs.


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As the popularity, utilization, and complexity of the facade increases, so does its impact on firefighting operations.

The following four areas should be considered when confronted by this construction.


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VENTILATION CUTTING TECHNIQUES

Dicing

20BCenter Rafter Louver Cut #1

Cut #2

Cut #3

Cut #4

Louver Section

21BPanelized

DICING

This technique is used for cutting 1” x 4” or 1” x 6” solid, spaced or diagonal sheathed roofs. Dicing has many advantages, first, it is directional. The roof team will always be working back toward their ladder. The roof team can work simultaneously, after the chain saw operator makes the third cut, the puller can start pulling boards and the chain saw operator can continue cutting the roof.


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Dicing does not require the cutter to know the exact location of the rafters. Rafter type and rafter direction is all that has to be known. Rafter type and direction has already been determined with diagnostic tools (plug cut, inspection hole, sounding, etc.)

If needed, the first cut performed in this operation is a score cut or a head cut. This cut is perpendicular to rafter direction and should be cut along the intended ventilation hole.

If a score cut or head cut is needed, the ventilation team moves back to the starting point of the cut and begins making parallel cuts (parallel to rafters) between rafters without concern as to the location of the rafters. The length of the dice cut is determined by the reach of the tool being used to pull the sheathing, (pick head axe, rubbish hook). The chain saw operator should be aware of rafter spacing, “DON’T” span two rafters. If the rafter spacing has not been previously determined, spacing should be apparent after the first few dice cuts have been removed. If two cuts are made between rafters, the cut material will fall through and possibly cause injury to interior firefighting crews. If the cuts are spaced to far apart and span two rafters, the cut sheathing may be difficult to pull and impossible to louver. The ventilation team should always work and cut toward the path of safety (towards ladder).


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The chain saw operator should cut a minimum of three dice cuts before the puller starts removing sheathing.

After the third dice cut is complete, puller removes roof sheathing. Always leave a minimum of one un-pulled section between

the cutter and the puller.

Always work back towards your ladder. On a roof constructed with multiple layers of roof composition or diagonal roof sheathing, an

additional score cut or bottom cut may be necessary.


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22BCENTER RAFTER LOUVER

Cut #1

Cut #2

Cut #3

Cut #4

Louver Section

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

LADDER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

LADDER

CENTER RAFTER LOUVER

In order to make a center rafter louver, you must first know rafter type and rafter direction. Next you must determine the location of three rafters. The rafter type and direction is determined by the use of diagnostic tools (plug cut, 45 degree inspection hole, sounding etc.) When over your ventilation area make a head cut to locate a minimum of three rafters.


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The head cut is started by first cutting away from your ladder to locate your first (outside) rafter.

Reverse directions and cut back towards your ladder. Roll the second (center) rafter and stop at the third (inside) rafter.

Move back to the first (outside) rafter and cut a parallel cut approximately 2 to 3 inches inside the rafter.


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Make the bottom cut, cutting towards the ladder. Start at the first (outside) rafter, roll over the second (center) rafter and stop at the third (inside) rafter.

Cut #1

Cut #2

Cut #3

Cut #4

Louver Section

Make a parallel cut approximately 2 to 3 inches inside the third (inside) rafter. Louver Section.

Expand Center Rafter Louver, With Construction

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

LADDER Move back to the first (outside) rafter and make a parallel

cut approximately 2 to 3 inches inside the rafter.


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RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

LADDER Make the bottom cut, cutting towards the ladder. Start at the first (outside) rafter, roll over the

second (center) rafter and stop at the third (inside) rafter.

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

LADDER Make a parallel cut approximately 2 to 3 inches

inside the third (inside) rafter.

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

LADDER Louver Section


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Center Rafter Louver, Against Construction

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

LADDER The head cut is started by first cutting away from your

ladder to locate your first (outside) rafter.

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

LADDER Reverse directions and cut back towards your ladder.


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RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

LADDER Roll rafters. Make “Head Cut” as long as intended hole.

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

LADDER Move back to the first (outside) rafter and cut a parallel cut approximately

2 to 3 inches inside the rafter. Make parallel cut approx. 3 ½ feet long.

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

LADDER Make the bottom cut, cutting towards the ladder.

Start at the first (outside) rafter.


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RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

LADDER Roll over the second (center) rafter and stop at the third (inside) rafter.

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

LADDER Make a parallel cut approximately 2 to 3 inches inside the third (inside) rafter.

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

LADDER Make fifth cut.


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RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

LADDER Louver Section.

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

LADDER Make bottom, fourth, and fifth cuts.

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

LADDER Louver Section.


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RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

LADDER Make bottom, fourth, and fifth cuts.

Louver Section.

Expand Center Rafter Louver, Against Construction

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

LADDER Move back to the first (outside) rafter and make a parallel cut approximately 2 to 3 inches inside the rafter. Make parallel cut approx. 3 ½ feet long. Make the bottom cut, cutting towards the ladder. Start at the outside rafter. Roll over the center rafter and stop at the third (inside) rafter. Make fifth cut.

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

LADDER Louver Section


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RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

LADDER Make the bottom cut, cutting towards the ladder. Roll over the center rafter and stop at the

third rafter. Make fourth and fifth cuts. Louver section.

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

RAFTER

LADDER Make the bottom cut, cutting towards the ladder. Roll over the center rafter and stop at the

third rafter. Make fourth and fifth cuts. Louver section.


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Panelized Roof Cutting Techniques

Drop Method (Offensive) Pull Back Method (Offensive) Offensive Louver (Offensive) Louver off A Lam Beam / Main Beam (Defensive) Louver off A Purlin (Defensive)


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DROP METHOD (OFFENSIVE)

While standing on Purlins, the first cut is made

parallel to Lam-Beam, stopping at Purlins.

Cut inside and parallel to Purlins. Cut completely through plywood and 2” x 4”

rafters. Cutters must work together. Cut 4 to 6 inches inside Purlins to avoid hitting metal hangers.

Cut from Lam-Beam to Lam-Beam. Always cut back toward your ladder.


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PULL BACK METHOD (OFFENSIVE)

Standing on Purlins, the first cut is made parallel to Lam-Beam,

stopping at Purlins.

Cut small triangles through roof decking. Insert rubbish hooks into triangles. Rubbish hooks

are used to pull back roofing and decking materials.

Cut completely through first rafter, and stop at the second rafter.


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Pullers pull back 4’ x 8’ panel with rubbish hooks.

Pullers insert rubbish hooks over exposed rafter.

Cutters cut completely through two rafters. Stop at third rafter.

Pullers pull back 4’ x 8’ panel with rubbish hooks.


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Pullers insert rubbish hooks over exposed rafter.

Cutters cut completely through two rafters. Stop at third rafter.

Pullers pull 4’ x 8’ panel with rubbish hooks.

Complete pull back from Lam-Beam to Lam-Beam.


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“OFFENSIVE” LOUVER

While standing on Purlins, the first cut is made

parallel to Lam-Beam, stopping at Purlins.

Cut parallel to Purlins.

Roll center rafter.


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Stop at third rafter.

Cut inside of third rafter.

Cut outside of third rafter.


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Louver section.

Cut parallel to Purlins, roll center rafter, and stop at third rafter.

Cut on both sides of third rafter. (4th and 5th cuts) Louver section.


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Continue offensive louver from Lam-Beam to Lam-Beam.


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LOUVER OFF A LAM-BEAM / MAIN BEAM (DEFENSIVE)

While standing on Lam-Beam, reach out (approximately 3 ½ feet)

and cut first cut parallel to rafters from Purlin to Purlin.

Cut parallel to outside Purlin, roll over center rafter, and stop at Lam-Beam.

Cut parallel to Lam-Beam, from Purlin to Purlin.


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Make fourth cut parallel to inside Purlin, roll center rafter and stop at Lam-Beam.

Cut parallel to Lam-Beam from Purlin to Purlin.

Repeat steps for additional panels Cut strip from parapet to parapet.

Louver Sections.


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LOUVER OFF A PURLIN (DEFENSIVE)

While standing on Purlin, start “Skim Cut”.

Reach out as far as you comfortably can (approx. 3 ½ feet). Start at outside Lam-Beam.

“Skim Cut” over rafters from Lam-Beam to Lam-Beam.

Cut parallel to Purlin and stop at Lam Beam.


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Cut Parallel to Purlin.

Roll center rafter and stop at third rafter.

Make fourth cut inside of third rafter.


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Make fifth cut outside of third rafter.

After fifth cut.

Cut Parallel to Purlin, roll center rafter, and stop at third rafter.


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Make fourth and fifth cuts parallel to third rafter.

After fifth cut.

Cut strip in sections, from Lam-Beam to Lam-Beam.

Louver sections.


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SMOKE REMOVAL The primary goal of effective ventilation operations is the reduction or removal of smoke, heat, and fire gases (contaminants) from a structure or enclosed area in a timely manner. Proper blower placement will assist in achieving this goal. This process will result in the following:

• Assist in search and rescue, extinguishment, overhaul, and other suppression operations.

• Reduce or eliminate the numerous products of combustion.

• Reduce the interior temperature within a structure.

• Improve visibility for occupants and fire suppression personnel.

• Increase safety for occupants and fire suppression personnel.

• Reduce fire loss.

A. VENTILATION METHODS

Plans for ventilation operations should begin by identifying the direction (horizontal or vertical) contaminants must travel to exit the contaminated area. Once the direction of travel is established, the method for moving the contaminated contents must be determined.

There are two basic methods that are utilized to pressurize a contaminated area to enhance or direct the travel of contaminants to the exterior. These are natural and mechanical positive pressure ventilation.

1. Natural Ventilation

As a fire burns within a confined building, the fire floor is filled with products of combustion that rise and fill all available spaces within a building. A simple method to ventilate products of combustion consists of utilizing natural convection currents. This is easily accomplished by opening doors, windows, skylights, and other similar openings. Although this method may perform satisfactorily, it is dependent on the following factors:

• Proximity of the ventilation opening to the contaminants to be removed. • Ability of the contaminants to travel unobstructed to a ventilation opening. • Number and size of ventilation openings. • Direction of wind. • Humidity. • Temperature differential between the interior and exterior of a building.

2. Pressure Ventilation


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Natural ventilation is a viable method that is effective within certain limitations. However, by utilizing portable blowers, the natural ventilation process can be dramatically assisted or replaced by FORCING the movement of contaminants to:

• Exit through pre-selected and/or controlled openings. • Allow the use of ventilation openings that are remote from the contaminants to be

removed. • Overcome interior - exterior temperature differentials. • Move contaminants to the exterior of a building through areas or openings not normally

utilized by natural ventilation. • Reduce the time necessary to ventilate a building when compared to natural ventilation

operations.

B. PRESSURIZED VENTILATION

The current methods that are utilized to provide pressurized ventilation with portable blowers are negative and positive pressure ventilation. To examine these two methods, the building in Figure 1 will be ventilated. In this example, the building is filled with various products of combustion from a fire. The warmer gases have risen to the top of the building, and the cooler gases have settled at the bottom of the building. The door and windows are closed.

FIGURE 1

1. Negative Pressure Ventilation

To ventilate the building, the door is opened and a blower is placed INSIDE the building to exhaust the contaminants as in Figure 2. This method will draw the contaminants within the building through the blower and exhaust the contaminants to the exterior of the building by creating a negative pressure within the building. By opening the window, the exhausting contaminants will be replaced with fresh incoming air. Although this method performs satisfactorily, negative pressure ventilation has the following disadvantages: • Personnel must be exposed to hazardous contaminants to position a blower. • Contaminants are drawn through the blower, creating additional equipment cleanup


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and maintenance. • Blowers placed in doorways or hallways can block entry or exit to the building. • To be effectively positioned, blowers suspended in doorways or windows must utilize

straps, ladders, or other accessories. • Interior blowers are not efficient in removing contaminants at the top of a room or building.

Air will follow the path of least resistance, which is normally a straight line from the fresh air inlet to the blower. This limits the flow of air at the top of the area to be ventilated.

Figure 2

2. Positive Pressure Ventilation

To ventilate the building, the door is opened and a blower is positioned OUTSIDE the building as in Figure 3. This method will force clean, fresh, pressurized air inside the building and create a positive pressure (similar to blowing up a balloon) inside the building.

FIGURE 3

The positive pressure will be equal at the top, bottom, and corners of the building common to the pressurized air. When the window is opened, the contaminants from ALL parts of the pressurized building will exhaust to the exterior (similar to piercing a hole in a blown-up


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balloon). Compared to negative pressure ventilation, positive pressure ventilation has the following advantages:

• Personnel are not exposed to hazardous interior contaminants while positioning exterior blowers.

• Contaminants are not drawn through blowers, resulting in minimal cleanup and maintenance.

• Doorways, windows, and halls do not need to be blocked by blowers.

• Exterior blowers are not dependent on additional equipment or accessories for setup and operation. Additionally, less time, and in some instances, less personnel are required to put exterior blowers into operation as no other equipment or accessories are necessary.

• Reduced noise level.

• Exterior blowers are efficient in removing contaminants at the top, bottom, and corners of a room or building.

• Compared to negative pressure ventilation, positive pressure ventilation is approximately twice as effective at removing contaminants from a building.

C. IMPLEMENTATION OF POSITIVE PRESSURE VENTILATION

The effective implementation of positive pressure is dependent on the entrance opening, airflow between openings, exhaust opening, weather, training and communication.

1. Entrance Opening

Blowers must be positioned so the cone of air issued from a blower will completely cover the entrance opening to eliminate contaminants being forced back through the "unsealed portions" of the entrance opening and being reintroduced into the pressurized building. This is accomplished by varying the distance from the blower to the entrance opening.

2. Air Flow Between Openings

It is imperative that the path of pressurized air between an entrance and exhaust opening be controlled to achieve maximum ventilation. If pressurized air is directed from an entrance opening to an appropriate exhaust opening (without being diverted to other openings), contaminants will be removed with the pressurized air in a minimal amount of time.


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Simultaneously opening multiple windows and/or doors will not facilitate a successful positive pressure ventilation operation.

3. Exhaust Opening

Exhaust openings can be selected to provide horizontal or vertical ventilation of contaminants. The location of the exhaust opening is dependent on the location of heat and smoke, and the prioritization of suppression operations (overhaul, search and rescue, extinguishment, etc.). The size of the exhaust opening is dependent on the size of the entrance opening, and capacity and number of blowers being utilized.

Positive pressure is most efficient when the exhaust opening (heat hole, window, door, etc.) is between three-fourths (3/4) to one and three-fourths (1 3/4) the size of the entrance opening. This variance is due to the number and cubic feet per minute rating (CFM) of blowers that are utilized. An 18 inch blower utilizes a smaller exhaust opening than a 24 inch blower. A single blower utilizes a smaller exhaust opening than multiple blowers in parallel or series configurations. Optimum efficiency is easily obtained by a combination of training and practical experience.

If a gasoline powered blower is being utilized and an exhaust odor is noticeable inside the building or area to be ventilated, this is an indicator that the exhaust opening is not large enough. The exhaust odor should disappear by increasing the size of the exhaust opening (opening another window, door, etc.)

4. Weather

Temperature, humidity, and rain do not have any appreciable effect on positive pressure ventilation. Although cold-damp weather conditions may limit the ability of smoke to rise, these atmospheric conditions will not limit the ability of blowers to move contaminants horizontally, and in most cases, vertically.

Wind can have an adverse effect on positive pressure ventilation, but its effect is dependent on direction and velocity. As in any ventilation operation, maximum efficiency can be obtained by utilizing the prevailing wind direction to an advantage (windward to leeward). It is most advantageous to pressurize the structure on the windward side and exhaust contaminants on the leeward side of the building. If it is not possible to utilize the prevailing wind as an advantage, positive pressure has proven effective AGAINST winds (leeward to windward) of up to 25 mph; efficiency will be reduced accordingly.

5. Training and Communication

The key to effective positive pressure ventilation is dependent on controlling the entrance opening, the path of the interior air flow, and the exhaust opening. These factors can only be maintained in their proper relationship if all personnel engaged in the ventilation operation have been properly trained and are aware of the goal of the intended operation. If personnel are not assigned specific tasks, they should not arbitrarily move and/or reposition blowers or alter exhaust openings.


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I. BLOWER PLACEMENT

A. SINGLE BLOWER

A single blower should be positioned so the cone of pressurized air JUST covers the entrance opening as in Figure 5. If the blower is too close to the opening, the opening will not be completely covered by pressurized air. If the blower is too far from the opening, pressurized air will strike the area around the opening, reducing the amount of pressurized air being forced inside the building. Optimum placement is dependent on the size of the entrance opening and the CFM of the blower. These two factors will regulate the distance between the blower and the entrance opening.

FIGURE 5

Small blowers (18") need to be moved back from entrance openings while larger blowers (24") can be placed closer to entrance openings to properly cover the opening with pressurized air. This is due to the size of the "pressurized cone" of air issued from a blower. This operation can be enhanced by "tilting" a blower. Tilting blowers at angles more than the manufacturer designed will result in a lack of lubrication to the crank shaft.

B. MULTIPLE BLOWERS

Multiple blowers can dramatically increase CFM when used in series or provide proper coverage of the opening when used in parallel. Multiple blowers can also reduce the time necessary to complete a ventilation operation.

1. In Series

For standard entrance openings maximum effectiveness is achieved by placing two blowers in series (in-line) with each other.

In Figure 6, Blower A is positioned about two-feet from the entrance opening. This ensures that all of the pressurized air from the blower enters the building, yet allows sufficient room for ingress/egress of personnel. Blower B is positioned behind Blower A. The proper location for


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Blower B is determined by the distance necessary to cover the entrance opening with pressurized air.

Blower B is utilized to cover the entrance opening with pressurized air, force pressurized air into the building, and increase the capacity of blower A by approximately 10%.

FIGURE 6 If two blowers of unequal CFM are utilized in the series position, place the large blower about two feet back from the entrance opening and utilize the smaller blower behind the larger blower to cover the entrance opening with pressurized air. This configuration will utilize the larger blower to provide most of the pressurized air for the ventilation operation while the small blower covers the entrance opening, and increases the efficiency of the larger blower.

If the area in front of an entrance opening is limited to three feet or four feet (i.e., raised porch), place the smaller blower in the entrance opening and the larger blower three to four feet back from the door. Use the larger cone of pressurized air to seal the entrance opening.

2. Parallel

For standard entrance openings, multiple blowers in a parallel (side-by-side) configuration are less effective than multiple blowers in a series configuration. However, for large entrance openings, multiple blowers in a parallel configuration (Figure 7), should be utilized due to their combined ability to cover the larger opening with pressurized air. The size of the opening will dictate the number of blowers that will be necessary to cover the opening with combined cones of pressurized air. Remember that some openings (i.e., loading-dock doors) can be reduced in size by partially closing the door which will reduce the size of the entrance opening that must be covered by pressurized air. Depending on the number of blowers that are available, large areas may be effectively ventilated by utilizing a combination of parallel (proper coverage of the opening) and series (increased CFM) blowers.


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FIGURE 7

STRUCTURAL CONSIDERATIONS

A. Below ground areas should be treated as any other smoke removal problem with the following added considerations: 1. Use of creative methods may be required to channel the smoke i.e., use of

salvage covers, additional blowers, etc.

2. The smoke that is exhausted from the below ground area in many cases will accumulate in the ground level floor (or higher) and will require evacuation from its new location.

3. Management of this smoke in the above ground area is vital.

4. Removal of the smoke at or above ground level will be accomplished using standard positive pressure ventilation techniques.

B. DWELLINGS

1. Single Story

Effective ventilation requires SYSTEMATIC VENTILATION of contaminated areas within a building. This process will provide the maximum amount of pressurized air from a blower to ventilate each contaminated area within a building. This results in maximum efficiency and minimal time for ventilation. During positive pressure operations, do not "open the structure up" as is common practice. This will reduce the flow of air through each room and increase the time for ventilation.

Additionally, remember that removing screens on windows prior to using these openings for ventilation purposes will increase the efficiency of these openings by at least 50%.


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Assume that a kitchen fire, in Figure 10, has charged the dwelling with smoke. All doors and windows are closed, a blower has been positioned to cover the front door with pressurized air, positive pressure would by utilized as follows:

Figure 8

• To clear the kitchen, living room, and dining room, open the exterior door in the kitchen and both interior doors to the kitchen. When these rooms have cleared, close the exterior kitchen door.

• To clear bedroom one, open the bedroom door and window. When cleared, close the window or door.

• To clear bathroom one, open the bathroom window. When cleared, close the window or door.

• To clear bedroom two, open the bedroom door and window. When cleared, close the window or door.

• To clear bathroom two, open the bathroom door and window. When cleared, close the window or door.

• To clear bedroom three, open the bedroom door and window. When cleared, close the window or door.

Closing a door or window of an area will yield the same results.

Additionally, an area that has open walls or ceilings (from a fire), or other large openings, can be isolated from a ventilation operation by closing an appropriate door if applicable. Remember that it is possible to ventilate several rooms at one time with multiple blowers.

2. Multiple Story

Assume a first floor fire, in Figure 9, has charged the multiple story dwelling with smoke.

Figure 9

To ventilate the first floor, ensure that all exterior windows on the upper floor are closed, or a stair shaft door to the upper floor is closed (whichever is appropriate). Position a blower at an appropriate entrance opening, and systematically ventilate the contaminated areas on the first floor of the structure. This will provide maximum pressurized air for ventilation on the first floor, and no flow of air on the second floor due to the lack of an exhaust opening. To ventilate the second floor, leave the blower in the same position and ensure that all exterior windows and doors are closed on the first floor. If a stair shaft door has been closed, open the door and systematically ventilate the contaminated areas on the second floor. Due to the lack of an exhaust opening on the first floor, pressurized air from the blower will pressurize the first and second floor, but will only create a flow of air on the second floor due to its exhaust openings.

.C MULTI-HABITATIONAL BUILDINGS

These types of buildings generally have multiple floors, and enclosed central hallways that provide access to numerous rooms within the building. The hallways may be of considerable length (depending on the size of the building) and may incorporate Ponet Doors at various intervals within the hallways. If Ponet Doors are present, they may be


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opened to allow pressurized air to travel to a specific location, or they may be closed to "compartmentalize" specific sections of a building. This may be useful to keep contaminants from spreading to uncontaminated areas, or to divert pressurized air to a specific area. Multi-habitational occupancies can be effectively ventilated with positive pressure by:

• First, pressurizing appropriate stairways and hallways. • Second, ventilating contaminated rooms or other areas that are common to a

pressurized hallway dependent on the location of the most heat and smoke, and the prioritization of suppression operations (overhaul, search and rescue, extinguishment, etc.).

Assume a third floor, rear apartment fire, in Figure 10, has charged the third floor with smoke. The building has an enclosed stair shaft that is common to each floor, and Ponet Doors separating each floor from the stair shaft.

FIGURE 10

Position blowers outside the building to cover the entrance of the stair shaft to be pressurized. Open the third floor hallway door to the stair shaft that is being pressurized with air from the blowers, and ensure that the Ponet doors to the first and second floors are closed. By opening the door to the involved apartment, the stair shaft, the third floor hallway, and the involved apartment will be pressurized. Horizontal and/or vertical exhaust openings can be used in the involved apartment. The hallway and apartment will be cleared of all contaminants. This is most effectively accomplished by opening a patio sliding glass door, large window, or using a room with the greatest number of windows as the initial exhaust opening. When the hallway and


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that portion of the apartment utilized as an exhaust opening is cleared, systematically ventilate the other portions of the apartment. Depending on the floor plan of a building and the location of the fire, opposing blowers as illustrated in Figure 11 can be effectively utilized to remove the contaminants in a hallway and an apartment. Blowers of unequal ratings or equal ratings can be effectively utilized for this ventilation operation.

FIGURE 11

D. COMMERCIAL BUILDINGS Commercial buildings vary in their size, height, and use. However, the following factors should be applied when considering ventilation operations for these types of buildings. Depending on the size of the structure, some commercial occupancies such as warehouses and manufacturing occupancies offer large open areas that are normally difficult to ventilate. These occupancies require a combination of blowers that are capable of providing adequate CFM for the area to be ventilated and an understanding of positive pressure principles. When possible, large areas of a building should be divided into smaller areas by closing partition doors, rolling or sliding fire doors, etc., and then systematically ventilating each contaminated area. Large structures that are comprised of smaller areas such as stock rooms, work stations, offices, etc., should be ventilated by using systematic ventilation techniques in a pre-planned, coordinated operation. When large ventilators, removed skylights, or ventilation openings in a roof (heat holes and strips) will negatively effect positive pressure operations, use these openings as vertical exhaust openings. Openings such as doors and windows that are below these exhaust openings must be closed to ensure the flow of pressurized air is maximized and directed to vertical exhaust openings.


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IV. OPERATIONAL GUIDELINES

Depending on the type of building, determine the effectiveness of removing contaminants horizontally or vertically. Include heat holes and strips when evaluating exhaust openings. Additionally, determine the path that pressurized air must travel to remove contaminants within the building. Consider where the most heat and smoke is in relationship to the location of the exhaust opening.

A. GENERAL

It may be necessary to pressurize vertical stair shafts to horizontally ventilate upper floors of a multi-story building. If possible, reduce large areas into smaller areas and ventilate systematically.

Large structures or large areas within structures require increased CFM to remove large quantities of contaminants. Consider the use of larger blowers for these applications. Multiple blowers in series will also provide additional CFM and enhance the removal of contaminants. Multiple blowers in parallel will provide proper coverage for large entrance openings. Various types of large doors can be partially closed to facilitate the pressurization of an entrance opening.

B. MULTIPLE FLOORS

Buildings with multiple floors can be ventilated by systematically ventilating each floor. Start where there is the most heat and smoke. This will most likely be the fire floor due to Ponet doors, it could also be the top floor where heat and smoke will have mushroomed because the Ponet Doors did not close. Stair shafts can be used to channel pressurized air to each floor as necessary. Position blowers(s) on the exterior of the building and pressurize the opening to the stair shaft that is common to the contaminated floors. Systematically ventilate each floor by opening a door to the pressurized stair shaft and an appropriate window as an exhaust opening.

C. OVERHAUL

Overhaul operations are conducted for the purpose of ensuring a fire is completely out, determining the probable fire cause, and leaving the owner or insurance adjusters some means of determining the loss. However, overhaul operations are often conducted in conditions that may be tenable yet hazardous to personnel.


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Unless a fire has been TOTALLY extinguished and the contaminated structure COMPLETELY ventilated, overhaul operations may be conducted within varying concentrations of smoke, heat, carbon monoxide, and other toxic gases.

Remember that any carbon monoxide that has been collected at the top of a room or building (as a result of a fire) may have cooled and settled within the area of overhaul personnel. Additionally, common building materials retain and radiate heat that has been generated by a fire. This can result in elevated temperatures during overhaul operations.

1. Carbon Monoxide Guidelines

Depending on the type of fire, concentrations of carbon monoxide within the range of 500 parts-per-million (ppm) to 1200 ppm are easily obtainable during overhaul operations.

NOTE: For comparative purposes, the following guidelines are regarded as acceptable carbon monoxide concentration standards:

• to 500 ppm of carbon monoxide can be inhaled for one hour without appreciable effects.

• to 700 ppm of carbon monoxide inhaled for one hour will cause some appreciable effects.

• to 1200 ppm of carbon monoxide inhaled for one hour is dangerous.

• Concentrations of 4000 ppm of carbon monoxide and over are fatal in less than one hour.

2. Overhaul Guidelines

The effectiveness of using positive pressure during overhaul operations is determined by the overhaul area (size and overhaul materials) and the blowers that are utilized for positive pressure. A single 18" blower is adequate for an average (2000 square feet) single family dwelling. Remember that as the CFM is increased, so is the effectiveness. A MODERATE movement of air is sufficient to cause smoke, heat, and carbon monoxide within the overhaul area to move in the direction of an exhaust opening. Positive pressure does not have a tendency to accelerate or spread fire that may still be in the overhaul area. However, caution should be exercised when using positive pressure with smoldering type fires (i.e., mattress, overstuff, etc.) If any fire does begin to accelerate or spread, it can easily be controlled by:

• Extinguishing the fire.

• Turning the blower 90 degrees away from opening.

• Reducing the RPM of the blower.


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• Increasing the distance between the overhaul area and the blower.

• Shutting the blower off.

NOTE: Positive pressure should never be utilized in place of a Self-Contained Breathing Apparatus (SCBA). SCBA should ALWAYS be used when personnel encounter hazardous atmospheres

Documents

TRAINING DIVISION VENTILATION TRAINING MANUAL