Upon completion of this unit of study, the student should be able to:

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3 UNIT OBJECTIVES Upon completion of this unit of study, the student should be able to: 1. Explain the principles of ventilation including advantages and effects of proper ventilation. 2. Identify the possible dangers present and precautions to take in performing ventilation. 3. Describe the indications, causes and effects of a backdraft explosion. 4. Describe the advantages and disadvantages of the different types of ventilation. 5. Identify the various tools used in ventilation. 6. Describe the characteristics and precautions required when ventilating various types of roofs. 7. Describe how different factors can be used to check a roof's integrity. 8. Identify the considerations that need to be made to determine the location and size of a ventilation opening. 9. Describe the method and precautions used when ventilating a basement. 10. Identify the various types of manual and automatic venting devices found in structures. 11. Demonstrate how to sound a roof to determine its integrity. 12. Demonstrate ventilation procedures for a roof. 13. Demonstrate forced ventilation procedures. Ventilation - 1

4 NFPA STANDARDS Successful completion of the information in this section is necessary to fulfill the requirements of the following sections of NFPA : Fire Fighter I Standard Perform horizontal ventilation on a structure operating as part of a team, given an assignment, personal protective equipment, ventilation tools, equipment, and ladders, so that the ventilation openings are free of obstructions, tools are used as designed, ladders are correctly placed, ventilation devices are correctly placed, and the structure is cleared of smoke. (A) Requisite Knowledge. The principles, advantages, limitations, and effects of horizontal, mechanical, and hydraulic ventilation; safety considerations when venting a structure; fire behavior in a structure; the products of combustion found in a structure fire; the signs, causes, effects, and prevention of backdrafts; and the relationship of oxygen concentration to life safety and fire growth. (B) Requisite Skills. The ability to transport and operate ventilation tools and equipment and ladders, and to use safe procedures for breaking window and door glass and removing obstructions Perform vertical ventilation on a structure as part of a team, given an assignment, personal protective equipment, ground and roof ladders, and tools, so that ladders are positioned for ventilation, a specified opening is created, all ventilation barriers are removed, structural integrity is not compromised, products of combustion are released from the structure, and the team retreats from the area when ventilation is accomplished. (A) Requisite Knowledge. The methods of heat transfer; the principles of thermal layering within a structure on fire; the techniques and safety precautions for venting flat roofs, pitched roofs, and basements; basic indicators of potential collapse or roof failure; the effects of construction type and elapsed time under fire conditions on structural integrity; and the advantages and disadvantages of vertical and trench/strip ventilation. (B) Requisite Skills. The ability to transport and operate ventilation tools and equipment; hoist ventilation tools to a roof; cut roofing and flooring materials to vent flat roofs, pitched roofs, and basements; sound a roof for integrity; clear an opening with hand tools; select, carry, deploy, and secure ground ladders for ventilation activities; deploy roof ladders on pitched roofs while secured to a ground ladder; and carry ventilation-related tools and equipment while ascending and descending ladders. 2 - Ventilation

5 NFPA STANDARDS Fire Fighter II Standard 6.3.2* Coordinate an interior attack line for a team s accomplishment of an assignment in a structure fire, given attack lines, personnel, personal protective equipment, and tools, so that crew integrity is established; attack techniques are selected for the given level of the fire (e.g., attic, grade level, upper levels, or basement); attack techniques are communicated to the attack teams; constant team coordination is maintained; fire growth and development is continuously evaluated; search, rescue, and ventilation requirements are communicated or managed; hazards are reported to the attack teams; and incident command is apprised of changing conditions. (A) Requisite Knowledge. Selection of the nozzle and hose for fire attack, given different fire situations; selection of adapters and appliances to be used for specific fireground situations; dangerous building conditions created by fire and fire suppression activities; indicators of building collapse; the effects of fire and fire suppression activities on wood, masonry (brick, block, stone), cast iron, steel, reinforced concrete, gypsum wallboard, glass, and plaster on lath; search and rescue and ventilation procedures; indicators of structural instability; suppression approaches and practices for various types of structural fires; and the association between specific tools and special forcible entry needs. (B) Requisite Skills. The ability to assemble a team, choose attack techniques for various levels of a fire (e.g., attic, grade level, upper levels, or basement), evaluate and forecast a fire s growth and development, select tools for forcible entry, incorporate search and rescue procedures and ventilation procedures in the completion of the attack team efforts, and determine developing hazardous building or fire conditions. Ventilation - 3

6 I. The Importance of Ventilation (Essentials p. 541) A. Proper ventilation is not accomplished haphazardly 1. Inadequate ventilation can cause death or injury to fire victims and fire fighters and cause destruction of the building 2. Fire fighters must know ventilation principles and implement them promptly, thoroughly, and routinely B. Properly done ventilation decreases fire spread and increases visibility for fire attack C. Ventilation is the systematic release and removal of heated air, smoke, and gases from a structure and replacing them with cooler air D. Newer buildings have more built-in mechanical ventilation than older structures E. Modern insulation practices increase ventilation problems 1. Multiple pane windows F. 2. Insulated steel doors 3. Building vapor barriers 4. Heat from a fire is retained inside the building for longer periods, increasing the risks of flashover and backdraft The increasing use of plastics and synthetics has greatly increased the fuel load in buildings adding to the need for ventilation 4 - Ventilation

7 G. Advantages of proper ventilation 1. Aids in life safety a. Removes smoke and gases that endanger the occupants b. Promotes fire fighter entry and improves visibility to speed rescue c. Reduces risk of steam burns to personnel 2. Fire attack and extinguishment a. Speeds attack and extinguishment by helping to localize the fire b. Reduces fire and water damage by reducing the amount of water needed for extinguishment 3. Aids in fire spread control a. Reduces mushrooming from heat and gases banking down and spreading laterally b. If crews are not ready to attack a fire, even proper ventilation will add air to the fire and allow it to grow 4. Reduction in flashover potential a. The potential for flashover is reduced by removing heat before flashover occurs b. Ventilation can remove the heated gases which are heating the contents to ignition to their ignition temperatures to create flashover Ventilation - 5

8 c. However, ventilation can also increase flashover potential by adding needed oxygen to a superheated area 5. Reduction of backdraft potential a. Flammable gases are vaporized from the combustibles burning (1) Oxygen has decreased by burning (2) The admission of air can cause the burning of gases with explosive force (3) The intensity depends on the degree of confinement, the amount of heated gases, and the rate and volume of fresh air admitted b. Carefully controlled ventilation must be done to direct the burning gases harmlessly and prevent backdraft conditions c. Usually vertical ventilation is the safest way to vent a building with backdraft potential d. Fire fighters must stay away from doors and windows until ventilation reduces the severity of the situation e. Personnel must always be aware of the indications of backdraft potential (1) Confinement and excessive heat (2) Heavily smoke-stained windows (3) Smoke puffing at intervals from building 6 - Ventilation

9 (4) Smoke coming through cracks (5) Little visible flame (6) Gray-yellow colored smoke (7) Windows rattling (8) Walls extremely hot to the touch 6. Property conservation a. Since proper ventilation speeds extinguishment, fire damage is lessened b. With smoke and heat vented, salvage operations can be started outside of the fire area even while fire attack is progressing II. Ventilation Considerations (Essentials p. 547) A. First consideration before ventilating is the safety of the occupants and fire personnel B. The size and type of building will determine the type of ventilation required or if possible C. Before ventilation is started, a series of decisions must be made 1. Considerations for the need for ventilation: a. Life hazards b. Extent of fire c. Available resources Ventilation - 7

10 d. Structural conditions 2. Ventilation location considerations: a. Exposures which might be subject to fire and smoke released from the ventilation opening b. The extent of fire will normally increase with ventilation c. Location of fire and the direction which it will be drawn by ventilation d. Wind direction will influence the direction to which the fire will be drawn e. Construction features which will assist or prevent ventilation f. The availability of natural vertical and horizontal openings g. The condition of the building may have deteriorated beyond the point of safe ventilation procedures 3. The decision whether to do horizontal or vertical ventilation should be used based on the fire fighter's knowledge of the methods of ventilation 4. Considering whether fire and structural conditions allow for safe roof operations a. Roof integrity must be the first priority before vertical ventilation is performed b. Fire may have burned undetected under roof for some time 8 - Ventilation

11 5. Determining if the personnel assigned to do ventilation are properly trained and equipped to handle the job D. Life safety hazards 1. As in any emergency situation, the safety of both fire fighters and a building's occupants must be the first consideration of responders 2. Depending on fire conditions, ventilation may be needed before search and rescue operations a. If necessary, the fire may need to be attacked first b. Sometimes search and rescue is done simultaneously with ventilation 3. Potential hazards with the accumulation of smoke and gases: a. Visibility impairment b. Presence of toxic gases and flammable gases c. Lack of oxygen d. Potential for backdraft and flashover E. Visible smoke conditions 1. Many tactical and ventilation considerations are based on the visible smoke conditions at the scene a. Smoke conditions vary with the progress of burning Ventilation - 9

12 b. Some fires in the early stages may produce light smoke c. If plastic and synthetic furnishings are involved the smoke may be very thick d. Smoke can hide that the structure has become well involved in fire e. Fire fighters must remember that smoke is fuel that has not ignited F. Type of building involved 1. The type and design of the building involved are key factors when considering what type of ventilation to use a. Number and size of wall openings b. Number of stories and roof openings c. The roof construction d. Built-in fire protection systems 2. High-rise buildings a. Vertical openings, such as pipe shafts, stairways, elevator shafts, and air-handling systems, contribute to the "stacking effect" where smoke and fire gases create an updraft and layer smoke on floors above the fire b. Ventilation has to be coordinated with fire attack and rescue efforts 10 - Ventilation

13 (1) Four to six times as many fire fighters will be needed for a high-rise building compared to a residential fire (2) Ventilation may be accomplished horizontally with mechanical devices c. Vertical ventilation in high-rise buildings may involve only one roof stairwell opening (1) Before doors on fire floors are opened, the door leading to the roof must be blocked open or removed (2) Using stairwells or elevator shafts for evacuation and ventilation simultaneously is ineffective and dangerous (3) Opening a stairwell at the top will draw smoke and heat into it and to anyone in it (4) The safest and most effective method may be to pressurize stairways with positive pressure ventilation fans 3. Basements and windowless buildings a. Access to a basement is extremely difficult without effective ventilation (1) Fire fighters must descend through the worst smoke and heat to get to the seat of the fire (2) If a ventilation opening is made opposite the entry point, fire and smoke can be pushed toward the opening with ventilation fans Ventilation - 11

14 b. Many buildings may have windowless wall areas (1) Windowless buildings complicate fire fighting and ventilation operations (2) Creating ventilation openings can take a large amount of time (3) Windowless building usually require mechanical ventilation, which also can spread the fire (4) Personnel must also be aware of the steam created by fire fighting efforts until adequate ventilation is established G. Location and extent of fire 1. Venting before the fire is located can spread the fire 2. The phase to which the fire has progressed is a primary consideration in determining ventilation procedures 3. Fire can spread vertically through: a. Stairwells and shafts b. Partitions and walls c. Windows and exterior openings d. Ceilings and floors by conduction through beams and pipes e. Collapse of floors and roofs 12 - Ventilation

15 f. Voids, concealed spaces, and ducts H. Selecting where to ventilate 1. There is no rule for selecting the point to open a roof to ventilation except as directly over the fire as possible 2. Factors to consider when selecting a vent location: a. Existing openings, such as skylights, vent shafts, and hatches b. Location of the fire and the direction the incident commander wants it to be drawn c. Type of construction d. Wind direction e. Extent of the fire and building conditions f. Melting or bubbling roof tar g. Indications of poor roof integrity h. The effect that ventilation will have on the fire i. Protection of exposures j. Readiness of attack crews I. Before ventilating a building, there must be adequate resources to control the fire because the fire may increase when ventilation is performed 1. If wind direction permits, entry should be made as near the fire as possible Ventilation - 13

16 2. Charged hoselines should be positioned at the entry point so attack can be started as soon as ventilation is done 3. Hoselines must also be in place at points to prevent fire from spreading to exposures III. Vertical Ventilation (Essentials p. 556) A. Vertical ventilation normally involves opening the roof or existing roof openings to allow smoke and heat to escape 1. Allows for natural convection of heat and gases upward 2. Improves interior visibility and lessens contaminated atmosphere B. Disadvantages of vertical ventilation 1. Possibility of weakened roofs 2. Time consuming 3. Some roofs may be difficult to ventilate 4. If not properly done, fire will be drawn to uninvolved areas C. Roof styles which be encountered 1. Three basic styles a. Flat b. Arched 14 - Ventilation

17 c. Pitched 2. Common roofs a. Gable b. Mansard c. Gambrel d. Hip e. Shed f. Lantern g. Butterfly h. Dome i. Sawtooth D. Fire fighters should know how roofs in their response area are constructed 1. Lightweight building materials are more susceptible to early collapse 2. Collapse potential is affected by: a. The volume of fire b. How long the fire has burned c. The type of construction d. The assembly fire-resistive rating e. The load on the roof Ventilation - 15

18 E. Before ordering vertical ventilation, the Incident Commander must consider: 1. If vertical ventilation can be safely and effectively done 2. The building's age and type of construction 3. The location, duration, and extent of the fire 4. Necessary safety precautions 5. Potential escape routes 6. Where to ventilation 7. How to move personnel and equipment to the roof F. The roof ventilation team leader's responsibilities include: 1. Maintaining constant communications with the supervisor 2. Ensuring the roof is safe to operate on 3. Ensuring that only the required openings are made 4. Working to minimize damage caused by fire fighting operations 5. Coordinating roof activities with other fire fighting efforts 6. Overseeing the safety of all personnel assisting with the roof operations 7. Ensuring the team leaves the roof as soon as their assignment is completed 16 - Ventilation

19 G. Vertical ventilation safety precautions 1. Wear full protective clothing and SCBA 2. Observe wind direction and exposures 3. Work with wind at back 4. Note existence of holes, obstructions, or weights on the roof 5. Consider fire duration time factor 6. Consider type of roof structure 7. Provide a secondary means of escape 8. Secure a lifeline on roof or use roof ladders 9. If used, make sure a roof ladder is firmly secured over the roof's peak 10. Guard the opening to prevent falls 11. Evacuate the roof when ventilation work is done 12. Be alert for electrical wires and overhead obstructions 13. Keep other personnel away from those using axes and power saws 14. Start power tools on the ground to make sure they operate but shut them off before raising them to the roof 15. Extend ladders four to five rungs above the roof line and secure ladders Ventilation - 17

20 16. Do not jump on a roof 17. Check the structural integrity of a roof before stepping on it and continue to check it during the operation 18. Always walk on bearing walls and strongest points of roof structure when possible 19. If working from aerial ladder platforms, the platform floor should be even with or slightly above roof level 20. Push down the ceiling using blunt end of pike pole to enhance ventilation 21. Be aware of the warning signs of unsafe roof conditions a. Melting asphalt or shingles b. "Spongy" roof c. Smoke coming from the roof d. Fire coming from the roof 22. Personnel must always work in teams of at least two on a roof but no more than necessary to get the job done 23. When cutting a ventilation hole in a roof: a. A large hole is better than several small ones b. Minimum of 4' x 4' in residential occupancies c. Minimum of 8' x 8' in commercial occupancies 18 - Ventilation

21 H. Determine the integrity of the roof 1. The type of construction should alert personnel to the presence of truss construction 2. Look for obvious sagging or heat damage to the roof indicating possible weakened areas 3. "Sound" the roof to determine its integrity and the location of supports a. The axe is held vertically with the top edge of the head downward b. The top is then struck on the roof to allow the fire fighter to hear the sound made c. Supported (over rafters/joists) and unsupported sections of a roof will sound differently when struck by the tool d. Roofs with several layers of roof coverings may sound solid even though they may be weakened by fire e. Roof covered with tiles or slates cannot be sounded until the coverings are removed I. Roof coverings 1. The first step in ventilating a roof is to remove the roof coverings 2. Roof coverings may be: a. Wood shakes or shingles b. Metal or rubber tiles or imitation shakes Ventilation - 19

22 c. Composition shingles d. Terra-cotta or concrete tile e. Synthetic membrane f. Built-up tar and gravel J. Existing roof openings should be used whenever possible 1. It is usually faster to open a natural opening than to cut a hole 2. These openings may not be in the best location or large enough for adequate ventilation 3. Existing roof openings a. Skylights b. Roof vents c. Roof monitors d. Scuttle hatches e. Dropout panels K. Roof characteristics 1. Flat roofs a. Common on mercantile, industrial, and apartment buildings b. Construction (1) Rafters - wooden or metal 20 - Ventilation

23 (2) Parallel cord trusses (3) Covered with sheathing (4) May be poured concrete, precast gypsum, or concrete slabs c. Ventilating a flat roof (1) Precautions (a) Be alert to signs of heat such as bubbling tar or melting shingles (b) Sagging or spongy roofs (2) Confirm the order to ventilate the roof (3) Select the location for ventilation (4) Outline the opening with an axe pick (5) Cut a three-sided (triangular) inspection opening to determine fire conditions (6) Cut the roof deck parallel to a roof truss or support on the side further from the ladder (escape route) (cut #1) (7) Cut the roof deck on one side of the opening perpendicular to the first cut (cut #2) (8) Cut the roof deck of the opposite side of cut #1 (9) Complete the ventilation hole by cutting between cut #2 and cut #3 (10)Remove the decking from the opening Ventilation - 21

24 (11) Working from upwind of the hole, open the ceiling under the opening by pushing the ceiling with the blunt end of a pike pole 2. Pitched roofs a. Elevated in the center along a ridge with a downward pitch to the eaves along the roof's edges b. Rafters or trusses run from ridge to walls for support c. Sheathing or decking material is attached to the rafters at right angles (1) May be placed solidly over the roof (2) May also consist of boards or planks with a small space between them (skip sheathing) d. Ventilating a pitched roof (1) Watch for signs of heat (2) Be prepared for sudden truss failure and collapse of entire roof (3) Confirm the order to ventilate the roof (4) Select the location for ventilation (5) Outline the opening with an axe pick (6) Cut the roof deck across the rafters on the high side parallel to the ridge 21 - Ventilation

25 (7) Cut the deck on the further side of the ventilation opening perpendicular to the first cut (8) Cut the deck on the opposite of the cut above (9) Complete the opening by cutting the bottom between the two parallel cuts (10)Remove the decking with an axe or pike pole (11) Working from upwind of the hole, open the ceiling under the opening by pushing the ceiling with the blunt end of a pike pole 3. Arched roofs a. Span large, open areas unsupported by pillars or posts b. Bowstring trusses (1) The lower chords may be covered by a ceiling, forming an enclosed cockloft or attic (2) These concealed spaces can hide fire long enough to weaken the truss system (3) If one member of a bowstring truss fails, the entire truss will probably fail and can push out other trusses and walls Ventilation - 22

26 c. Trussless or "Lamella" construction enables all parts of the roof to be visible (1) Made up of relatively short boards of uniform length (2) Boards are beveled and bored at the ends and bolted together at an angle (3) Forms an interdependent structural member network (4) Supported by buttresses or tie rods or both (5) These roofs can fail when one part of the network of boards burns through d. Some trussless arched roofs use massive arches of steel, concrete, or laminated wood buttressed to the ground at both ends (1) Arches are connected to each other by horizontal members called "purlins" (2) A large hole can be cut or burned through this type of arched roof without causing collapse e. Ventilation procedures for arched roofs are similar to those for flat or pitched roofs (1) The biggest problem in venting arched roofs is that the roof curvature prevents ladders from laying flat or being hooked onto the roof (2) Fire fighters must sound an arched roof and walk only on trusses or strong points 24 - Ventilation

27 (3) An inspection hole should be cut in the roof to locate trusses and determine fire involvement under the roof 4. Concrete roofs a. Precast concrete roofs are becoming more common b. "Lightweight concrete" roof decks may be poured in place over form boards and steel roof decking (1) Lightweight concrete is made of gypsum plaster and portland cement mixed with other aggregates (2) Usually finished with roofing felt and mopped with hot tar c. Breaching concrete roofs should be avoided if possible (1) Some lightweight concrete roof may be penetrated with a hammerhead pick or power saw with a concrete blade (2) Heavier roofs may require a jackhammer or diamond-tipped chain saw (3) Existing roof openings should be utilized before trying to open a concrete roof 5. Metal roofs a. May be constructed of: (1) Light-gauge steel decks Ventilation - 25

28 (2) Cold-formed steel (3) Galvanized sheet metal (4) Aluminum b. Metal cutting tools or power saws with metal cutting blades are needed to open metal roofs c. Metal roofs on industrial buildings usually have roof openings, such as skylights or hatches L. Trench or strip ventilation 1. Used to stop spread of fire in long, narrow structures 2. A large hole or trench at least 4-feet wide is cut in roof from one exterior wall to the opposite exterior wall 3. Hole is cut ahead of advancing fire to set up a defensive line 4. Advantage is to stop horizontal spread of fire 5. Disadvantages: a. Danger to personnel if roof is weakened b. Takes large amount of time to complete c. Requires several fire fighters M. Basement fire ventilation 1. Without built-in vents, ventilation of basement fires is essential to avoid vertical extension 26 - Ventilation

29 2. Direct ventilation of basements a. If windows are available, these can be used for horizontal ventilation b. Natural paths, such as stairways, can be used if the smoke and gases can be ventilated to the outside without endangering other areas of the building c. As a last resort, a hole can be cut in the floor near a door or window and a smoke ejector used to force the heat and smoke to the exterior N. Disrupting vertical ventilation 1. Fire streams must never be projected down into a ventilation opening a. Heat and gases can be forced down into the building on fire fighters and contribute to fire spread b. If streams are to be used to cool the thermal column from a ventilation opening, they should be operated above the hole and aimed slightly upward 2. Other factors that can disrupt effective ventilation: a. Improper forced ventilation b. Excessive window breakage c. Breaking skylights d. Additional openings between the attack team and the roof opening Ventilation - 27

30 IV. Horizontal Ventilation (Essentials p. 570) A. Horizontal ventilation is the venting of heat, smoke, and gases through wall openings such as windows and doors B. Used in situations where the building: 1. Is not heavily charged with fire and the attic is not involved 2. Has high windows 3. Is a multistory structure 4. Has large unsupported open spaces under the roof 5. Is so weakened by fire that vertical ventilation is unsafe 6. Has a daylight (walkout) basement C. Advantages 1. Easier to accomplish than vertical ventilation 2. May be more effective 3. May be used with other methods D. Disadvantages 1. Cannot be used if backdraft potential is suspected 2. If not properly done, can draw fire into uninvolved areas 3. Always consider interior and exterior exposures 28 - Ventilation

31 4. Opening extra doors and windows can disrupt ventilation E. Wind must always be a consideration when using horizontal ventilation 1. Cannot be used if wind will push fire toward an exposure or through structure a. May draw smoke and gases to the passageways being used for evacuation b. May ignite higher portions of the fire building c. May ignite adjacent structures 2. When there is a lack of wind, horizontal ventilation will be less effective 3. Open top windows on leeward side and open lower windows on windward side (side where the wind is striking) F. Charged hose lines must be ready to attack the fire whenever horizontal ventilation is used G. Opening a door or window on the windward side of a building without an opening on the leeward side may upset normal thermal layering H. Daylight basement ventilation 1. Found in homes built on a slope with exterior windows and exterior doors 2. Usually easier to ventilate than conventional basements Ventilation - 29

32 3. Opening exterior doors and windows can provide adequate ventilation V. Forced Ventilation (Essentials p. 572) A. Accomplished mechanically with fans or hydraulically with fog streams when natural ventilation is ineffective B. Situations where forced ventilation can be effective: 1. When natural ventilation is unsuitable 2. When the fire is below ground level 3. When there is no fire but an undesirable atmosphere a. Oxygen deficiency b. Toxic gases c. Explosive or flammable atmospheres C. Advantages 1. Insures more positive control 2. Supplements natural ventilation 3. Speeds smoke removal 4. Reduces smoke damage D. Disadvantages 1. Improperly used it can spread fire and smoke to uninvolved areas 2. Dependent on a power source 30 - Ventilation

33 3. May require special equipment E. Negative pressure ventilation 1. Uses fans or smoke ejectors to pull smoke out of buildings 2. Fan should be placed to pull smoke out in same direction as wind 3. Air recirculating around fan can be a problem a. Recirculation is referred to as "churning" b. Opening around fan should be covered to prevent churning 4. Attempt to keep air flow in as straight a line as possible to avoid turbulence 5. Avoid opening windows or doors near the fan 6. Remove obstacles to air flow a. Window screens b. Curtains c. Debris 7. Only fans with intrinsically safe motor should be used when venting flammable atmospheres 8. Exhaust fans should be shut off when moved Ventilation - 31

34 F. Positive pressure ventilation (PPV) 1. High-volume fans blow fresh air into building to create higher pressure in building which forces smoke out to lower pressure areas 2. Blower is placed 4 to 10 feet outside of door so that cone of air completely covers opening 3. Smoke is ejected from another opening about the same size as the point of entry 4. Doors inside structure may be closed to clear one area at a time to speed smoke removal 5. With multiple floors, fans should be placed at the lowest level 6. Personnel must avoid standing in openings which could block flow of air 7. Keys to effective positive pressure ventilation: a. Take advantage of wind conditions b. Make sure the cone of air from the fan fills the entry opening c. Reduce the size of the area pressurized to speed up the process d. Keep the exit opening about the same size as the entry opening e. Avoid creating horizontal openings by breaking glass or opening doors 32 - Ventilation

35 8. Advantages of positive pressure ventilation a. Can be set up without personnel entering smokefilled area b. Can be effective with vertical or horizontal ventilation c. Removes smoke faster than negative pressure ventilation d. Heat and smoke may be directed away from unburned areas e. Fans do not block means of egress f. Can be effective in all types of structures g. The velocity of air currents within a building is minimal with little effect on the contents or smoldering fires h. The cleaning and maintenance of PPV fans is less than required for smoke ejectors i. Heat and smoke is directed away from unburned areas j. Exposed buildings can be pressurized to reduce fire spread into them 9. Disadvantages of positive pressure ventilation a. Structure must be intact b. Fan exhaust can create higher carbon monoxide levels c. Hidden fires may be accelerated and spread Ventilation - 33

36 G. Hydraulic ventilation 1. May be used when other types of forced ventilation are not being used 2. Performed by crews making an interior attack after a fire has been controlled 3. Wide fog pattern is set on nozzle and held about 2- feet from window 4. Fog pattern should fill 85% to 90% of window opening 5. Air drawn into fog pattern will pull smoke out along with water 6. Advantages a. Removes more than mechanical smoke ejector b. Only a hoseline is needed c. Water fog also protects personnel 7. Disadvantages a. Water damage may be increased b. Increased drain on the available water supply c. In freezing temperatures, the amount of ice is increased d. Fire fighters must be in heated atmosphere during hydraulic ventilation operations in order to operate hoselines 34 - Ventilation

37 e. The operation may have to be interrupted when personnel exhaust their air supplies VI. Building Ventilation Systems Effects (Essentials p. 579) A. Heating, ventilation, and air-conditioning (HVAC) systems may draw in smoke and heat and spread fire B. System may automatically shut down when smoke or heat is detected in the air ducts or fire fighters may have to shut down the system to control smoke and heat spread C. During overhaul, area around system should be checked for fire extension D. Personnel should rid system of smoke before reactivating it E. System may be equipped with dampers or smoke detectors which shut system down if smoke is present F. Fire fighters should not attempt to operate smoke control systems during fire conditions G. Building engineers should be called to operate smoke control systems at the direction of fire personnel VII. Ventilation Summary A. Properly done ventilation decreases fire spread and increases visibility for fire attack 1. Aids in life safety 2. Speeds fire attack and extinguishment Ventilation - 35

38 3. Aids in fire spread control 4. Reduces the potential for flashover and backdraft 5. Helps with property conservation B. Inadequate or improper ventilation can cause death or injury to fire victims and fire fighters and cause destruction of the building C. Before ventilation can be started, officers must make numerous decisions based not only on fire conditions but also their experience and knowledge 36 - Ventilation

39 VENTILATION QUIZ Name: Date: 1. Which of the following terms is used to describe a particular type of explosion which may occur when unburned gases ignite and burn rapidly when oxygen is introduced? a. Mushrooming b. Ventilation c. Flashover d. Backdraft 2. Which of the following is not considered an advantage of performing ventilation? a. The potential for backdraft is increased b. Speeds fire attack c. Mushrooming is reduced d. Confinement can be provided 3. Which of the following is not an indicator of the potential for a backdraft? a. Open free-burning fire b. Window rattling c. Smoke stained windows d. Smoke coming through cracks 4. An advantage of vertical ventilation is. a. interior visibility decreases b. the natural convection of heat and gases is allowed for c. contaminated atmospheres are confined to the fire area d. mushrooming can be contained to the area of origin 5. One method to help determine the integrity of a roof is. a. vertical ventilation b. sounding c. cutting the roof in several areas to examine it d. opening under the roof for a visual inspection before venting Ventilation - 37

40 VENTILATION QUIZ 6. When opening a residential roof for vertical ventilation, a hole is recommended as a minimum. a. 2'x2' b. 4'x4' c. 6'x6' d. 8'x8' 7. For proper horizontal ventilation, the bottom of the windows should be opened on the side. a. windward b. leeward c. windward or leeward d. leeway 8. Which of the following is a disadvantage of forced ventilation? a. Positive control is decreased b. Smoke damage may be increased c. Natural ventilation may be hampered d. It is dependant on a power source 9. When placing fan or blower for positive pressure ventilation. a. it should be placed several feet outside of the door b. the opening around the fan should be covered to prevent air from recirculating c. the fan should be placed to draw smoke out in the same direction as the wind d. hidden fires are not a concern 10. When using hydraulic ventilation, the fog pattern should fill of the window opening to be effective. a. 50% to 60% b. 75% c. 85% to 90% d. 100% 38 - Ventilation

41 INSTRUCTOR'S GUIDE PRACTICAL SKILLS These Lead Instructor Practical Skills are designed to provide the Lead Instructor for a Fire Fighter I and II course with a more detailed overview of the practical skills required of all students. The appropriate skills from NFPA are listed at the front of each skill's section. Although the skills from NFPA are written as Job Performance Requirements, these have been divided into individual skill elements. This is to allow for consistency in the evaluation of each skill element. Students must successfully complete each step of each practical skill during the practical skills evaluation portion of a Fire Fighter I and II course. At the time of a Fire Fighter I and II Certification Examination, the skill steps have been prioritized to allow a student to miss a predetermined number of steps Ventilation

42 MISSOURI DIVISION OF FIRE SAFETY FIRE FIGHTER I & II PRACTICAL SKILLS Ventilation Successful completion of the practical skills in this section are necessary to fulfill the requirements of the following sections of NFPA : Fire Fighter I Standard Perform horizontal ventilation on a structure operating as part of a team, given an assignment, personal protective equipment, ventilation tools, equipment, and ladders, so that the ventilation openings are free of obstructions, tools are used as designed, ladders are correctly placed, ventilation devices are correctly placed, and the structure is cleared of smoke Perform vertical ventilation on a structure as part of a team, given an assignment, personal protective equipment, ground and roof ladders, and tools, so that ladders are positioned for ventilation, a specified opening is created, all ventilation barriers are removed, structural integrity is not compromised, products of combustion are released from the structure, and the team retreats from the area when ventilation is accomplished. Ventilation - 41

43 MISSOURI DIVISION OF FIRE SAFETY FIRE FIGHTER I & II PRACTICAL SKILLS Ventilation - NFPA , Demonstrate Negative Pressure Ventilation Skill Objective: The candidate shall demonstrate the proper set up of a smoke ejector in a door or window to ventilate a structure using negative pressure ventilation. Skill Procedure: The evaluator shall locate a suitable structure to be ventilated using negative pressure ventilation. The student shall properly set up a smoke ejector or fan and operate the equipment to demonstrate techniques for either negative ventilation. Students are allowed two chances at each skill for successful completion. Any step listed in italics missed shall result in failure of the skill. Otherwise, students are allowed to miss a maximum of one of the following steps and pass this skill. Items to be checked If the candidate: 1. Places smoke ejector so exhaust flows in the same direction as the natural wind 2. Seals around ejector to eliminate air recirculating 3. Opens windows and doors on windward side of structure to aid in ventilation process 4. Keeps airflow in as straight a line as possible 5. Removes all obstacles to airflow 6. Starts smoke ejector 42 - Ventilation

44 MISSOURI DIVISION OF FIRE SAFETY FIRE FIGHTER I & II PRACTICAL SKILLS Ventilation - NFPA , Demonstrate Positive Pressure Ventilation Skill Objective: The candidate shall demonstrate the proper set up of a fan in a door to ventilate a structure using positive pressure ventilation. Skill Procedure: The evaluator shall locate a suitable structure to be ventilated using positive pressure ventilation. The student shall properly set up a fan and operate the equipment to demonstrate techniques for positive ventilation. Students are allowed two chances at each skill for successful completion. Any step listed in italics missed shall result in failure of the skill. Otherwise, students are allowed to miss a maximum of one of the following steps and pass this skill. Items to be checked If the candidate: 1. Places fan so location does not interfere with entry and exit of fire fighters from the building 2. Starts positive pressure fan 3. Directs fan so that the cone of air from the blower completely covers the opening 4. Ensures that exhaust opening should be approximately the same size as the entry opening 5. Opens interior doors systematically to maintain positive pressure in the structure Ventilation - 43

45 MISSOURI DIVISION OF FIRE SAFETY FIRE FIGHTER I & II PRACTICAL SKILLS Ventilation - NFPA , Demonstrate Hydraulic Ventilation Skill Objective: The candidate shall demonstrate the proper use of a charged hoseline in a window to ventilate a structure. Skill Procedure: The evaluator shall locate a suitable structure to be ventilated using hydraulic ventilation. The student shall properly set up charged hoseline and operate the equipment to demonstrate techniques for hydraulic ventilation. Students are allowed two chances at each skill for successful completion. Any step listed in italics missed shall result in failure of the skill. Otherwise, students are allowed to miss a maximum of one of the following steps and pass this skill. Items to be checked If the candidate: 1. Extends the nozzle outside of the opening and open the nozzle 2. Sets the fog nozzle wide enough to cover 85% to 90% of the opening 3. Closes the nozzle and brings the nozzle about 2 feet inside of the building 4. Opens the nozzle and directs the fog pattern out of the opening 5. Monitors progress of ventilation 44 - Ventilation

46 MISSOURI DIVISION OF FIRE SAFETY FIRE FIGHTER I & II PRACTICAL SKILLS Ventilation - NFPA , Demonstrate Ventilating a Roof Skill Objective: The candidate, positioned on a flat or pitched roof, will choose the equipment needed to ventilate the roof and then demonstrate making an adequate opening in the roof for ventilation purposes. Skill Procedure: The evaluator shall locate a flat or pitched roof on a structure available for simulation. The evaluator shall identify location of simulated fire, wind direction/ strength and existing exposures. The candidate should then choose adequate equipment and additional help in order to perform ventilation on the roof. Students are allowed two chances at each skill for successful completion. Any step listed in italics missed shall result in failure of the skill. Otherwise, students are allowed to miss a maximum of two of the following steps and pass this skill. Items to be checked If the candidate: 1. Confirms order to ventilate roof 2. Organizes and collects necessary tools 3. Accesses the roof safely (proper ladder technique, etc.) 4. Correctly sounds the roof 5. Picks most suitable location to ventilate 6. Outlines ventilation with pick on axe 7. Remove roof coverings to expose decking 8. Cuts roof deck across the rafters on the high side parallel to the ridge (cut #1) 9. Cuts (cut #2) deck on further side of opening perpendicular to cut #1 10.Cuts (cut #3) roof deck on opposite side of cut #2 11.Completes opening by cutting between bottom of two parallel cuts (cuts #2 & #3) 12.Removes decking with axe or pike pole 13. Opens the ceiling under the opening by pushing with the blunt end of a pike pole Ventilation - 45