1. Ventilation (Fire Fighter I)
CHAPTER 15
Ventilation
(Fire Fighter I) 1

2. Fire Fighter I Objectives
Describe the two components of ventilation operations.
Explain the conditions that lead to an underventilated fire.
Describe the potential hazards posed by an underventilated fire and products of combustion.
Describe how ventilation operations affect the behavior of the products of combustion. 2

3. Fire Fighter I Objectives
Describe how convection aids in fire spread.
List the benefits of ventilation.
Explain how proper ventilation operations can aid in preventing backdraft and flashover.
Explain how the principles of heat transfer affect ventilation operations.
Explain how wind and atmospheric forces affect ventilation operations. 3

4. Fire Fighter I Objectives
Explain how fire-resistive construction affects ventilation operations.
Describe how the characteristics of ordinary and wood-frame construction affect ventilation operations.
List the two basic types of ventilation.
Explain how horizontal ventilation removes contaminated atmosphere from a structure.
List the two methods of horizontal ventilation. 4

5. Fire Fighter I Objectives
Explain how natural ventilation removes contaminated atmosphere from a structure.
Describe the techniques used to provide natural ventilation to a structure.
Explain how mechanical ventilation removes contaminated atmosphere from a structure.
Describe the techniques used to provide mechanical ventilation to a structure. 5

6. Fire Fighter I Objectives
Describe how negative-pressure ventilation removes contaminated atmosphere from a structure.
Describe the techniques used to provide negative-pressure ventilation to a structure.
Describe how positive-pressure ventilation removes contaminated atmosphere from a structure.
Describe the advantages of positive-pressure ventilation. 6

7. Fire Fighter I Objectives
Describe the disadvantages of positive- pressure ventilation.
Describe the techniques used to provide positive-pressure ventilation to a structure.
Describe how hydraulic ventilation removes contaminated atmosphere from a structure.
Describe how vertical ventilation removes contaminated atmosphere from a structure. 7

8. Fire Fighter I Objectives
Describe the how to ensure fire fighter safety during vertical ventilation operations.
Identify the warning signs of roof collapse.
Describe the components and characteristics of roof support structures.
Explain how roof construction affects fire resistance.
List the differences in solid-beam construction and truss construction in roofs. 8

9. Fire Fighter I Objectives
List the basic types of roof design.
Describe the characteristics of flat roofs.
Describe the characteristics of pitched roofs.
Describe the characteristics of arched roofs.
Describe the techniques of vertical ventilation.
List the tools used in vertical ventilation.
List the types of roof cuts used in vertical ventilation operations. 9

10. Fire Fighter I Objectives
Describe the characteristics of a rectangular or square cut.
Describe the characteristics of a triangular cut.
Describe the characteristics of a peak cut.
Describe the characteristics of a trench cut.
Describe the special considerations in ventilating concrete roofs.
Describe the special considerations in ventilating metal roofs. 10

11. Fire Fighter I Objectives
Describe the special considerations in ventilating basements.
Describe the special considerations in ventilating high-rise buildings.
Describe the special considerations in ventilating windowless buildings. 11

12. Fire Fighter I Objectives
Describe the special considerations in ventilating large buildings
Explain how to ensure that ventilation equipment is in a state of readiness. 12

13. Introduction Ventilation
The process of removing smoke, heat, and toxic gases from a burning building and replacing them with cooler, cleaner, more oxygen-rich air 13

14. Introduction Two components:
Removal of smoke, toxic gases, hot air
Addition of cooler, cleaner, oxygen-rich air
Modern construction uses lightweight and manufactured building components
Firefighters may assume the fire is small, fuel is gone, or fire is in decay 14

15. Fire Behavior and Ventilation
Proper ventilation:
Locates and rescues victims
Enables hose teams to advance and locate source of fire
Prevents fire spread 15

16. Fire Behavior and Ventilation
Primary method of fire spread is convection.
Mushrooming occurs when the products of combustion reach the highest point. 16

17. Benefits of Proper Ventilation
Locate trapped occupants faster
Fresh air to occupants
Advance hose lines rapidly and safely
Reduce backdraft and flashover
Limit fire spread
Reduce property loss 17

18. Benefits of Proper Ventilation
A. Vented structure.
B. Unvented structure. 18

19. Backdraft
Occurs when building is charged with hot gases and oxygen has been consumed
When air is introduced, fuel can ignite and explode. 19

20. Backdraft
Release heat and unburned particles without allowing entry of clean air.
Ventilate as high as possible. 20

21. Flashover Needs both ventilation and cooling Occurs when:
Air in room is very hot
All combustibles are near their ignition point
Applying water cools the atmosphere.
Ventilation draws heat and flames away 21

22. Factors Affecting Ventilation
Convection
Heated gases will always follow the path of least resistance.
Ill-fitting and tight-fitting windows can cause dangerous fire conditions. 22

23. Factors Affecting Ventilation
Mechanical ventilation activities
Negative-pressure
Positive-pressure
Hose streams
Fire fighters should evaluate for signs of backdraft before creating ventilation. 23

24. Factors Affecting Ventilation
Wind and atmospheric forces
Wind speed and direction
Temperature and humidity 24

25. Building Construction Considerations
The way a building is constructed will affect ventilation operations. 25

26. Fire-Resistive Construction
Noncombustible structural components
Paths of fire spread
Heating, cooling, plumbing, electrical
Elevator shafts
Stairwells
Roofs generally steel or concrete 26

27. Ordinary Construction
Construction design
Exterior walls noncombustible
Interior walls/floors of wood
Roof is wood decking and structural support. 27

28. Ordinary Construction
Paths of fire spread
Plumbing and electrical chases
Void spaces in walls
Cockloft
© Steven Townsend/Code 3 Images 28

29. Wood-Frame Construction
Combustible exterior walls
Paths of fire spread
Attics and cocklofts
Wood truss roofs and floors
Construction types
Balloon-frame
Platform 29

30. Location and Extent of Smoke and Fire Conditions
Factors to consider
Size of the fire
Stage of combustion
Location within the building
Available ventilation options 30

31. Location and Extent of Smoke and Fire Conditions
Where to ventilate
As close to the fire as possible
If unable to vent close to the fire:
Predict how location will affect the fire.
Anticipate fire spread.
Courtesy of District Chief Chris E. Mickal/New Orleans Fire Department, Photo Unit 31

32. Location and Extent of Smoke and Fire Conditions
Determine fire size, intensity, and fuel
Light smoke, moving lazily—small fire of ordinary combustibles
Large amount of black rolling smoke—petroleum- based fire
Cool days may cause smoke inversion.
Sprinkler activation may cause fog. 32

33. Types of Ventilation Two basic types of ventilation Horizontal
Uses horizontal openings in a structure such as doors and windows
Vertical
Involves openings in the roofs or floors 33

34. Horizontal Ventilation
Commonly used in residential fires and room-and-contents fires
Generally fast and easy to use
Can be used from inside or outside the building
Courtesy of District Chief Chris E. Mickal/New Orleans Fire Department, Photo Unit 34

35. Horizontal Ventilation
Most effective when opening is directly to outside
More difficult when there are no openings
Limits structural damage
Only open doors when the host line is charged and the attack team is ready to advance. 35

36. Natural Ventilation
Depends on convection currents, wind, and other natural air movements
Used when air currents are adequate
Used when ventilation is needed quickly
Open leeward side of building first, then windward. 36

37. Natural Ventilation Breaking glass Try to open first. Wear full PPE.
Ensure no one will be struck by the glass.
Always use a tool.
Keep hands above or to the side of glass.
Use a tool to clear remaining glass. 37

38. Natural Ventilation Opening doors Provide large openings.
May compromise entry/exit points
May be best for clean air points
Good location for mechanical ventilation devices 38

39. Mechanical Ventilation
Negative-pressure ventilation
Limitations:
Positioning
Power source
Maintenance
Air flow control
Advantages
Explosion-proof motors
Courtesy of Super Vacuum Mfg. Co., Inc. 39

40. Mechanical Ventilation
Positive-pressure ventilation
Large, powerful fans
Advantages:
Quick and efficient
Increased safety
Disadvantages
May spread the fire
May increase carbon monoxide levels 40

41. Mechanical Ventilation
Hydraulic ventilation
Fog or broken pattern
Advantages
Move several thousand cubic feet of air per minute
Disadvantages
Water damage
Safety hazards 41

42. Vertical Ventilation Releases combustion products vertically
Occurs naturally if there is an opening
May be assisted by mechanical means 42

43. Vertical Ventilation Safety considerations
Determine roof construction first
Opening should not be between fire fighters and exit.
Have a charged hose line ready.
Leave the area once done. 43

44. Vertical Ventilation Safety considerations “Sound” the roof
Walk on areas of greatest support
Make cuts from:
Upwind
With clear exit path
While standing on firm section
© craig robinson/iStockphoto.com 44

45. Roof Construction Two components Support structure Roof covering
Solid beams of wood, steel, or concrete
System of trusses of wood, steel, or wood and steel
Roof covering
Made of various weather-resistant materials
Supported by the roof decking 45

46. Effects of Roof Construction on Fire Resistance
Support system failure
Supporting structure fails
Often a sudden and total collapse
Roof covering failure
Burns through roof covering
Spreads out, causing roof failure
In warmer climates burn through quickly; in colder climates burn with little evidence 46

47. Solid Beam vs Truss Solid beam Truss Girders, beams, and rafters
Lightweight components
Wood or steel bars
Triangular configuration 47

48. Roof Designs Flat roofs Pitched roofs
Can be constructed with many types of supports, decking, and materials
Pitched roofs
Have a visible slope for rain, ice, and snow runoff 48

49. Roof Designs Arched roofs Generally found in commercial structures
Use bowstring trusses in which fire can severely and quickly weaken structure
© NicVW/Alamy Images 49

50. Roof Ventilation Objectives: Provide largest opening
Put in appropriate location
Use least amount of time
Use safest technique 50

51. Roof Ventilation
Before starting vertical ventilation, assess the following:
Construction features
Indications of fire damage
Safety zones and exit paths
Built-in roof openings 51

52. Roof Ventilation Most effective at highest point and over seat of fire
May need to cut an examination hole
One hole is better than several small ones
Minimum size 4'×4' 52

53. Tools Used in Vertical Ventilation
Power saws
Axes
Halligan tools
Pry bars
Tin cutters
Pike poles, other types of hooks
Utility rope 53

54. Types of Roof Cuts Rectangular cut
Requires four cuts completely through the decking
Use care to not cut structural supports.
Stand upwind and have a safe exit.
If several layers exist, may have to peel a layer at a time 54

55. Types of Roof Cuts Louver cut
Used for flat or sloping roofs with plywood decking
Power saw or axe used to make the cuts
Can quickly create a large opening 55

56. Types of Roof Cuts Triangular cut
Used to prevent metal decking from rolling away as it is cut
A saw or axe is used.
Several may be needed because of their small size. 56

57. Types of Roof Cuts Peak cut
Used for peaked roofs with plywood sheeting
A tool is used to reveal the roof covering along the peak.
A power saw or axe is used to make a series of vertical cuts. 57

58. Types of Roof Cuts Trench cut
Used to stop the progress of a large fire in a narrow building
Creates large opening ahead of the fire
“Writes off” part of the building 58

59. Special Considerations
Poor access or obstructions
Multiple roofs and roof layers
Boarded or sealed window openings
Security measures such as steel bars and shutters 59

60. Ventilating Concrete Roofs
Generally flat and hard to breach
May collapse from weakened support systems when exposed to fire
Search for alternative openings 60

61. Ventilating Metal Roofs
Discoloration and warping may indicate seat of fire.
Tar roof covering can melt and leak into the building.
Metal can roll down and create a dangerous slide directly into the opening. 61

62. Ventilating Basements
Usually requires both horizontal and vertical ventilation
Make as many openings on one side as possible and allow fire fighters to enter from the other.
A cellar nozzle or hose line may be needed. 62

63. Ventilating High-Rise Buildings
Many have hard to break sealed windows.
Newer buildings have smoke management in the HVAC.
Designate one stairwell as a rescue route.
Positive-pressure fans can keep smoke out of the stairs. 63

64. Ventilating High-Rise Buildings
A cold outer atmosphere and a heated interior will cause smoke to rise quickly through vertical openings. 64

65. Ventilating High-Rise Buildings
A hot outer atmosphere and a cooled interior will cause smoke to push down the vertical openings. 65

66. Ventilating Windowless Buildings
Traps heat and smoke
Treat similar to a basement fire.
Ventilate high.
© olaf schlueter/ShutterStock, Inc. 66

67. Ventilating Large Buildings
More difficult than small ones
Smoke cools as it travels, causing stratification.
When possible, use interior walls and doors to create smaller areas. 67

68. Equipment Maintenance
Must be kept in good repair and operate at peak efficiency
Read and follow manufacturer’s instructions.
Filled with fuel
Practice using ventilation tools. 68

69. Summary
Ventilation removes smoke, heat, and toxic gases from a burning building.
Flashback or backdraft is caused by the addition of oxygen-rich air to a smoke-filled and fuel-rich atmosphere.
New construction leads to a large fuel supply.
Ventilation can save lives and reduce property damage. 69

70. Summary
An increase in fire produces more smoke, heat, and toxic gases.
Convection controls the spread of the products of combustion.
In convection, heated gases expand and become less dense than cooler gases.
Proper ventilation includes improved visibility, removal of heat and steam, reduction of backdraft, and limited fire spread. 70

71. Summary Backdraft can be reduced by ventilation.
Ventilation and cooling are needed to relieve potential flashover conditions.
Convection currents carry smoke and superheated gases to uninvolved areas.
The direction and force of the wind should be considered. 71

72. Summary
Structural components in fire-resistive construction are made of noncombustible or limited-combustible materials.
Ordinary construction buildings have exterior walls composed of noncombustible or limited- combustible materials.
Wood-frame buildings contain void spaces.
Fire fighters must be able to recognize when ventilation is needed. 72

73. Summary Vertical ventilation makes structural holes.
Horizontal ventilation include natural and mechanical methods.
Vertical ventilation allows the products of combustion to travel up and out.
Fire fighters must evaluate all pertinent safety issues and avoid unnecessary risks.
When working on a roof, fire fighters should have two safe exit routes. 73

74. Summary Roofs are composed of support structures and roof coverings.
Roof designs can be flat, pitched, or arched.
Vertical ventilation openings include built-in, inspection, primary, and secondary.
Commercial or industrial structures have concrete roofs. 74

75. Summary
Metal roofs conduct heat and are supported by lightweight steel metal joists.
Venting a basement may include both horizontal and vertical.
HVAC systems may be used to ventilate high- rise buildings.
All equipment and tools must be in a ready state and be properly maintained. 75