1. 14
Ventilation

2. Objectives (1 of 4)
Define ventilation as it relates to fire suppression activities.
List the effects of properly performed ventilation on fire and fire-suppression activities.
Describe how fire behavior principles affect ventilation.

3. Objectives (2 of 4)
Describe how building construction features within a structure affect ventilation.
List the principles, advantages, limitations, and effects of horizontal ventilation.
List the principles, advantages, limitations, and effects of natural ventilation.

4. Objectives (3 of 4)
List the principles, advantages, limitations, and effects of mechanical ventilation.
List the principles, advantages, limitations, and effects of negative-pressure and positive-pressure ventilation.
List the principles, advantages, limitations, and effects of hydraulic ventilation.

5. Objectives (4 of 4)
List the principles, advantages, limitations, and effects of vertical ventilation.
List safety precautions for ventilating roofs.
List the basic indicators of roof collapse.
Explain the role of ventilation in the prevention of backdraft and flashover.

6. Introduction (1 of 2) Ventilation
The process of removing smoke, heat, and toxic gases from a burning building and replacing them with cooler, cleaner, more oxygen-rich air

7. Introduction (2 of 2) Primary method of fire spread is convection.
Mushrooming occurs when the products of combustion reach the highest point.
Products of combustion present a risk.

8. Benefits of Proper Ventilation (1 of 2)
Locate trapped occupants faster
Fresh air to occupants
Advance hose lines more rapidly and safely
Reduce backdraft and flashover
Limit fire spread
Reduce property loss

9. Benefits of Proper Ventilation (2 of 2)

10. Backdraft (1 of 2)
Occurs when building is charged with hot gases and oxygen has been consumed
When air is introduced, fuel can ignite and explode.

11. Backdraft (2 of 2)
Release heat and unburned particles without allowing entry of clean air.
Ventilate as high as possible.

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

13. Factors Affecting Ventilation (1 of 2)
Convection
Heated gases will always follow the path of least resistance.
Use this basic principle to cause the convection flow to draw heated products out of the building.
Mechanical ventilation activities
Negative-pressure
Positive-pressure
Hose streams

14. Factors Affecting Ventilation (2 of 2)
Wind and atmospheric forces
Wind speed and direction
Temperature and humidity

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

16. Fire-Resistive Construction
Construction design
Structural components noncombustible
Compartmentalization
Paths of fire spread
Heating, cooling, plumbing, electrical
Elevator shafts
Stairwells
Roofs generally steel or concrete

17. Ordinary Construction (1 of 2)
Construction design
Exterior walls noncombustible
Interior walls/floors of wood
Roof is wood decking and structural support.

18. Ordinary Construction (2 of 2)
Paths of fire spread
Plumbing and electrical chases
Void spaces in walls
Cockloft
© Steven Townsend/Code 3 Images.

19. Wood-Frame Construction
Exterior walls are combustible
Paths of fire spread
Attics and cocklofts
Wood truss roofs and floors
Construction types
Balloon-frame
Platform

20. Ventilation and Tactical Priorities
Ventilation is directly related to tactical priorities.
Courtesy of District Chief Chris E. Mickal/New Orleans Fire Department, Photo Unit.

21. Venting for Life Safety
Life safety is the primary goal.
Gives occupants a greater chance to survive
Makes searches faster
Limits fire spread to other occupants and fire fighters

22. Venting for Containment
Second highest priority is contain the fire and control the situation.
Prevents fire spread
Makes fire attacks easier

23. Venting for Property Conservation
Can significantly limit property damage
Rapid ventilation reduces damage from smoke, heat, and water.

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

25. Horizontal Ventilation (1 of 2)
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 Chris E. Mickal/New Orleans Fire Department, Photo Unit.

26. Horizontal Ventilation (2 of 2)
Most effective when opening is directly to outside
More difficult when there are no openings
Limits structural damage
May utilize natural and mechanical methods

27. Methods of Ventilation
Natural
Depends on convection currents, wind, and other natural air movement
Mechanical
Uses mechanical means to augment natural ventilation

28. Natural Ventilation Used when air currents are adequate
Used when ventilation is needed quickly
Open leeward side of building first, then windward.

29. Breaking Glass (1 of 2) General rules Try to open first.
Wear full protective clothing and eye protection.

30. Breaking Glass (2 of 2) General rules (continued)
Ensure no one will be struck by the glass.
Always use a tool.
Keep hands above or to the side of the glass.
Use a tool to clear remaining glass.

31. Opening Doors Provide large openings. May compromise entry/exit points
May be best for clean air points
Good location for mechanical ventilation devices

32. Mechanical Ventilation
Methods of mechanical ventilation
Negative-pressure
Positive-pressure
Hydraulic

33. Negative-Pressure Ventilation
Ejectors
Limitations:
Positioning
Power source
Maintenance
Air flow control
Advantages
Explosion-proof motors
Courtesy of Super Vacuum Mfg. Co., Inc.

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

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

36. Vertical Ventilation (1 of 2)
Releases combustion products vertically
Occurs naturally if there is an opening
May be assisted by mechanical means

37. Vertical Ventilation (2 of 2)
Make opening close to seat of fire
Determine hottest point
Courtesy of Captain David Jackson, Saginaw Township Fire Department.

38. Safety Considerations (1 of 2)
Structural stability of the roof
Falling from the roof
Two exit routes
Opening should not be between fire fighters and exit.
Have a charged hose line ready.
Leave the area once done.

39. Safety Considerations (2 of 2)
“Sound” the roof
Walk on areas of greatest support
Make cuts from
Upwind
With clear exit path
While standing on firm section

40. Basic Indicators of Roof Collapse
Spongy feeling
Visible sagging
Roof separating from the walls
Structural failure in another portion of building
Sudden increase in fire intensity

41. 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

42. Types of Roof Failures Support system failure Roof covering 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

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

44. Roof Designs (1 of 2) 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
Type of construction dictates how to ventilate

45. Roof Designs (2 of 2) Arched roofs
Generally found in commercial structures to create a large span without columns
Use bowstring trusses in which fire can severely and quickly weaken structure
Courtesy of Captain David Jackson, Saginaw Township Fire Department.

46. Objectives of Vertical Ventilation
Provide the largest opening
Put in an appropriate location
Use the least amount of time
Use the safest technique

47. Vertical Ventilation Assessment (1 of 2)
Construction features
Indications of fire damage
Safety zones and exit paths
Built-in roof openings
Courtesy of Four Seasons Solar Products, LLC.

48. Vertical Ventilation Assessment (2 of 2)
Locate 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' x 4'

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

50. Types of Roof Cuts Rectangular cut Louver cut Triangular cut Peak cut
Trench cut

51. Rectangular Cut Requires four cuts completely through the decking
Use care to not cut structural supports.
Stand upwind and have a safe exit.
Can use a triangular cut to help pry up
If several layers exist, may have to peel a layer at a time

52. 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

53. 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.

54. 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.

55. Trench Cut
Used as a defensive tactic to stop the progress of a large fire in a narrow building
Creates a large opening ahead of the fire
“Writes off” part of the building
Requires both time and manpower

56. Special Considerations
Obstacles preventing ventilation
Concrete roofs
Metal roofs
Basement fires
High-rise buildings
Windowless buildings
Large buildings

57. Obstacles to Ventilation
Poor access
Multiple roofs and roof layers
Sealed and boarded abandoned buildings
Security measures such as steel bars and shutters

58. Ventilating a Concrete Roof
Found in commercial and industrial structures
Generally flat and hard to breach
May collapse from weakened support systems when exposed to fire
Search for alternative openings

59. Ventilating a Metal Roof
Discoloration and warping may indicate seat of fire.
As fire heats the metal deck, tar roof covering can melt and leak into the building.
Metal can roll down and create a dangerous slide directly into the opening.

60. Venting a Basement Usually few windows
Usually requires both horizontal and vertical ventilation
Fire fighters must descend the stairs through the venting combustion products.
Make as many openings on one side and allow fire fighters to enter from the other

61. High-Rise Buildings Many have hard to break sealed windows.
Unique smoke patterns with stack effect.
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.

62. Stack Effect Smoke Patterns

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

64. 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.

65. Summary (1 of 3) Ventilation provides many benefits.
Several factors affect ventilation.
Building construction affects ventilation.
Ventilation is related to life safety, fire containment, and property conservation.

66. Summary (2 of 3)
Assessing the location and extent of smoke and fire will determine ventilation.
The types of ventilation are horizontal and vertical.
Horizontal ventilation uses horizontal openings in a structure.

67. Summary (3 of 3)
Vertical ventilation refers to the release of heat and smoke in a vertical direction.
Many obstacles can be encountered during ventilation operations.
Ventilation is a major consideration in backdraft and flashover.