Session Reference: 1-3
Time Required: 90 Minutes
• Truck Company Fireground Operations, Second Edition, Chapters 4 and 5
• Essentials of Fire Fighting, Third Edition, Chapter 7
Objective (SPO): 1-3-1
The student will demonstrate a basic understanding of ventilation theory, ventilation decisions, methods of ventilation, and ventilation techniques.
• Basic principles
• Natural ventilation
• Forced ventilation
• Smoldering fires
SESSION 1-3 VENTILATION
SPO 1-3-1 The student will demonstrate a basic understanding of ventilation theory, ventilation decisions, methods of ventilating, and ventilation techniques.
1-3-1 Define ventilation and describe the importance of ventilation to the overall fire suppression activity.
1-3-2 Describe convection currents and their effect on ventilation.
1-3-3 Explain natural ventilation.
1-3-4 Explain forced ventilation.
1-3-5 Describe the signs and special ventilating considerations related to smoldering fires.
I. Definition (1-3-1)
A. Ventilation is the controlled removal of smoke, heat, and gases and the replacement with fresh air.
B. Ventilation contributes directly to accomplishment of basic fire fighting objectives by
1. Reducing danger to trapped occupants and extend time for rescue operations
2. Increasing visibility thereby decreasing danger inherent in other fireground operations and increasing
3. Permitting quicker and easier entry to allow search operations or to advance lines
4. Minimizing time required to locate seat of fire
5. Minimizing time required to find areas to which fire has spread
6. Decreasing or stopping spread of fire
7. Reducing chance of flashover or backdraft
C. Results depend on size and type of occupancy involved, extent and location of fire, and whether fire is free burning or smoldering
D. When properly performed, ventilation increases effectiveness of most operations
E. Ventilation techniques require doing damage to building
F. Small amount of ventilation damage results in larger reduction in fire damage
G. Ventilation aids in saving lives
II. Basic Principles (1-3-2)
A. Fire travel by convection presents greatest fire fighting problem
B. Smoke moves vertically and horizontally – mushrooming
C. A separate fire may ignite from hot air and combustion products rising
D. Accumulation of hot air and combustion products under roof must be allowed to escape
E. Opening should be under hot air and combustion product accumulation
F. Accumulation on fire floor should be relieved also
G. General rule is open fire building so that all accumulations of heat and combustion products leave building by natural convection
III. Natural Ventilation (1-3-3)
1. When time permits, windows should be opened; avoid breaking glass, if possible
a. Double hung windows should be opened two-thirds down from the top and one-third up from
b. Open other types of windows as much as possible
c. Storm windows must also be opened or removed
d. Shades, blinds, drapes, curtains, and other window coverings must be moved away or removed
2. Effects of wind
a. When wind is a factor, windows on leeward side should be opened first
b. Windows on windward side should then be opened
c. If windward side is opened first, wind will churn smoke and gas around in interior
3. Window and roof ventilation
a. When roof or roof features must be opened for venting, windows on top floor should be
b. If windows on several floors must be opened, begin at top and work down
c. Opening windows from below first may cause fire and smoke spread
B. Natural roof openings