Ventilation Flashcards
Fire growth potential is based on
Available fire load
Decay stage
The stage of fire development within a structure characterized by either a decrease in fuel load or available oxygen to support combustion resulting in lower temperatures and lower pressure in fire area
Note fire with modern content will have 2 decay stages
Flashover will occurs in a compartment fire when surfaces exposed to thermal radiation from fire gases reach
In excess of 1100 degrees F
Flow path
Movement of heat and smoke from higher pressure within the fire area towards lower pressure areas via doors window openings and roof structures
Gases heat move out fresh air pulled in
May be several flow paths
Fully developed stage
Peak heat release within compartment
Usually after flashover
Results in floor to ceiling burning within compartment
Heat conditions untenable for members
Growth stage
Stage of fire development when heat release rate from incipient fire has increased to point where heat transferred from fire and combustion products are pyrolyzing adjacent fuel sources. The fire begins to spread across the ceiling of the fire compartment ( rollover)
Heat release rate
The rate at which energy is generated by the burning of a fuel and oxygen mixture. As the heat release rate increases the heat smoke production and pressure within the area will increase and spread along available flow paths toward lower pressure areas
Incipient stage
The early stage of fire development where fires progression is limited to a fuel source and the thermal hazard is localized to the area of the burning material
Modern content fire
Fires that involve hydrocarbon and synthetic based contents such as foam rubber , nylon, rayon and polypropylene . Modern fires have have a relatively high heat rate when compared to natural fiber products found in legacy fires . Modern fires rapidity react to ventilation and the in- flow of additional 02
Pyrolysis
The transformation of materials into their basic compound when subjected to heat . Contents will continue to off- gas and add to the flammable fuel load within the compartment as long as the material is subjected to elevated temps
In what stage does rollover occur
In growth stages
Note is an indicator that flashover is imminent
Ventilation induced flashover
Flashover initiated by the introduction of o2 int preheated fuel rich , smoke filled o2 deficient are
Can occur with legacy fire
Prevalent in modern content fire so
VEIS
VENT ENTRY ISOLATE SEARCH
Approved tactic when entering structure through openings ( window or door)
Priority when entering via window isolate area by closing door to that area
Doorway control door until fire area further isolated or charged line is advancing on fire
Traditional fire growth stages
- Incipient
- Growth
- Fully devolved
- Decay
Modern content development stages
- Incipient stage
- Rapid growth stage that consumes the available o2
- Early O2 limited decay stage
- If o2 introduced 2nd. Growth stage
- Vent induced flashover into fully developed stage
- Second decay stage
TICS must be
Carried and used at all structural fires
Vent profile observed during size up should note the following
- Location where smoke or fire venting from building
- Evaluation of the volume, pressure and velocity of the smoke venting from building
- Amount of fire venting from building including when fire or smoke is not venting out window openings
Fire and smoke should be venting outwards and upwards not downward horizontal or pulsing from an open window
Any change in fire conditions as incident progress or as a result of vent tactics communicated to officer in fire area and IC
Any unusually vent profile must be immediately communicated to ladder officer inside fire are to be vented and IC . True or false
True
Absence of smoke pushing from building with a modern content fire is a positive sign
No negative
Initial vertical vent is considered ?
Venting of :
Bulkheads
Scuttles
Skylights over stairs and hallways
When can the roof may perform vertical vent without direct contact with ladder officer in fire area
- Hearing radio transmission that interior team has control of door on fire floor
- Or charged hose line advancing into fire apt
