SOGs-17-Ventilation Flashcards
(45 cards)
What is the definition of flow path?
Movement of heat and smoke from the higher pressure within the fire area toward the lower pressure.
If the thermal layering is disturbed blocked etc. hot air will travel out on top and cool air will travel in on the bottom
What is the definition of fuel limited?
The heat release rate of the fire is limited primarily by the chemical and physical characteristics of the available fuels.
Define hydraulic ventilation
Using water flow to draw the air out of a structure
Define mechanical ventilation
Using machinery and/or devices to assist in the movement of air like positive pressure fans and building systems
Define natural ventilation
Allowing air to naturally move without any assistance lake wind opening windows creating openings at the highest point of the structure
Define tactical ventilation
The planned systematic and coordinated removal of heat smoke and fire gases and the replacement with cooler fresh air
Define vent limited
A fire in which heat release rate and fire growth are regulated by the available oxygen within the space
What are some indicators of a fuel limited fire?
Indicators may include: An incipient or early growth fire High neutral plane Better visibility Relatively low temperatures
What are some indicators of a vent limited fire?
Fire is beyond incipient stage
Mid to low neutral plane
Poor visibility
Flames exiting outside a window or door
Air drawn into the fire when doors are opened
Increased temperatures but will be declining if in decay stage
All common Backdraft indicators
What is a ventilation profile?
The ventilation points showing the flow paths of heat and smoke out of the structure as well as any air movement into the structure
What should be considered when determining a structure’s ventilation profile?
Existing and/or potential flow path The location and stage of the fire Fuel or vent limited Wind direction Exposures Rescue or suppression Building layout and construction Integrated ventilation systems Smoke conditions: volume velocity density colour
What is the purpose of door control?
Controlling fresh air flow to feed a developing fire by opening or closing a door.
Closing a door immediately upon arrival will help control the heat release rate of the fire
What should be considered when choosing your tactical plan for ventilation?
Tactics that complement the IAP
The location of personnel committed to interior operations
Occupant location
How tactics may affect flow paths, fire behaviour and operational time frames
When is any PPV usage utilized?
After fire control
After PPV operations when should consideration be made of discontinuing the use of the fan?
When checking for extension
Where should a PPV fan be placed?
For complete airflow coverage of the inlet
Define backflow as it relates to a PPA?
Pressurized air coming out at the inlet point
Define transitional attack
Offensive fire attack initiated by an exterior indirect hand line operation into the fire compartment to initiate cooling while transitioning into interior direct fire attack in coordination with ventilation
What needs to happen if a positive pressure attack is initiated and heavy smoke or fire is exhausting out the inlet point?
Create a larger/additional exhaust
Throttle down the fan; reattempt
What considerations should the IC consider prior to committing to a PPA operation?
360 size up has been completed
Flow paths have been determined
Confirm any VEIS operations are complete and protected themselves and the occupant
Fire location is determined
Fire does not involve the structure
Minimum two crews on scene
Exhaust locations have been determined
Where should fans be placed for a positive pressure attack?
The point of entry from the unburned side of a fire
2 m back from the entry point
Create a pressure ”cone” effect around the door
What are the three basic terms when deciding whether to continue with the PPA attack or terminate it
Improves the atmosphere - continue with it Makes no change - review all aspects, re-position if necessary Worsening atmosphere - discontinue its use
What is the preferred flow path if available?
Upwind to downwind
What is the preferred tactical consideration for a positive pressure attack?
Combining a transitional attack simultaneously with a PPA
