Structural Firefighting Flashcards
Structural Firefighting
Stages of fire progression
Phase 1: Developing Fire Phase 2: Flashover
Phase 3: Fully Developed Phase 4: Decay
What is the neutral plane?
The area between over pressure (hot fire gases) and under pressure (fresh air)
Hot fire gasses could pose a risk of becoming?
Fire gas ignition
7 Signs of Flashover
- Ventilation controlled, vented fire2. Painful radiant heat3. Hot surfaces 4. Fingers of flame through smoke 5. Increased rate of pyrolysis 6. Low turbulent neutral plane 7. Increased turbulence of neutral plane
Signs of backdraught
- Ventilation controlled, non vented fire2. Lack of visible flame3. Dirty smoke4. Smoke pulsating through small gaps and openings5. Air drawn in (whistling noises)6. Indicators of extreme heat e.g. blistering of paintwork, crazing of glass in windows
Flammability range is the ratio of
Fuel to air Too low concentration and things cant burn Too high concentration and things cant burn
The decomposition of a substance is
Pyrolysis caused by heat
Direct attack - what is the correct branch setting
Jet, flow rate 115 to 475 lpm
What is the branch setting when gas cooling
30-60degreecone angle, 115 lpm at 700kpa
What is gas cooling, when is it used
Used to control the fire environment when advancing during fire attack, to perform search & rescue and for protection.The water droplets are converted to steam, the flammable gases are cooled and diluted below their Auto ignition temperature. The steam expands by absorbing the thermal energy/heat of the fire gases, and displacing the oxygen away from the fire
What are the Gas laws
Thornton’s rule - As oxygen increase, the heat rate increasesCharles’s law - Gases expand when heated. Gases become less dense and will rise when heated Gay-Lussac’s law - when gases are confined and heated, pressure increases. Increased pressure, higher temperatures.
Definition of a fire gas ignition?
Fire gas explosion ignited in another compartment e.g. second floor, adjacent room
When do we use door entry
Always
Ventilation vs fuel control signs - scenarios will be given in exam, list which one it is e.g. bush fire
Fuel Controlled signs- Developing fire- high neutral plane- better visibility- bright yellow flame- fire in decay stageVentilation - fully developed fire- low neutral plane- poor visibility- air being drawn back in to fire- smoke pulsations- smouldering fire- whistling sounds
Intent of an indirect fire extinguish attack and what is it most suited for?
To extinguish a fire by creating large amounts of steam. This has a smothering effect on the fire by displacing the oxygen. This method is generally used when the fire is fully involved or to suppress a suspected backdraught risk.
List the extinguisher colours and what they are most suited for
Red - Water - AWhite - Dry powder - A,B, C & EBlue - Foam - A & BBlack - CO2 - B & EA - Wood, Paper, PlasticsB - Flammable LiquidsC - Flammable gasesE - Electrical
What is meant by overhaul
Overhaul involves the systematic checking, turning over and wetting down of structural materials and contents to ensure that no pockets of fire still exist
What are 5 signs of structural collapse
- Falling plaster, mortar, bricks or from walls or ceilings 2. Cancerous concrete spalling3. walls leaning or bulging4. ceilings sagging5. floors spongey or springy6. gaps appearing in between walls, beams or ceilings, or walls and floors7. cracked or sagging arches over door or window openings8. displacement of supporting pillars, joists or beams
What is salvage operations
Salvage describes the actions taken during and immediately after the fire to minimise the damage caused by fire and by the water used to extinguish it.
What are some assisted evacuation producers for high rises?
Smoke curtains, pressurised stairs, pressurised zones and sprinkler systems
