At a factory fire, gas cylinders are being impacted by fire and there is a high risk of a BLEVE occurring. Define the acronym BLEVE and describe how it occurs.
Boiling Liquid Expanding Vapour Explosions occur when cylinder contents impacted by fire expand to such an extend that the cylinder can’t contain the pressure and ruptures due to the intense heat.
At the incident above, describe the firefighting response and identify the signs that would indicate to you that a BLEVE may occur.
Indications;
- Flame impingement
- Container distortion
- Sounding of relief valve
Response;
- Withdraw immediately
- Report / communicate hazard
- Apply cooling from protected position
- Do not extinguish the flame
State the 3 general properties of gas, and then identify what 4 measures you would consider using when trying to combat a gas leak?
- Gases can be compressed.
- Gases can expand to fill any container.
- Gases will expand when heated.
1a. Turn off supply (if possible).
2a. Eliminate any potential ignition sources.
3a. Dilute with air and/or water spray.
4a. Disperse with water spray.
On arrival at an incident involving a backyard BBQ cylinder on fire, identify the correct steps you would take to combat this scenario.
- Do not extinguish
- Cool the container from safe distance
- Only approach from side on (45 degree angle)
- Take cover whilst cooling
On arrival at a fire at a shopping centre with an installed fire safety system, what functions would you expect the sprinkler system to have performed?
- Automatically activated
- Prevented further spread of fire
- Contained the fire
- Alerted occupants and DFES
- Helps to identify specific area of the fire
During salvage and overhaul operations at a structure fire, you identify vital evidence that has to be moved to a safer location. What are the procedures you would take before doing this?
- Verbally notify the OIC and other FF’s
- Limit further water, where possible
- Document, photograph and/or video the scene prior to moving
- Ensure new location will not require another move
When firefighting at a bushfire incident, in conjunction with fixed wing or rotary aircraft, what are the precautions you can take to ensure the safety of yourself and your LT crew member.
- Maintain comms with GC
- Move off fire line when directed to
- Return when all clear from GC
- If caught in drop:
- Ensure helmet is on
- Move away from fire line
- Don’t run or panic
- Watch your footing
- Hand tools to be well clear
- Watch for falling debris
- If hit by foam – decon immediately
A fire has been reported in a Zone 2 Automated Response Zone, what aerial resources are automatically activated for an incident in that area?
2x fire bombers with air attack supervisor
2x aerial appliances either fixed wing or rotary
You have been asked by the SO to act as Ground Controller at an incident, what 4 prerequisites must be met for you to undertake this role?
- Have a sound knowledge of bush firefighting strategies and tactics
- Ability to read and interpret maps
- Ability to quickly assess a bush fire situation and make recommendations
- Clear and concise radio communication skills
Explain and describe what the acronym AIT stands for? What is the concern for you as a firefighter if you identify objects approaching their AIT?
Auto ignition temperature
- When a fuel/air mixture is heated to its AIT it will ignite without a light or spark.
- The intensity of the ignition is dependent upon degree of mixing.
List in order the 6 stages of branch control.
- Left for life
- Set to flush
- Open the branch
- Call or signal for water on
- Set your flow rate
- Set your flow pattern
Identify and explain what occurs during the 4 phases of combustion.
- Incipient - Decomposition by way of pyrolysis
- Smouldering - products released at the surface of the fuel become visible as smoke
- Flaming - Vapours from the decomposing fuel have been ignited
- Heat - Combustion has reached the point where the fire is much more rapid and creating considerable heat
On entry into a structure fire you would expect fire gases to be present. As these fire gases reach their LEL, what are the types of ignition sources that could be present to cause an explosion to occur?
- Sparks due to impact or friction
- Pilot lights
- Flames
- Sparks from vehicle
You have been tasked to don BA, make entry and carry out primary search and rescue. Explain the correct door entry procedure you should use to safely make entry into the structure.
- Ensure hose line is charged, flushed and set to spray
- Check direction of door opening by examining hinges
- Adopt a position of safety behind door or wall
- Paint door to find level of neutral plane - test door with back of hand for heat
- Gas cool above the door before opening communicating with number 2
- Open door - gas cool within compartment and shut door - allow for effect
- Assess entry, enter when safe
As the pump operator at an incident you identify a sudden drop in pressure on the compound gauge. You are pumping from a reticulated supply. Describe 3 potential causes for this sudden drop occurring;
- Burst hose from hydrant
- Blocked internal strainer
- Over supply of water to delivery lines
As crew member working in your LT at a bushfire incident, you identify a loss in communications with your Sector Commander. What actions could you take to re-establish radio contact? Describe at least 3.
- Check/change battery
- Change position/location or move to higher ground
- Use vehicle mounted radio
- Relocate to the last place you had comms
When firefighting at a bushfire there are always 3 priorities that you must consider. Identify and describe these priorities in order.
- Preservation of life - public/bystanders directly affected
- Protection of property - property directly under threat, structural triage to prioritise
- Protection of environment - stay on tracks/road, leave smallest possible footprint
As the designated pump operator, your OIC has asked you to provide foam to the branch operator. Identify and describe 3 disadvantages of foam being used in firefighting operations.
- Foam concentrate can be expensive
- Foam may be attacked by certain chemical agents
- Application may be affected by strong winds
You arrive at a Class C fire. Identify the preferred firefighting method to be used to combat this incident and why?
- Isolate fuel supply
- Turn gas off at source
- Do not extinguish flame
- Cool cylinder
- Protect exposures
Heat build-up is a very late indicator and should not be used as a warning sign for which particular fire phenomenon? What other signs can be used to identify this earlier and potentially allow you to prevent it occurring?
Flashover - Look for products beginning to pyrolyse, thermal layer lowering, smoke darkening.
Ventilate vertically and gas cool.
Explain the affects of increased temperature on the characteristics of water. How does this directly affect the application of water in an Internal Structure Firefighting scenario?
The expansion ratio of water turning to steam changes with temperature. At temps above 100 degrees the ratio is approx 1:1700. Above 600°C approx. 1:3400.
Meaning small amounts of water can be used to great effect. Three dimensional fire trap.
High thermal capacity - 4,200 Joules per litre to raise the temperature by 1°C.
High latent heat capacity - 2,260 kJ is required to convert a litre of water at 100 °C to steam.
During a suction drill you are not able to achieve the Maximum Theoretical suction lift or Maximum Practical suction lift. List the 6 recognised causes.
- Friction loss
- Turbulence
- Density of water
- Temperature of the water
- Altitude
- Creating flow
You arrive to a house fire, what are the signs you are looking for to indicate that a Backdraught may occur? What steps can we take to ensure that we avoid a Backdraught event.
- Blackening and crazing of windows
- Pulsating smoke and whistling noises
- Turbulent movement of smoke
- Dense smoke with no obvious sign of flame
- Neutral Plane very low
- Fire gases igniting on leaving the compartment
Ensure crews are aware of the situation so that accidental ventilation does not occur. Only ventilate vertically. Do not enter until internal gases are sufficiently cooled using correct door entry procedures.
Identify the 3 types of fire streams used, and describe 2 pros and 2 cons of using each at a structure fire;
- Jet - Long reach, Good penetration, High chance of damage, jet reaction.
- Spray - Water curtain protects, economical, less throw, less penetration.
- Fog - Absorbs heat, enhances rate water converts to steam, Wind affected, short reach.
