Fire Service - Firefighting and Hazardous Materials
Fire Service - firefighting and hazardous materials
This domain tests fire behaviour, correct extinguishing agents, firefighter safety, and the first actions at a hazardous materials incident.
Fire behaviour and agents
- Fire tetrahedron - fuel, oxygen, heat and chemical chain reaction. Extinguishing means removing at least one.
- Classes and agents - A (solids: water, foam), B (flammable liquids: foam, CO2, dry powder; never a water jet), C (gases: isolate supply, dry powder), D (metals: dry powder or sand, never water), electrical (isolate current first), K (cooking oils: wet chemical).
- PASS - Pull, Aim, Squeeze, Sweep, from a safe distance with an exit behind you.
- Interior attack - never enter a burning compartment without SCBA and a charged line, working in pairs. Warning signs of flashover: rollover of flame in the smoke layer, darkening smoke, rapidly rising heat.
Hazardous materials
Approach from upwind, uphill and upstream, and park at a distance. Identify the substance from the placard or UN number, consult the emergency response guide, and set hot, warm and cold zones with a single entry control point. Deny entry, keep ignition sources away, and decontaminate before transport. Do not enter a hot zone to rescue unless trained and equipped for it.
Worked example
A kitchen LPG cylinder is burning at the regulator. Reasoning: evacuate and call, approach upwind with a charged line, and cool the cylinder with water fog from behind cover. Do not extinguish the flame unless the valve can actually be closed - a flame that goes out while gas still escapes turns the room into an explosive atmosphere.
Traps that cost marks
- Water on a pan of burning oil, or a water jet on live electrical equipment.
- Entering smoke without SCBA because "the fire looks small".
- Extinguishing a gas flame without isolating the leak.
- Standing in contaminated run-off, or approaching a hazmat scene from downhill.