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Difficulty: HardFires and Fire Extinguisher Use

During a post-trip inspection at a logistics terminal, a driver discovers that spilled diesel fuel has ignited underneath a trailer auxiliary unit and flames are spreading toward energized electrical wiring. Which of the following procedures must the driver follow to safely control this fire using the onboard equipment?

  1. A
    Apply water under high pressure to cool the electrical wiring, then switch to a Class A dry chemical extinguisher to smother the liquid fuel pool.
  2. B
    Remove the protective compartment panels to directly expose the wiring, then discharge extinguishing agent directly into the center of the rising flames.
  3. Utilize a B:C rated dry chemical extinguisher, stay as far away as effective, and sweep the nozzle side to side across the base of the fire.Answer
  4. D
    Position downwind and discharge a Class D dry powder canister into the air directly above the flames to allow extinguishing dust to settle over the wiring.

Answer

Utilize a B:C rated dry chemical extinguisher, stay as far away as effective, and sweep the nozzle side to side across the base of the fire.
Diesel fuel fires represent Class B hazards (flammable liquids) and electrical systems represent Class C hazards (energized electrical equipment). The correct procedure requires a B:C rated dry chemical extinguisher applied from a safe distance directly at the base of the fire with a sweeping motion to starve the fire of oxygen and break the chemical reaction.

Step-by-Step Solution

1
Identify the fire classifications involved in the incident.
The fire involves burning diesel fuel (Class B - flammable liquids) and energized wiring (Class C - electrical equipment).
Correctly identifying the fuel source prevents selecting hazardous or ineffective extinguishing agents such as water.
2
Select the proper fire extinguisher rating required by commercial vehicle safety regulations.
A Type B:C or multi-purpose A:B:C dry chemical extinguisher is selected.
Commercial motor vehicles require fire extinguishers rated for both liquid fires and electrical fires to prevent conductivity and spread.
3
Execute the proper suppression technique from a safe upwind distance.
Stay as far back as the stream allows, keep enclosures shut to restrict oxygen, and sweep the chemical agent across the base of the fire.
Aiming at the base of the fire smothers the fuel where combustion originates, while sweeping ensures complete coverage without spreading burning fuel.

Key Concept

Selection of B:C rated extinguishers for liquid and electrical fires, avoiding water on electrical/fuel fires, and aiming at the base of the fire.
Estimated Time:1m 30s
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Topics

Fires and Fire Extinguisher Use

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