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Difficulty: HardFires and Fire Extinguisher Use

After safely maneuvering a refrigerated combination unit onto a wide gravel shoulder due to dense smoke surging from the front wheel wells, the driver cuts the ignition to stop electrical and fuel flow. When preparing to suppress the engine compartment blaze with a portable extinguisher, which action should the driver take?

  1. A
    Unlatch and fully raise the engine hood to pinpoint the origin of the blaze before deploying the dry chemical extinguisher.
  2. B
    Deploy a Class A water extinguisher from the cab emergency equipment compartment to douse the electrical harnesses and fuel lines.
  3. Direct the extinguishing agent through the front grille, side louvers, or from underneath the vehicle while keeping the hood closed.Answer
  4. D
    Prop the hood open several inches with a pry tool to spray extinguishing agent directly onto the upper wiring harnesses.

Answer

Direct the extinguishing agent through the front grille, side louvers, or from underneath the vehicle while keeping the hood closed.
In an engine fire, the compartment must remain closed because introducing fresh air will dramatically increase the fire's intensity. Drivers should direct extinguishing agent through louvers, the radiator grille, or from beneath the vehicle to smother the fire at its base.

Step-by-Step Solution

1
Maintain oxygen starvation by keeping the hood completely shut.
The fire remains contained within the compartment without access to open ambient airflow.
Opening the hood introduces fresh oxygen, causing rapid flame expansion and severe burn risk.
2
Locate exterior openings such as the radiator grille, fender louvers, or underside gaps.
Direct paths to the engine compartment are established without breaking the thermal barrier.
These apertures allow the dry chemical extinguishing agent to penetrate the engine bay effectively.
3
Discharge the properly rated (B:C or A:B:C) extinguisher at the base of the fire through the openings.
The extinguishing agent blankets the fuel and electrical sources, knocking down the blaze.
Aiming at the base rather than the flames interrupts the chemical reaction and smothers the fire.

Key Concept

Commercial Motor Vehicle Engine Fire Containment and Suppression Protocol
Estimated Time:1m 30s
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Topics

Fires and Fire Extinguisher Use

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