Vehicle fire investigation science and technology
This domain tests how fire science and vehicle engineering combine at a vehicle fire scene. The CVFI candidate should explain fire behavior in vehicle compartments, identify plausible ignition sources in each system, and connect damage to a fire direction rather than merely list burned parts.
Core concepts
- Fire requires fuel, oxygen, heat, and an uninhibited chemical chain reaction; vehicle fuels include liquids, vapors, plastics, composites, and battery electrolytes.
- Treat the vehicle as interacting systems: fuel delivery, 12/24 V electrical, high-voltage propulsion, exhaust and aftertreatment, brake/hydraulic, HVAC, and occupant-protection systems.
- Fire patterns indicate direction and intensity, but ventilation, melting, collapse, suppression, and corrosion can distort them.
- High-voltage systems, including orange cables and battery packs, create electrical and chemical hazards; thermal runaway can cause re-ignition, jetting, and stranded energy.
- Compare pre-fire condition, service history, crash damage, and post-fire damage before assigning an origin.
- Document both damaged and undamaged components; negative findings help exclude systems.
Worked example
A sedan burns in a parking lot. The engine compartment is heavily damaged, but the left-front tire and wheel are intact. Melted aluminum is concentrated near the exhaust manifold, and the passenger compartment has only smoke damage. A battery positive cable has a bead with a clean, round cross-section. Reasoning: the bead is consistent with an arc from an energized conductor, but arc beads can also form after fire exposure. The concentrated manifold damage and limited passenger-compartment burning support an engine-compartment origin; the bead alone does not prove an electrical cause. The investigator should test fuel-line, exhaust, and electrical hypotheses against service records and witness observations.
Traps that cost marks
- Calling melted wiring an electrical cause; copper melting and arcing are often fire effects.
- Treating “most damage” as origin without checking ventilation, fuel load, and suppression.
- Ignoring high-voltage safety or assuming every orange cable is de-energized.
- Confusing fuel-line fire damage with a pre-fire fuel leak.