Process of Investigation

The key factors are listed below:

  1. There is significant variation in layout and equipment based on the fuel and drive system used. Owner’s manuals and service manuals should be consulted for information relevant to the specific vehicle. It is important to research or see an exemplar especially when inspecting vehicles of unfamiliar design.
  2. As in traditional vehicle fire investigation, each fluid system should be checked for involvement in fire.
  3. FFVs have generally similar configurations and flammable materials as in traditional vehicles. Investigators may need to consider the characteristics of the alternative fuels used. (Specifications of both alternative and traditional fuels are included in the Fuels section.)
  4. For BFVs, fire investigators have two separate fuel containment systems and two fuel delivery systems to inspect.
  5. Electric drive motors operate at voltages well above the electrical systems in traditional vehicles thereby increasing the risk of fire due to electrical ignition. Higher voltages result in greater tendency for arcing, higher energy arcs when they occur, and the potential for arc tracking to create conductive pathways in polymers.
  6. Compressed and cryogenic gas cylinders have additional risk factors for fire and explosion.
  7. Hydrogen and methanol may burn with a colorless flame. Witnesses may not accurately detect when fire began. The presence of contaminants in the flame (as would occur if vehicle components become involved) is likely to produce observable color.
  8. Propane is heavier than air; leaking fuel will pool in low, un-vented areas. Hydrogen and CNG are lighter than air; leaking gas will gather in high un-vented areas.
  9. Location of pressure relief devices (PRDs) may be important prior to and during a fire. If a PRD vents due to overpressurization of the system, it would be desirable to have gas released in a vented region and in a direction that venting during a fire would minimize exposure to those in the area.
  10. Catastrophic overpressurization of a tank, during fire or otherwise, may indicate improper functioning of the PRD.

References

  1. www.fueleconomy.gov for DOE government site, January 2020.