The MINIMUM temperature to which a fuel in air must be heated to initiate self-sustained combustion without initiation from an independent ignition source is best described as:

• A. Autoignition temperature
• B. Flash point
• C. Boiling point
• D. Ignition point

Answer: (A)

This item tests autoignition temperature—the minimum temperature at which a fuel in air will ignite by itself without an external ignition source. At that temperature, heat from the chemical reactions in the vapor-air mixture is sufficient to sustain combustion once started.

The flash point, in contrast, is the temperature at which enough vapor is produced to form an ignitable mixture with air, but an ignition source is still required to ignite it. Boiling point is simply the temperature at which a liquid turns into vapor and is not about ignition. Ignition point is not the standard hazmat term used here; the precise term for self-ignition without an external source is autoignition temperature.