I guess it’s okay if you “try not to be one,” as long as you don’t adopt the mantle of science when you testify. Too many investigators who do not want to do the “science” nevertheless start out their testimony with a “scientific” description of the behavior of fire. They testify under the color of science, hoping to enhance their credibility by doing so.

Despite the sometimes-daunting terminology, it is important that those who hold themselves out as fire experts actually understand certain concepts, despite educational handicaps. It’s 2007. You ought not to be allowed to send someone to prison or cost someone their life savings on the basis of your “professional opinion” unless you can explain (at least) the following:

1. The heat release rate of an ignition source or a fire, as measured in watts or kilowatts.
2. The HRR of some common fuels.
3. The difference between temperature and energy, and what really causes “high” temperatures.
4. How fire patterns are developed.
5. The concept of radiant heat flux, measured in kilowatts per square meter.
6. Some typical radiant heat flues, and the effects of those heat fluxes.
7. The concept of critical radiant heat flux.
8. The difference in behavior between confined and unconfined fires.
9. The definition of a “fuel controlled” and a “ventilation controlled” fire.
10. How flashover occurs.

This stuff is science, but it is not rocket science. Certainly, it is easier for those educated in science or engineering to explain the above concepts, but it should be mandatory for everyone doing fire investigations for a living to understand these concepts.

Even if you’re not a scientist, and don’t want to be one, it’s not okay to tell a jury that “heat rises” and “abnormal” temperatures at floor level indicate that accelerants must have been used. It’s not okay to say that you can visually discern a “pour pattern” in a fully involved compartment. It’s not okay to rely on the discredited arson myths that scientists have proved to be wrong.

All of the above concepts are explained in Chapters 5 and 6 of NFPA 921.

John Lentini, CFI, D-ABC
Fire Investigation Consultant
Florida Keys
[www.firescientist.com]