Certified Fire Investigator Practice Exam

Which wood pyrolysis zone indicates insufficient heat to ignite?

1. Less than 392 F

2. 392 F to 536 F

3. 536 F to 932 F

4. Greater than 932 F

The correct answer is: Less than 392 F

The zone indicating insufficient heat to ignite wood is classified as less than 392 degrees Fahrenheit. At this temperature, the conditions are not conducive to reaching the ignition point because the energy required to break down the wood structure has not been sufficiently supplied. In pyrolysis, wood undergoes thermal decomposition, which requires certain temperatures to initiate changes, such as drying, decomposing, and finally, reaching the ignition point. Temperatures below 392 degrees Fahrenheit are generally associated with moisture evaporation and softening of wood without creating combustible gases or conditions necessary for ignition. Understanding these temperature thresholds is critical for fire investigations, as it helps to identify the phases of wood behavior in fire scenarios. Higher temperature ranges, such as 392 degrees to 536 degrees Fahrenheit, lead to the release of flammable gases, creating a more ignitable environment.