Certified Fire Investigator Practice Exam

What does "Pyrolysis" refer to?

1. A process solely involving combustion

2. The decomposition of material by heat alone

3. The transfer of heat in liquids

4. A reaction between gases at high temperatures

The correct answer is: The decomposition of material by heat alone

Pyrolysis refers specifically to the thermal decomposition of materials when they are subjected to high temperatures in the absence of oxygen or limited oxygen. This process breaks down complex organic molecules into simpler substances, often resulting in the formation of gases, liquids (such as bio-oil), and solid residues (like char). In the context of fire investigation, understanding pyrolysis is crucial because it describes how certain materials can begin to break down and evolve flammable gases, which may contribute to fire growth even before visible flames appear. This can lead to a more profound understanding of how fires can start and develop in various materials. The other choices do not encompass the full scope of what pyrolysis entails. For example, the combustion process involves both heat and the presence of oxygen, which is not the case with pyrolysis. Similarly, while heat transfer in liquids and reactions between gases at high temperatures are related to thermal processes or combustion phenomena, they do not accurately describe the specific process of pyrolysis. Thus, option B is the most precise definition regarding the thermal decomposition of materials through heat.