Cooperative Personnel Services Firefighter (CPS) Practice Exam

Ignition of powders in bulk typically occurs due to exothermic reactions and heat generation. When two or more substances interact in a chemical reaction, they may release energy in the form of heat, which can raise the temperature of the surrounding material. If the temperature of the bulk powder reaches its ignition point, combustion can occur.

Exothermic reactions are particularly noteworthy in situations where dust or powder particles are involved because their large surface area can facilitate rapid reactions. Additionally, many powders can become chemically active when they are disturbed or mixed, which can lead to increased heat generation and potential ignition.

While high temperatures, static electricity, and open flames can also contribute to ignition under certain circumstances, they do not explain the primary mechanism responsible for ignition in bulk powders. High temperatures can indeed trigger ignition, but they do not cause it in the absence of other conditions. Static electricity can ignite fine powders but is not a fundamental cause for all bulk powders. Open flames certainly can cause ignition, but like the other factors, they are not the overarching reason for ignition in bulk powders, which is fundamentally rooted in chemical reactions and heat.