Cooperative Personnel Services Firefighter (CPS) Practice Exam 2025 - Free Firefighter Exam Questions and Study Guide

The correct answer identifies the three types of explosions associated with combustible dust as primary, propagating, and secondary.

In the context of combustible dust, a primary explosion occurs when an initial ignition causes a significant burst or shockwave. This explosion can create conditions favorable for further explosions. The propagating explosion refers to the chain reaction that occurs when the fire or explosion spreads to additional sources of combustible dust, causing further explosions in adjacent areas. The secondary explosion is particularly critical because it typically involves a much larger and more destructive event following the initial primary explosion. Secondary explosions can result from the dispersal of dust clouds created by the primary explosion, leading to widespread damage and increased risk to both personnel and equipment.

This understanding of explosive sequences is essential for safety measures and protocols in environments where combustible dust is present, highlighting the importance of hazard identification and risk assessment.