Phoenix Fire Department (PFD) Written Practice Exam 2025 - Free Firefighter Practice Questions and Study Guide

Class B extinguishers are specifically designed to combat fires involving flammable liquids. These flammable liquids include substances like gasoline, oil, grease, and solvents, which can ignite and cause hazardous situations. The extinguishing agents used in Class B extinguishers, such as foam, dry chemical, or carbon dioxide, effectively smother the flames and prevent oxygen from reaching the fuel, which is essential for extinguishing this type of fire.

Understanding the types of fires is crucial to selecting the appropriate extinguisher. Electrical fires, wood and paper fires, and combustible metal fires require different types of extinguishing agents, as using a Class B extinguisher on those fires could be ineffective or even dangerous. For example, using water on electrical fires can result in electrocution, while Class B extinguishers might not be effective on metal fires, which typically require specific agents designed for that purpose. Therefore, Class B extinguishers are uniquely suited for handling flammable liquid fires, making this understanding vital for safety and effective fire response.