Which class includes Flammable Liquids?

• A. Class 2
• B. Class 7
• C. Class 3
• D. Class 5

Answer: (C)

Flammable liquids are designated as Class 3 in hazardous materials transport. The main factor here is the flash point—the lowest temperature at which a liquid can form ignitable vapors. Liquids with a flash point at or below 60°C (140°F) are classified as flammable liquids, which is why they fall under Class 3. This grouping is based on the primary hazard they pose: the ease with which their vapors can ignite.

The other classes cover different hazards: gases are Class 2, which involve substances that remain in a gaseous state under normal conditions; radioactive materials are Class 7; and oxidizers and organic peroxides are Class 5. These are distinct risks from flammable liquids, so those options don’t describe the hazard in question.

In practice, common flammable liquids like gasoline, acetone, and ethanol ignite readily because their vapors can reach ignitable concentrations at relatively low temperatures, which is why they’re classified as Class 3.