Which hazmat class consists of liquids or liquid mixtures that give off flammable vapors?

• A. Class Three - Flammable Liquids
• B. Class One - Explosives
• C. Class Two - Gases
• D. Class Seven - Radioactive Material

Answer: (A)

Liquids that can release ignitable vapors are defined by their flash point. If the vapors from a liquid can ignite in air under normal handling conditions, that liquid is classified as a flammable liquid. In hazmat terms, this is Class 3. The hazard comes from the vapor phase forming a flammable mixture with air, even though the material may be a liquid at room temperature. Examples include gasoline and many common solvents, which have flash points at or below 60°C. The other hazard classes describe different dangers: explosives involve rapid energy release, gases are already in the gaseous state at room temperature, and radioactive materials involve radiation. Because the defining feature here is a liquid’s ability to produce ignitable vapors, the correct classification is flammable liquids.