🔍 Key Concepts

• Fuel oil vapors vs. liquid fuel – how vapors behave compared to the liquid itself • Vapor density – what “heavier than air” implies about where vapors accumulate • Fire and explosion triangle – fuel, oxygen, and ignition source

💭 Think About

• If vapors are heavier than air, where will they tend to collect on a vessel, and what hazard does that create? • Think about what makes fuel oil dangerous when it is heated and gives off vapors: is the main concern smell, visibility, toxicity, or something else? • In confined or low spaces on a ship, what property of fuel vapors would be most critical for safety procedures?

✅ Before You Answer

• Verify which option describes a safety-critical hazard that requires strict precautions on board ships • Consider whether fuel vapors must be visible or have a smell to be dangerous • Ask yourself: which choice is most directly connected to fire and explosion risk in enclosed or low areas like bilges and tanks?