Fuel oil is a collection of various fractions obtained from the distillation of crude oils, including lighter and heavier fractions. It includes heavy fuel oil, marine fuel oil, furnace oil, gas oil, heating oils, and diesel fuel. Fuel oil is typically used in furnaces or boilers to generate heat or in engines for power generation. It does not include other liquid oils with a flash point of around 42°C or oils burned in cotton or wool-wick burners.
Fuel oil consists of long-chain hydrocarbons, including alkanes, cycloalkanes, and aromatics. Small molecules in fuel oils have low boiling points and are removed at the start of the fractional distillation process. Heavier petroleum-derived oils like diesel fuel and lubricating oil are less volatile and distill out more slowly.
