Fractions

Part of a hydrocarbon mixture isolated according to the temperature where it evaporates. Distillation units ordinarily divide a combination of liquid hydrocarbons, such as crude oil or the output stream of a cracker, by sorting its molecules into portions with different boiling ranges. These parts, or fractions, also go by the name, cuts. The bottom and top temperatures of a fraction sometimes serve as its designation, as in 180-330 fraction.