Sub-Product

Light Ends is a term used in the petroleum industry to identify products that condense at the top of the distillation tower during the refining process.

In a refinery, crude oil is heated causing vapors to rise up through a tower, where they condense at various levels. Those that condense at the highest point are sometimes referred to by oil people as light ends. Propane distilled from crude oil is a light end. By extension, petrochemical conversion processes also produce light ends in the distillation section.

Light ends are generally combustible gases that may be recycled in the processes, burnt as fuel, or released in the atmosphere.

Source: Rhys, 21^st Oct 2014, Light Ends, PEI.