කාර්මික ආසවනය is typically performed in large, vertical cylindrical columns known as ""distillation or fractionation towers"" or ""distillation columns"" with diameters ranging from about 65 centimetres to 6 metres and heights ranging from about 6 metres to 60 metres or more. The distillation towers have liquid outlets at intervals up the column which allow for the withdrawal of different fractions or products having different boiling points or boiling ranges. By increasing the temperature of the product inside the columns, the different hydrocarbons are separated. The ""lightest"" products (those with the lowest boiling point) exit from the top of the columns and the ""heaviest"" products (those with the highest boiling point) exit from the bottom of the column.