Technically, a distillate is a product obtained from the condensation of vapors during a distillation process. In this sense, most petroleum products – gasoline, diesel fuel, kerosene and jet fuel–are, to some degree, distillates. The process by which they are produced involves heating crude oil and allowing it to rise in a tower-like chamber. Vapor thus created condenses at various levels in the tower, and the liquid is drawn off.
In petroleum marketing, however, the term distillate is reserved for products in the middle distillation range. These products include heating oils and diesel fuel. The main distillate classifications are Nos. 1, 2, and 4 fuel oils, and Nos. 1, 2, and 4 diesel fuels. Kerosene is also a distillate, similar to No. 1 oils, but is often listed separately for statistical purposes.
See also Refining process.