What is Fuel oil?
[[Image:Bunkering-or-taking-fuel.jpg|thumb|right|300px|An [[oil tanker]] taking on bunker fuel.]]'''Fuel oil''' is a [[fractional distillation|fraction]] obtained from [[petroleum]] [[distillation]], either as a distillate or a residue at the [[oil refinery]]. Broadly speaking, fuel oil is any liquid petroleum product that is burned in a [[furnace]] or boiler for the generation of heat or used in an [[engine]] for the generation of power, except oils having a [[flash point]] of approximately +40 °C and oils burned in cotton or wool-wick burners. In this sense, [[diesel]] is a type of fuel oil. Fuel oil is made of long [[hydrocarbon]] chains, particularly [[alkane]]s, [[cycloalkane]]s and [[aromatic]]s. The term ''fuel oil'' is also used in a stricter sense to refer only to the heaviest commercial fuel that can be obtained from [[crude oil]], heavier than [[gasoline]] and [[naphtha]]. ==Six classes== Fuel oil in the United States is classified into six classes, according to its boiling temperature, composition and purpose. The boiling point, ranging from 175 to 600 °C, and [[carbon chain]] length, 20 to 70 [[atom]]s, of the fuel increases with number. [[Viscosity]] also increases with fuel oil number and the heaviest oil has to be heated to get it to flow. Price usually decreases as the fuel number increases. '''No. 1 fuel oil''', '''No. 2 fuel oil''' ([[heating oil]]), and '''No. 3 fuel oil''' are referred to as '''distillate fuel oils''', '''diesel fuel oils''', '''light fuel oils''', '''gasoil''' or just '''distillate'''. For example, No. 2 fuel oil, No. 2 distillate and No. 2 diesel fuel oil are almost the same thing. Diesel is different in that it also has a [[cetane number]] limit which describes the ignition quality of the fuel. Distillate fuel oils are distilled from [[crude oil]]. ==Related pages== *[[Diesel]] *[[Gasoline]] *[[Kerosene]] *[[Naphtha]] ==Sources== *[http://www.bunkerworld.com Bunkerworld - media site for the marine fuels industry] *[http://www.nature.nps.gov/hazardssafety/toxic/fuelo