Kerosene, or paraffin, is a combustible hydrocarbon liquid which is derived from petroleum. It is widely used as a fuel in aviation as well as households. Its name derives from Greek: κηρός (keros) meaning “wax”, and was registered as a trademark by Canadian geologist and inventor Abraham Gesner in 1854 before evolving into a generic trademark. It is sometimes spelled kerosine in scientific and industrial usage.
Kerosene is widely used to power jet engines of aircraft (jet fuel), as well as some rocket engines in a highly refined form called RP-1. It is also commonly used as a cooking and lighting fuel, and for fire toys such as poi. In parts of Asia, kerosene is sometimes used as fuel for small outboard motors or even motorcycles. World total kerosene consumption for all purposes is equivalent to about 5,500,000 barrels per day as of July 2023.
The term kerosene is common in much of Argentina, Australia, Canada, India, New Zealand, Nigeria, and the United States, while the term paraffin (or a closely related variant) is used in Chile, Eastern Africa, South Africa, Norway, and the United Kingdom. The term lamp oil, or the equivalent in the local languages, is common in the majority of Asia and the Southeastern United States.
Confusingly, the name paraffin is also used to refer to a number of distinct petroleum byproducts other than kerosene. For instance, liquid paraffin (called mineral oil in the US) is a more viscous and highly refined product which is used as a laxative. Paraffin wax is a waxy solid extracted from petroleum.
To prevent confusion between kerosene and the much more flammable and volatile gasoline (petrol), some jurisdictions regulate markings or colourings for containers used to store or dispense kerosene. For example, in the United States, Pennsylvania requires that portable containers used at retail service stations for kerosene be colored blue, as opposed to red (for gasoline) or yellow (for diesel).
The World Health Organization considers kerosene to be a polluting fuel and recommends that “governments and practitioners immediately stop promoting its household use”.Kerosene smoke contains high levels of harmful particulate matter, and household use of kerosene is associated with higher risks of cancer, respiratory infections, asthma, tuberculosis, cataracts, and adverse pregnancy outcomes.
Properties and grades
Kerosene is a low-viscosity, clear liquid formed from hydrocarbons obtained from the fractional distillation of petroleum between 150 and 275 °C (300 and 525 °F), resulting in a mixture with a density of 0.78–0.81 g/cm3. It is miscible in petroleum solvents but immiscible in water. It is composed of hydrocarbon molecules that typically contain between 6 and 20 carbon atoms per molecule, predominantly containing 9 to 16 carbon atoms.
Regardless of crude oil source or processing history, kerosene’s major components are branched- and straight-chain alkanes (hydrocarbon chains) and naphthenes (cycloalkanes), which normally account for at least 70% by volume. Aromatic hydrocarbons such as alkylbenzenes (single ring) and alkylnaphthalenes (double ring), do not normally exceed 25% by volume of kerosene streams. Olefins are usually not present at more than 5% by volume.
The heat of combustion of kerosene is similar to that of diesel fuel; its lower heating value is 43.1 MJ/kg (around 18,500 Btu/lb), and its higher heating value is 46.2 MJ/kg (19,900 Btu/lb).
The ASTM International standard specification D-3699-19 recognizes two grades of kerosene: grades 1-K (less than 0.04% sulfur by weight) and 2-K (0.3% sulfur by weight). 1-K-grade kerosene burns cleaner with fewer deposits, fewer toxins, and less frequent maintenance than 2-K-grade kerosene, and is the preferred grade of kerosene for indoor kerosene heaters and stoves.
In the United Kingdom, two grades of heating oil are defined. BS 2869 Class C1 is the lightest grade used for lanterns, camping stoves, wick heaters, and mixed with petrol in some vintage combustion engines as a substitute for tractor vaporising oil. BS 2869 Class C2 is a heavier distillate, which is used as domestic heating oil. Premium kerosene is usually sold in 5- or 20-liter containers from hardware, camping and garden stores, and is often dyed purple. Standard kerosene is usually dispensed in bulk by a tanker and is undyed.
National and international standards define the properties of several grades of kerosene used for jet fuel. Flash point and freezing point properties are of particular interest for operation and safety; the standards also define additives for control of static electricity and other purposes.
Melting, freeze and flash points
Kerosene is liquid around room temperature: 25 °C (77 °F). The flash point of kerosene is between 37 °C (99 °F) and 65 °C (149 °F), and its autoignition temperature is 220 °C (428 °F). The freezing point of kerosene depends on grade, with commercial aviation fuel standardized at −47 °C (−53 °F).
1-K-grade kerosene freezes around −40 °C (−40 °F, 233 K).
History
The process of distilling crude oil/petroleum into kerosene, as well as other hydrocarbon compounds, was first written about in the ninth century by the Persian scholar Rāzi (or Rhazes). In his Kitab al-Asrar (Book of Secrets), the physician and chemist Razi described two methods for the production of kerosene, termed naft abyad (نفط ابيض”white naphtha”), using an apparatus called an alembic. One method used clay as an absorbent, and later the other method using chemicals like ammonium chloride (sal ammoniac). The distillation process was repeated until most of the volatile hydrocarbon fractions had been removed and the final product was perfectly clear and safe to burn. Kerosene was also produced during the same period from oil shale and bitumen by heating the rock to extract the oil, which was then distilled. During the Chinese Ming Dynasty, the Chinese made use of kerosene through extracting and purifying petroleum and then converted it into lamp fuel. The Chinese made use of petroleum for lighting lamps and heating homes as early as 1500 BC.
Production
Kerosene is produced by fractional distillation of crude oil in an oil refinery. It condenses at a temperature intermediate between diesel fuel, which is less volatile, and naphtha and gasoline, which are more volatile.
Kerosene made up 8.5 percent by volume of petroleum refinery output in 2021 in the United States, of which nearly all was kerosene-type jet fuel (8.4 percent).
Toxicity
The World Health Organization considers kerosene to be a polluting fuel and recommends that “governments and practitioners immediately stop promoting its household use”. Kerosene smoke contains high levels of harmful particulate matter, and household use of kerosene is associated with higher risks of cancer, respiratory infections, asthma, tuberculosis, cataract, and adverse pregnancy outcomes.
Ingestion of kerosene is harmful. Kerosene is sometimes recommended as a folk remedy for killing head lice, but health agencies warn against this as it can cause burns and serious illness. A kerosene shampoo can even be fatal if fumes are inhaled.
People can be exposed to kerosene in the workplace by breathing it in, swallowing it, skin contact, and eye contact. The US National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit of 100 mg/m3 over an 8-hour workday.
