Jet fuel or aviation turbine fuel (ATF, also abbreviated avtur) is a type of aviation fuel designed for use in aircraft powered by gas-turbine engines. It is colorless to straw-colored in appearance. The most commonly used fuels for commercial aviation are Jet A and Jet A-1, which are produced to a standardized international specification. The only other jet fuel commonly used in civilian turbine-engine powered aviation is Jet B, which is used for its enhanced cold-weather performance.
Jet fuel is a mixture of a variety of hydrocarbons. Because the exact composition of jet fuel varies widely based on petroleum source, it is impossible to define jet fuel as a ratio of specific hydrocarbons. Jet fuel is therefore defined as a performance specification rather than a chemical compound. Furthermore, the range of molecular mass between hydrocarbons (or different carbon numbers) is defined by the requirements for the product, such as the freezing point or smoke point. Kerosene-type jet fuel (including Jet A and Jet A-1, JP-5, and JP-8) has a carbon number distribution between about 8 and 16 (carbon atoms per molecule); wide-cut or naphtha-type jet fuel (including Jet B and JP-4), between about 5 and 15.Salvatore J. Rand (ed), Significance of Tests for Petroleum Products (8th Edition) ASTM International, 2010, page 88
History Fuel for piston-engine powered aircraft (usually a high-octane gasoline known as avgas) has a high volatility to improve its carburetion characteristics and high autoignition temperature to prevent preignition in high compression aircraft engines. Turbine engines (as with diesel engines) can operate with a wide range of fuels because fuel is injected into the hot combustion chamber. Jet and gas turbine (turboprop, helicopter) aircraft engines typically use lower cost fuels with higher flash points, which are less flammable and therefore safer to transport and handle.
The first axial compressor jet engine in widespread production and combat service, the Junkers Jumo 004 used on the Messerschmitt Me 262A fighter and the Arado Ar 234B jet recon-bomber, burned either a special synthetic "J2" fuel or diesel fuel. Gasoline was a third option but unattractive due to high fuel consumption. Other fuels used were kerosene or kerosene and gasoline mixtures.
Pressure to move from Jet fuel to sustainable aviation fuel, i.e. Aviation biofuel or Electrofuel, has existed since before the 2016 Paris Agreement.
Standards Most jet fuels in use since the end of World War II are kerosene-based. Both British and American standards for jet fuels were first established at the end of World War II. British standards derived from standards for kerosene use for lamps—known as paraffin in the UK—whereas American standards derived from aviation gasoline practices. Over the subsequent years, details of specifications were adjusted, such as minimum freezing point, to balance performance requirements and availability of fuels. Very low temperature freezing points reduce the availability of fuel. Higher flash point products required for use on aircraft carriers are more expensive to produce. In the United States, ASTM International produces standards for civilian fuel types, and the U.S. Department of Defense produces standards for military use. The British Ministry of Defence establishes standards for both civil and military jet fuels. For reasons of inter-operational ability, British and United States military standards are harmonized to a degree. In Russia and the CIS members, grades of jet fuels are covered by the State Standard (GOST) number, or a Technical Condition number, with the principal grade available being TS-1.
Types
Jet A/A-1
Jet A specification fuel has been used in the United States since the 1950s and is usually not available outside the United States and a few Canadian airports such as Toronto, Montreal, and Vancouver, whereas Jet A-1 is the standard specification fuel used in most of the rest of the world, the main exceptions being Russia and the CIS members, where TS-1 fuel type is the most common standard. Both Jet A and Jet A-1 have a flash point higher than , with an autoignition temperature of . Jet A-1 is also known as AVTUR (aviation turbine) fuel.
Vehicles, pipelines, and storage tanks containing Jet A or Jet A-1 should be marked with black bands, and for vehicles and tanks should also be marked with "Jet A" or "Jet A-1" in white text on a black background.
Differences between Jet A and Jet A-1
The differences between Jet A and Jet A-1 are twofold. The primary difference is the lower freezing point of Jet A-1 fuel: Jet A's is Jet A-1's is
The other difference is the mandatory addition of an antistatic additive to Jet A-1 fuel.
Typical physical properties for Jet A and Jet A-1 Jet A-1 fuel must meet: DEF STAN 91-91 (Jet A-1), ASTM specification D1655 (Jet A-1), and IATA Guidance Material (Kerosene Type), NATO Code F-35.
Jet A fuel must reach ASTM specification D1655 (Jet A).
+Typical physical properties for Jet A / Jet A-1 Jet A-1 Jet AFlash point Autoignition temperature Freezing point Max adiabatic burn temperature open air burn temperature: Density at Specific energy Energy density
Jet B
Jet B is a naphtha-kerosene fuel that is used for its enhanced cold-weather performance. However, Jet B's lighter composition makes it more dangerous to handle. For this reason, it is rarely used, except in very cold climates. A blend of approximately 30% kerosene and 70% gasoline, it is known as wide-cut fuel. It has a very low freezing point of , and a low flash point as well. It is primarily used in northern Canada and Alaska, where the extreme cold makes its low freezing point necessary, and which helps mitigate the danger of its lower flash point. Jet B is also known as AVTAG (aviation turbine gasoline).
GOST standards The GOST standard 10227 specifies civilian fuels, among which are TS-1, T-1, T-1S, T2 and RT. Military fuels such as T-1pp, T-8V (aka T-8B) and T-6 are specified by GOST 12308. Icing inhibitors are specified by GOST 8313. Some researchers refer to T-6 as "ram rocket fuel"; others have patented a method used to produce T-1pp from a mixture of T-6 and RT, the latter of which has been characterized as "unified Russian fuel for sub- and supersonic aircraft".
TS-1
TS-1 is a jet fuel made to Russian standard GOST 10227 for enhanced cold-weather performance. It has somewhat higher volatility than Jet A-1 (flash point is minimum). It has a very low freezing point, below .
Additives The DEF STAN 91-091 (UK) and ASTM D1655 (international) specifications allow for certain additives to be added to jet fuel, including:Standard Specification for Aviation Turbine Fuels, ASTM D1655-09a (2010). ASTM International, West Conshohocken, Pennsylvania, United States. Antioxidants to prevent gumming, usually based on alkylated phenols, e.g., AO-30, AO-31, or AO-37; Antistatic agents, to dissipate static electricity and prevent sparking; Stadis 450, with dinonylnaphthylsulfonic acid (DINNSA) as a component, is an example Corrosion inhibitors, e.g., DCI-4A used for civilian and military fuels, and DCI-6A used for military fuels; Fuel system icing inhibitor (FSII) agents, e.g., 2-(2-Methoxyethoxy)ethanol (Di-EGME); FSII is often mixed at the point-of-sale so that users with heated fuel lines do not have to pay the extra expense. Biocides are to remediate microbial (i.e., bacterial and fungal) growth present in aircraft fuel systems. Two biocides were previously approved for use by most aircraft and turbine engine original equipment manufacturers (OEMs); Kathon FP1.5 Microbiocide and Biobor JF. Biobor JF is currently the only biocide available for aviation use. Kathon was discontinued by the manufacturer due to several airworthiness incidents. Kathon is now banned from use in aviation fuel. Metal deactivator can be added to reduce the negative effects of trace metals on the thermal stability of the fuel. The one allowable additive is the chelating agent salpn (N,N′-bis(salicylidene)-1,2-propanediamine).
As the aviation industry's jet kerosene demands have increased to more than 5% of all refined products derived from crude, it has been necessary for the refiner to optimize the yield of jet kerosene, a high-value product, by varying process techniques.
New processes have allowed flexibility in the choice of crudes, the use of coal tar sands as a source of molecules and the manufacture of synthetic blend stocks. Due to the number and severity of the processes used, it is often necessary and sometimes mandatory to use additives. These additives may, for example, prevent the formation of harmful chemical species or improve a property of a fuel to prevent further engine wear.
Water in jet fuel It is very important that jet fuel be free from water contamination. During flight, the temperature of the fuel in the tanks decreases, due to the low temperatures in the upper atmosphere. This causes precipitation of the dissolved water from the fuel. The separated water then drops to the bottom of the tank because it is denser than the fuel. Since the water is no longer in solution, it can form droplets which can supercool to below 0 °C (32 °F). If these supercooled droplets collide with a surface they can freeze and may result in blocked fuel inlet pipes. This was the cause of the British Airways Flight 38 accident. Removing all water from fuel is impractical; therefore, fuel heaters are usually used on commercial aircraft to prevent water in fuel from freezing.
There are several methods for detecting water in jet fuel. A visual check may detect high concentrations of suspended water, as this causes the fuel to become hazy in appearance. An industry standard chemical test for the detection of free water in jet fuel uses a water-sensitive filter pad that turns green if the fuel exceeds the specification limit of 30 ppm (parts per million) free water.
Military jet fuels
Military organizations around the world use a different classification system of JP (for "Jet Propellant") numbers. Some are almost identical to their civilian counterparts and differ only by the amounts of a few additives; Jet A-1 is similar to JP-8, Jet B is similar to JP-4. Other military fuels are highly specialized products and are developed for very specific applications.
JP-1 was an early jet fuelAviation Fuel - US Centennial of Flight Commission, Retrieved 3 January 2012 specified in 1944 by the United States government (AN-F-32). It was a pure kerosene fuel with high flash point (relative to aviation gasoline) and a freezing point of . The low freezing point requirement limited availability of the fuel and it was soon superseded by other "wide cut" jet fuels which were kerosene-naphtha or kerosene-gasoline blends. It was also known as avtur.
JP-2 an obsolete type developed during World War II. JP-2 was intended to be easier to produce than JP-1 since it had a higher freezing point, but was never widely used.Larry Reithmaier, Mach 1 and Beyond: The Illustrated Guide to High-Speed Flight, (McGraw-Hill Professional, 1994), , page 104
JP-3 was an attempt to improve availability of the fuel compared to JP-1 by widening the cut and loosening tolerances on impurities to ensure ready supply. In his book Ignition! An Informal History of Liquid Rocket Propellants, John D. Clark described the specification as, "remarkably liberal, with a wide cut (range of distillation temperatures) and with such permissive limits on olefins and aromatics that any refinery above the level of a Kentucky moonshiner's pot still could convert at least half of any crude to jet fuel". It was even more volatile than JP-2 and had high evaporation loss in service.
JP-4