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Jet fuel is a type of aviation fuel designed for use in jet-engined aircraft.
| JET A-1 | |
| Flash point: | 38°C |
| Autoignition temperature: | over 425°C |
| Freezing point: | -47°C (-40 °C for JET A) |
| Open air burning temperatures: | 260-315 degrees C |
| Maximum burning temperature: | 980 degrees C |
Modern fuels
The most common fuel worldwide is a kerosene/paraffin oil-based fuel classified as JET A-1, which is produced to an internationally standardized set of specifications. In the United States only, a version of JET A-1 known as JET A is also used. See the section for JET A-1 below.
The only other jet fuel that is commonly used in civilian aviation is called JET B. JET B is a fuel in the naptha-kerosene region that is used for its enhanced cold-weather performance. However, JET B's lighter composition makes it more dangerous to handle, and it is thus restricted only to areas where its cold-weather characteristics are absolutely necessary.
Both JET A and JET B can contain a number of additives:
- Tetra-ethyl lead (TEL) to increase the fuel's flash point;
- Antioxidants to prevent gumming, usually based on alkylated phenols, eg. AO-30, AO-31, or AO-37;
- Antistatic agents, to dissipate static electricity and prevent sparking; Stadis 450, with dinonylnaphthylsulfonic acid (DINNSA) as the active ingredient, is an example
- Corrosion inhibitors, eg. DCI-4A used for civilian and military fuels, and DCI-6A used for military fuels;
- Fuel System Icing Inhibitor (FSII) agents, eg. 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;
- Biocide additives.
Militaries around the world use a different classification system of JP 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-5 fuel is fairly common, and was introduced to reduce the risk of fire on aircraft carriers. Other fuels were specific to one type of aircraft. JP-6 was developed specifically for the XB-70 Valkyrie and JP-7 for the SR-71 Blackbird. Both these fuels were engineered to have a high flash point to better cope with the heat and stresses of high speed supersonic flight. One aircraft-specific jet fuel still in use by the USAF is JPTS, which was developed in 1956 for the Lockheed U-2 spy plane.
Jet fuels are sometimes classified as kerosene or naphtha-type. Kerosene-type fuels include Jet A, Jet A1, JP-5 and JP-8. Naphtha-type jets fuels include Jet B and JP-4.
Jet A
Jet A is the standard jet fuel type in the U.S. since 1950's and is only available there. JET A is similar, except for its higher freezing point of -40°C rather than JET A-1's freezing point of -47 °C. Like JET A-1, JET A has a fairly high flash point of min. 38°C, with an autoignition temperature of over 425°C. Jet A can be identified in trucks and storage facilities by the fuel code 1863. Jet A trucks, storage tanks and pipes that carry Jet A will be marked with a black sticker with a white "JET A" written over it, next to another black stripe. Jet A will have a clear to straw color if it is clean and free of contamination. Water is heavier than Jet A, and will collect on the bottom of a tank. Jet A storage tanks must be sumped on a regular basis to check for water contamination. It is possible for water particles to become suspended in Jet A, which can be found by performing a "Clear and Bright" test. A hazy appearance can indicate water contamination beyond the acceptable limit of 30ppm (parts per million).
The U.S. commercial fuels are not required by law to contain antistatic additives, and generally do not contain them.
History of jet fuel
Fuel for a piston-engine powered aircraft (usually a high-octane gasoline known as AvGas) has a low flash point to improve its ignition characteristics. Turbine engines can operate with a wide range of fuels, and jet-aircraft engines typically use fuels with higher flash points, which are less flammable and therefore safer to transport and handle. The first jet fuels were based on kerosene or a gasoline-kerosene mix, and most jet fuels are still kerosene-based.
Commercial fuels
Commercial jet fuels had their origins in military fuels, but commercial use worldwide now greatly exceeds military use. As noted above, Jet-A, similar to JP-8, is a pure kerosene, while Jet-B is a kerosene-gasoline mix similar to JP-4.
See also
External links
- History of Jet Fuel
- Aviation Fuels (by Chevron)
- Day, Dwayne A., Aviation Fuel
- Jet fuel information
"Jet fuel"