Jet fuel collectively refers to the various types of propellants used to operate jet engines (gas turbine, turbo jet or turbo fan). Its primary application is in aviation, although it is also relevant for jet-powered boats, jet-powered generators, other jet propulsion applications, as well as in diesel engines when necessary. Today, most jet fuel is kerosene-based, and the types vary depending upon specific chemical composition and the kinds of additives used in it.
Jet fuel is generally kerosene-based. The reason for this is that kerosene has a higher flash-point than other petroleum fuels, which makes it safer to store and transport. It is also thinner than other fuels such as gasoline, which is a characteristic needed for it to burn effectively in a turbine engine. An additional benefit is that it burns more efficiently and is more environmentally friendly than other petroleum based fuels.
Civilian jet fuel today is primarily available in three types: Jet A-1, Jet A and Jet B. Jet A-1 is the most common type of jet fuel and is the fuel of choice for most commercial airliners and is produced according to strict international standards. Jet A is nearly identical to Jet A-1, except that it has a different combination of additive. Jet A is primarily used in the United States and is generally interchangeable with Jet A-1. Jet B primarily differs from Jet A-1 in that it will burn more efficiently at extremely low temperatures. Because of this, it is useful in aircraft operating in extreme winter conditions. However because Jet-B is also much more volatile than Jet A-1, it is only used when absolutely necessary.
The standardized classifications for jet fuel are different for civilian and military uses. Military jet fuel is produced in a greater number of varieties than civilian fuel, and is classified using the designator JP followed by a number that identifies the specific variety. U.S. military fuels are available in nine variants, numbered one through eight, and an additional type, JPTS, which was engineered specifically for the Lockheed U-2 aircraft. Jet A-1 is approximately equivalent to JP-8. Jet B is approximately equivalent to JP-4.
Kerosene-based jet fuels are fully transparent and have a pale straw color that can also appear clear depending upon the lighting. They are thin liquids and are not sticky to the touch. If it appears cloudy, this is a sign that it may be contaminated. Water is much denser than any jet fuel, and therefore will visibly settle to the bottom of any container if added to the fuel. Trucks, pipes, and tanks carrying jet fuel are normally marked with standardized codes identifying the specific type of fuel.
Jet fuel is chemically similar to diesel fuel, and most diesel engines are capable of burning any type of jet fuel. In fact, many major airports around the world make a point to employ ground vehicles that have diesel engines, so that they have the option of running on jet fuel. This helps to reduce the number of different fuels that must be stored at the airport. Jet fuels are more expensive than regular diesel as they are produced to tighter standards and also usually have more additives.
