Due to the millions of years of high pressure exerted on the decomposed phytoplankton and algae that once lived in shallow seas, the earth possesses petroleum, a natural resource that, since the Industrial Revolution, has found usage in an assortment of fuels used for a variety of purposes. Kerosene is essentially just a distillation product of petroleum. While pure kerosene was once used to power the turbine engines of jet engines, jet fuel, which could be called an enhancement or adjustment of kerosene (or kerosine, as it is sometimes called in industrial or scientific usage), remains the means of powering commercial airliners and some other types of aircraft.
Aviation turbine fuel is a complex mixture composed mainly of hydrocarbons, but its exact structure varies depending on crude source and manufacturing processes used in its conception. For this reason, it is impossible to define the exact composition of jet fuel. However, by definition, the primary grades of jet fuel meet the specifications of ASTM D1655-19: Standard Specification for Aviation Turbine Fuels.
ASTM D1655-19 covers the use of purchasing agencies in formulating specifications of aviation turbine fuel under contract. It prescribes the properties of aviation turbine fuel at the time and place of delivery. The international standard describes the minimum property requirements of two types of aviation turbine fuels:
Jet A: This type of jet fuel is used primarily in the United States, and it typically does not contain static dissipater as an additive. It must have a freezing point of -40 degrees Celsius or below.
Jet A-1: This type of aviation turbine fuel must have a freezing point of -47 degrees Celsius or below, and this fuel normally contains static dissipater. This fuel is used commonly outside of the United States.
As you can see, the primary difference between these two fuel grades, which are both relatively high flash point distillations of the kerosine type and may derive from crude oil, natural gas, shale oil, or other sources, is their freezing point. However, there are other distinctions in properties between these two grades, such as in their composition, volatility, fluidity, combustion, corrosion, thermal stability, contaminants, and additives. The differences in their requirements are laid out in the ASTM D1655-19 document.
Previous versions of the ASTM D1655 specification cited the requirements for another type of aviation turbine fuel:
Jet B: This jet fuel, while rarely used, is known for its enhanced cold-weather performance, giving it applications in very cold climates. However, it is more dangerous to handle. Its mixture strongly differs from the two other grades, as it is defined as a “relatively wide boiling range volatile distillate.” This grade also has a lower freezing point, at -50 degrees Celsius or below.
Jet B is defined in ASTM D6615-15a: Standard Specification for Jet B Wide-Cut Aviation Turbine Fuel.
ASTM D1655-19: Standard Specification for Aviation Turbine Fuels and ASTM D6615-15a: Standard Specification for Jet B Wide-Cut Aviation Turbine Fuel are available on the ANSI Webstore.