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JP-4 is a colorless to strawcolored
liquid with the odor of gasoline and/or
kerosene. JP-7 is a liquid, usually colorless and
with the odor of kerosene. JP-4 can be made
by refining either crude petroleum oil or shale
oil. It is called a wide cut fuel because it is produced
from a broad distillation temperature
range and contains a wide array of carbon chain
lengths, from 4- to 16. It consists of approximately
13% (v/v) aromatic hydrocarbons, 1.0%
olefins, and 86% saturated hydrocarbons.1 JP-
7 is made by refining kerosene, a product of
refined crude petroleum. It was developed for
use in advanced supersonic jets because of its
thermal stability and high flash point.
Aviation fuels consist primarily of hydrocarbons
(paraffins and cycloparaffins or naphthenes
primarily but also aromatics and
olefins). Paraffins have a high hydrogen-tocarbon
ratio, with a high heat release per unit
of weight and a cleaner burn than other hydrocarbons.
Cycloparaffins have a lower hydrogen-
to-carbon ratio and produce less heat
release but increase the density and reduce the
freezing point of the fuel. Aromatic hydrocarbons
are a good energy source but produce
smoke on burning; therefore, the maximum
levels are restricted (20–25% by volume in JP-
4, 5% by volume in JP-7). Olefins are similar to paraffins but are unsaturated (double and
triple C-C bonds) with lower hydrogen-tocarbon
ratios, are the most reactive of the
hydrocarbons, and are allowed at only 5% by
volume in JP-4. Benzene is present as a contaminant
at less than 0.5% in JP-4. Other
ingredients of lesser importance are sulfur
and sulfur compounds as well as additives
to improve performance (antioxidants, metal
deactivators, fuel system icing inhibitors, corrosion
inhibitors, static dissipater additives). |
