Vaporization of JP-8 Jet Fuel in a Simulated Aircraft Fuel Tank ...

2.1.2 Fuel Flash Point
The flash point is defined as the lowest temperature at which a liquid can form an
ignitable mixture in air near the surface of the liquid. It is determined by the ASTM D56
standard, which is commonly referred to as the Tag closed cup test. In this test, a small
sample (50 ml) is placed in a closed cup (130 ml), corresponding to a mass loading of
300 kg/m 3 , surrounded by a water bath. The sample is gradually heated at 2°F per
minute, and a small flame is introduced into the vapor space at regular temperature
intervals for one second. The temperature at which the first ignition, or “flash”, is
observed is the flash point of the fuel. ASTM D 1655 specifies a minimum flash point of
100°F for Jet-A. This is very high when compared to gasoline, which has a flash point of
about -40°F. It is important to remember that the fuel flash point “is not a fundamental
property but rather the result of a standardized test carried out at one specific fuel loading
and atmospheric pressure” [17]. Also, the flash point, while a good reference when
comparing the flammability of one fuel to another, cannot give a precise indication of the
overall flammability of a mixture for multi-component fuels. This is because the flash
point, as determined by standardized testing, is dependent upon the vapor composition,
which has been shown to vary for multi-component fuels as a function of temperature and
mass loading [17].
2.1.3 Fuel Vapor Pressure
Liquid in a closed container will form vapor in the space above the liquid surface until
the space becomes saturated. At this point, known as equilibrium, the rate of molecules
leaving the liquid equals the rate of molecules returning to the liquid surface. This
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