THE EFFECT OF ULLAGE ON THE FLASH POINT AND LOWER FLAMMABILITY LIMIT TEMPERATURES OF JP-5 JET FUELS
NAVAL RESEARCH LAB WASHINGTON DC
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From theoretical considerations it can be shown that the relative size of the free-space ullage above a liquid fuel mixture can be a significant factor in the flammability properties of such a system. A simple apparatus has been used to test the effect of ullage on flash point and lower flammability limit temperatures of JP-5 jet fuels. Results indicate that both ullage and time to achieve equilibrium conditions are factors. In general, flammability limit temperatures decreased with decreasing ullage, the rate and magnitude of the decrease depending on the composition of the fuel. Thus, at smaller ullages, flammability hazard is increased. In one instance, the extrapolated flammability temperature of a specification JP-5 jet fuel was 26F lower than its ASTM flash point as ullage approached zero. The data suggest that both the rate of temperature decrease with decreasing ullage, and the limiting value at zero ullage are important information in evaluating flammability properties of JP-5 fuel mixtures.
- Safety Engineering
- Combustion and Ignition