Study on the pressure dependence of boiling point, flashpoint, and lower flammability limit at low ambient pressure

The boiling point, flashpoint, and flammability limit are key parameters to evaluate the combustion behavior of flammable liquids. In this study, the boiling point (TB), the flashpoint (TF), and the lower flammable limit (LFL) of two multiplecomponent fuels (diesel and Jet A) and two single-component fuels (n-hexanol and n-decane) were measured at low pressures ranging from 35 to 101 kPa. The dependences of TB, TF, and LFL on pressure have been theoretically derived to explain the experimental measurements. In addition to the observation that both boiling point and flashpoint decrease with decreasing pressure, the measurements also revealed that the open-cup and closed-cup flashpoints decrease at different rates. The lower flammability limit, on the other hand, was shown to increase with the decreasing of pressure. The measurements of the lower flammability limit versus pressure were well correlated with different theoretical formulas proposed in the literature and the current study. The relationships among TB, TF, and LFL at low pressure are also discussed and verified against the measurements.