Experimental Measurements of Flammability at Elevated Conditions Using Thermal Criterion

Accurate measurements of flammability limits for combustible gases and vapors are necessary for the prevention of fire and explosion.  The flammability limit, which is the maximum or minimum fuel concentration at which a gas mixture is flammable in a given atmosphere, has been studied for decades.  However, due to the measurement conditions and apparatus set difference, the flammability values provided by different experimental methods are inconsistent, especially at elevated conditions.  In this study, the flammability limits of methane-air were measured in an 8-L closed cylindrical vessel with upward flame propagation at maximum initial temperature of 300°C and maximum initial pressure of 2 bar.  During the experimental measurement, a new thermal criterion was used to define if the gas is flammable and the experimentally determined flammability limits were compared with existing data reported in the literature.  Finally, the temperature and pressure effect on flammability was investigated and compared with the modified Burgess-Wheeler Law.