Correlation between ignition temperature of mixtures and mixture-proportions under pressures above normal pressure
Experiments; measuring of ignition temperatures; variation of pressure and of mixtures
Investigations on auto ignition temperatures at elevated pressures up to 15 bar on binary mixtures (11 binary mixtures of flammable substances, 4 aqueous mixtures with at least 3 different compositions) and the respective pure substances have been carried out to derive estimation methods.
Taking into account data of pure substances published earlier by PTB the following results can be given:
The concentrations at which the auto ignition temperatures are found are high.
Pressure dependence for pure substances and binary mixtures:
The auto ignition temperatures decrease with increasing pressure whereas normally the largest decrease occurs between the auto ignition temperature at ambient pressure and the data at 2 bar. For pressures larger than 5 bar the decay mostly is very low.
The pressure dependence of the auto ignition temperature follows a SEMENOFF correlation. This allows to interpolate and extrapolate (to a certain amount) if 2 (better 3) auto ignition temperatures at elevated pressures are known. More (PDF, 28 kB)
-cross sectoral-Type of hazard:
Brand- und Explosionsschutz, Lösungsmittel, Physikalische FaktorenDescription, key words:
solvent vapour, ignition temperature