Hybrid Mixtures Explosions: When Vapours Met Dusts

The aim of this work is to demonstrate the peculiar aspects of hybrid mixtures explosion as regard to vapours or dusts explosions. This work has been focused on pharmaceutical products from excipients (magnesium stearate), vitamins (niacin) to active principles (antibiotics) and their associated solvants (ethanol, diisopropyl ether, toluene. . .). Explosion spheres have been used to determined the influences of dusts and vapours concentrations on explosion severity (maximum pressure Pmax and maximum rate of pressure rise (dP/dt)max). Results clearly show that the explosion behaviour of such hybrid mixtures reveals significant differences with vapours or dusts explosions; especially a promotion effect on the combustion kinetics and on the rate of pressure rise for poor mixtures. The influences of the introduction of small amount of vapours on dust minimum explosion concentration (MEC) and of dust addition on the lower explosion limit (LEL) are noteworthy.