T5-16 - Relation between Ignition Energy and Limiting Oxygen Concentration for powders

Abstract

Inertisation is a measure to avoid an explosion hazard. It means that the oxygen of the air will be exchanged with nitrogen or any other inert gas. A reasonable approach is a steady relation between two asymptotes. One asymptote represents the energy threshold, below which no ignition at all is possible even in a pure Oxygen atmosphere. Second asymptote represents the real Limiting Oxygen Concentration. During a preceding examination, a relation was found between the ignition energy of a dust cloud and the Oxygen concentration. This relation was tested for a series of different products and it was found to work well always. But it is not possible to use this relation for calculating the Limiting oxygen concentration of a powder. The work described in the chapter is designed to investigate in general the relationship between the oxygen concentration and the ignition energy of powder-nitrogen-oxygen mixtures. For this reason, the used ignition energy varies within a huge range from 1 mJ up to 10 kJ. For all products, a steady relation is found across the whole energy range. In addition, with the results obtained though this work a model can be developed showing the fundamental relationship between the oxygen concentration and ignition energy.