Although the minimum ignition temperature is an important safety characteristic and hybrid mixtures are of high relevance in different industrial processes, the focus of research is directed towards single-substance systems.
Unlike the situation in the industry the standards, too only focus on single-phase mixtures. To get minimum ignition temperatures for frequently used hybrid mixtures, first, the minimum ignition temperatures and ignition frequencies were determined in the Godbert-Greenwald furnace for two single-phase solids (corn starch and lycopodium) and a burnable gas (methane). Second, minimum ignition temperatures and ignition frequencies were determined for the combinations of the pure systems as a hybrid mixture of dust and gas.
By repeating each test point five times, the probability of ignition of the substance system could be analyzed in addition to the Minimum Ignition Temperature. No noticeable decrease of minimum ignition temperatures below the MIT of the pure solids was observed for the hybrid mixture consisting of methane and starch or lycopodium respectively, but a more widely dispersed area of ignition is shown. In accordance with previous findings, the results demonstrate a strong relationship between the likelihood of explosion and the amount of added gas. In consequence, the hybrid mixture is characterized by a minimum ignition temperature that is dominated by the lower igniting component of the mixture.