Comparative Analysis of the Explosion Parameters of Selected Gluten-Free Flour Dusts

Flour dust explosions are chemical explosions characterized by violent thermal decomposition and oxidation reactions, accompanied by a sudden increase in pressure and temperature. Combustible dusts undergo thermal decomposition, releasing flammable gases; thus, in this context, a dust explosion is similar to an explosion of a flammable gas–air mixture. Flour explosions in the food industry have been the subject of many studies, but there is limited number of publications on the explosion safety of gluten-free flours. Five dusts were selected for comparative characterization under common standardized conditions: green pea flour, soybean flour, millet flour, lentil flour, and maize flour. The following parameters were determined: the minimum ignition temperature, the maximum explosion pressure (pmax) and its derivative (dp/dt)max, and the lower explosion limit; Thermogravimetric Analysis; and heat of combustion tests. The tested flours show different values of basic flammability and explosiveness parameters, e.g., the green pea flour 5 mm dust layer ignited from the heated surface at temperatures as low as 310 °C. The lowest temperature of maximum mass loss (291 °C) was recorded for green pea flour. The obtained KSt values range from 55 to 81 bar·m·s−1 (class St 1), the LEL is between 125 and 250 g·m−3, and the 5 mm dust layer MIT values range from 310 to over 400 °C. The results show that there is a need to apply dedicated explosion protection means in plants where the processing, and transportation of the gluten-free flours takes place.