Fire hazard potential of non-metallic powder layers induced by deposit surfaces

Abstract

Combustible dust may result in a catastrophic dust explosion with much larger accident consequences than that of combustible gas or vapors. By considering the significant contribution of dust layer fire to dust explosion, fire hazards of dust layer were investigated to clarify the possible worsening situation induced by the properties of deposit surface. The results showed that the effect of thermal conductivity of deposit surface on layer fire hazard was complex even for the same powder material, which depended on the contribution of conductivity to the layer flame spreading. Good permeability of the deposit surfaces (e.g., metal gauze) could contribute to a bottom fire with high flame height and temperature. For whatever deposit surfaces (i.e., ceramic and metal plate, or metal gauze), the inclination angle of the dust layer could result in a high flame spread velocity (FSV). As a result, good permeability deposit surfaces coupled with a large inclination angle would significantly enhance the fire hazard of the dust layer, which should be taken enough consideration in the powder process industries or public activities where combustible powders were used.