Towards a new standard: Procedure proposal for the determination of mist explosion characteristics

Despite the occurrence of numerous accidental mist explosions, standards for the determination of liquid aerosols explosivity are still not available. This is mainly due to the lack of means of characterization, available data, and scientific knowledge in such a matter. This article proposes a complete procedure allowing the evaluation of the ignition sensitivity and explosion severity of fuel mist clouds. Specific test procedures were recommended based on a classification system dividing liquids into four quadrants according to their flash point and droplet stability during secondary atomization (i.e. the Weber ratio). The dedicated test equipment is based on a 20L explosion sphere modified to generate a hydrocarbon mist with controlled characteristics (diameter, concentration, etc.). The proposed procedures were successfully applied to seven fuels (e.g. kerosene and lube oil) and could then serve as the basis for a new standard. This article also put forward the application of such procedures in industrial cases to illustrate the importance of considering scenarios involving the generation of fuel mists, particularly those with high flashpoints, and the need to assess the safety parameters of mists through experimental means for standardization. Suitable prevention, protection and mitigation measures can then be implemented in a harmonized and systematic way.