Connecting standards and theoretical models for minimum ignition energy Estimation: a procedure to optimize the number of experimental tests

Dust explosions pose a significant concern in the process industry, particularly in the context of risk assessment. Such explosions can be initiated by various ignition sources, including electrical (e.g., static discharges, arcs, equipment-generated sparks) and thermal (e.g., hot surfaces, flame pockets) triggers. Assessing the likelihood and severity of dust explosions is inherently complex. However, the experimental determination of key dust parameters can greatly support the risk evaluation process. Among these parameters, electrical resistivity and Minimum Ignition Energy (MIE) are crucial. Unfortunately, a regular MIE testing demands up to 1 kg of powder, and no existing standard outlines how to reduce the number of required tests. However, EN ISO/IEC 80079-20-2 does not require to carry out a full screening on every possible combination of parameters, but to identify non-combustion and combustion regions. In this framework, theoretical models may offer preliminary MIE estimates, optimizing the experimental procedure. This study proposes a screening flow chart that integrates MIE and electrical resistivity values along with process-specific information (e.g., quantity of dust handled, presence of ignition sources). The aim is to prioritize potentially hazardous substances in the plant for detailed safety evaluation. The advantages and limitations of the proposed flow chart are also discussed.