Beyond the worst-case scenario: Inconsistencies in dust flammability parameter determination for organic solid fuels

The use of solid organic fuels is expected to continue increasing during the near future, requiring bigger facilities and storage units. It is known that one of the main risks associated to these materials is the risk of fire and explosion. While flammability parameters and testing standards have been adapted from fossil fuel research, these adaptations often fail to account for the unique properties and behaviour of organic dusts. This study aims to critically evaluate the applicability of current flammability testing standards to organic solid fuels, identify inconsistencies in parameter determination, and propose improvements to enhance safety assessments. Special attention is given to the influence of particle size, moisture content, and composition on ignition sensitivity. A comprehensive literature review was conducted alongside experimental thermogravimetric analysis (TGA) of wood pellet dusts under varying conditions. The study examined how methodological variables (such as crucible size, heating rate, and gas atmosphere) affect thermal decomposition profiles and ignition-related parameters. The results reveal that current standards often overlook critical variables such as sample preparation, dispersion method, and equipment configuration, leading to inconsistent or non-representative results. TGA parameters like maximum weight loss temperature and induction temperature were found to be sensitive to test conditions. The study underscores the need for more detailed and standardized testing protocols tailored to organic dusts. It advocates for a shift beyond worst-case scenario assumptions toward more realistic, scenario-specific assessments. These improvements are essential for enhancing the reliability of flammability data and ensuring safer industrial practices involving combustible dusts.