TY - CONF A1 - Dufaud, O. A1 - Krietsch, Arne A1 - Santandrea, A. A1 - Vignes, A. A1 - Perrin, L. A1 - Laurent, A. T1 - Some key considerations when evaluating explosion severity of nanopowders N2 - Protection from explosion events requires the determination of key safety parameters like lower explosion limit, maximum explosion over-pressure, and maximum rate of pressure rise. These parameters are routinely obtained through standard tests performed typically either in a 20 L-sphere or a 1 m3-container. But several aspects are worth a closer investigation. Firstly, the test apparatus must be able to disperse a fairly uniform dust cloud. However, previous investigations showed that actually the current dispersion system can be improved. Secondly, the influence of humidity on the explosivity is not considered in current standards. It is just stated that the relative humidity should be checked and noted down, though some provisions exist in American standards. Thirdly, the ignition delay time is sometimes modified to study the impact of the dust cloud turbulence on flame propagation but is often misunderstood. Maybe these aspects have not been thoroughly considered for micron powders. However, in the case of nanopowders, the importance of these influencing factors was shown in order to duly evaluate explosion parameters. Experimental evidences confirm these aspects and alternative solutions will be presented. T2 - Loss Prevention Symposium 2019 CY - Delft, Netherlands DA - 16.06.2019 KW - Nanopowder KW - Dust explosion KW - Safety characteristics PY - 2019 AN - OPUS4-50105 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krietsch, Arne A1 - Vignes, A. A1 - Dufaud, O. A1 - Santandréa, A. A1 - Perrin, L. A1 - Bouillard, J. T1 - Course of Explosion Behaviour of Metallic Powders - from Micron to Nanosize N2 - This work presents an overview about the explosion behaviour of metallic powders from micron to nanosize. Aluminium, magnesium, titanium, iron and zinc were considered and their explosion safety parameters were analysed as a function of their mean primary particle size either determined by BET measurements, particle size distribution. To depict the course of explosion behaviour for these metals, extensive literature review has been performed and additional experimental tests were also performed. Generally, decreasing the particle size in a metallic powder leads to a higher explosion severity. It appears that this statement is true till a critical Diameter below which the explosion severity (pmax, dp/dtmax) decreases for all the considered powders. This critical size can be explained by theoretical considerations on the nature of thermal transfer in the flame, namely by analysing the Cassel model. Finally, semi-empirical models were also developed for aluminium to highlight the specific micrometre and nanometre behaviour and the influence of turbulence, particle burning time, Diameter and concentration. The influence of these key parameters needs to be further assessed in a future work in order to better understand the mechanisms involved and to extend the scope to other powdered materials. KW - Dust explosion KW - Metallic powders KW - Nanopowder KW - Nanomaterials PY - 2019 U6 - https://doi.org/10.1016/j.jhazmat.2019.120767 VL - 379 SP - 120767-1 EP - 120767-9 PB - Elsevier B.V. AN - OPUS4-48711 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -