TY - JOUR A1 - Santandrea, A. A1 - Vignes, A. A1 - Krietsch, Arne A1 - Brunello, D. A1 - Perrin, L. A1 - Laurent, A. A1 - Dufaud, O. T1 - Evaluating the explosion severity of nanopowders: International standards versus reality N2 - The maximum explosion overpressure and the maximum rate of pressure rise, which characterize thedust explosion severity, are commonly measured in apparatuses and under specific conditions defined byinternational standards. However, those standards conditions, designed for micropowders, may not befully adapted to nanoparticles. Investigations were conducted on different nanopowders (nanocellulose,carbon black, aluminum) to illustrate their specific behaviors and highlight the potential inadequacyof the standards. The influence of the sample preparation was explored. Various testing procedureswere compared, focusing on the dust cloud turbulence and homogeneity. Dust dispersion experimentsevidenced the importance of the characterization of the dust cloud after dispersion, due to the frag-mentation of agglomerates, using metrics relevant with nanoparticles reactivity (e.g. surface diameterinstead of volume diameter). Moreover, the overdriving phenomenon (when the experimental resultsbecome dependent of the ignition energy), already identified for micropowders, can be exacerbated fornanoparticles due to their low minimum ignition energy and to the high energy used under standardconditions. It was evidenced that for highly sensitive nanopowders, pre-ignition phenomenon can occur.Finally, during severe explosions and due to a too long opening delay of the ‘fast acting valve’, the flamecan go back to the dust container. KW - Dust explosions KW - Gas explosions KW - Minimum ignition temperature KW - Hybrid mixtures PY - 2020 DO - https://doi.org/10.1016/j.psep.2020.04.011 VL - 138 SP - 279 EP - 291 PB - Elsevier B.V. AN - OPUS4-50944 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Krietsch, Arne A1 - Dufaud, O. A1 - Santandrea, A. A1 - Vignes, A. A1 - Perrin, L. A1 - Laurent, A. T1 - Some keys 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. lt 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 - Nanopowders KW - Dust explosion KW - Safety characteristics PY - 2019 SN - 978-88-95608-72-3 SN - 2283-9216 VL - 75 SP - 1 EP - 6 PB - AIDIC AN - OPUS4-49547 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 DO - 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 - TY - JOUR A1 - Spitzer, Stefan A1 - Askar, Enis A1 - Benke, Alexander A1 - Cloney, C. A1 - D’Hyon, S. A1 - Dufaud, O. A1 - Dyduch, Z. A1 - Gabel, D. A1 - Geoerg, P. A1 - Heilmann, V. A1 - Jankuj, V. A1 - Jian, W. A1 - Krause, U. A1 - Krietsch, Arne A1 - Mynarz, M. A1 - Norman, F. A1 - Skrinsky, J. A1 - Taveau, J. A1 - Vignes, A. A1 - Zakel, S. A1 - Zhong, S. T1 - 1st international round robin test on safety characteristics of hybrid mixtures N2 - There is no applicable existing standard for the determination of safety characteristics for hybrid mixtures. While developing a new standard in a joint research project in Germany first results from parameter studies led to a standard procedure that can be adopted by laboratories that are already testing dusts in the so called 20L-sphere with as little additional effort as necessary. In fact, one of the main objectives of this research project was to keep modifications and adjustments from the generally accepted dust testing procedures as easy and minimal as possible so as to limit potential deviations from one laboratory to another. In this first round robin test on hybrid mixtures ever, with methane as gas component and a specific corn starch as dust sample, the practicality of the whole procedure, the scattering of the results and the deviation between the testing apparatuses is investigated. This paper summarizes the experimental procedure adopted and objectives of the first round-robin phase involving three of the four original German companies, plus volunteering laboratories from Australia, Belgium, Czech Republic, France, Poland and P.R. China. The results will have an impact on the new standard and may lead to robust data for later simulation purposes. KW - Hybrid mixtures KW - 20L-sphere KW - Round robin test KW - Turbulent combustion PY - 2022 DO - https://doi.org/10.1016/j.jlp.2022.104947 SN - 0950-4230 VL - 81 SP - 1 EP - 8 PB - Elsevier CY - Amsterdam AN - OPUS4-56516 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Vignes, A. A1 - Krietsch, Arne A1 - Dufaud, O. A1 - Deray, B A1 - Binotto, G A1 - Bouillard, J. T1 - Current status in nanodust explosion topic N2 - Nanotechnology has been identified as a Key Enabling Technology for the European Union (Horizon 2020) and already has a wide field of applications. However, hazardous properties of nanomaterials such as their flammability and explosivity, have to be determined to ensure their sustainable development. This poster gives an overview of the current status in nanodust explosion research, standardization and european collaboration as well as highlighting current and future perspectives. T2 - 16th Congress of the French Chemical Engineering Society CY - Nancy, France DA - 11.07.2017 KW - Dust explosions KW - Nanomaterials KW - Combustible dust PY - 2017 AN - OPUS4-43084 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -