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In this presentation the results of the Project HySpark are shown. Mechanical impacts are among the important possible ignition sources to be considered in explosion protection. Hydrogen is particularly prone to be ignited by mechanical impacts compared to natural gas. The effectivity of mechanical impacts as ignition source is dependent from different parameters. In this work the effectivity of impacts as an ignition source for hydrogen containing atmospheres was studied experimentally depending on the inhomogeneous material pairing of the impact. Moreover it was studied, how the effectivity of mechanical impacts as ignition source changes when hydrogen is added to natural gas.
Mechanical friction, impact or abrasion is one of the ignition sources that must be avoided in hazardous zones with explosive atmospheres. The effectiveness of mechanical impacts as ignition source is dependent from several parameters including the minimum ignition energy of the explosive atmosphere, the properties of the material pairing, the kinetic impact energy or the impact velocity. By now there is no standard procedure to determine the effectiveness of mechanical impacts as ignition source. In this work the effectiveness of mechanical impacts with defined and reproducible kinetic impact energy as ignition source for hydrogen containing atmospheres was studied systematically in dependence from the inhomogeneous material pairing considering materials with practical relevance like stainless steel, low alloy steel, concrete, and non-iron-metals. It was found that ignition can be avoided, if non-iron metals are used in combination with different metallic materials, but in combination with concrete even the impact of non-iron-metals can be an effective ignition source if the kinetic impact energy is not further limited. Moreover, the consequence of hydrogen admixture to natural gas on the effectiveness of mechanical impacts as ignition source was studied. In many cases ignition of atmospheres containing natural gas by mechanical impacts is rather unlikely. No influence could be observed for admixtures up to 25% hydrogen and even more. The results are mainly relevant in the context of repurposing the natural gas grid or adding hydrogen to
the natural gas grid.
In this presentation the capabilities and different research activities at BAM in the field of hydrogen safety are outlined. A deep dive focussing the transport of hydrogen in pipelines adressing issues on material compatibility, gas quality and test methods is presented. Another deep dive is presented focussing on safety aspects of liquid hydrogen adressing issues of rapid phase transition (RPT) and Boiling liquid expanding vapour explosion (BLEVE). Finally a brief overview on other safety related research activities is given.
The hybrid mixture of combustible dusts and flammable gases/vapours widely exist in various industries, including mining, petrochemical, metallurgical, textile and pharmaceutical. It may pose a higher explosion risk than gas/vapor or dust/mist explosions since the hybrid explosions can still be initiated even though both the gas and the dust concentration are lower than their lower explosion limit (LEL) values. Understanding the explosion threat of hybrid mixtures not only contributes to the inherent safety and sustainability of industrial process design, but promotes the efficiency of loss prevention and mitigation. To date, however, there is no test standard with reliable explosion criteria available to determine the safety parameters of all types of hybrid mixture explosions, nor the flame propagation and quenching mechanism or theoretical explanation behind these parameters. This review presents a state-of-the-art overview of the comprehensive understanding of hybrid mixture explosions mainly in an experimental study level; thereby, the main limitations and challenges to be faced are explored. The discussed main contents include the experimental measurement for the safety parameters of hybrid mixtures (i.e., explosion sensitivity and severity parameters) via typical test apparatuses, explosion regime and criterion of hybrid mixtures, the detailed flame propagation/quenching characteristics behind the explosion severities/sensitivities of hybrid mixtures. This work aims to summarize the essential basics of experimental studies, and to provide the perspectives based on the current research gaps to understand the explosion hazards of hybrid mixtures in-depth.
Performance of the standardized testing method for detonation fl ame arresters at increased pressure
(2022)
Detonation flame arresters are typically used as autonomous protection systems in industrial applications to prevent potential hazards associated with flammable and/ or explosive chemicals. To verify and examine the suitability of detonation flame arresters, a testing method originating from the DIN EN ISO 16852 standard is used, which is mainly designed for atmospheric conditions.
In order to optimize the production capabilities, numerous industrial processes are taking place at pressures, temperatures, or oxygen concentrations beyond the ambient range, i.e. at non-atmospheric conditions and information on the performance of the regulated testing method are therefore required when the standard testing protocols are modified with regard to pressure, temperature or oxidizer.
The main objective of this study is to develop an improved testing method for detonation flame arresters, which offers a higher reproducibility and moreover, an applicability under non-atmospheric conditions. Therefore, an interlaboratory comparison on the performance of in-line flame arresters for stable and unstable detonations is jointly conducted by the project partners (PTB, BAM, Braunschweiger Flammenfilter GmbH and IBExU GmbH). The experiments are performed according to the testing method regulated in the DIN EN ISO 16852 standard for different pressures before ignition and different explosion groups. The experimental data is analyzed in detail to further optimize the test method and to thus achieve an improved reproducibility of detonation tests at high pressures, especially regarding the deflagration to detonation transition.
Potential ambiguities of the standardized testing method that might lead to the differing results at the different institutes are identified from the interlaboratory comparison and the test method is modified accordingly. Based on these results, an improved testing method for detonation flame arresters will be developed, which will ensure a greater safety at process plants while handling combustibles.
Experimental study on the performance of the standardized test method for detonation flame arresters
(2022)
Flame arresters are autonomous protection systems and are among the constructive explosion protection measures that limit the effects of an explosion.
In this study, the performance of the standardized test method regulated in the DIN EN ISO 16852 standard for in-line flame arresters for stable and unstable detonations, which is mainly designed for atmospheric conditions, is examined. In an interlaboratory comparison, experiments are performed for different pressures before ignition and explosion groups according to the standardized test method. The experimental data is analyzed in detail to further optimize the test method and to thus achieve an improved reproducibility of detonation tests at high pressures, especially regarding the deflagration to detonation transition.
Based on these results, an improved test method for detonation flame arresters will be developed, which will ensure better reproducibility as well as applicability under non-atmospheric conditions.
The safety characteristics of flammable gases and liquids are required when identifying potentially explosive mixtures and taking appropriate actions concerning explosion protection. Examples are given here of the safe handling and evaluation of hazards during the processing, storage, transport, and disposal of flammable liquids and gases. The CHEMSAFE database is presented as a reliable source of safety characteristic data, and its new open-access version is introduced. CHEMSAFE currently contains assessed properties for about 3000 liquids, gases and mixtures. The lack of a broad experimental foundation in the extensive field of non-atmospheric conditions shows the need for further investigation and standardization. This article summarizes experimental evidence and estimation methods for safety characteristic data under non-atmospheric conditions pointing out current limitations. Suggestions for pre-normative research on safety data under non-atmospheric conditions are given.
The safety characteristics of flammable gases and liquids are required when identifying potentially explosive mixtures and taking appropriate actions concerning explosion protection. Examples are given in this review of the safe handling and evaluation of hazards during the processing, storage, transport, and disposal of flammable liquids and gases. The CHEMSAFE database is presented as a reliable source of safety characteristic data, and ist new open-access version is introduced. CHEMSAFE currently contains assessed properties for about 3000 flammable liquids, gases and mixtures. The lack of a broad experimental foundation in the extensive field of non-atmospheric conditions shows the need for further investigation and standardization. This review summarizes experimental evidence and estimation methods for safety characteristic data under non-atmospheric conditions pointing out current limitations. Suggestions for pre-normative research on safety data under nonatmospheric conditions are given.
The safety characteristics of flammable gases and liquids are required when identifying potentially explosive mixtures and taking appropriate actions concerning explosion protection. Examples are given in this review of the safe handling and evaluation of hazards during the processing, storage, transport, and disposal of flammable liquids and gases. The CHEMSAFE database is presented as a reliable source of safety characteristic data, and ist new open-access version is introduced. CHEMSAFE currently contains assessed properties for about 3000 flammable liquids, gases and mixtures. The lack of a broad experimental foundation in the extensive field of non-atmospheric conditions shows the need for further investigation and standardization. This review summarizes experimental evidence and estimation methods for safety characteristic data under non-atmospheric conditions pointing out current limitations. Suggestions for pre-normative research on safety data under nonatmospheric conditions are given.