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- Explosion limits (2)
- Ignition criterion (2)
- Non-atmospheric conditions (2)
- Standardization (2)
- Classification (1)
- Druckeinfluss (1)
- Explosion protection (1)
- Explosionsgrenzen (1)
- Explosionsschutz (1)
- Flammable Gas (1)
Organisationseinheit der BAM
Many industrial processes are run at non-atmospheric conditions (elevated temperatures and pressures, other oxidizers than air). To judge whether and if yes to what extent explosive gas(vapor)/air mixtures will occur or may be generated during malfunction it is necessary to know the safety characteristic data at the respective conditions. Safety characteristic data like Explosion limits, are depending on pressure, temperature and the oxidizer. Most of the determination methods are standardized for ambient conditions.
In order to obtain determination methods for non-atmospheric conditions, particularly for higher initial pressures, reliable ignition criteria were investigated. Ignition tests at the explosion Limits were carried out for mixtures of methane, propane, n-butane, n-hexane, hydrogen, ammonia and acetone in air at initial pressures up to 20 bar. The tests have been evaluated according to different ignition criteria: visual flame propagation, temperature and pressure rising. It could be shown that flame propagation and occasionally self-sustained combustion for several seconds occurred together with remarkable temperature rise, although the pressure rise was below 3%. The results showed that the combination of a pressure rise criterion of 2% and a temperature rise criterion of 100 K seems to be a suitable ignition criterion for the determination of explosion limits and limiting oxidizer concentration at higher initial pressures and elevated temperatures. The tests were carried out within the framework of a R&D project founded by the German Ministry of Economics and Technology.
Die Kenntnisse der Einflüsse von Druck, Temperatur und Oxidationsmittel auf sicherheitstechnische Kenngrößen wie Explosionsgrenzen sind eine notwendige Voraussetzung, um zu entscheiden, ob mit den bei atmosphärischen Bedingungen geltenden Kenngrößen eine ausreichende Sicherheit zu gewährleisten ist. Dies wird anhand von Beispielen erklärt und die Konsequenzen für die praktische Anwendung in der Industrie diskutiert.
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.