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- Explosionsschutz (25)
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- Nichtelektrische Geräte (6)
- Explosionsdruckentlastung (5)
- Richtlinie 2014/34/EU (5)
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Eingeladener Vortrag
- nein (55)
Nach dem Prinzip der integrierten Explosionssicherheit sind bei der Planung von Anlagen
folgende Maßnahmen in Betracht zu ziehen:
a) Vermeidung der Bildung von explosionsfähiger Atmosphäre
b) Vermeidung der Entzündung von explosionsfähiger Atmosphäre und
c) Vorrichtungen, die anlaufende Explosionen umgehend stoppen und/oder den von einer Explosion betroffenen Bereich begrenzen.
Im Folgenden werden einige Aspekte der konstruktiven Maßnahmen zur Auswirkungsbegrenzung von Explosionen nach c) erläutert.
Die vier wesentlichen, eingeführten und erprobten derartigen Schutzmaßnahmen sind Explosionsdruckentlastung, explosionsfestes Gerät, Explosionsunterdrückung und Explosionsentkopplung.
The effects of a gas explosion in enclosures like vessels can be limited e.g. by gas explosion venting systems. The major design step of this constructive explosion protection method is to determine the required vent area, which depends significantly on whether turbulent combustion exists. However, current standards like NFPA 68 or EN 14994 are applicable only to limited boundary conditions and as far as possible only to laminar flame propagation. Difficulties arise in the assessment or predictability of gas explosion hazard when turbulence occurs. In this research especially venting at elevated initial pressure has been shown to accelerated flame propagations and therefore, to a considerably higher reduced pressure. Therefore, it is essential to provide a broader data base of turbulent combustion and explosion behavior to verify the existing rules or to determine their safety-relevant parameters. For a better safety assessment or design of protective systems the turbulent combustion and accelerated gas explosion behaviour of quiescent methane and hydrogen in air were investigated at initial pressures up to 8 bar using vessels up to 100 litres. In particular a systematic study was performed to investigate the influence of turbulence on the overpressure development during accelerated gas explosion. Moreover, the present study consider the position of the spark igniters, the burning velocity and the maximum pressure rise for different concentration of fuel as well as the size of orifice and/or vent area. A choice of experimental tests showed under the investigated conditions that not only turbulence inducing obstacles but also over sized vent areas could lead to an increased pressure development and therefore to an inacceptable safety state.
Zur Bemessung von Druckentlastungseinrichtungen bei Gasexplosionen in Umschließungen existieren derzeitig nur wenige wissenschaftlich fundierte Auslegungskriterien, die die konstruktiven Randbedingungen oder Prozessbedingungen der explosionsgefährdeten Anlagenteile ausreichend berücksichtigen. Aus diesem Grund werden in der Praxis häufig stark konservative Annahmen getroffen, die zu erheblichen Überdimensionierungen der Druckentlastungseinrichtungen führen können.
Aus sicherheitstechnischer Perspektive können gerade diese vermeintlichen Sicherheitsmargen zu einer erheblichen Beschleunigung des transienten Druckverlaufs und damit eher zu einer Unterdimensionierung führen oder sogar den Übergang von Deflagrationen zu Detonationen begünstigen.
Sowohl Messungen als auch erste Simulationen mit Hilfe von CFD-Modellen begründen die Notwendigkeit weiterer Untersuchungen mit
explosionsgefährdeten Gasanlagen.
Da insbesondere bei turbulenten Verbrennungsvorgängen in den Normen Verbesserungspotential herrscht, wird bei der BAM zukünftig verstärkt dieses Thema in Forschungsarbeiten berücksichtigt.
Deflagration, stabile/instabile Detonation - eine Flammendurchschlagsicherung für alle Fälle?
(2001)
The method described in this paper enabled reliable and accurate positioning of an overdriven detonation by calculation of shock wave velocities (detonation and retonation) for hydrogen explosions in a closed 18 m long horizontal DN150 pipe. This enabled an empirical correlation between the ignition position and the run-up distance to DDT to be determined. It was shown that the initial ability of the flame to expand unobstructed and the piston-like effect of burnt gas expanding against the closed end of the tube contributed to initial flame acceleration and hence were able to affect the run-up distance to overdriven detonation. Flame speeds and rates of initial pressure rise were also used to explain how these two competing effects were able to produce a minimum in the run-up distance to DDT. The shortest run-up distance to DDT, relative to the ignition position, for this pipe and gas configuration was found when the ignition position was placed 5.6 pipe diameters (or 0.9 m) from the closed pipe end. The shortest run-up distance to DDT relative to the end of the pipe was recorded when the ignition source was placed 4.4 pipe diameters or 0.7 m from the pipe end.
Effects of the "new" ATEX Directive 2014/34/EU - consequences for manufacturers - claims by users
(2016)
Directive 94/9/EC of the European Parliament and of the Council of 23 March 1994 on the approximation of the laws of the Member States concerning equipment and protective systems intended for use in potentially explosive atmospheres has been substantially amended. The new ATEX Di-rective 2014/34/EU on equipment and protective systems intended for use in potentially explosive atmospheres replaces Directive 94/9/EC. The new Directive was published on March 29, 2014, became enacted on April 19, 2014 and will become effective starting April 20, 2016. It was the aim of the revision to harmonize the requirements with the New Legal Framework (New Legislative Framework - NLF). The NLF consists of the following two documents: the Regulation (EC) No 765/2008 of the European Parliament and of the Council of 9 July 2008, which sets out the re-quirements for accreditation and market surveillance relating to the marketing of products, and the Decision No 768/2008/EC of the European Parliament and of the Council of 9 July 2008, which sets on a common framework for the marketing of products.
The harmonization with the NLF especially results in a lot of new definitions and a new structure compared with the “old” ATEX. Some content which was in the annexes of the “old” ATEX is now turned into distinct chapters or articles in the main part. New content was included which comprises things like presumption of conformity, principles of CE marking, notification of conformity as-sessment bodies, Union market surveillance, and Union safeguard procedure. What is more, the definitions of the economic operators like manufacturer, distributor and importer and the description of their duties are now in separate chapters. Thus, the “new” ATEX is much bigger than the “old” one. With the publication of the Directive 2014/34/EU a lot of questions were raised especially from manufacturers.
These questions include:
- Did everything change now?
- Does the new Directive affect essential safety and health requirements (ESHR) for equipment and protective systems intended for use in hazardous areas?
- Is the module system for conformity assessment changed?
- What happens with existing certificates?
- What happens with products which were already produced before April 20, 2016 but will be placed on the market later?
The presentation will deal with some of these questions. But it has to be stated that the essential health and safety requirements for equipment and protective systems intended for use in potentially explosive atmospheres have not changed. That means: A product which was safe under the Directive 94/9/EC is still a safe product in the sense of the Directive 2014/34/EU.
Effects of the "new" ATEX Directive 2014/34/EU - consequences for manufacturers - claims by users
(2016)
Directive 94/9/EC of the European Parliament and of the Council of 23 March 1994 on the approx-imation of the laws of the Member States concerning equipment and protective systems intended for use in potentially explosive atmospheres has been substantially amended. The new ATEX Di-rective 2014/34/EU on equipment and protective systems intended for use in potentially explosive atmospheres replaces Directive 94/9/EC. The new Directive was published on March 29, 2014, became enacted on April 19, 2014 and will become effective starting April 20, 2016. It was the aim of the revision to harmonize the requirements with the New Legal Framework (New Legislative Framework - NLF). The NLF consists of the following two documents: the Regulation (EC) No 765/2008 of the European Parliament and of the Council of 9 July 2008, which sets out the re-quirements for accreditation and market surveillance relating to the marketing of products, and the Decision No 768/2008/EC of the European Parliament and of the Council of 9 July 2008, which sets on a common framework for the marketing of products.
The harmonization with the NLF especially results in a lot of new definitions and a new structure compared with the “old” ATEX. Some content which was in the annexes of the “old” ATEX is now turned into distinct chapters or articles in the main part. New content was included which comprises things like presumption of conformity, principles of CE marking, notification of conformity as-sessment bodies, Union market surveillance, and Union safeguard procedure. What is more, the definitions of the economic operators like manufacturer, distributor and importer and the description of their duties are now in separate chapters. Thus, the “new” ATEX is much bigger than the “old” one. With the publication of the Directive 2014/34/EU a lot of questions were raised especially from manufacturers.
These questions include:
- Did everything change now?
- Does the new Directive affect essential safety and health requirements (ESHR) for equipment and protective systems intended for use in hazardous areas?
- Is the module system for conformity assessment changed?
- What happens with existing certificates?
- What happens with products which were already produced before April 20, 2016 but will be placed on the market later?
The presentation will deal with some of these questions. But it has to be stated that the essential health and safety requirements for equipment and protective systems intended for use in potentially explosive atmospheres have not changed. That means: A product which was safe under the Directive 94/9/EC is still a safe product in the sense of the Directive 2014/34/EU.
Bereits einfache Rohreinbauten wie 90°-Rohrbögen erhöhen den Turbulenzgrad einer Strömung signifikant. Bei Explosionsversuchen von Propan/Luft-Gemischen in einer DN150-Rohrleitung mit einem 90°-Rohrbogen wurden sowohl stark beschleunigte Deflagrationen als auch Detonationen mit maximalen Explosionsdrücken von über 65 bar (abs.) beobachtet.