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Für die Durchführung einer Dichtheitsprüfung und für die Bewertung des Ergebnisses ist es wichtig, den sich unter Betriebsbedingungen im Prüfobjekt einstellenden Überdruck zu kennen. Entspricht der Prüfüberdruck nicht dem Betriebsüberdruck, so ist es oft erforderlich, die unter Prüfbedingungen gemessenen Leckageraten auf den realen Betriebsüberdruck umzurechnen. Im Bereich der Gefahrgutverpackungen ist jedoch der spätere maximale Betriebsüberdruck nicht genau bekannt. Er hängt für jede einzelne Verpackungsbauart von dem eingefüllten Füllmedium mit seinen spezifischen Stoffeigenschaften, dem Füllgrad sowie den Beförderungsbedingungen, insbesondere der mittleren Transporttemperatur, ab. Es werden Berechnungsansätze vorgestellt, mit denen sich der Überdruck in Gefahrgutverpackungen unter Beförderungsbedingungen rechnerisch ermitteln lässt. Die theoretisch berechneten Überdrücke werden mit Überdruck-Messwerten verglichen, die mit verschiedenen Füllmedien in unterschiedlichen Verpackungsbauarten ermittelt wurden.
In den von der BAM anerkannten Prüfstellen kommen derzeit unterschiedliche Methoden der Schüttwinkelmessung zum Einsatz. Es ist unklar, welche dieser Methoden sich prinzipiell für welche Füllgüter eignen. Daher werden derzeit systematische Untersuchungen an der BAM durchgeführt, die im folgenden vorgestellt werden.
Die in den von der BAM anerkannten Prüfstellen für Gefahrgutverpackungen gängigen Schüttwinkel-Messmethoden werden verglichen, anhand der Messung an fünf pulverförmigen oder körnigen Stoffen mit gefährlichen Eigenschaften. Zusätzlich wird die Untersuchung des Einflusses einer unterschiedlichen klimatischen Vorlagerung vorgenommen.
Es ist bislang noch keine einheitliche Vorgehensweise und kein bestimmtes Prüfverfahren für die Schüttwinkelmessung festgelegt. Bei den Prüffüllgütern handelt es sich nicht nur um gefährliche Ersatzfüllgüter, sondern zum Teil auch um gefährliche Originalfüllgüter. Es liegen noch keine systematische Untersuchungen darüber vor, welche der in den Prüfstellen gängigen Methoden sich prinzipiell für die Anwendung bei bestimmten Extremfällen von Füllgütern eignen. Ziel der Untersuchungen ist daher ein systematischer Vergleich bei der Anwendung verschiedener in den Prüfstellen gängiger Schüttwinkelmessmethoden.
Vergleichende Fallversuche zur Bewertung von Fallfundamenten - Ausblick auf Untersuchungen der BAM
(2020)
Oft verfügen Produktionsstätten über bereits verbaute Fallfundamente, die nicht das geforderte Massenverhältnis von 1:50 aufweisen. Gemäß ADR ist jedoch auf dem Niveau der Musterprüfung zu prüfen. Es ist daher fraglich, ob die Prüfungen im Rahmen der Eigenüberwachung und die Baumusterprüfungen vergleichbare Ergebnisse liefern, wenn die Fallfundamente unterschiedlich beschaffen sind. Ziel der Untersuchungen ist daher die Entwicklung eines Untersuchungs- und Prüfkonzepts für bereits verbaute Fallfundamente für Gefahrgutverpackungen im Rahmen einer ingenieurwissenschaftlichen Promotionsarbeit.
Der derzeit in den Gefahrgutvorschriften genannte Bubble Test ist keine geeignete Prüfmethode, um für alle Verpackungsvolumina ein Dichtheitsniveau sicherzustellen, welches auf Sicherheitsbetrachtungen unter Beförderungsbedingungen basiert. Für kleinere Verpackungsbauarten müssten theoretisch empfindlichere Prüfmethoden angewandt werden. Auf der anderen Seite sollten Bauartprüfungen für Gefahrgutverpackungen nicht zu kompliziert sein. Daher sollte die Auswahl einer Methode erfolgen, die sowohl eine ausreichende Empfindlichkeit aufweist als auch über eine einfache Art der Durchführung verfügt.
In den internationalen Gefahrgutvorschriften ist vorgeschrieben, dass Säcke und flexible Großpackmittel (Flexible Intermediate Bulk Container – FIBC) staubdicht sein müssen. Eine quantitative Definition des Terminus Staubdichtheit, wie in anderen Technikgebieten üblich, ist jedoch nicht gegeben. Auch geeignete Prüfverfahren zum Nachweis der Staubdichtheit sind in den Vorschriften nicht genannt.
In der Praxis der stichpunkartigen Kontrollen von Gefahrguttransporten durch die Schwerlastgruppe der Autobahnpolizei Münster werden immer wieder Austritte von pulverförmigen oder körnigen Gefahrgütern aus eigentlich intakten Säcken und FIBC detektiert. Es wird ein Überblick über die im Jahr 2018 festgestellten Gefahrgutaustritte aus diesen Gefahrgutverpackungen sowie eine systematische Einordnung hinsichtlich betroffener Bauarten und möglicher Ursachen gegeben.
Bei der Stofffreisetzung aus intakten Gefahrgutverpackungen liegt ein mechanischer Transport von Partikeln durch Leckkanäle, z. B. im Verschluss-, Naht- oder Wandungsbereich, vor. Generell kommen zwei Freisetzungswege in Frage: Einerseits eine Langzeit-Freisetzung während des Transports, hervorgerufen durch eine kombinierte Wirkung von Stapellast des Füllguts und Transportvibrationen; andererseits eine stoßartige Freisetzung.
Auf Grundlage von durchgeführten Untersuchungen hinsichtlich der stoßartigen Freisetzung pulverförmiger Stoffe aus Gefahrgutsäcken werden erste Lösungsansätze hin zu einer Verbesserung der Staubdichtheit von Gefahrgutsäcken und -FIBC vorgestellt. Es wird ein Ausblick auf nachfolgende Arbeiten gegeben.
In den internationalen Gefahrgutvorschriften ist vorgeschrieben, dass Säcke und flexible Großpackmittel (Flexible Intermediate Bulk Container – FIBC) staubdicht sein müssen. Eine quantitative Definition des Terminus Staubdichtheit, wie in anderen Technikgebieten üblich, ist jedoch nicht gegeben. Auch geeignete Prüfverfahren zum Nachweis der Staubdichtheit sind in den Vorschriften nicht genannt.
In der Praxis der stichpunkartigen Kontrollen von Gefahrguttransporten durch die Schwerlastgruppe der Autobahnpolizei Münster werden immer wieder Austritte von pulverförmigen oder körnigen Gefahrgütern aus eigentlich intakten Säcken und FIBC detektiert. Es wird ein Überblick über die im Jahr 2018 festgestellten Gefahrgutaustritte aus diesen Gefahrgutverpackungen sowie eine systematische Einordnung hinsichtlich betroffener Bauarten und möglicher Ursachen gegeben.
Bei der Stofffreisetzung aus intakten Gefahrgutverpackungen liegt ein mechanischer Transport von Partikeln durch Leckkanäle, z. B. im Verschluss-, Naht- oder Wandungsbereich, vor. Generell kommen zwei Freisetzungswege in Frage: Einerseits eine Langzeit-Freisetzung während des Transports, hervorgerufen durch eine kombinierte Wirkung von Stapellast des Füllguts und Transportvibrationen; andererseits eine stoßartige Freisetzung.
Auf Grundlage von durchgeführten Untersuchungen hinsichtlich der stoßartigen Freisetzung pulverförmiger Stoffe aus Gefahrgutsäcken werden erste Lösungsansätze hin zu einer Verbesserung der Staubdichtheit von Gefahrgutsäcken und -FIBC vorgestellt. Es wird ein Ausblick auf nachfolgende Arbeiten gegeben.
Gemäß den internationalen Gefahrgutvorschriften müssen Säcke und flexible Großpackmittel (Flexible Intermediate Bulk Container - FIBC) für feste Gefahrgüter staubdicht sein.
In der Praxis der stichpunktartigen Kontrollen von Gefahrguttransporten durch die Autobahnpolizei Münster werden jedoch immer wieder Austritte von pulverförmigen oder körnigen Gefahrgütern aus eigentlich intakten Säcken und FIBC detektiert.
Es wird ein Überblick über die im Jahr 2019 festgestellten Gefahrgutaustritte aus diesen Arten von Gefahrgutverpackungen gegeben. Darauf aufbauend wird eine systematische Einordnung hinsichtlich betroffener Bauarten und eine Diskussion möglicher Lösungsansätze vorgenommen.
Sift-proofness is a requirement for different types of dangerous goods packagings for solid substances according to the international Dangerous Goods Regulations. In these regulations, a sift-proof packaging is defined as a packaging that is completely impermeable to dry contents. This means indirectly that absolutely no mass transport of solid substances is allowed. Moreover, this requirement applies both to the original filling substance and to fine solid material generated during transport. Further specifications, test conditions or tolerable limit values are not given. This is in contrast to physical principles and the usual practice in other fields of technology in which sift-proofness is relevant. This paper shows the necessary steps for how the requirements for sift-proofness of dangerous goods packagings can be defined more precisely. Physical basics of the term ‘sift-proofness’ are explained. A qualitative as well as a quantitative approach is possible. In any case, it is essential to carry out appropriate vibration tests to assess the siftproofness. There is a need for systematical investigations of the sift-proofness of dangerous goods packagings.
Sift-proofness is a requirement for different types of dangerous goods packagings for solid substances according to the international Dangerous Goods Regulations. In these regulations, a siftproof packaging is defined as a packaging which is completely impermeable to dry contents. This means indirectly that absolutely no mass transport of solid substances is allowed. Moreover, this requirement applies both to the original filling substance and to fine solid material generated during transport. Further specifications, test conditions or tolerable limit values are not given. This is in contrast to physical principles and the usual practice in other fields of technology in which sift-proofness is relevant.
This article shows the necessary steps for how the requirements for sift-proofness of dangerous goods packagings can be defined more precisely. Physical basics of the term “sift-proofness” are explained. A qualitative as well as a quantitative approach are possible. In any case, it is essential to carry out appropriate vibration tests to assess the sift-proofness. There is a need for systematical investigations of the sift-proofness of dangerous goods packagings.
Abstract: The leaks of dangerous goods from actually intact bags detected in the years 2018 to 2020 tend to be at an almost constant high level. These releases of powdery or granular dangerous goods represent violations of the sift-proofness required in the dangerous goods regulations. This article first analyzes the causes. The components of the bags that are affected by leaks are micro-perforations, joins and closures, in particular internal sleeve valves.
A distinction must be made between bags closed in conformity with or contrary to the manufacturer's instructions.
The particle release is determined by a number of influencing factors of the filling substance, the packaging and other boundary conditions. Therefore, a comprehensive test concept is developed in this work, which takes all these factors into account. The application of this test concept facilitates the planning of the test setup and the experiments. On this basis, the complex mechanisms involved in the release of solid substances can be systematically investigated in the test laboratory. To prevent releases of powdery or granular substances from intact bags, it is necessary that the user has access to the closing instructions and the relevant properties of the test substance used for the design type approval. Further experimental investigations are needed to assess whether filling substances change their properties during transport and whether this enables them to escape.
The leaks of dangerous goods from actually intact bags detected in the years 2018 to 2020 tend to be at an almost constant high level. These releases of powdery or granular dangerous goods represent violations of the sift-proofness required in the dangerous goods regulations. This article first analyzes the causes. The components of the bags that are affected by leaks are micro-perforations, joins and closures, in particular internal sleeve valves. A distinction must be made between bags closed in conformity with or contrary to the manufacturer's instructions. The particle release is determined by a number of influencing factors of the filling substance, the packaging and other boundary conditions. Therefore, a comprehensive test concept is developed in this work, which takes all these factors into account. The application of this test concept facilitates the planning of the test setup and the experiments. On this basis, the complex mechanisms involved in the release of solid substances can be systematically investigated in the test laboratory. To prevent releases of powdery or granular substances from intact bags, it is necessary that the user has access to the closing instructions and the relevant properties of the test substance used for the design type approval. Further experimental investigations are needed to assess whether filling substances change their properties during transport and whether this enables them to escape.
The leaks of dangerous goods from actually intact bags detected in the years 2018 to 2020 tend to be at an almost constant high level. These releases of powdery or granular dangerous goods represent violations of the sift-proofness required in the dangerous goods regulations. This article first analyzes the causes.
The components of the bags that are affected by leaks are micro-perforations, joins and closures, in particular internal sleeve valves. A distinction must be made between bags closed in conformity with or contrary to the manufacturer's instructions. The particle release is determined by a number of influencing factors of the filling substance, the packaging and other boundary conditions.
Therefore, a comprehensive test concept is developed in this work, which takes all these factors into account. The application of this test concept facilitates the planning of the test setup and the experiments. On this basis, the complex mechanisms involved in the release of solid substances can be systematically investigated in the test laboratory.
To prevent releases of powdery or granular substances from intact bags, it is necessary that the user has access to the closing instructions and the relevant properties of the test substance used for the design type approval. Further experimental investigations are needed to assess whether filling substances change their properties during transport and whether this enables them to escape.
Der innere Überdruck, der sich unter Beförderungsbedingungen im freien Dampfraum einer Gefahrgutverpackung bildet, die mit einer gefährlichen Flüssigkeit gefüllt ist, hängt von verschiedenen Faktoren ab: Den spezifischen Stoffeigenschaften des jeweiligen Füllguts, dem Füllgrad, der Nachgiebigkeit der Verpackungsbauart, der Befülltemperatur und der Temperatur bei Beförderungsbedingungen.
Zu den normalen Beförderungsbedingungen von befüllten Gefahrgutverpackungen zählt der interkontinentale Transport in Frachtcontainern. Es werden die Ergebnisse einer Klimamessfahrt vorgestellt, die mit einem instrumentierten Frachtcontainer auf der Fahrt von Hamburg nach Singapur und zurück gewonnen wurden. Hierdurch lassen sich durchschnittliche und maximale Beförderungstemperaturen beim interkontinentalen Containertransport ermitteln. Es werden Modellgleichungen vorgestellt, mit denen sich für verschiedene Annahmen der sich einstellende Überdruck in einer Gefahrgutverpackung berechnen lässt.
The objective was to find out whether an explosive atmosphere can be created in a freight container by gaseous leakage flow of vapour-air-mixture through leaks in the closures of dangerous goods packagings filled with hazardous liquids. Because of high temperatures during intercontinental carriage, there is a gauge pressure in the free vapour phase inside the packagings which can cause a gaseous leakage flow. Two different methods were applied:
Helium limit leakage rates for 23 quantitatively important hazardous liquids concerning their lower explosion limit (LEL) were calculated for a worst case transport scenario (Method 1).
Helium leakage rates of five closure types of dangerous goods packagings with volumes of approximately 6 l were measured using the pressure technique by accumulation (Method 2).
All types of closures of steel packagings were uncritical. The maximum measured leakage was 33% of the limit leakage rate. The leakage rates of screw closures of plastic jerricans can exceed the LEL if there are production-related patterns such as non-concentricity of the closures and flashes on the neck. Especially for plastic packagings it is important to minimize gaseous leakage flow, because an explosive atmosphere can also be reached by permeation of the individual filling substance or by a combination of both effects. For the assessment of potentially explosive mixtures in freight containers, both mass transfer mechanisms have to be taken into account.
The objective of this work was to determine the maximum gauge pressure in the vapour phase above the liquid in different design types of dangerous goods packagings under normal conditions of carriage. The design types investigated were steel and plastic packagings with a volume of approximately 6 l.
Two different methods were applied. In method 1, the pressure inside the packaging filled with a certain filling substance (dichloromethane) was directly measured under simulated conditions of carriage (degree of filling: 90%; filling temperature: 15°C; temperature during storage: 31°C). The maximum measured gauge pressures were between 89 mbar for a light plastic jerrican and 336 mbar for a steel drum.
In method 2, the gauge pressure was calculated. The consideration of a rigid packaging combined with the assumption of a vapour pressure of zero during filling and sealing can serve as a worst case scenario. The calculated gauge pressure is approximately 1061 mbar. This procedure leads to the highest safety factor and does not require any experimental investigations.
For a more realistic approximation of the gauge pressure of a non-rigid packaging, a packaging-specific function of relative expansion can be used, which is determined by a hydraulic pressure test. The calculated values ranged from 105 to 347 mbar. Method 2 provides conservative results. No hazardous filling substance is needed, and it allows a prediction of gauge pressure for other temperatures, substances and filling degrees. Therefore, this method could serve as alternative to UN Model Regulations 6.1.5.5.4 (a).
Es werden die Ergebnisse von Leckageratenmessungen an den Verschlüssen von Gefahrgutverpackungen unterschiedlicher Bauarten vorgestellt. Die Prüfungen wurden mit dem Überdruckverfahren mit Ansammlung unter Verwendung des Prüfgases Helium vorgenommen. Die gemessenen Deckelleckageraten zeigen Größenordnungsunteschiede von mehreren Zehnerpotenzen. Durch einen Vergleich mit berechneten Grenzwerten lässt sich die Indentifizierung kritischer Bauarten vornehmen.
This work focuses on the question if the bubble test prescribed in the Dangerous Goods Regulations has sufficient sensitivity to detect leakage rates which could result in the formation of explosive atmospheres during transport. The sensitivity of the bubble test is not directly comparable with other leak testing methods because of its different flow conditions.
Therefore, a normalized minimum detectable leakage rate under Helium test conditions is calculated for the bubble test. This sensitivity of the bubble test under reference conditions is compared with limit leakage rates for a worst-case transport scenario. The sensitivity of the bubble test is not sufficient to prove the limit leakage rates for 6-L packagings. The Formation of explosive vapour-air-mixtures cannot be excluded. Therefore, more sensitive leak testing methods should be considered for smaller packaging design types.
This work focuses on the question if the bubble test prescribed in the Dangerous Goods Regulations has sufficient sensitivity to detect leakage rates, which could result in the formation of explosive atmospheres during transport. The sensitivity of the bubble test is not directly comparable with other leak testing methods because of its different flow conditions. Therefore, a normalized minimum detectable leakage rate under Helium test conditions is calculated for the bubble test. This sensitivity of the bubble test under reference conditions is compared with limit leakage rates for a worst‐case transport scenario. The sensitivity of the bubble test is not sufficient to prove the limit leakage rates for 6‐L packagings. The formation of explosive vapour‐air‐mixtures cannot be excluded. Therefore, more sensitive leak testing methods should be considered for smaller packaging design types.
Abstract: The dangerous goods regulations UN/ADR 6.1.5.5.4 a) prescribe a maximum filling degree for determining the test pressure for the hydraulic pressure test by real measurements. The assumption is that the maximum filling degree of the liquid phase is the worst case concerning the gauge pressure. Therefore the main objective of this study is to investigate the effect of the filling degree on the gauge pressure.
Gauge pressure measurements and calculations for different substances were carried out at different filling degrees for a steel drum and a steel jerrican (heating-up from 15 °C to 55 °C).
The assumption that the maximum filling degree is the most critical is only valid for relatively rigid packagings: If the relative expansion of the packaging is smaller than the volume increase of the liquid phase due to heating-up, the gauge pressure increases with increasing filling degree.
But the opposite is true for relatively flexible packagings: If the relative expansion of the packaging exceeds the relative volume expansion of the liquid, the gauge pressure increases for decreasing filling degrees. The current regulations for the hydraulic test pressure determination at a maximum filing degree do not lead to the intended safety level. For a lower level than the maximum filling degree, the prescribed safety factor of 1.5 is not respected. Under transport conditions it is possible that the inner gauge pressure exceeds the test pressure. This can result in a failure of the packaging. There is a need to reconsider the regulations.
The dangerous goods regulations UN/ADR 6.1.5.5.4 (a) prescribe a maximum filling degree for determining the test pressure for the hydraulic pressure test by real measurements. The assumption is that the maximum filling degree of the liquid phase is the worst case concerning the gauge pressure. Therefore, the main objective of this study is to investigate the effect of the filling degree on the gauge pressure. Gauge pressure measurements and calculations for different substances were carried out at different filling degrees for a steel drum and a steel jerrican (heating up from 15°C to 55°C). The assumption that the maximum filling degree is the most critical is only valid for relatively rigid packagings: If the relative expansion of the packaging is smaller than the volume increase of the liquid phase due to heating up, the gauge pressure increases with increasing filling degree. But the opposite is true for relatively flexible packagings: If the relative expansion of the packaging exceeds the relative volume expansion of the liquid, the gauge pressure increases for decreasing filling degrees. The current regulations for the hydraulic test pressure determination at a maximum filing degree do not lead to the intended safety level. For a lower level than the maximum filling degree, the prescribed safety factor of 1.5 is not respected. Under transport conditions, it is possible that the inner gauge pressure exceeds the test pressure. This can result in a failure of the packaging. There is a need to reconsider the regulations.
In practice, checks on dangerous goods transports often detect leaks of powdered dangerous goods from valved bags. In this work, the influence factors of a sudden release of powdery substances from the valves of valved bags were investigated. Drop tests were carried out on paper bags of UN design type 5M2 with internal sleeve valve using two different powdery substances (Esplas H130 and zinc oxide “Rotsiegel”).
The internal sleeve valves of all test samples were not sift-proof with respect to both filling substances. For almost all test samples, the Esplas H130 powder already leaked out of pasted joints during manual filling. This is a contradiction to the requirement in UN 6.1.4.18.1, according to which closures and joints of paper bags 5M2 should be sift-proof.
In the drop tests, longer valve lengths had a greater sealing effect for both filling substances (for filling degrees of at least 95% and for test samples which had already been mechanically loaded). As an extreme example, at the drop height of 1.20 m and a filling degree of 100%, the released amount of zinc oxide powder from a 10 cm long valve was about 16 times higher than from a valve length of 12.5 cm. The valve length is therefore a safety-relevant parameter and should be specified by the manufacturer.
To ensure that only filling goods with similar physical properties in comparison to the test substance are used for valved bags, the user must be informed of the particle size of the test substance.
In practice, checks on dangerous goods transports often detect leaks of powdered dangerous goods from valved bags. In this work, the influence factors of a sudden release of powdery substances from the valves of valved bags were investigated.
Drop tests were performed on paper bags of UN design type 5M2 with internal sleeve valve using 2 different powdery substances (Esplas H130 and zinc oxide “Rotsiegel”).
The internal sleeve valves of all test samples were not sift‐proof with respect to both filling substances. For almost all test samples, the Esplas H130 powder already leaked out of pasted joints during manual filling. This is a contradiction to the requirement in UN 6.1.4.18.1, according to which closures and joints of paper bags 5M2 should be sift‐proof.
In the drop tests, longer valve lengths had a greater sealing effect for both filling substances (for filling degrees of at least 95% and for test samples which had already been mechanically loaded). As an extreme example, at the drop height of 1.20 m and a filling degree of 100%, the released amount of zinc oxide powder from a 10‐cm‐long valve was about 16 times higher than from a valve length of 12.5 cm.
The valve length is therefore a safety‐relevant parameter and should be specified by the manufacturer.
To ensure that only filling goods with similar physical properties in comparison with the test substance are used for valved bags, the user must be informed of the particle size of the test substance.
The Dangerous Goods Regulations currently do not include limit leakage rates or sensitivity requirements for industrial leak testing procedures that are equivalent to the bubble test, which is the prescribed test method for design type testing of dangerous goods packagings. During series production of such packagings, various methods are used which often do not reach the sensitivity of the bubble test. Based on a suitable pragmatic approach, its sensitivity under industrial conditions can be considered 10-4 Pa m³/s (SLR).
For the selection of a suitable industrial leak testing method, however, factors other than the sensitivity are also important, for example flow direction, pressure level and automatability. The following methods are in principal suitable and equally effective as the bubble test: pressure rise test (vacuum chamber), ultrasonic bubble leak detection and gas detection methods (pressure technique by accumulation and vacuum chamber technique).
To ensure a uniform test level during design type testing and production line leak testing and therefore a comparable safety level as required by the Dangerous Goods Regulations, it is necessary to include a more precise specification in these regulations. On the one hand, this requires an information about the sensitivity of the bubble test, on the other hand, the inclusion of a list of suitable, equally effective industrial test methods with their specific boundary conditions
The Dangerous Goods Regulations currently do not include limit leakage rates orsensitivity requirements for industrial leak testing procedures that are equivalent tothe bubble test, which is the prescribed test method for design type testing ofdangerous goods packagings. During series production of such packagings, variousmethods are used, which often do not meet the requirements of the bubble test withregard to important criteria.Sensitivity, flow direction, pressure level and automatability are particularly importantfactors when selecting a suitable industrial leak testing method.The following methods are in principle both suitable and equally effective as thebubble test: pressure rise test (vacuum chamber), ultrasonic bubble leak detectionand gas detection methods (pressure technique by accumulation and vacuumchamber technique).To ensure a uniform test level during design type testing and production line leaktesting and therefore a comparable safety level as required by the Dangerous GoodsRegulations, it is necessary to include a more precise specification in these regula-tions. This requires, on the one hand, information about the sensitivity of the bubbletest and, on the other hand, the inclusion of a list of suitable, equally effective indus-trial test methods with their specific boundary conditions.
For dangerous goods packagings, drop testing onto an essential unyielding target can be used to assess the mechanical resistance to impact loads. Adopted regulations like ADR/RID require that the impact surface provided shall be integral with a mass at least 50 times than that of the heaviest package to be tested. The problem is that many manufacturers do not possess impact targets that satisfy the required 50 times mass ratio for regulative drop tests during series production. The objective of this work is to verify existing and define improved criteria for impact target structures based on systematic investigations. Previous evidence highlights the relevance of other parameters in addition to the mass ratio. Therefore, in this research, a variation of drop test parameters was carried out experimentally. Furthermore, numerical vibration analysis was applied to investigate the deformability of the impact surface. The results conclude that the mass ratio of 1:50 cannot be defined as a decisive criterion. In order to determine the influence of further drop test parameters, the research findings were used to validate a parametric model which assesses impact target deflection. An approximation quality of over 90 % was achieved. As a result, new evaluation criteria are proposed. Firstly, a method for identifying critical impact target designs is provided. Secondly, a new comprehensive formula compares the approximated maximum deflection of a real impact target to the respective theoretical threshold derived from a worst-case assumption. In practice, this leads to great advantages in the evaluation of already installed impact targets for dangerous goods packagings.
For dangerous goods packagings, drop testing onto an essential unyielding target can be used to assess the mechanical resistance to impact loads. Adopted regulations like ADR/RID require that the impact surface provided shall be integral with a mass at least 50 times than that of the heaviest package to be tested. The problem is that many manufacturers do not possess impact targets that satisfy the required 50 times mass ratio for regulative drop tests during series production. The objective of this work is to verify existing and define improved criteria for impact target structures based on systematic investigations. Previous evidence highlights the relevance of other parameters in addition to the mass ratio. Therefore, in this research, a variation of drop test parameters was carried out experimentally. Furthermore, numerical vibration analysis was applied to investigate the deformability of the impact surface. The results conclude that the mass ratio of 1:50 cannot be defined as a decisive criterion. In order to determine the influence of further drop test parameters, the research findings were used to validate a parametric model which assesses impact target deflection. An approximation quality of over 90 % was achieved. As a result, new evaluation criteria are proposed. Firstly, a method for identifying critical impact target designs is provided. Secondly, a new comprehensive formula compares the approximated maximum deflection of a real impact target to the respective theoretical threshold derived from a worst-case assumption. In practice, this leads to great advantages in the evaluation of already installed impact targets for dangerous goods packagings.
The flow properties of powdery or granular filling substances for dangerous goods packagings are safety-relevant parameters. To specify the flow behavior, the angle of repose is measured in the recognized test centers for dangerous goods packagings in Germany. Previous investigations performed on non-hazardous substances revealed that some of the methods currently used have disadvantages in application. Additionally, for occupational health and safety reasons, it was generally viewed critically to carry out measurements of the angle of repose for dangerous goods at all. Instead, the dimensionless Hausner ratio to describe the flow behavior was proposed.
In this work, the investigations were extended to real hazardous substances to concretize the assessment. Five exemplary hazardous substances were tested for their angle of repose using the methods commonly applied in the test centers. The Hausner ratio was also determined. In addition, the influence of a different climatic preconditioning on the angle of repose measurement was examined using three selected non-hazardous bulk materials.
The results show that the measurement of the angle of repose is not fundamentally excluded for dangerous goods. However, for reasons of applicability, repeatability and occupational health and safety, only the ISO method can be applied for dangerous filling substances. This method provides conservative results regarding a safety-related evaluation of flow properties for the transport of dangerous goods.
In principle, both the ISO method and the determination of the Hausner ratio can be used for dangerous goods. It is also essential especially with finely powdered filling goods, to carry out controlled preconditioning.
The flow properties of powdery or granular filling substances for dangerous goods packagings are safety-relevant parameters. To specify the flow behavior, the angle of repose is measured in the recognized test centers for dangerous goods packagings in Germany. Previous investigations performed on non-hazardous substances revealed that some of the methods currently used have disadvantages in application. Additionally, for occupational health and safety reasons, it was generally viewed critically to carry out measurements of the angle of repose for dangerous goods at all. Instead, the dimensionless Hausner ratio to describe the flow behavior was proposed.
In this work, the investigations were extended to real hazardous substances to concretize the assessment. Five exemplary hazardous substances were tested for their angle of repose using the methods commonly applied in the test centers. The Hausner ratio was also determined. In addition, the influence of a different climatic preconditioning on the angle of repose measurement was examined using three selected non-hazardous bulk materials.
The results show that the measurement of the angle of repose is not fundamentally excluded for dangerous goods. However, for reasons of applicability, repeatability and occupational health and safety, only the ISO method can be applied for dangerous filling substances. This method provides conservative results regarding a safety-related evaluation of flow properties for the transport of dangerous goods.
In principle, both the ISO method and the determination of the Hausner ratio can be used for dangerous goods. It is also essential especially with finely powdered filling goods, to carry out controlled preconditioning.
The International Dangerous Goods Regulations prescribe the immersion under water method (“bubble test”) as standard method for the leakproofness test of dangerous goods packagings. But this test procedure acts as a test method for leak localisation, not for quantitative leakage rates measurement. Additionally, the sensitivity in detecting leaks of small diameters is restricted, depending on the test liquid and the test pressure. The bubble test is not suitable for a comparison with quantitative limit leakage rates based on realistic transport conditions. This is especially important when estimating the risk of the formation of an explosive atmosphere during the intercontinental carriage of dangerous goods packagings in freight containers. To compare measured leakage rates with limit leakage rates, a quantitative leak testing procedure is required. Therefore a new approach for dangerous goods packagings is implemented: The pressure technique by accumulation using Helium as a tracer gas. This work presents the test equipment necessary for the quantitative measurement of Helium leakage rates through closures of different kinds of dangerous goods packagings. The essential steps to achieve good repeatable results are: A controlled Helium filling process to reach a defined test pressure in the test sample, a sufficient homogenisation of the Helium-air-mixture inside the test sample and the ensuring of a constant pressure level of the test sample during the test. The Helium loss rate of the accumulation chamber has to be measured separately to receive a correction factor for the measured leakage rates. Different constructional measures are introduced to prevent a disturbing influence of the Helium leakage rate of the filling valves on the measurement results. Methods to estimate the disturbing effect of Helium permeation through permeable parts of the test sample are also presented. As a supporting method for the experimental investigations the Helium sniffer test can be applied. This practical application-oriented advice can enable other users to establish a pressure technique by accumulation for their own technical field.
The International Dangerous Goods Regulations prescribe the immersion under water method (“bubble test”) as standard method for the leakproofness test of dangerous goods packagings. But this test procedure acts as a test method for leak localisation, not for quantitative leakage rates measurement. Additionally, the sensitivity in detecting leaks of small diameters is restricted, depending on the test liquid and the test pressure. The bubble test is not suitable for a comparison with quantitative limit leakage rates based on realistic transport conditions. This is especially important when estimating the risk of the formation of an explosive atmosphere during the intercontinental carriage of dangerous goods packagings in freight containers.
To compare measured leakage rates with limit leakage rates, a quantitative leak testing procedure is required. Therefore a new approach for dangerous goods packagings is implemented: The pressure technique by accumulation using Helium as a tracer gas.
This work presents the test equipment necessary for the quantitative measurement of Helium leakage rates through closures of different kinds of dangerous goods packagings. The essential steps to achieve good repeatable results are: A controlled Helium filling process to reach a defined test pressure in the test sample, a sufficient homogenisation of the Helium-air-mixture inside the test sample and the ensuring of a constant pressure level of the test sample during the test. The Helium loss rate of the accumulation chamber has to be measured separately to receive a correction factor for the measured leakage rates. Different constructional measures are introduced to prevent a disturbing influence of the Helium leakage rate of the filling valves on the measurement results. Methods to estimate the disturbing effect of Helium permeation through permeable parts of the test sample are also presented. As a supporting method for the experimental investigations the Helium sniffer test can be applied. This practical application-oriented advice can enable other users to establish a pressure technique by accumulation for their own technical field.
To ensure safety when transporting dangerous goods, it is important to specify the flow properties of the respective solid filling substance of the packagings. For this purpose, the angle of repose is currently used for the UN approvals in Germany. Measurements were carried out on 12 powdery or granular substances applying the angle of repose measuring methods customary in the test centres. The results of the methods differ significantly from each other. In addition, some of the techniques cannot be applied for very cohesive or coarse-grained materials. The results for the angle of repose show a strong scatter for some constellations (coefficient of variation more than 20 %). Safety during transport of dangerous goods cannot be guaranteed with this currently practiced system of measuring the angle of repose. As a consequence, an alternative parameter to characterize the flow properties of bulk materials should be used in the recognized test centers for dangerous goods packagings, such as the Hausner ratio. This approach leads to more precise test results for the substances examined (maximum coefficient of variation 2.8 %). It also has advantages in terms of applicability and occupational safety.
Since the flow properties are safety-relevant, both in terms of mechanical safety and safety against the release of dangerous substances, the testing practice in the recognized test labs should be improved and standardized.
To ensure safety when transporting dangerous goods, it is important to specify the flow properties of the respective solid filling substance of the packagings. For this purpose, the angle of repose is currently used for the UN approvals in Germany. Measurements were carried out on 12 powdery or granular substances applying the angle of repose measuring methods customary in the test centres. The results of the methods differ significantly from each other. In addition, some of the techniques cannot be applied for very cohesive or coarse-grained materials. The results for the angle of repose show a strong scatter for some constellations (coefficient of variation more than 20 %). Safety during transport of dangerous goods cannot be guaranteed with this currently practiced system of measuring the angle of repose. As a consequence, an alternative parameter to characterize the flow properties of bulk materials should be used in the recognized test centers for dangerous goods packagings, such as the Hausner ratio. This approach leads to more precise test results for the substances examined (maximum coefficient of variation 2.8 %). It also has advantages in terms of applicability and occupational safety.
Since the flow properties are safety-relevant, both in terms of mechanical safety and safety against the release of dangerous substances, the testing practice in the recognized test labs should be improved and standardized.
Fazit:
Nachteile der Schüttwinkel-Messmethoden:
Einschränkungen bei der Anwendbarkeit auf Füllgüter mit bestimmten Eigenschaften;
Die einzelnen Methoden liefern dann unterschiedliche Ergebnisse (statist. signifikante Abweichung der Mittelwerte);
Schlechte Wiederholbarkeit;
Bedienereinfluss spielt Rolle;
Gewährleistung des Arbeitsschutzes schwierig;
Bestimmung des Hausner-Faktors:
Keins dieser Defizite
Mögliche Abhilfemaßnahmen:
Prüfbericht und Zulassungsschein sollten zumindest die Methode angeben, die zur Messung des Schüttwinkels 𝛼 eingesetzt wurde;
Einheitliches Verfahren zur Schüttwinkelmessung (DIN-Methode)?
Umstellung des Systems auf einen alternativen Parameter zur Bestimmung der Fließeigenschaften:
Hausner-Faktor 𝐻:
Bessere Wiederholbarkeit der Ergebnisse;
Zuverlässige Anwendbarkeit auch auf Extremfälle von Schüttgütern;
Sicherere Handhabung von Gefahrgütern
Packagings for the transport of dangerous goods need to meet special requirements to get an approval. This includes free fall drop testing onto an essentially unyielding surface as a means to assess a package’s resistance to mechanical damage. A main requirement for drop tests is that the impact target’s mass shall be at least 50 times that of the heaviest package to be tested. Nevertheless, many manufacturers do not possess foundation structures with the required mass ratio. Previous evidence highlights that the mass ratio is not a decisive criterion on its own. Parameters such as the impact target foundation’s connection and the impulse experienced by the impacting object are essential as well. However, these factors are not easily verifiable since experimental measurements are not possible at most facilities. The objective of this work is to provide a detailed analysis on the interaction between impact target foundation and subgrade in dynamic impact testing using validated finite-element (FE) models. This research is highly beneficial for industrial application since it allows manufacturers to make informed predictions about the mechanical response of installed impact target foundations.
Untersuchung der stoßartigen Freisetzung pulverförmiger Füllgüter aus Ventilsäcken für Gefahrgüter mit Innenventil. Fallprüfungen an einem Papiersack 5M2 mit zwei Füllgütern (Esplas H130 und Zinkoxid). Variation von Ventillänge, Fallhöhe und Füllgrad in Kombination mit der Anzahl der Fallversuche pro Prüfmuster. Bei Esplas H 130 war ein Pulveraustritt aus den Klebestellen bereits beim Befüllen zu verzeichnen. Dies ist ein Widerspruch zu UN 6.1.4.18.1 (Staubdichheit). Bei beiden Substanzen waren die Ventile aller Prüfmuster nach der Fallprüfung nicht mehr staubdicht. Es wird auf erste mögliche Lösungsvorschläge eingegangen.
Untersuchung der stoßartigen Freisetzung pulverförmiger Füllgüter aus Ventilsäcken für Gefahrgüter mit Innenventil. Fallprüfungen an einem Papiersack 5M2 mit zwei Füllgütern (Esplas H130 und Zinkoxid). Variation von Ventillänge, Fallhöhe und Füllgrad in Kombination mit der Anzahl der Fallversuche pro Prüfmuster. Bei Esplas H 130 war ein Pulveraustritt aus den Klebestellen bereits beim Befüllen zu verzeichnen. Dies ist ein Widerspruch zu UN 6.1.4.18.1 (Staubdichheit). Bei beiden Substanzen waren die Ventile aller Prüfmuster nach der Fallprüfung nicht mehr staubdicht. Es wird auf erste mögliche Lösungsvorschläge eingegangen.