Leakproofness of dangerous goods packagings—comparison of worst‐case limit leakage rates and sensitivity of the bubble test

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.     

Permeation Through Plastic Dangerous Goods Packaging During Transport in Freight Containers – Detection of Potentially Explosive Mixtures in Containers Under Normal Conditions of Carriage

The key point within the scope of this research project was to find out whether there was a risk of creating an explosive atmosphere by permeation of flammable liquid compounds during transport of dangerous goods in freight containers under normal conditions of carriage. Therefore, all aspects that had an influence on the formation of such an atmosphere had to be considered. The most important influencing factors were permeation, air change in the freight container and ambient temperature. The first step was to investigate the permeation with different packaging materials, charge and temperatures. Furthermore, the air change rates of different freight containers were measured. A few climate tests with containers on ships, e.g. to Singapore, were performed to assess normal conditions of carriage. Another important point was measuring the solvent (toluene) concentration in the gas phase in a freight container loaded with plastic intermediate bulk containers (IBCs) filled with toluene. To confirm that the measured values were in the right range, the toluene concentration in the gas phase in a container was calculated with different packaging materials, air change rates and temperatures. The results of the measurements and calculations have shown that safety layers in the packaging wall, e.g. the copolymer of ethylene and vinyl alcohol (EVOH) and polyamide, can reduce the rate of permeation by more than a decimal power, but the lower explosive limit of toluene is easily reached within a few hours at 40°C charge temperature if there is no barrier. Copyright © 2012 John Wiley & Sons, Ltd.     

Maximum Gauge Pressure in Dangerous Goods Packagings Under Normal Conditions of Carriage – Comparison of Direct Measurement and Calculation

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). Copyright © 2014 John Wiley & Sons, Ltd.     

Sift‐proofness of Dangerous Goods Packagings – An Incompletely Defined Requirement

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 sift‐proofness. There is a need for systematical investigations of the sift‐proofness of dangerous goods packagings. Copyright © 2017 John Wiley & Sons, Ltd.     

Industrial leak testing of dangerous goods packagings

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 meet the requirements of the bubble test with regard to important criteria. Sensitivity, flow direction, pressure level and automatability are particularly important factors when selecting a suitable industrial leak testing method. The following methods are in principle both 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. This requires, on the one hand, information about the sensitivity of the bubble test and, on the other hand, the inclusion of a list of suitable, equally effective industrial test methods with their specific boundary conditions.     

Validation of an Alternative Method for Testing the Chemical Compatibility of Liquids with Polyethylene Packagings for Dangerous Goods

Safety risks may ensue when the chemicals contained in polyethylene packagings ^a age and damage them. To prevent subsequent accidents, the European Dangerous Goods Regulations have laid down requirements for testing the chemical compatibility of liquid dangerous goods transported in polyethylene packagings. The test procedures include 6 months in which the chemical is prestored in the packaging. After this time, the respective design‐type tests are performed. Alternative methods with so‐called standard liquids, simulating the different types of damaging effects, are also possible. If a packaging has successfully passed the design type tests with a standard liquid, other dangerous goods may also be transported in this packaging, as long as it is demonstrated that they have a less damaging effect than the standard liquid. However, in this area there is only little information and research available. A new potentially effective and time‐saving method for comparing the stress crack damaging influence of liquids with standard liquids was proposed by a major German chemical company. The validation of this method, which was carried out on two polyethylene materials, showed the general applicability of the method. Two kinds of wetting solutions were applied to simulate cracking under stress. The influence of prestorage, test temperatures, wetting agents and material was examined. FEM calculations were carried out to ascertain the influence of the sample shape. Copyright © 2012 John Wiley & Sons, Ltd.     

The effectiveness of the United Nations' leakproofness tests

The regulations for the packaging of dangerous goods, which are applicable world-wide for the various modes of transport, include performance tests. It is impossible to conduct laboratory tests for every environmental condition, but the tests can produce a conservative estimate of the situation during transport. This paper analyses the so-called leakproofness test as one of the design-type tests for packagings covered by the United Nations' (UN) recommendations for dangerous goods.     

Experimental Investigations Concerning the Sensitivity of the Leakproofness Test for Dangerous Goods Packagings Relating to the Leak Diameter

The objective of this experiment was to verify that in regards to the leakproofness bubble test for packagings of dangerous goods, a reduction of the air overpressure from 0.2 to 0.1 bar can be compensated for by reducing the water surface tension to a value of approximately 33.2 mN/m by adding a wetting agent. It was experimentally proven that this method will yield the same leak diameters. This is important to avoid irreversible deformations during the leaktesting of intermediate bulk containers (IBCs) while using a test overpressure of 0.2 bar. Bubble test experiments were carried out on artificial borehole‐shaped leaks manufactured of two different materials high density polyethylene (HDPE) and stainless steel by ultrashort pulse laser technology and with two different immersion test liquids (deionized water and a 0.1% Lutensol FSA fabric softener active 10 solution). The characteristic diameters of the boreholes investigated were from 11.5 to 30.3 µm in length. Copyright © 2013 John Wiley & Sons, Ltd.     

The importance of the compression test procedure for plastic drums for dangerous goods

Packagings for the transport of dangerous goods are tested by four tests:- free fall, leakproofness, hydraulic pressure and stacking. However, the test procedures can be interpreted in different ways, particularly the stacking test. Some test authorities apply a guided load to the top of the package and others, including the LNE in France, use non-guided loads. The objective of recent research carried out at LNE was to evaluate the risk (in terms of stack stability for dangerous goods packagings) if the stacking tests are performed with guided loads rather than non-guided loads. The stacking tests were carried out on a limited number of plastic drums (200 of four types) submitted for qualification testing using the above four tests, with either guided or non-guided loads. From the results we conclude that:

• i for the transport of dangerous goods of Danger Group I, the field of use is not altered when tested by either procedure.
• ii with goods of Danger Groups II and III, the use of either procedure does not alter the position as far as transport is concerned. However, there is a risk in warehousing: the non-guided procedure being preferred.

     

Helium‐Testlecks

Helium test leaks Leak localization and tightness control with Helium provides a very sensitive testing method. Frequently, the sensitivity of a leak has to be testspecified quantitatively. In particular, quality control requires a reliable verification of the sensitivity. For this purpose, test leaks with well‐known leakage are used. In the article, various types of test leaks and their properties are described. Test leaks are commercially available over a wide range of leak rates. Their leakage flow can be calibrated with good accuracy. In the usage of the test leaks, the temperature‐dependency of the leak rate has to be taken into account, as well as the slow decrease of the leak rate due to the continuous loss of gas from the reservoir.     

Helium‐Testlecks zur Kalibrierung von Lecksuchern

In order to perform reliable quantitative measurements of leak rates, the used leak detection equipment is calibrated by injection of a known leakage flow delivered by a test leak. Well‐proven are Helium test leaks of the diffusion type with internal gas reservoir. The present paper deals with the construction of such leaks, the temperature dependence and response time of the leak rate, and their calibration. In case of careful handling, the relative uncertainty of the delivered leakage flow can amount to only 3 % (2σ).     

Developments in plastics packaging for the transport of dangerous goods

Several interesting developments in plastics packagings and intermediate bulk containers (IBCs) for the transport of dangerous goods are of importance. Significant developments include the application of new materials and packaging concepts, the increasing re‐use of packaging and the possibility of the application of recycled material. How these developments have influenced or should influence the UN recommendations and regulations on the transport of dangerous goods is discussed. Further, the role of CEN and ISO standards, which are under development, is indicated. In this context, the European project CHEMPACK funded by the EC within the framework of the Standards, Measurements and Testing programme, is outlined. This project is executed in cooperation with raw materials manufacturers, packaging/IBC manufacturers and research institutes, and is coordinated by TNO. The aim of the project is to develop harmonized test methods and procedures for the assessment of the chemical compatibility of plastics packagings and IBCs. Copyright © 1999 John Wiley & Sons, Ltd.     

Compatibility of High‐Density Polyethylene Grades with Biofuels

The aim of this work was to study the interaction between high‐density polyethylene (HDPE) grades as material for dangerous goods packagings and biofuels such as E85 and biodiesel. Jerricans made of two polyethylene (PE) grades were filled with these fuels and exposed to temperatures of 20°C and 40°C for 1 year. Tensile properties (tensile strength, breaking elongation and elasticity modulus) and melt flow rate (MFR) were determined once a month, and Fourier transform infrared (FTIR) spectroscopy was used to evaluate changes in the chemical structure. Measurements of the MFR and tensile properties of the PE grades after 1 year of exposure to E85 showed only a slightly damaging influence. An increase in the peak of 1585 cm^‐1 (C=C) stretching vibrations is visible in the FTIR spectra after the immersion tests with E85. Therefore, packagings made of HDPE grades are suitable for the transport of E85. An increase in the MFR with immersion time of the grades in biodiesel was measured, in particular, after 1 year of exposure. The elasticity modulus of the PE grades was reduced with immersion time. The FTIR spectra showed a broadening of the C?O peak of 1740 cm^‐1 and the appearance of the hydroxyl group at 3500 cm^‐1. Both results are explained by secondary degradation products of the PE decomposition process caused by increasing unsaturated fatty acid content in the biodiesel. In light of the above mentioned, it was concluded that HDPE grades are not suitable as packaging materials for the transport of biodiesel. Copyright © 2013 John Wiley & Sons, Ltd.     

Explosion protection for vehicles intended for the transport of flammable gases and liquids--an investigation into technical and operational basics

In Europe, the transport of flammable gases and liquids in tanks has been impacted by new developments: for example, the introduction of the vapour-balancing technique on a broad scale and the steady increase in the application of electronic components with their own power sources; furthermore, new regulatory policies like the ATEX Directives are being enforced in the European Union. With this background in mind, the present investigation aims to provide a basis for future developments of the relevant explosion protection regulations in the safety codes for the transport of dangerous goods (RID/ADR). Specifically, the concentration of gas in the air was measured under various practical conditions while tank vehicles were being loaded with flammable gases or liquids. These spot-test data were supplemented by systematic investigations at a road tanker placed in our test field. With respect to non-electrical ignition sources, a closer investigation of the effect of hot surfaces was carried out. With regard to improving the current regulations, the results of our investigation show that it would be reasonable to implement a stronger differentiation of the characteristics of the dangerous goods (gaseous/liquid, flashpoint) on the one hand and of the techniques applied (loading with and without vapour-balancing system) on the other hand. Conclusions for the further development of the current international regulations are proposed.     

Quantification of the UN leakproofness test method

In this paper a theoretical model is described for the UN leakproofness test, which is one of the test methods of the UN test programme for the type testing of packaging for liquids for the transport of dangerous goods. The test is also required for every single packaging produced. Quantification was thought necessary in order to be able to evaluate production line leakproofness test methods which should be as effective. The model was verified with an experimental programme which was performed with leaks of the pinhole type. The results show that the process of bubble formation and flow of the UN leakproofness test method can be modelled assuming laminar flow and taking into account capillary pressure and bubble frequency. For a leak of the pinhole type and a realistic set of parameters the detection limit of the method can be indicated as being in the order of 20 μm of hole diameter. It is discussed whether analysis of the concept of leakproofness testing might be necessary.     

可燃制冷剂R32室内空调器泄漏扩散特性的实验研究

制冷剂R32具有良好的环保特性和热工性能,但其可燃性限制了它的应用推广,因此需要对R32的安全性进行分析。实验研究了分体壁挂式空调用制冷剂R32在空调运行时,蒸发器不同泄漏位置和不同泄漏速度对室内R32浓度分布的影响,得出R32在空调运行时的泄漏扩散特性。研究表明:可燃性制冷剂R32在室内机蒸发器处发生泄漏时,泄漏过程可分为快速泄漏阶段和低速泄漏阶段;蒸发器出口泄漏比蒸发器入口泄漏危险性高;仅在蒸发器出口大流量泄漏时,室内机附近区域R32浓度最大值为16.79%,超过可燃下限(14.4%)16.6%。可燃浓度持续了22 s,存在着火的可能性,但概率较低;排风作用对各测点的浓度衰减影响强烈,可有效降低室内R32的浓度。     

Influence of the length of the internal sleeve valve on the release of powdery substances from the closures of valved bags for dangerous goods

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.     

Large‐Scale Roll‐to‐Roll Patterned Oxygen Indicators for Modified Atmosphere Packages

We demonstrate roll‐to‐roll fabrication of ultraviolet A light‐activated colorimetric oxygen indicators on paper and plastic substrates. Such large‐scale, cost‐effective and non‐toxic oxygen indicator and production method can find applications as a very low‐cost leakage indicator for modified atmosphere packages by printing the material directly or gluing the pre‐printed indicator label inside the lid. The introduction of leakage indicators onto all modified atmosphere packages could result in improved food safety and reduced food spoilage. Copyright © 2017 John Wiley & Sons, Ltd.     

出口锂电池危险品运输包装的安全设计与防护

目的研究出口锂电池危险品运输包装的设计要素和防护措施。方法针对出口锂电池危险品的特性,系统总结国际技术法规对于锂电池运输包装的安全规范,并比较分析国际海运危险货物运输规则(IMDG CODE)和国际航空运输协会危险品运输规则(IATA DGR)中的特定指引要求。依据跌落试验、堆码试验的物理性能指标的设计,研究出口锂电池危险品运输包装的物理安全性能。结果提出了保证出口锂电池危险品运输包装安全的建议,同时基于此类危险品包装的整体安全设计和单元防护,提出了锂电池组合包装、有效防短路保护、塑胶外壳防护等安全要素优化方案。结论研究提出的安全设计要素和防护措施,可以为锂电池危险品运输包装的安全防护提供重要的实践指导。     

Comparison of the Material Parameters of Polyethylene Grades with the Test Performance Behaviour of Packagings for the Transport of Dangerous Goods in Relation to the Pre‐Storage Time with 55% Nitric Acid

The material parameters melt flow rate (MFR), density (D), notched impact strength (NIS) at –30°C, stress crack resistance [determined with the Full Notch Creep Test (FNCT)] and resistance to oxidative degradation (Ox) have been selected for a comparison of polyethylene grades in the European standard EN 15507. These parameters have a relationship with design type tests of packagings for the transport of dangerous goods. This paper presents the results of additional investigations to determine the impact of the pre‐storage time of jerricans with 55% nitric acid at 40°C and 23°C on the marginal drop heights in drop tests at –18°C, on the MFR and on the tensile properties. Jerricans made of different polyethylene grades were pre‐stored with 55% nitric acid for 21, 42 and 84 days at 40°C and for six months at 23°C. The tests showed that the NIS values at –30°C of polyethylene grades were not comparable with marginal drop heights determined in drop tests at –18°C. Pre‐damage with 55% nitric acid for 21 days at 40°C led to an increase in the marginal drop heights of the jerricans. Altering the test regulations by increasing pre‐storage time with 55% nitric acid to 42 days would be an alternative. The test results demonstrated clearly that pre‐storage of the jerricans for six months at 23°C caused a higher increase in the MFR and lower marginal drop heights for the jerricans when compared with pre‐stored jerricans for 21 days at 40°C. Copyright © 2013 John Wiley & Sons, Ltd.