Release of powdery or granular substances from intact dangerous goods bags during road transport—Analysis of the causes and development of a test concept

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 analyses 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.

Flow properties of powdery or granular filling substances of dangerous goods packagings—Comparison of the measurement of the angle of repose and the determination of the Hausner ratio

“…In the case of German approvals for packagings for solid dangerous goods, the test report and the certificate of approval must also indicate the minimum angle of repose of the filling substances for which the packaging may be used 2 . In this context, the angle of repose serves as a parameter to describe the flow behaviour of a bulk material.…”

“…On the one hand, the weak points of the packaging play a role, but on the other hand, also properties of the powdery or granular substance, such as the flow properties. In the case of a powder with good flowability, powder can emerge from insufficiently pasted joins already during manual filling 2,6 …”

“…Reports from practice of dangerous goods controls show that dangerous goods are repeatedly released during transport from packagings that are actually intact 2,7,8 . Figure 1 shows the release of a flammable solid of UN No.…”

“…In the case of German approvals for packagings for solid dangerous goods, the test report and the certificate of approval must also indicate the minimum angle of repose of the filling substances for which the packaging may be used. 2 In this context, the angle of repose serves as a parameter to describe the flow behaviour of a bulk material. The user must ensure that only those filling substances are transported in the approved packaging whose angle of repose is higher than the angle of repose specified in the approval according to the design type test report.…”

“…In the case of a powder with good flowability, powder can emerge from insufficiently pasted joins already during manual filling. 2,6 Reports from practice of dangerous goods controls show that dangerous goods are repeatedly released during transport from packagings that are actually intact. 2,7,8 Figure 1 shows the release of a flammable solid of UN No.…”