The Overpack That Hid a Conflict
A shipper presents an overpack containing three inner packages: one package of UN1263 Paint, Class 3, PG II, 4 L; one package of UN1993 Flammable liquid, n.o.s., Class 3, PG III, 6 L; and one package of UN3082 Environmentally hazardous substance, liquid, n.o.s., Class 9, PG III, 5 L. The overpack is marked with the UN number and proper shipping name of the paint only, and bears a Class 3 label. The shipper states that because the paint is the 'primary' dangerous good, the overpack marking is sufficient. The overpack is to be carried on a passenger aircraft. The inner packages are packed in accordance with their respective packing instructions, and the total net quantity of Class 3 liquids is 10 L.
1. Assess whether the overpack marking and labelling comply with the DGR, and identify what must be corrected.
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The overpack marking is non-compliant. When dangerous goods of different UN numbers are packed in an overpack, the overpack must be marked with:
- The UN number and proper shipping name of each dangerous good contained, or the words 'Overpack' plus the required information for each item.
- The Class 3 label for the flammable liquids AND the Class 9 label for the environmentally hazardous substance.
- The orientation arrows if the inner packages contain liquids.
The shipper's 'primary dangerous good' theory has no basis in the DGR. Every dangerous good in the overpack must be reflected. In addition, the overpack must show the total quantity of dangerous goods where required, and the shipper must ensure the overpack is not used to circumvent per-package quantity limits.
2. Determine whether the overpack can travel on a passenger aircraft and calculate the relevant quantity.
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The Class 3 liquids total 10 L net. For passenger aircraft, the per-package limit for UN1263 PG II is 5 L, and for UN1993 PG III it is 60 L. However, the overpack is treated as a single package for the purpose of quantity limits. That means the combined Class 3 content of 10 L must be compared against the most restrictive applicable limit - 5 L for the PG II paint. Since 10 L exceeds 5 L, the overpack cannot be carried on a passenger aircraft as assembled.
The Class 9 UN3082 content (5 L) is within its passenger limit, but the Class 3 content is the binding constraint. The shipper must either split the overpack so that the PG II paint is in its own package of 5 L or less, or move the shipment to a cargo aircraft. This is the trap: the shipper looked only at the paint's own package, ignoring that the overpack aggregates the contents.