Every package of dangerous goods carries a fixed set of markings so that handlers, responders and inspectors can read the contents and the packaging’s performance level without paperwork.
The standard marking set (5.2.1)
- UN number prefixed
UN— the general rule for every package, minimum height 12 mm for packages > 30 L or > 30 kg, 6 mm for 5–30 L/kg and for gas cylinders of up to 60 L water capacity, proportionate to package size for smaller ones (5.2.1.1) - Proper shipping name — not a general package requirement. It appears only where ADR specifically prescribes it, e.g. for Class 1 goods (5.2.1.5) and on refillable gas receptacles of Class 2 (5.2.1.6)
- UN packaging code (6.1.3) certifying the packaging construction — e.g.
1A1/Y1.4/250/23/NL/ABCfor a non-removable-head steel drum rated for PG II/III liquids up to relative density 1.4, hydraulic test pressure 250 kPa, manufactured in 2023, mark authorized by the Netherlands, manufacturer code ABC
Additional marks by substance type
- Orientation arrows (5.2.1.10.1) — two arrows on opposite vertical sides, pointing up — on combination packagings whose inner packagings contain liquids, on single packagings fitted with vents and on cryogenic receptacles. Not required on outer packagings containing pressure receptacles other than cryogenic ones, on outer packagings whose inner packagings each hold not more than 120 ml with enough absorbent material between them, on outer packagings whose hermetically sealed inner packagings hold not more than 500 ml, or on articles that are leak-tight in any orientation such as thermometers and aerosols (5.2.1.10.2).
- Environmental hazard mark (5.2.1.8) — fish-and-tree pictogram for marine-polluting or environmentally hazardous substances (UN 3077, UN 3082, and any substance meeting 2.2.9.1.10 criteria). Not required when a single packaging, or the inner packaging of a combination packaging, holds ≤ 5 L (liquid) or ≤ 5 kg (solid).
- Battery mark (5.2.1.9) — on packages of lithium cells or batteries and of sodium ion cells or batteries prepared in accordance with special provision 188 or 400 of Chapter 3.3. The mark shows the UN number — UN 3090/3091/3480/3481 for lithium, UN 3551/3552 for sodium ion. Consignments carried under the full regime instead bear label model 9A from Column (5) of Table A.
Legibility (5.2.1.2) — marks must be readily visible, legible and able to withstand open weather exposure. Labels are placed so that no part or attachment of the packaging and no other label or mark covers or obscures them (5.2.2.1.6).
Salvage packaging (5.2.1.3) — in addition to the other marks, the word SALVAGE in lettering at least 12 mm high.
Common mistake — printing the UN number on a sticker below the required height “because the box is small.” 5.2.1.1 ties minimum height to package size — a 200 L drum always needs at least 12 mm. Roadside inspectors measure, and undersized markings are a non-conformity.
References — ADR 2025 5.2.1 (package marking), 5.2.1.1 (UN number height), 5.2.1.8 (environmental hazard mark), 5.2.1.9 (battery mark), 5.2.1.10 (orientation arrows), 6.1.3 (UN packaging code).