Dangerous goods marks: specific details and requirements
Correct dangerous goods marking starts with classification and the way the goods will be carried. The same substance in drums, a freight container or a tank may require different external identification. Copying a tank vehicle’s marking arrangement onto a curtain-sided truck can produce the wrong result.
This article covers the road leg under ADR 2025, the edition applicable at the source check on 29 October 2026. When arranging dangerous goods transport, packaging, markings, documentation and the vehicle must each be checked. An orange plate alone does not demonstrate that a shipment is ready to move.
Establish the goods information before selecting labels
Identify the UN number, proper shipping name, class, subsidiary hazards and packing group where assigned. Physical state, packaging type, method of carriage and applicable special provisions also matter. A trade description such as “solvent” or “reagent” is insufficient.
Section 14 of the current Safety Data Sheet provides useful starting information but does not replace verification of the transport classification. If the SDS, invoice and actual product composition disagree, resolve the classification with the supplier first. Adding a label “just in case” is not a sound approach: excessive or incorrect marking can also mislead everyone handling the shipment.
Check the specific entry in ADR Table A. Column 5 identifies the hazard label models, while column 6 lists special provisions that may affect preparation.
Distinguish marks, labels and packaging approval
The letters UN followed by a four-digit number identify the dangerous goods. A diamond-shaped hazard label communicates the relevant hazard. A packaging approval mark, such as a code containing the UN packaging symbol and packaging type, relates to the tested packaging itself. It does not replace the product’s UN number.
GHS/CLP pictograms on a chemical product label are not an automatic substitute for ADR transport labels. Their purposes and application rules differ. In chemical logistics, check each system where applicable rather than choosing one label for every purpose.
Level | Main identification | Typical error |
|---|---|---|
Package containing dangerous goods | UN number, required hazard labels and additional marks where applicable | Only the product label or packaging approval code is present |
Freight container | Placards appropriate to its contents and the applicable transport regime | Placards appear only on the doors |
Transport unit | Orange plates; placards and numbered plates in the prescribed cases | A tank vehicle’s arrangement is copied onto every truck |
Package labelling requirements
The standard minimum size of a package hazard label is 100 × 100 mm. ADR allows specific exceptions, including provisions for small packages. Marks and labels must remain visible, legible and weather-resistant. Tape, securing straps and carrier labels must not obscure them.
The UN number is preceded by the letters “UN”. The general minimum character height is 12 mm, with different requirements for specified smaller packages. Label design should therefore follow the rule, not simply the largest font that fits a chosen sticker. IBCs with a capacity exceeding 450 litres and large packagings must carry the applicable marks and labels on two opposite sides.
A subsidiary hazard cannot be omitted to simplify the label. For example, UN 1230 METHANOL is assigned labels 3 and 6.1 in Table A: flammable liquid and toxic hazard. A flame label alone does not provide the complete required set.
The environmentally hazardous substance mark and orientation arrows have their own conditions of application. Where required, orientation arrows appear on two opposite vertical sides. They are not automatically mandatory on every drum containing liquid.
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Figure 1. UN 1230 example under full ADR. The UN number and labels 3 and 6.1 are shown; this is not a complete checklist for a particular package. Basis: Table A, 5.1.2 and 5.2 of ADR 2025.
Label models: ADR 2025, 5.2.2.2.2, © United Nations 2024. Educational diagrams, not artwork for printing signs.
Wrapped pallets and OVERPACK requirements
A pallet containing several packages secured together by wrapping or another method may constitute an overpack. It does not turn the inner packages into a newly approved packaging type or remove the requirements applying to each one.
If the marks and labels representative of all the contents are not visible externally, the required identification must be reproduced on the overpack and the word OVERPACK displayed. Its letters must be at least 12 mm high; ADR 5.1.2.1 specifies the language requirements. Identical labels do not need to be repeated for every inner box, but all applicable hazards must be represented.
Orientation arrows must also be reproduced externally where required. Check the finished unit after wrapping: even transparent film can reflect light, and several layers may obscure the identification. For packaged cargo transport, photographs of the completed pallet immediately before loading provide a useful record.
Packaged goods on a vehicle and inside a freight container
For ordinary carriage of packages in classes such as 3 or 6.1 under the full ADR requirements, orange plates are required at the front and rear of the transport unit. In the typical case, these plates are unnumbered. Large hazard diamonds on the sides and rear of such a curtain-sided vehicle do not become mandatory merely because it carries dangerous goods packages. Classes 1 and 7 have separate provisions and exceptions.
A freight container has a different arrangement. The appropriate placards are displayed on both sides and both ends: four faces in total. If the required container placards are not visible outside the carrying vehicle, corresponding placards must also be displayed on both sides and at the rear of the vehicle. The transport unit’s orange plates must be checked separately.
This distinction matters in road container transport: identification on the inner packages, the container and the vehicle serves different purposes. The general minimum placard size is 250 × 250 mm, subject to the exceptions specified in ADR.
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Figure 2. Identification for packages of UN 1230. A vehicle carrying the container also requires the applicable orange plates; obscured container placards are repeated under 5.3.1.3. Basis: 5.3.1 and 5.3.2 of ADR 2025.
Label models: ADR 2025, 5.2.2.2.2, © United Nations 2024. Educational diagrams, not artwork for printing signs.
Tanks, bulk carriage and orange plates
Tank vehicle transport and carriage in bulk have separate placarding and numbered-plate arrangements. The substance, number of compartments and whether one or several dangerous goods are carried all matter. A single-compartment tank’s arrangement cannot simply be transferred to a multi-compartment vehicle.
On a numbered orange plate, the hazard identification number appears above the UN number. The upper number is not merely the class number. Use the identification assigned by ADR; do not construct a number yourself. Placement must follow section 5.3.2, taking account of the permitted alternatives.
A standard orange plate measures 400 × 300 mm. Reduced dimensions are permitted only under specified conditions, for example where the vehicle’s size and construction leave insufficient surface for a standard plate. A small sticker placed wherever convenient is not a universal substitute.
Class 5, special regimes and empty packaging
Distinguish division 5.1, oxidizing substances, from division 5.2, organic peroxides. They use different labels. “Bleach” is a household or trade description, not enough information to establish a transport classification without knowing the composition and relevant classification.
Batteries create another common source of confusion. The special 9A label is used on the relevant packages, but the class 9 placard is model 9, not an enlarged 9A label. Check the particular goods entry and method of carriage to establish the correct set.
Limited and excepted quantities, LQ and EQ, have their own marking requirements. These are distinct regimes, not permission to leave packages unidentified. The 1,000-point rule under 1.1.3.6 does not remove all requirements either: applicable package marks and hazard labels remain required. Quantity calculations and selection of the correct labels are separate checks.
Empty but uncleaned packaging or a tank may still contain dangerous residues. It must not automatically be treated as ordinary empty equipment with all identification removed. Conversely, marks and placards that no longer relate to the goods or residues must be removed or covered as required by the rules.
A check before the vehicle arrives
1. Match the UN number, proper shipping name, primary hazard and subsidiary hazards to the current product information.
2. Inspect each package for the required marks and labels, their size, condition and visibility.
3. Inspect finished pallets and overpacks after wrapping and securing.
4. Establish the correct arrangement for the vehicle, container, tank or bulk carriage.
5. Compare the identification with the transport document and check for obsolete or unnecessary signs.
6. Keep photographs and resolve discrepancies before the journey starts.
For example, drums of methanol carried under the full ADR requirements need the appropriate package identification. The typical external arrangement on a curtain-sided vehicle differs from carriage of the same drums inside a freight container: the latter also requires the relevant container placards on four faces. This is an educational comparison, not a universal instruction for every quantity of methanol.
The consignor, packer and carrier have their own ADR duties; a contractual agreement does not remove them. If the route continues by sea or air, check the documents, packaging and identification against the requirements for that mode as well.
To coordinate an enquiry with Save Pro Solutions, send the current SDS, UN number, packaging types and quantities, mass, photographs of the prepared goods and the route. These details allow the transport requirements to be compared with the actual shipment before the vehicle arrives.
