C&G Safety & Environmental Limited

What are Dangerous Goods?

Goods dangerous for transport are grouped into nine main United Nations hazard classes according to their properties. Some of these classes are further sub-grouped into nine divisions:

• Class 1    Explosive
• Class 2    Gases
• Class 3    Flammable liquids
• Class 4    Other flammables
• Class 5    Oxidising and organic peroxides
• Class 6    Toxic and infectious
• Class 7    Radioactive
• Class 8    Corrosive
• Class 9    Miscellaneous

International Agreements - The UN recommendations

Transportation legislation follows in principle, but not always in detail, the UN Recommendations and Model Regulations (the Orange Book) whose principle of identifying each hazardous substance with a UN Number and specifying for each their principal and subsidiary hazard classes and packing groups has been adopted by all modes of transport, road, rail, air, sea and inland waterways. Although great efforts have been made to harmonize these various modal regulations, there still remain difference between them. The Orange Book contains recommendations for the transport regulators to take into account when framing their regulations, but do not in themselves have any force of law.

The nine classes (some of which are sub-divided into divisions, eg. 6.1 toxic substances) reflect the chief danger each substance presents; there may also be 'subsidiary risks'. Each class or division has a diamond-shaped label with a pictorial representation of the danger. The level of danger is indicated by the Packing Group - PGI is high danger, PGII medium danger and PGIII low danger. The packing groups form the basis of the allocation of Transport Categories (0 – 4 where Transport categories 1, 2 and 3 correspond in general with the UN packing group but note that this is not a universal rule).

Dangerous goods within the UN classes 1 – 9 are mostly chemicals, either individually named substances eg. 'Tetrachloroethylene', or generic descriptions eg. 'Flammable liquid N.O.S.' (Not Otherwise Specified) but also articles eg. 'Matches, safety'. The criteria for classification in the various UN classes are largely harmonised between the transport modes, for example flammable liquids, class 3 are defined (with some exceptions) as those having a flash point not exceeding 60°C and the initial boiling point will determine the appropriate packing group (and hence the Transport Category). These criteria allow the correct classification of goods which are not individually named. There are procedures for correctly classifying materials possessing multiple hazards.

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