Classification and hazards
The classes, the packing groups and the properties that determine how dangerous goods are classified and which hazards have to be communicated.
Auto-ignition Temperature (°C)
Lowest temperature at which a substance ignites spontaneously in a normal atmosphere without an external source of ignition.
Class
A category of dangerous goods according to the predominant hazard they present, numbered 1 to 9 (1 Explosives; 2 Gases; 3 Flammable liquids; 4.1, 4.2, 4.3 Flammable solids; 5.1 Oxidizing substances; 5.2 Organic peroxides; 6.1 Toxic; 6.2 Infectious; 7 Radioactive; 8 Corrosive; 9 Miscellaneous).
Compatibility Group
Letter (A-N, S) identifying the compatibility group of explosive substances and articles of Class 1, used in classification (e.g. 1.1A) and in segregation provisions.
Environmentally Hazardous
Mark indicating substances that are environmentally hazardous (e.g. marine pollutants), required when the substance meets the criteria of UN 3077 or UN 3082 or is classified as a marine pollutant.
Flash-point
Lowest temperature of a liquid at which its vapours form a flammable mixture with air. Closed-cup measurement is the reference method.
Forbidden
Status of a substance whose carriage is forbidden under the relevant regulation (forbidden entry in the Dangerous Goods List).
Hazard Number
Hazard identification number (Kemler code) shown on orange-coloured plates for tank or bulk carriage, indicating the principal hazards of the substance carried.
Marine Pollutant
A substance or mixture identified as hazardous to the aquatic environment and subject to additional marking, documentation and stowage requirements for carriage.
Packing Group
A group to which, for packing purposes, certain substances may be assigned according to their degree of danger: I great danger, II medium danger, III minor danger.
Segregation
Separation to be maintained between dangerous goods that react dangerously with one another. The IMDG Code establishes four degrees of separation between packages, from away from to separated longitudinally by an intervening complete compartment or hold from, while ADR expresses the same principle as mixed loading prohibitions.
Segregation Group
Grouping of dangerous goods having certain similar chemical properties IMDG (SGG1 to SGG18) and used for stowage segregation purposes.
Stowage category
Category assigned in column 16a of the IMDG Code dangerous goods list, from A to E for packaged goods, which determines where the goods may be stowed on board, on deck or under deck, and whether carriage on passenger ships is permitted.
Subsidiary Hazard
An additional hazard exhibited by a dangerous substance or article in addition to its primary hazard, indicated by the subsidiary hazard label and a Dangerous Goods List column entry.
Transport category
Category from 0 to 4 assigned to each dangerous good in ADR, which determines the multiplying factor applied to the quantity carried per transport unit and the threshold of 1 000 points of the partial exemption for quantities carried per transport unit.