![](\"https:\/\/www.safetyadr.com\/wp-content\/uploads\/2019\/04\/Hazard-identification-number.png\")
<\/h4>\n<\/h4>\nCHAPTER 5.3 PLACARDING AND MARKING OF CONTAINERS, BULK CONTAINERS, MEGCs, MEMUs, TANK-CONTAINERS, PORTABLE TANKS AND VEHICLES
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5.3.2.3 Meaning of hazard identification numbers<\/p>\n
5.3.2.3.1 The hazard identification number consists of two or three figures. In general, the figures indicate the<\/p>\n
following hazards:<\/p>\n
2 Emission of gas due to pressure or to chemical reaction<\/p>\n
3 Flammability of liquids (vapours) and gases or self-heating liquid<\/p>\n
4 Flammability of solids or self-heating solid<\/p>\n
5 Oxidizing (fire-intensifying) effect<\/p>\n
6 Toxicity or risk of infection<\/p>\n
7 Radioactivity<\/p>\n
8 Corrosivity<\/p>\n
9 Risk of spontaneous violent reaction<\/p>\n
NOTE: The risk of spontaneous violent reaction within the meaning of figure 9 include the possibility following from the nature of a substance of a risk of explosion, disintegration and polymerization reaction following the release of considerable heat or flammable and\/or toxic gases.<\/em><\/p>\n Doubling of a figure indicates an intensification of that particular hazard.<\/p>\n Where the hazard associated with a substance can be adequately indicated by a single figure, this is followed by zero.<\/p>\n The following combinations of figures, however, have a special meaning: 22, 323, 333, 362, 382, 423, 44, 446, 462, 482, 539, 606, 623, 642, 823, 842, 90 and 99, see 5.3.2.3.2 below.<\/p>\n