Dangerous Goods Classes and Symbols

TDG

Dangerous Goods Classes and Symbols

Little Pro on 2016-01-07

There are 9 dangerous goods classes. Substances (including substances and mixtures), and articles are assigned to one of the following 9 classes according to the most predominant hazards they pose in transport. Some of the classes can be further divided into divisions, e.g., Class 1, while others do not have sub-divisions, e.g., Class 3.

The picture below shows hazard symbols for Class 4 dangerous goods. You can download all hazard symbols for all hazard classes above by clicking the picture below.

Primary Hazard Class and Subsidiary Class for Dangerous Goods

Some dangerous goods have multiple hazards. The primary class is the class of dangerous goods that takes precedence over any other class. The subsidiary class is the other class that further identifies the hazards of the dangerous goods. More than one subsidiary class is possible. For most of dangerous goods, the primary class and subsidary class can be found in Dangerous Goods List.

For goods having multiple risks which are not specifically mentioned by name in Dangerous Goods List, you have to follow the following hazard precedence rules to determine their primary hazard class and subsidiary class.

Rule	How It Works
Packing Group Rule	The following packing group always takes precedence irrespective of hazards: I (High Danger) > II (Medium Danger) > III (Low Danger)
Dominant Hazard Rule	The following hazard class always takes precedence irrespective of packing groups: Materials of class 7 (except radio-active materials in excepted packages) Substances and articles of class 1 Gases of class 2 Liquid desensitised explosives of class 3 Self-reactive substances and solid desensitised explosives of division 4.1 Pyrophoric Substances of division 4.2 Substances of division 5.1 Substances of division 6.1 or class 3 with packing group I by inhalation Infectious substances of division 6.2
Hazard Precedence Table	If above two rules do not apply, please refer to the following hazard precedence table to choose primary hazard.

Rule

How It Works

Packing Group Rule

The following packing group always takes precedence irrespective of hazards:

I (High Danger) > II (Medium Danger) > III (Low Danger)

Dominant Hazard Rule

The following hazard class always takes precedence irrespective of packing groups:

Materials of class 7 (except radio-active materials in excepted packages)
Substances and articles of class 1
Gases of class 2
Liquid desensitised explosives of class 3
Self-reactive substances and solid desensitised explosives of division 4.1
Pyrophoric Substances of division 4.2
Substances of division 5.1
Substances of division 6.1 or class 3 with packing group I by inhalation
Infectious substances of division 6.2

Hazard Precedence Table

If above two rules do not apply, please refer to the following hazard precedence table to choose primary hazard.

dangerous goods class

References

http://www.unece.org/fileadmin/DAM/trans/danger/publi/unrec/rev16/English/02E_Part2.pdf

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