The 9 classes of dangerous goods
Apr 20, 2018

The 9 classes of dangerous goods

Rachel Chesterfield Rachel Chesterfield

The Australian Dangerous Goods Code establishes all hazardous substances into 9 different dangerous goods classes according to their physical and chemical properties and the risks that they present.

As the Australian dangerous goods code explains: “Substances (including mixtures and solutions) and articles subject to this code are assigned to one of nine classes according to the hazard or the most predominant of the hazards they present”.  Some of these classes are subdivided into divisions. These classes and divisions are:

Class 1: Explosives

  • Division 1.1: substances and articles which have a mass explosion hazard.
  • Division 1.2: Substances and articles which have a projection hazard but not a mass explosion hazard
  • Division 1.3: Substances and articles which have a fire hazard and either a minor blast hazard or a minor projection hazard or both, but not a mass explosion hazard
  • Division 1.4: Substances and articles which present no significant hazard
  • Division 1.5: Very insensitive substances which have a mass explosion hazard
  • Division 1.6: Extremely insensitive articles which do not have a mass explosion hazard

Class 2: Gases

  • Division 2.1: Flammable gases
  • Division 2.2: Non-flammable, non-toxic gases
  • Division 2.3: Toxic gases

Class 3: Flammable liquids

There are no sub-divisions for Class 3 flammable liquids.

Class 4: Flammable solids; substances liable to spontaneous combustion; substances which, on contact with water, emit flammable gases

  • Division 4.1: Flammable solids, self-reactive substances and solid desensitised explosives
  • Division 4.2: Substances liable to spontaneous combustion
  • Division 4.3: Substances which in contact with water emit flammable gases

Class 5: Oxidizing substances and organic peroxides


Class 6: Toxic and infectious substances

Class 7: Radioactive material

There are no sub-divisions for Class 7 Radioactive Material

Class 8: Corrosive substances

There are no sub-divisions for Class 8 Corrosive Substances

Class 9: Miscellaneous dangerous substances and articles

There are no subdivisions for Class 9 Miscellaneous Dangerous Goods

Now, let's go into a little more detail by looking at the definitions of each class of dangerous goods as per the relevant Australian standard per class;

Class 1: Explosives


According to section 2.1.1.1 of the Australian Dangerous Goods Code, Class 1 dangerous goods can be defined in a more detailed manner as:

  • Explosive substances (a substance which is not itself an explosive but which can form an explosive atmosphere of gas, vapour or dust is not included in Class 1), except those that are too dangerous to transport or those where the predominant hazard is appropriate to another class; and
  • Explosive articles, except devices containing explosive substances in such quantity or of such a character that their inadvertent or accidental ignition or initiation during transport will not cause any effect external to the device either by projection, fire, smoke, heat or loud noise; and
  • Substances and articles not mentioned under (a) and (b) which are manufactured with a view to producing a practical, explosive or pyrotechnic effect.

Class 2: Gases

According to section 2.2.1.1 of the Australian dangerous goods code, A gas is a substance which:

At 50 °C has a vapour pressure greater than 300 kPa; or is completely gaseous at 20 °C at a standard pressure of 101.3 kPa.

  • Division 2.1 Flammable gases -  Gases which at 20 °C and a standard pressure of 101.3 kPa: (i) are ignitable when in a mixture of 13 per cent or less by volume with air; or (ii) have a flammable range with air of at least 12 percentage points regardless of the lower flammable limit.
  • Division 2.2 Non-flammable, non-toxic gases - Gases which: (i) are asphyxiant – gases which dilute or replace the oxygen normally in the atmosphere; or (ii) are oxidizing – gases which may, generally by providing oxygen, cause or contribute to the combustion of other material more than air does; or (iii) do not come under the other divisions;
  • Division 2.3 Toxic gases - Gases which: (i) are known to be so toxic or corrosive to humans as to pose a hazard to health; or (ii) are presumed to be toxic or corrosive to humans because they have an LC50 value (as defined in 2.6.2.1) equal to or less than 5,000 ml/m3 (ppm).

Class 3: flammable liquids

Most people would know what flammable liquids are; they are liquids that will burn in the presents of an ignition source. They are used to run commonly used equipment such as:

  • Vehicles
  • Generators
  • Brush cutters

The Australian Dangerous Goods Code defines Class 3 Flammable Liquids as;

Flammable liquids are liquids, or mixtures of liquids, or liquids containing solids in solution or suspension (for example, paints, varnishes, lacquers, etc., but not including substances otherwise classified on account of their dangerous characteristics) which give off a flammable vapour at temperatures of not more than 60 °C, closed-cup test, or not more than 65.6 °C, open-cup test, normally referred to as the flash point.  This class also includes:

  • Liquids offered for transport at temperatures at or above their flash point; and
  • Substances that are transported or offered for transport at elevated temperatures in a liquid state and which give off a flammable vapour at a temperature at or below the maximum transport temperature.

It’s important to note that in the presence of any impurity, the flash point of a flammable substance may vary.

Class 4: flammable solids

Flammable solids are substances liable to spontaneous combustion and/or substances which, in contact with water, emit flammable gases. When flammable solids combust, they often emit toxic gases.

Class 4 dangerous goods are divided into three divisions as follows:

  • Division 4.1 Flammable solids are solids which, under conditions encountered in transport, are readily combustible or may cause or contribute to fire through friction; self-reactive substances which are liable to undergo a strongly exothermic reaction; solid desensitized explosives which may explode if not diluted sufficiently;
  • Division 4.2 Substances liable to spontaneous combustion are substances which are liable to spontaneous heating under normal conditions encountered in transport, or to heating up in contact with air, and being then liable to catch fire;
  • Division 4.3 Substances which in contact with water emit flammable gases Substances which, by interaction with water, are liable to become spontaneously flammable or to give off flammable gases in dangerous quantities.

Class 5: Oxidizing Substances & Organic Peroxides

The Australian Dangerous Goods Code defines Class 5 dangerous goods as:

  • Division 5.1 Oxidizing substances are substances which, while in themselves not necessarily combustible, may, generally by yielding oxygen, cause, or contribute to, the combustion of other material.  Such substances may be contained in an article;
  • Division 5.2 Organic peroxides Organic substances which contain the bivalent -0-0- structure and may be considered derivatives of hydrogen peroxide, where one or both of the hydrogen atoms have been replaced by organic radicals.  Organic peroxides are thermally unstable substances, which may undergo exothermic self-accelerating decomposition. In addition, they may have one or more of the following properties: (i) be liable to explosive decomposition; (ii) burn rapidly; (iii) be sensitive to impact or friction; (iv) react dangerously with other substances; (v) cause damage to the eyes.

Class 6: toxic and infectious substances

Class 6 is divided into two divisions. These definitions for each sub-division according to the ADG code are outlined blow:

  • Division 6.1 Toxic substances These are substances liable either to cause death or serious injury or to harm human health if swallowed or inhaled or by skin contact;
  • Division 6.2 Infectious substances These are substances known or reasonably expected to contain pathogens.  Pathogens are defined as micro-organisms (including bacteria, viruses, rickettsiae, parasites, fungi) and other agents such as prions, which can cause disease in humans or animals.

Class 7: Radioactive material

According to section 2.7.1.1 of the ADG code,  Radioactive materials are defined as:

Any material containing radionuclides where both the activity concentration and the total activity in the consignment exceed the values specified in the relevant Australian standard, (AUST ST. FOR CLASS 7)

For more detailed information, check with your supplier, the relevant MSDS, or a professional Dangerous Goods Consultant.

Class 8: Corrosive Substances

The Australian Dangerous Goods Code defines corrosive substances as:

Class 8 substances (corrosive substances) are substances which, by chemical action, will cause severe damage when in contact with living tissue, or, in the case of leakage, will materially damage, or even destroy, other goods, substances, or objects.

Class 9: Miscellaneous dangerous substances and articles

According to the Australian Dangerous Goods Code, Class 9 dangerous goods are defined as:

Class 9 substances and articles (miscellaneous dangerous substances and articles) are substances and articles which, during transport present a danger not covered by other classes. This includes:

  • Environmentally hazardous substances which are not covered by other classes;
  • Elevated temperature substances (i.e. substances that are transported or offered for transport at temperatures equal to or exceeding 100 °C in a liquid state or at temperatures equal or exceeding 240 °C in a solid state); (c) GMMOs or GMOs which do not meet the definition of infectious substances (see Section 2.6.3) but which are capable of altering animals, plants or microbiological substances in a way not normally the result of natural reproduction.

Next Steps

Each dangerous goods class has different chemical and physical properties, and therefore each different class must be stored and managed in a safe and compliant manner. Each dangerous goods class has a relevant Australian Standard that outlines the requirements for its storage and handling. For example the Australian Standards that outlines requirements for the storage and handling of flammable liquids is AS1940. If you would like more information on how to reduce the risks associated with flammable liquids, download our FREE eBook by clicking on the image below.  

How to reduce the risk of flammable liquids in the workplace

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