Table of contents
The dangerous goods classes reveal, at a glance, what risk certain substances pose during transportation. Classification and labelling are regulated through various agreements and laws to form an international standard. In this guide, you will find a detailed description of all dangerous goods classes, as well as an overview of the regulations for the design and placement of dangerous goods labels.
What are dangerous goods and why is labelling so important?
Dangerous goods are defined as all substances, liquids, and objects in which the transportation of said goods poses an increased risk to the health of people, animals, and/or the environment. As opposed to ATEX zones, which classify an area as potentially hazardous, dangerous goods labelling is product-specific.
When dealing with dangerous goods, it is important that all parties involved immediately recognise the type and extent of the risk posed. For this reason, dangerous goods classification is mandatory in many cases. This can help clarify the safety measures necessary for proper transportation, as well as assist rescue services in the event of an accident. Clear labelling can reduce the threat to nearby workers, civilians, and the environment.
How many classes of dangerous goods are there?
The classification of potentially hazardous substances is based on the United Nations (UN) Recommendations on the Transport of Dangerous Goods. In total, there are nine main classes, alongside several subclasses, and each isdefined based on specific characteristics.
The table below provides an overview of the various dangerous goods classes:
| Dangerous goods classes | Subclass | Description |
|---|---|---|
| Dangerous goods class 1 – Explosive substances | • 1.1 Mass explosive substances (explosion could comprise entire cargo.) • 1.2 Danger posed by the formation of shrapnel • 1.3. Fire hazard and high radiant heat • 1.4. Explosive effects mainly contained by packaging • 1.5 Very insensitive explosive substances • 1.6 Extremely insensitive non-explosive substances | For the transport of potential explosives, it is important to know if and how different substances might react with each other. Therefore, you must also determine the compatibility group of a substance and mark it with the corresponding capital letter (A to L, N or S). For example, substances of groups C, D, and E may be packaged and transported together. |
| Dangerous goods class 2 – Gases and gaseous substances | • 2.1. Flammable gases • 2.2 Non-flammable, non-toxic gases • 2.3 Toxic Gases | Gases in any form, whether compressed, liquefied or dissolved, for example: hydrogen, propane gas, nitrous oxide, or hairspray. In addition, the degree of danger is marked with a capital letter: • A – Asphyxiating • O – Oxidising • F – Flammable • T – Toxic • C – Corrosive |
| Dangerous goods class 3 – Flammable liquids | Liquid or molten substances that ignite when a certain temperature or pressure is reached, for example, alcohol or gasoline. These dangerous goods are classified according to their flash point and any additional hazards posed (toxic, explosive, etc.). The same letter codes apply as for class 2. For example: • F1 – Flash point of maximum 60°C • F2 – Flash point higher than 60 °C • FTC – flammable liquids, toxic, corrosive | |
| Dangerous goods class 4 – Flammable solids | • 4.1 Flammable solids • 4.2 Spontaneously combustible substances • 4.3 Substances that emit flammable gases when in contact with water | Substances that can ignite due to flying sparks or friction, e.g. sulphur, matches. Substances that ignite after a brief time when they come into contact with air or heat up continuously and ignite after a long time (hours to days), e.g. varnish, white phosphorus. Substances whose gases form a flammable or explosive mixture when they come into contact with air. |
| Dangerous goods class 5 – Oxidising substances | • 5.1 Flammable (oxidising) substances • 5.2 Organic Peroxide | Substances that can cause or intensify a fire, but are not necessarily flammable themselves, e.g. hydrogen peroxide, sodium chloride. All organic peroxides that • contain more than 1% active oxygen and more than 1% hydrogen peroxide or • contain more than 0.5% active oxygen and 7% hydrogen peroxide |
| Dangerous goods class 6 – Toxic substances | • 6.1 Toxic substances • 6.2 Infectious substances | • Substances that are harmful to health or even cause death when inhaled, ingested, or come in contact with skin, e.g. arsenic, pesticides, hydrogen cyanamide. • Substances containing or suspected of containing pathogens, e.g. laboratory samples, waste from clinics, and medical practices. |
| Dangerous goods class 7 – Radioactive substances | Substances that are radioactive or contain radioactive components, e.g. uranium, plutonium, certain physical and medical instruments. | |
| Dangerous goods class 8 – Corrosive substances | Substances which, in direct contact, cause damage to the skin or mucous membranes or material damage to other transported goods. | |
| Dangerous goods class 9 – Miscellaneous dangerous goods | All transported goods that pose a hazard that cannot be assigned to one of the previous classes. | |
| Dangerous goods class 9A – Lithium-ion batteries | All lithium-ion containing substances and materials whose hazard potential does not fall under classes 1-8 or under the special regulation SV 188. |
Legal regulations for the labelling of dangerous goods classes
Various international and national laws regulate the labelling of dangerous goods. For example, the UN classification forms the basis for international agreements on dangerous goods law, which in turn are transposed into country-specific law. In the UK, the following apply:
- ADR (European Agreement concerning the International Carriage of Dangerous Goods by Road)
- RID (Regulation on the International Carriage of Dangerous Goods by Rail)
- ADN (European Agreement concerning the International Carriage of Dangerous Goods by Inland Waterways) applies in the UK but the UK is not required to comply
- In the UK, the transportation of dangerous goods is mostly covered by Regulation 5, including substances that fall within the applicable requirements of ADR or RID, as well as those that do not.
- MDG code for international sea shipments of dangerous goods
- IATA / ICAO for international air shipment of dangerous goods
In addition to an overview of the dangerous goods classes and examples for each, the legal texts contain detailed information about the conditions under which you are allowed to transport the respective goods. This includes regulations on packaging, loading and transport, as well as education and training for all those involved.
There is a legal obligation to label dangerous goods. If you do not meet these or do so insufficiently, you may face penalties and considerable fines. Hazardous goods must be labelled on packaging and transport vehicles. This requires a hazard label and a hazard plate.
Correctly marking dangerous goods classes
First, assign a dangerous goods class to each product or substance according to the UN’s overview. The UN have implemented a universal system for classifying, packaging, marking, and labelling dangerous goods, often with the help of pictograms and numbers. This system aims to ensure the safe transport of dangerous goods. Both national and international regulations governing road, rail, sea, and air transport are based on the UN system. .
- Dangerous goods labels: Dangerous goods labels are classified according to ADR. These prescribe clearly visible and unambiguous labelling of dangerous goods on the truck and on the containers.
- The ADR Hazard Identification Number (HIN) or Kemler Code is a two- or three-digit sequence of digits that indicates the specific hazard characteristics. The doubling of a number stands for an increased danger; a preceding X means that the substance reacts dangerously with water.
- The UN number or substance number is a four-digit sequence that has been determined individually for each substance by a UN committee. The specific numerical sequence for all substances is included as a list in the legal regulations for the transport of dangerous goods.
Hazard label
The hazard label is a square standing on its tip. In the upper half, there is the hazard symbol and the hazard class, in the lower half the UN number assigned to the specific goods. In addition, the note must have a certain colour, which also depends on the respective dangerous goods classes.
Hazard labels should have a dimension of 10 x 10 cm and are attached to the packaging units (drums, boxes, etc.) or to the goods themselves.
Placards
Large labels (also known as placards) differ from hazard labels only in their dimensions (at least 25 x 25 cm). They are used when the vehicle itself is the “packaging unit”, for example in the case of attachment tanks, containers, or tankers.
For proper labelling, you must attach the large labels to both the rear and sides of the container or tank.
Hazard plates
A warning sign is also required to make the vehicle. This should be attached to the rear and front of the truck or top-mounted tank. It has a dimension of 30 x 40 cm and is orange.
Normally, the hazard plate is divided into two parts, showing the hazard number in the upper part and the UN number in the lower part. However, if a transport contains various dangerous goods, the board remains empty. This means that dangerous goods are being transported and that more detailed information can be found on individual hazard labels or placards.
FAQ on dangerous goods classes
Dangerous goods are all substances, liquids, and objects whose transport pose an increased risk to human and animal health, the environment or public safety. In contrast to hazardous substances, this risk exists exclusively during or due to transport. However, this does not rule out the possibility that a dangerous good can also be a hazardous substance at the same time.
Classification is based on the UN Recommendations on the Transport of Dangerous Goods. There, nine dangerous goods classes with several subclasses are defined based on specific characteristics.
• Dangerous goods class 1 – Explosive substances
• Dangerous goods class 2 – Gases and gaseous substances
• Dangerous goods class 3 – Flammable liquids
• Dangerous goods class 4 – Flammable solids
• Dangerous goods class 5 – Oxidising substances
• Dangerous goods class 6 – Toxic substances
• Dangerous goods class 7 – Radioactive substances
• Dangerous goods class 8 – Corrosive substances
• Dangerous goods class 9 – Miscellaneous dangerous goods
• Dangerous goods class 9A – Lithium-ion batteries
The UN number or substance number is a four-digit number that identifies hazardous materials, and articles (such as explosives, flammable liquids, oxidizers, toxic liquids, etc.). The specific UN numbers for all substances range from UN0001 to about UN3600 and are assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods.
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