What Are The Nine Classes of Dangerous Goods?
Dangerous goods are materials or items with properties which, if not properly controlled, present a potential hazard to human health and safety and/or infrastructure. Dangerous goods are separated into categories through a classification system is outlined by the UN Model Regulations. Each dangerous substance or article is assigned to a class. There are 9 classes and they're determined by the nature of the danger they present.
Class 1: Explosives
The danger of explosives is pretty self-explanatory – they can explode. Class 1 goods are products that possess the ability to alight or detonate during a chemical reaction. There are 6 sub-divisions of explosives, which relate to the product's behaviour when initiated.
- 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
- Division 1.4: Substances and articles which present no significant hazard; only a small hazard in the event of ignition during transport with any effects largely confined to the package
- 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
Examples include fireworks, flares and ignitors.
Class 2: Gases
Class 2 consists of compressed gases, gases in their liquefied form, refrigerated gases, mixtures of gases with other vapours and products charged with gases or aerosols. These sorts of gases are often flammable and can be toxic or corrosive. They're also hazardous because they can chemically react with oxygen. They are split into three sub-divisions:
- Division 2.1: Flammable gases
- Division 2.2: Non-flammable, non-toxic gases
- Division 2.3: Toxic gases
Examples include aerosols and fire extinguishers.
Class 3: Flammable liquids
A flammable liquid is defined as a liquid, a mixture of liquids, or liquids containing solids that require a much lower temperature than others to ignite. These temperatures are so low that there is a high risk of the liquids igniting during transportation. This makes flammable liquids very dangerous to handle and transport, as they are very volatile and combustible. Flammable liquids are usually used as fuels in internal combustion engines for motor vehicles and aircraft. This means they make up the largest tonnage of dangerous goods moved by surface transport. Many household products also contain flammable liquids, including perfumery products and acetone (which is used in nail polish remover).
Class 4: Flammable solids, Spontaneously combustible and Dangerous when wet
Class 4 dangerous goods are classified as products which are easily combustible and likely to contribute to fires during transportation. Some goods are self-reactive and some are liable to spontaneously heating up. There are 3 sub-divisions for Class 4 dangerous goods:
- Class 4.1 Flammable solids: These will burn easily than normal combustible materials. The burning of flammable solids is also fierce and rapid; they are also incredibly dangerous because they can decompose explosively, burn vigorously, or produce toxic gases.
- Class 4.2 Spontaneously combustible: These can be either solids or liquids. They ignite spontaneously when in contact with oxygen.
- Class 4.3 Dangerous when wet: These goods react with water to generate flammable gas that can be ignited by the heat of the reaction.
Examples of class 4 dangerous goods include metal powders, sodium batteries and seed cake. 'Seed cake' is the term used to describe oil-bearing seeds – don't worry, your lemon poppyseed cake won't spontaneously self-combust during Afternoon Tea!
Class 5: Oxidising Agents and Organic peroxides
Class 5 dangerous goods are subdivided into 'oxidising agents' and 'organic peroxides'
- Class 5.1 Oxidising Agents: Also known as oxidisers, these substances that can cause or contribute to combustion as a product of chemical reactions. Oxidisers aren't necessarily combustible on their own, but the oxygen they produce can cause combustion with other materials.
- Class 5.2 Organic peroxides: The molecular structure of these materials makes them extremely liable to ignition. This means they're liable to combust individually. They are designed to be reactive for industrial purposes, so they are unstable and can be explosive.
Examples include hydrogen peroxide and lead nitrate.
Class 6: Toxins and Infectious substances
- Class 6.1 Toxins: Toxic substances are liable to cause death because they're, as the name suggests, toxic. They can cause serious injury or harm to human health if they enter the body through swallowing, breathing in, or absorption through the skin. Some toxics will kill in minutes, however, some might only injure if the dose isn't excessive.
- Class 6.2 Infectious substances: These are goods that contain micro-organisms that cause infectious disease in humans or animals, otherwise known as pathogens.
Examples include medical waste, clinical waste and acids.
Class 7: Radioactive material
Radioactive materials contain unstable atoms that change their structure spontaneously in a random fashion. They contain 'radionuclides', which are atoms with an unstable nucleus. It's this unstable nucleus that releases the radioactive energy. When an atom changes, they emit ionising radiation, which could cause chemical or biological change. This type of radiation can be dangerous to the human body. Examples include smoke detectors and yellowcake ('yellowcake' is a type of uranium concentrate powder, your lemon cake is still safe!).
Class 8: Corrosives
Corrosives are highly reactive, corrosive materials. Due to their reactivity, corrosive substances cause chemical reactions that degrade other materials when they encounter each other. If these encountered materials happen to be living tissue, they can cause severe injury. Examples include batteries, chlorides and flux.
Class 9: Miscellaneous dangerous goods
This category covers substances that present a danger not covered in the other classes. Examples include dry ice, GMO's, motor engines, seat belt pretensioner, marine pollutants, asbestos, airbag modules and magnetised material.