Hazardous goods are materials or items with dangerous properties. If they are not controlled properly, they could set forth potential danger to human health and safety or their transport. Dangerous goods are separated into different classes which determine how they must be packaged and transported. If limited quantities are being shipped, the rules are not as strict. The sender or consignor is responsible for packaging, classifying, and marking any hazardous goods that are to be transported.
Class 1 – Explosives
Explosives are made from molecules that that rapidly change from their solid state into extremely hot gas which then produces a violent and sudden physical effect. This change is usually achieved by exposing the molecules to sudden shock.
There are 6 divisions of explosives in class ones and the divisions indicate the way that the explosives will react when exposed to shock/heat.
- 1.1 – Mass explosion hazard
- 1.2 – Projection Hazard only
- 1.3 – Fire hazard and minor blast or minor projection hazard
- 1.4 – Minimal hazard
- 1.5 – Blasting agents
- 1.6 – Very insensitive detonating articles
Class 2 – Gases
Gases are transported under pressure because this reduces their volume and creates more space for goods. Because the gas is pressurised, this can cause a hazard in itself it is released suddenly. If a cylinder valve gets knocked off, the gas inside is so concentrated that it essentially turns into a powerful jet of gas that could make the cylinder take off like a rocket and cause lots of damage. Most gas is heavier than air and has less molecules so if they leak into a confined or sealed space it can cause suffocation.
The Gas class is separated into three divisions because they also present chemical hazards.
- 2.1 – Flammable Gas
- 2.2 – Non-flammable, Non-toxic Gas
- 2.3 – Toxic Gas
Class 3 – Flammable Liquids
Some flammable liquids are manufactured through industrial or natural processes, e.g. alcohol and other flammable liquids derive from petroleum, e.g. kerosene, petrol. Flammable liquids are mostly used as fuels in engines for vehicles and aircraft. They can also be used in smaller quantities for chemical reasons in paints, adhesives, varnishes and more.
Different flammable liquids have different flashpoints. The flashpoint is the temperature above which the flammable liquid releases enough vapour to create a flammable mixture with the air. Below the flashpoint, there is not enough vapour to set fire. The lower the flashpoint, the greater risk the liquid poses as the vapour forms at a normal temperature.
The flammable liquids are placed in ‘Packing Groups’ depending on their flashpoint and boiling point.
Packing Group I, Boiling point below 35º C
Packing Group II, Boiling point above 35º C, Flashpoint below 23º C
Packing Group III, Boiling point above 35º C, Flashpoint >23º C and <60º C
Class 4 – Flammable Solids
Flammable solids are separated into three divisions, Flammable solids, Spontaneously combustible and dangerous when wet.
- 4.1 – Flammable Solids
Flammable solids burn very easily, even more than regularly combustible materials such as paper or wood. The burning that is presented by the solids can be rapid and fierce, generating lots of heat. Some of the flammable solids can be set fire by being self-reactive, breaking down chemically, combust above certain temperatures or by being exposed to shock. They could then explode, vigorously burn or produce toxic gas.
- 4.2 – Spontaneously Combustible
In class 4.2 this can contain both liquids and solids. The materials under 4.2 will spontaneously set fire when it comes into contact with oxygen so the material must be kept airtight at all times in a package for the solids or under a gas/liquid blanket for the liquid. Some spontaneously combustible materials set fire within 5 minutes of being exposed to air but others will only ignite if they are in a large amount after long periods of exposure.
- 4.3 – Dangerous When Wet
In this division, the materials react with water when it is in a liquid or vapour form and generate a flammable gas. The gas can then set fire due to the heat of the reaction. They must be kept in watertight packages to avoid any entry of moisture of water.
Class 5 – Oxidising Substances
- 5.1 – Oxidising Agents
Oxidising agents contain lots of oxygen and they may react with other combustible or flammable materials. These fires may break out in confined spaces and once they are started it is difficult to extinguish as the material is emitting the oxygen. Large amounts of water are the only way the fire can be distinguished but the fire may be hard to get to.
- 5.2 – Organic Peroxides
They are designed to be reactive for industrial purposes but can be unstable and sometimes explosive. They can be in Class 1 or Class 5.2 depending on how it is going to be used. Most of the time they have to be maintained in refrigeration to make sure that are inactive.
Class 6 – Toxic & Infectious Substances
- 6.1 – Toxic Substances
Toxic substances are poisons that can damage the human body. They must not get inside the body through breathing, swallowing or absorption through the skin. Some toxic substances can kill in minutes and others can just injure if the dose is not fatal. They can be in liquid form or in solid for. Toxic gasses are in Class 2.3.
- 6.2 – Infectious Substances
In division 6.2 the substances contained are pathogens which can cause infectious diseases in humans and animals. They are graded into three groups but only the first two are considered dangerous to transport.
Category A – Capable of causing permanent disability or fatal disease to humans or animals. Examples would be Ebola Virus, Hepatitis B Virus and Rabies Virus.
Category B – Infectious substances which causes disease in animals. Examples would be African Horse sickness Virus and Sheep-Pox Virus.
Class 7 – Radioactive Material
Radioactive materials contain atoms that are unstable and can change their structure spontaneously and randomly over a certain period of time. As the atoms change, they emit invisible radiation that can cause biological or chemical change. This can damage the body in different ways depending on the type of radiation and the duration of exposure to the radioactive material.
The radiation level at the surface must be below 5 m Sv/hour and declared as radioactive. The packages are perfectly safe to transport because the packaging acts a shield.
Class 8 – Corrosives
Corrosive materials are highly reactive and produce chemical effects that changes the materials it comes into contact with. They are very damaging to the human body and work by destroying the tissue. These can be either alkalis or acids which are placed in Packaging Groups depending on how destructive they are and the amount of time it takes for them to cause destruction.
Class 9 – Miscellaneous Hazardous goods
This class covers materials and substances that present a hazard but are not covered by any other class. An example of this would be self-inflating life rafts which include compressed gas, explosive flares, flammable solids and flammable liquids all in one package.