Class A: Compressed Gas
This symbol indicates that the contents of the container are under pressure - anything done to weaken the structure of the container could result in an explosion or a dramatic release of pressure. A compressed gas is a material which is a gas at normal room temperature and pressure, and is packaged under compression.
Helium and propane are common examples of materials that are supplied as a compressed gas.
Class B: Flammable/Combustible
"Flammable / Combustible" materials are solids, liquids or gases that will ignite and continue to burn if exposed to a flame or source of ignition. These materials may also be explosive in certain situations or react with other materials to produce a flammable material.
Diesel and gasoline are examples of commonly used flammable materials.
Class C: Oxidizing Materials
These materials produce oxygen or another oxidizing substances, which can cause or contribute to the combustion of another substance.
Chlorine is an example of an oxidizing material.
Class D: Poisonous and Infectious
These materials are further separated into three categories D1, D2, and D3.
D1: Materials causing immediate and serious toxic effects
The effects of Class D1 materials are very harmful based on short-term exposures. Very little exposure can produce serious toxic effects or possibly death. These materials are classified for toxicity based on information such as the lethal dose and the lethal concentration.
Cyanide is an example of a material that causes immediate and serious toxic effects.
D2: Other Toxic Effects
Class D2 substances can produce many different toxic effects. They also have a wide variety of classifications. For example, D2 substances can be classified as carcinogens, teratogens, reproductive toxins, respiratory tract sensitizers, irritants, or chronic toxic hazards. Exposure effects range from short term (e.g. dizziness, difficulty breathing), to long term (cancer, lung disease).
Asbestos is an example of this class of material.
D3: Biohazard Infectious Materials
Class D3 materials refer to any organism, or the toxins produced by these organisms, that have been shown or are believed to be a biological hazard in either humans or animals. These materials are usually limited to laboratory and testing environments.
Class E: Corrosive
Class E materials are corrosives that can cause decomposition of other materials (e.g. metals) or damage human tissue.
Sulphuric Acid and Ammonia are examples of corrosive materials.
Class F: Dangerously Reactive
Class F materials may react with other substances to produce a wide range of negative reactions. These reactions can range from decomposition to condensation. The stability of these materials may be adversely affected by exposure to certain elements such as water, pressure, or temperature.
Ozone is an example of a dangerously reactive material.