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Hazchem Signs, Their Classes and Uses

Here are the 9 classes of hazardous categories and their subclasses explained
Related pages: hazchem Home page | Buy hazchem labels | Find info about hazardous substances

Class 1 Explosives
sub class symbol Description Examples
  These materials will explode Pyrotechnics

Class 2 Gases
sub class symbol Description Examples
2.1 Flammable Gases These are gases which will burn Propane
Class 2.2
Non-toxic gases
These gases are usually compressed and so are a source of stored energy and some may also present an anoxic hazard (that is, they will exclude oxygen and so kill through asphyxiation). These containers may rocket if valves are damaged or containers are involved in a fire. Oxygen Air
Carbon dioxide
Class 2.3 Toxic Gas These gases are toxic. Being gases they will rapidly disperse if there is a leak. This may reduce the concentration and the hazard, but it will also spread the gas further, so increasing the risk of poisoning people. Chlorine
Methyl Bromide
Nitric Acid

Class 3 Flammable Liquids
sub class symbol Description Examples
  These liquids will burn. Petrol

Class 4 Flammable Solids
sub class symbol Description Examples
Class 4.1
Flammable solids
self- reactive and related substances and desensitised explosives
Solids easily ignited and readily combustible. These are ordinarily flammable solids which don't fit into Class 4.2 or 4.3 Sulphur
Picric Acid
Class 4.2 Spontaneously combustible The materials will catch fire if exposed to air without any heat being applied (that is, the heat from the normal air is sufficient for them to catch fire - no other source of heat is required). Charcoal (non-activated)
Class 4.3 Dangerous when wet This class is also know as 'Emits flammable gases when wet'. This class has a particular hazard: not only can moisture from the air cause a fire, but if water or foam is used to extinguish them, it will make the situation worse. Calcium Carbide

Class 5 Oxidising substances
sub class symbol Description Examples
Class 5.1
Oxidising agent
These are all oxidising agents other than organic peroxides. When substances burn in air, they combine with oxygen and so are said to have been oxidised. Other chemicals have a similar 'burning' effect and so are said to be oxidising agents. The largest group of these are organic peroxides Chlorine
Calcium Hypochlorite
Sodium Peroxide
Class 5.2
Organic peroxides (liquid or solid)
These are a particular class of oxidising agent. They have all the normal hazards of oxidising agents (that is, they will cause a 'chemical burning'). In addition, they will often be explosive under certain conditions - especially, if they are allowed to dry out Benzoyl Peroxides
Methyl ethyl Ketone peroxides (MEKP)

Class 6 Poisonous & infectious substances
sub class symbol Description Examples
Class 6.1a Toxic These are liable to cause death or serious injury to human health if inhaled, swallowed or absorbed through the skin. They are covered by special regulations and need special recognition. Cyanides
Class 6.1b Harmful These materials which must be stored away from food stuffs but which are not classified as poisons. Pesticides
Heavy Metals
Class 6.2
Infectious Substances
Substances containing viable micro-organisms that may cause disease in humans or animals Diagnostic specimens or live vaccines

Class 7 Radioactive substances
sub class symbol Description Examples
  Materials or combinations of materials which spontaneously emit ionising radiation. Uranium
Radio Isotopes

Class 8 Corrosives
sub class symbol Description Examples
  These chemicals will eat away at a wide range of materials including some materials of construction for tanks and probably your eyes and skin. Care must be taken to ensure the containers and packages are made from the right materials and the chemicals do not contact your clothes, skin or eyes. Special protective equipment needs to be worn. Hydrochloric acid
Sodium Hypochlorite (liquid pool chlorine)
Sodium Hydroxide (caustic soda)

Class 9 Miscellaneous Goods
sub class symbol Description Examples
  Substances and articles which have potentially dangerous properties that are relatively minor, or are not covered by any of the classes already described Aerosols
Polyester beads

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