Hazardous chemicals are substances that can cause immediate and immediate damage to people, equipment and the environment. Dangerous goods in many countries  are classified and labeled according to
the United Nations (UN) system . This system helps to identify the characteristics and dangers of such substances quickly. In this system, dangerous goods are classified into 6 classes based on their dangerous characteristics. These classes include 9 specific classes and one class of miscellaneous materials. Hazards for each class are marked with special diamond-shaped labels. Sometimes, if a substance has other risks in addition to the main hazard, a smaller rhombus can be used next to the main rhombus. For example, hydrofluoric acid is a corrosive and toxic substance. Some dangerous goods, including classes 8, 4, 1, 2, and 9, have further divisions or subclasses that indicate a specific aspect of the substance’s dangers, for example, the second class is gases and subclass 112 is flammable gases. In addition , in some classes, there are further divisions including packaging groups  that indicate  the relative risk of the substance within a class (PGIII low risk, PGII medium risk, PGI high risk) . All packages (except very small packages), containers and tankers containing dangerous goods must be properly labeled with the appropriate class. This sticker (or danger rhombus) indicates the nature of the danger using a color system and special symbols, as well as the class number of the dangerous goods. Therefore, manufacturers and importers of such goods must ensure that these materials are correctly classified and labeled.

Class 1 Explosives _

Contains materials that can cause explosions or pyrotechnic effects. In general, the production of explosives is limited and subject to relevant regulations. The use of explosives for research purposes is subject to obtaining the necessary permits from the responsible organizations.

Explosives include 6 different subclasses:

Class 1-1  Explosives with a risk of sudden and massive explosion

Example: TNT , nitroglycerine, mercury fulminate

Class 1-2  explosives with the risk of launch (but not the risk of massive explosion)

Example: bombs, grenades

Class 1-3  explosives with massive fire hazard

Example: Gunpowder, fireworks

Class 1-4  Explosives without massive explosion

Example: fireworks in toys

Class 1-5  explosives with low explosive sensitivity

Detapower like  Proprietary Example: Explosives

Class 1-6  explosives with very low explosive sensitivity

Class 2 gases  

Dangerous goods of this class include gases under pressure, liquefied gases or soluble gases under pressure.

Gases include 3 subclasses:

Class 2-1  Flammable gases

Class 2-2  non-flammable and non-toxic gases

Class 2-3  toxic gases

The meaning of toxic gases are gases whose inhalation causes death or serious damage to human health.

Example: CO , chlorine and ammonia.

Class 3 Flammable Liquids

Flammable liquids are liquids, a mixture of liquids or liquids containing dissolved or suspended solids that can ignite in contact with an ignition source, such as gasoline, thinner, paints, varnishes, and flammable solvents.
It should be noted that in the older division of this class, they  were divided into two classes: 0-2 and 0-1, but in the new division, subclasses are  not considered for flammable liquids, but for these materials, there are packaging groups. PG I, II, III )  is considered.

Class PGI -3  highly flammable liquids

with an initial boiling point of less than 08 degrees Celsius

Example: diethyl ether, carbon disulfide

Class PGII -3  highly flammable liquids

with an initial boiling point of more than 08 degrees Celsius and a flash point of less than 10 degrees Celsius,
such as: gasoline, stan

Packing groups I  and II  were previously divided under the title of subclass 0-2.

Class PGIII – 3  Flammable liquids with a flash point of 10 to 92 degrees Celsius

Example: kerosene, mineral turpentine

This group was called subclass 2-3 in the previous classification.

Class 4 Flammable  Solids

Dangerous goods in this class include substances with the potential of spontaneous combustion and substances that create flammable gases in contact with water. Also, solids (other than explosives) that immediately ignite or cause fire are also classified in this class.

This class includes 3 subclasses:

Class 4-1 Flammable solids

Materials that are easily ignited and combustible.
Example: nitrocellulose, phosphors, matches and picric acid

Class 2-4 Solids with the potential for spontaneous combustion

Example: coal, cotton and white phosphorus

Class 4-3 Hazardous solids in the wet state

Contains solids that form flammable gases in contact with water.
Example: aluminum phosphide and calcium carbide

Class 5 Oxidizing Substances

Oxidizing substances include 2 subclasses:

Class 1-5  Oxidizing substances (other than organic peroxides)

Such as hydrogen peroxide, calcium hypochlorite (used in swimming pools), ammonium nitrate, and
organic nitrates.

Class 5-2 Organic peroxides (solid or liquid)

Example: methyl ethyl ketone peroxide, benzoyl peroxide, dibenzene and peracetic acid.
Oxidizing substances are not necessarily combustible by themselves, but may cause the combustion of other substances. For example, sodium peroxide in the presence of water causes a strong exothermic (exothermic) reaction, and the need to mix with coal also causes spontaneous combustion.
Organic peroxides have a structure with divalent oxygen. These materials are thermally unstable and therefore may decompose spontaneously, which can sometimes cause explosive reactions or burn quickly, or be sensitive to impact or friction, or cause dangerous reactions with other materials.

Class 6: Toxic and Infectious  Substances

This class includes two subclasses, toxic substances and infectious substances, although toxic gases, which are already classified in class 2-3, are not included in this class.

Class 6-1 Toxic substances (including toxic liquids and solids)

Toxic substances include substances that lead to death or serious injuries and harm to human health if swallowed, inhaled or through skin contact.
Example: sodium cyanide ( NaCN ) cyanides and arsenic compounds.

Class 6-2 Infectious substances

Aseptic materials are materials that are known to be infectious or possibly contain pathogens (microorganisms include bacteria, viruses, rickettsia, parasites, and fungi. Vaccines and pathology specimens are examples of this. Storage instructions, how to work And how to dispose of infectious materials should be subject to health regulations and how to transport this group of materials should be subject to environmental protection regulations.

Class 7 Radioactive  Substances

This class includes substances or combinations of substances that constantly emit radioactive waste. More precisely, radioactive material is a material whose specific activity  is greater than 70 KBq/kg. The meaning of specific activity is the amount of activity per unit mass of radioactive material. No special subclass is considered for Ian Kalas, but different packing groups are considered.
Example: radioisotopes and uranium

Class 8 Corrosives

Corrosive substances are solid or liquid substances that can cause damage to living tissues and devices and equipment through chemical effects when they come into contact with them. In other words, corrosive substances are substances that cause severe damage by chemical effect when they come into contact with living tissues, tools and equipment and destroy other substances.
Example: hydrofluoric acid, sodium hydroxide and chlorine in swimming pools.

Class 9, miscellaneous materials (Miscellaneous)

This class represents the danger of miscellaneous substances that are not mainly severe and are not divided into other classes. Such as strong magnetic materials, aerosols, ammonium nitrate fertilizers and polyester granules.

General label of dangerous goods

This label indicates different classes of dangerous goods and is used during the transportation of these goods.