Argon accounts for less than one per cent of the atmosphere, but is the most abundant truly inert gas. It is used to provide a shielding atmosphere in welding, metal fabrication, aluminium processing, micro-electronics, glass coating, and other industrial processes.



Physical Properties

Argon, symbol Ar, is an inert gaseous element that is the third most prevalent gas in the earth's atmosphere. Argon is in group 8 of the periodic table, which is also known as the noble gases. The atomic number of argon is 18.

Gas Argon
Chemical formula Ar
Molecular weight 39.9
Gas density 1.69 Kg/m3
SG vapour 1.38
Boiling point -186°C
Critical temperature -122°C
Critical pressure 49 bar


The most common source of argon is through extraction from air. In the air extraction process, crude liquid argon is formed in the distillation column of an air separation unit. This is taken for further purification to give a typical purity of 99.9995%.


Argon in high enough concentrations may cause asphyxiation and death. Because it is heavier than air it will collect in low-lying areas and therefore can be particularly dangerous when used in confined spaces. For more detail on the hazards associated with argon check the Safety Data sheet.

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