Argon (Ar) is a relatively common noble gas. GB number 22011. CAS number 7440-37-1. Its molecular weight is 39.95. Colorless and odorless; Vapor pressure: 202.64 kPa(-179℃); Melting point: -189.2℃; Boiling point: -185.7℃; Solubility: slightly soluble in water; Relative density (water =1): 1.40(-186℃); Relative density (air =1): 1.38; Chemical stability: stable; Hazard mark: 5 (non-combustible gas).

Argon and the insulating glass

The density and dynamic viscosity of argon are higher than that of air while its thermal conductivity and specific heat capacity are lower. Argon is present in air at 1%, making it the most economical inert gas when compared with krypton and xenon. If the space between the two panes of insulating glass is filled with Argon gas, it can lower the heat convection and conduction between the sheets of glass, therefore, mitigate the overall thermal conductivity and reduce the K value of the insulating glass.