This invention provides a method for on-site production of a protective
gas mixture for arc joining, in particular for arc welding. Gaseous argon
is removed from a liquid argon supply and helium is added to the argon,
and a doping gas premix which is prepared separately on-site is added.
Various combinations of argon, helium and the doping gas premix are
supplied via a protective gas supply device which supplies multiple
workplaces with different gas mixtures without the need for specialty gas
mixing equipment.