EN379 - Variable or dual scale welding protection filters
Specifies the requirements relating to welding filters which automatically switch their transmission factor in the clear zone to a lower value when a welding arc is struck (known as welding filters with switchable scale numbers). The specifications of the standard apply if such a filter is to be used for the continuous observation of the welding process and if it is only used during the period where the arc is ignited. The standard also specifies the requirements for welding filters with different welding scale numbers in the clear zone (called welding filters with a double scale number). These filters are used for welder protective eyewear or system-mounted protection.