Welding helmet

Different welding processes need stronger lens shades with auto-darkening filters, while goggles suffice for others.

Both conditions are caused by unprotected exposure to the highly concentrated infrared and ultraviolet light emitted by the welding arc.

Most welding helmets include a window (visor) covered with a filter called a lens shade, through which the welder can see to work.

[5] In 1981, Swedish manufacturer Hornell International (now owned by 3M[6]) introduced an LCD electronic shutter that darkens automatically when sensors detect the bright welding arc,[7] the Speedglas Auto-Darkening Filter.

In the United States, the industry standard for welding helmets is ANSI Z87.1+, which specifies performance of a wide variety of eye protection devices.

The standard requires that auto-darkening helmets provide full protection against both UV and IR even when they are not in the darkened state.

[10] The 1967 edition of ANSI Z49.1.7.2.2.10 specifies that "all filter lenses and plates shall meet the test for transmission of radiant energy prescribed in paragraph 6.3.4.6 of the Safety Code for Head, Eye and Respiratory Protection, USA Standard Z2.1-1959".

In oxyfuel gas welding or cutting where the torch produces a high yellow light, it is desirable to use a filter lens that absorbs the yellow or sodium line in the visible light of the (spectrum) operation.Per ANSI Z87.1-2003,[12]: 42  "shade numbers" are derived as such: Shade Number,

[12] The actual ANSI-specified shades are not specific numbers, but ranges; each has a designated maximum, minimum, and nominal transmittance value.

[12] While ANSI shades are ranges based on a specific illuminant, and do not directly convert into other measurements of transmittance, the following table gives a rough approximation (in terms of neutral density filter numbers and f-stops).