Lenses, filters, visors and fittings for one maker's welding helmets: what the types of part do and how to choose the right one.
What do the numbers in an optical class such as 1/1/1/2 mean on an auto-darkening filter?
Many automatic filters are marked with an optical class of four digits, for example 1/1/1/2, taken from the older EN 379 standard. Each digit is scored from 1 (best) to 3 and rates one aspect of clarity: distortion of the view, how uniform and free of impurities the lens is, how consistently dark it stays across its surface, and how the view holds up when you look at the arc from a sharp angle.
The first three are generally seen as the most important because they affect everyday welding. EN 379 has since been withdrawn and replaced by the EN ISO 16321 series, so newer filters may be marked differently. When replacing a filter, check the class and markings on the old one and in the helmet manual rather than assuming all filters are equal.
How do I choose the right shade number for a replacement filter lens?
The shade depends on the welding process, the current, the material and the working conditions, so there is no single right number. Helmet makers publish shade tables in the manual, and the older EN 169 standard for fixed filters included selection guidance in an annex, but published tables do not all agree.
A variable auto-darkening filter lets you set the shade within its range, whereas a fixed lens has one shade only. Check the range or shade marked on the old lens and the maker's instructions. Do not pick a lighter shade just to see better, because too little protection from arc radiation can injure your eyes. Base the choice on the manual and your risk assessment.
Why must replacement filters meet the relevant standards?
Arc welding gives off intense light and radiation that can cause arc eye, an acute injury to the front of the eye. The HSE says welding eye protection, including filters, should conform to the relevant British and European standards, which cover impact resistance, auto-darkening filters and fixed filters.
A lens that is not marked to the right standard, or is the wrong type for your helmet, may not protect you properly. Check the markings on the old part and in the manual, and ask our team if you are unsure. Never keep using a filter that is cracked, chipped or damaged.
How should I store helmet parts and how often should I replace them?
The HSE advises keeping reusable PPE clean, storing it in a dry, clean place when not in use, using the correct replacement parts and following the manufacturer's replacement schedule. For a helmet that means checking the maker's manual for how often lenses and fittings should be changed, rather than guessing.
It also helps to keep spare lenses in their wrapping until needed so they stay clean and unscratched, and to report any obvious defect rather than carrying on with a damaged part.
Can I chip slag or grind with just my welding filter and cover lens?
Not on that basis alone. The HSE advises wearing goggles when chipping slag or wire brushing welds, because those tasks throw particles at the eyes. A dark welding filter is designed for arc radiation and is not a substitute for suitable impact eye protection.
Many helmets have a clear flip-up visor or a clear lens for related tasks. Whether it is suitable for grinding or chipping depends on its markings, the maker's instructions and your risk assessment. If in doubt, wear separate suitable eye protection.
What is the difference between EN 169, EN 379 and EN 175 on helmet parts?
These are older European standards that are still seen marked on helmet parts. EN 169 covered welding filters that do not switch, meaning fixed-shade lenses. EN 379 covered automatic filters that switch to a darker shade when the arc is struck. EN 175 covered the frames and mountings the filters are fitted into.
All three have now been withdrawn and their requirements brought into the EN ISO 16321 series, so newer parts may carry different markings. A marking tells you which type of part it is, which helps when checking that a replacement is the right type. Always check the data on the old part and in the manual before ordering.