View source for Welding helmet

{{Short description|Helmet that protects eyes during welding}}
[[File:Equip per soldar.jpg|thumb|right|A welding helmet in use.]]
A '''welding helmet''' is a piece of [[personal protective equipment]] used by welders to protect the user from concentrated light and flying particles. Different welding processes need stronger lens shades with auto-darkening filters, while goggles suffice for others. [[OSHA]] and [[ANSI]] regulate this technology, defining shades based on the [[transmittance]] of light.

== Purpose ==
[[File:Members of the Women's Royal Naval Service (WRNS) practice welding at a Government Training Centre as part of their training to become Ship Mechanics in 1943. D17082.jpg|thumb|right|Trainees wearing protective goggles while learning to weld (1943).]]
Welding helmets are most commonly used in [[arc welding]] processes such as [[shielded metal arc welding]], [[gas tungsten arc welding]], and [[gas metal arc welding]]. They are necessary to prevent [[arc eye]], a painful condition where the [[cornea]] is inflamed. Welding helmets can also prevent [[retina]] burns, which can lead to a loss of vision. Both conditions are caused by unprotected exposure to the highly concentrated [[infrared light|infrared]] and [[ultraviolet light]] emitted by the welding arc.<ref>[http://www.elvex.com/facts11.htm Elvex Safety Products ''How Light Affects the Eye'']</ref> Ultraviolet emissions from the welding arc can also damage uncovered skin (such as of the face and neck), causing a [[sunburn]]-like condition in a relatively short period of welding. In addition to the radiation, gases or splashes can also be a hazard to the skin and the eyes.<ref>{{Cite news|url=https://www.testbericht-testsieger.de/kaufberatung-automatik-schweissmasken-schweisshelme/|title=Testbericht zur Automatik-Schweißmaske Speedglas 100 von 3M|date=2017-01-12|newspaper=Testberichte für Testsieger|language=de-DE|access-date=2017-01-29}}{{Dead link|date=August 2023 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>

All welding helmets are susceptible to damages such as cracks that can compromise the protection from ultraviolet and infrared rays. In addition to protecting the eyes, the helmet protects the face from hot metal [[Spark (fire)|sparks]] generated by the arc and from UV damage. When overhead welding, a leather skull cap and shoulder cover are used to prevent head and shoulder burns.<ref>{{Citation |last=Miller |first=Mark R. |title=Welding Licensing Exam Study Guide |page=[https://archive.org/details/isbn_9780071493765/page/5 5] |year=2007 |postscript=. |url=https://archive.org/details/isbn_9780071493765/page/5 |publisher=McGraw-Hill Professional |isbn=978-0-07-149376-5 |url-access=registration}}</ref>

== Design ==
Most welding helmets include a window ([[visor]]) covered with a filter called a lens shade, through which the welder can see to work. The window may be made of tinted glass, tinted plastic, or a variable-density filter made from a pair of [[polarizer|polarized]] lenses. Different lens shades are needed for different welding processes. For example, [[Gas metal arc welding|metal inert gas]] (MIG) and [[Gas tungsten arc welding|tungsten inert gas]] (TIG) welding are low-intensity processes, so a lighter lens shade will be preferred.[[File:Gas-welding-goggles.jpg|thumb|Oxyfuel welding goggles]]
Welding goggles are protective eyewear that has dark shading, meant to protect eyes from the bright light produced by [[oxyfuel welding]] and allied processes, and also from sparks and debris.<ref>{{cite book| first = Richard | last = Finch | url=https://books.google.com/books?id=B4UGKKYFUD4C&q=intitle:Welder%27s+intitle:Handbook+intitle:A+intitle:guide+intitle:to+intitle:plasma+intitle:cutting+intitle:oxyacetylene+intitle:ARC+intitle:MIG+intitle:and+intitle:TIG |title=Welder's Handbook: A guide to plasma cutting, oxyacetylene, ARC, MIG and TIG | publisher = HP Trade | edition = Revised | year = 2007 | isbn = 978-1-55788-513-5 | pages = 31–33 | accessdate = May 26, 2010 }}</ref> Open electrical arcs (as created by [[arc welding]] and other processes) generate much higher amounts of light and [[ultraviolet|UV]] radiation, requiring the whole face to be protected; most welding goggles do not have a dark enough shade for arc welding.[[Image:Speedglas.jpg|thumb|Speedglas welding helmet.]]
The modern welding helmet used today was first introduced in 1937 by Willson Products.<ref>[https://books.google.com/books?id=79oDAAAAMBAJ&dq=Popular+Science+1933+plane+%22Popular+Mechanics%22&pg=PA217 "One Piece Helmet Cut To Protect The Welder] ''Popular Mechanics'', August 1937 -- bottom-left of page 217</ref> In 1981, Swedish manufacturer Hornell International (now owned by 3M<ref>{{cite web|url=https://news.3m.com/press-release/company/3m-acquire-hornell-international-expands-safety-products-line|title=3M to Acquire Hornell International: Expands Safety Products Line|website=3M News - United States}}</ref>) introduced an LCD electronic shutter that darkens automatically when sensors detect the bright welding arc,<ref name=":0">{{Cite news|url=https://www.testbericht-testsieger.de/technische-entwicklung-automatischer-schweisserschutzfilter/|title=Technische Entwicklung automatischer Schweißerschutzfilter |date=19 January 2017 |newspaper=Testberichte für Testsieger |language=de-DE |access-date=29 January 2017 |archive-url=https://web.archive.org/web/20170202073719/https://www.testbericht-testsieger.de/technische-entwicklung-automatischer-schweisserschutzfilter/ |archive-date=2 February 2017}}</ref> the Speedglas Auto-Darkening Filter. With such electronic auto-darkening helmets, the welder no longer has to get ready to weld and then nod their head to lower the helmet over their face. The advantage is that the welder does not need to adjust the position of welding helmet manually, which not only saves time but also reduces the risk of exposure to the harmful light generated by the welding process.

==Regulation==
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.<ref name=":0" /> The standard is voluntary, so buyers should confirm that the helmet is ANSI Z87.1 compliant (indicated by appropriate labeling).

United States [[OSHA]] requirements for welding helmets are derived from standards like [[ANSI]] Z49.1, ''Safety in Welding and Cutting'', section 7 (''Protection of Personnel'')<ref name="z49">{{cite web |date=1967 |title=ANSI Z49.1 Safety in Welding and Cutting |url=https://archive.org/details/gov.law.ansi.z49.1.1967 |publisher=American National Standards Institute |edition=3}}<!--Note: This document has been incorporated by reference into law.--></ref> and ANSI Z89.1 (''Safety Requirements for Industrial Head Protection'').<ref name="ansiz89">{{cite web |date=1969 |title=ANSI Z89.1 Safety Requirements for Industrial Head Protection |url=https://archive.org/details/gov.law.ansi.z89.1.1969 |publisher=American National Standards Institute |page=14 |edition=3}}</ref> OSHA also recommends certain shade numbers based on the weld's type and current rating.<ref>{{Cite web |last=U.S. Department of Labor |date=2012 |title=Eye Protection against Radiant Energy during Welding and Cutting in Shipyard Employment |url=https://www.osha.gov/sites/default/files/publications/OSHAfactsheet-eyeprotection-during-welding.pdf |access-date=5 November 2024 |website=Occupational Safety and Health Administration}}</ref>

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".<ref name="z49" />

As of 2023, [[OSHA]]'s website provides standards for minimum protective shades under standard 1910.133 (''Eye and face protection''), section (a)(5):<ref name="osha1910">{{cite web |title=1910.133 - Eye and face protection. |url=https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.133 |publisher=United States Department of Labor, Occupational Safety and Health Administration}}</ref><blockquote>As a rule of thumb, start with a shade that is too dark to see the weld zone. Then go to a lighter shade which gives sufficient view of the weld zone without going below the minimum. 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.</blockquote>

== Shades ==
Per ANSI Z87.1-2003,<ref name="ANSIZ87.1">{{cite web|url=https://archive.org/details/gov.law.ansi.z87.1.2003|title=ANSI Z87.1-2003: Practice for Occupational and Educational Eye and Face Protection, 29|author1=American National Standards Institute|author2=American Society of Safety Engineers|date=2003}}</ref>{{rp|42}} "shade numbers" are derived as such:

<blockquote>Shade Number, <math>S</math>, is related to [[Transmittance#Luminous_transmittance|luminous transmittance]] <math>T_{L}</math> (expressed as a fraction, not as a percent) by the equation:<br />
<math>S = \dfrac{7}{3} log_{10}\dfrac{1}{T_{L}} + 1</math><ref name="ANSIZ87.1"/>
</blockquote>
<math>T_{L}</math> is defined with respect to CIE [[Standard illuminant#Illuminant A|Illuminant A]] (i.e a reference point for typical domestic [[incandescent lighting]]) and the [[CIE 1931]] [[standard colorimetric observer|Standard Colorimetric Observer]].<ref name="ANSIZ87.1"/>

The actual ANSI-specified shades are not specific numbers, but ranges; each has a designated maximum, minimum, and nominal transmittance value. Moreover, acceptable transmittance values for [[far ultraviolet]] are far lower than those for the Illuminant A light ("shall be less than one tenth of the minimum allowable luminous transmittance").<ref name="ANSIZ87.1"/>

=== Transmittance values ===
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-stop]]s).

{{excerpt|Neutral-density_filter|Ratings}}

==Notes==
{{Reflist}}

==Further reading==
*Jeffus, Larry (1999). ''Welding: Principles and Applications''. Albany: Thomson Delmar. {{ISBN|0-8273-8240-5}} .

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[[Category:Helmets]]
[[Category:Welding safety]]
[[Category:Protective gear]]
[[Category:Functional masks]]