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Posted By Paul L Williams
Dear all,
I have been asked a question to which I didn't know the answer and wondered if anyone could throw any light on it? Does the distance a person views an arc welding light from affect the potential damage to their eyes and if so what would be a safe distance to view it from?
Many thanks
Paul
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Posted By Paul Leadbetter
Paul
As the intensity of the UV radiation will drop with the square of the distance from the welding operation, the risk of injury will be less for someone further away. However, the initial intensity at the weld will depend on the welding process (MIG or TIG) and the welding current. It is not practicable, therefore, to give a safe viewing distance and, in any event, that would be a poor control measure as it would be too easy to circumvent.
Paul
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Posted By holmezy
Hello,
only slightly related to the question..
a mate of mine who is a welder at another company told me that "normal specs protect from arc eye when over 2m away".
didnt know whether to believe him and couldn't be bothered to find out at the time because my firm dont do welding....
anyone..??
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Posted By Merv Newman
As said, the inverse square law does apply but the point intensity of a spot welding arc is extremely high (don't ask me how much)
A person only occasionally exposed at some meters distance is unlikely to suffer permanent harm. From my point of view, as a non-welder, this is difficult to assess
However, frequent or continuing exposure may cause considerable damage.
My brother was a welder and suffered every day from arc-eye. And holes in his pully.
PPE and screens are, I think, the only answer.
Merv (non expert. what's a TIG ?)
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Posted By mark limon
AS an ex time served welder there will be a safe distance but no one will know exactly what it is.
It could be 20/30 or more yards away.
Eye protection is a must and normal glasses (not recommending them,suitable protection will come from the risk assessment) ) will stop you getting a flash(arc eye) from less than 2 metres away but will not stop you being dazzled.
TIG=Tungsten inert gas shield welding
The intensity of the arc does have a bearing on the severity of the flash.ARC AIR gouging is probably the worse
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Posted By John Murgatroyd Ordinary glass stops about 90% of UV, so GLASS spectacle lenses would do as well. Just to throw more confusion into the pot, if the welding arc is CO2 shielded then you can expect more cases of arc-eye ! You should be aware, however, that arc eye is extremely painful even to a person who has had it many times ! To a person having it for the first time it causes not only pain but near panic. More easily described as "having hot sand put into your eye"..........rubbing makes it worse. The only treatment is a painkiller (I use aspirin because of the anti inflammatory properties it has) and covering the eye/s with a WET, COLD CLOTH....and going to bed. Believe me, you won't be doing much else. Driving is hard work, because of blurred vision and at night every street light has a large halo ! (very pretty, at any other time !) http://en.wikipedia.org/wiki/Gas_metal_arc_weldingYou can (at present) be assured that the damage is transient and heals rapidly, with no long-term effects. http://www.rsc.org/deliv...=b205044g&JournalCode=PP
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Posted By mark limon
I dont think CO2 shielded would be anymore likely to than any other to cause a flash.I think its the distance away you are and the intensity of the arc(from any source)that leads to a mild or severe flash.
Speaking from a lot of experience,aspirin or other painkillers doesnt seem to make any difference and a mild flash hurts like hell .
A wet cold teabag on the eyes does help
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Posted By Jane Blunt
There was some research done by the US Military (sorry, am unable to track down the reference on the web) who put out some typical figures for the distance and duration from an arc where the UV radiation was reduced to the US daily threshold limit values.
Some examples:
MMA, mild steel, 100-200 amps, 10 minutes at 10 metres, 8 hours at 70 metres.
MIG, CO2, mild steel, 350 amps, 10 min at 13 metres, 8 hours at 90 metres.
TIG, mild steel, 150 amps, 10 min at 3 metres, 8 hours at 20 metres.
Jane
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