With the eye protection issue, there are different types of light.
A oxy fuel flame gives off infrared light mostly, with fewer Ultraviolet. The IR light is what does the damage. Most cutting glasses filter 99.9% of IR light, regardless of shade. Now the intensity of the light itself, may necessitate a darker lens, but that is largely up to operator preference in most cases.
A plasma torch gives off the same UV light that a welding arc does, and in so doing the plasma flame requires similar UV protection which almost all GOOD helmets filter well over 99% of the UV light emitted at any shade. Even the autodarks filter the UV at the light shade. Believe it or not, OSHA only has suggested shades, no REQUIRED standards for minimum shade darkness. They recommend a 8 shade, but freely admit that it isn't required because of the nature of the plasma flame is usually buried in the work and not directly visible. The reason for the shade differences is to protect from temporary blindness of course and to allow the operator to sufficiently see the puddle, but not from the damages that are more permanent from the UV burning out your retinas, and getting eyeball cancer. :shocked:Though radiant energy is definitely a part of the issue as well, which most welding helmets block almost all IR as well.
Oxyfuel glasses may or may not offer suitable protection for plasma cutting. And of course, due to the dangers of the UV light, additional face protection is recommended as well. The best thing is to have a helmet that offers a full range of shades so that the face is protected too. The Everlast Fabricator helmet offer a shade range of 4/ 7-15 for this type use. From the osha ppe standards:
Filter Lenses for Protection Against Radiant Energy
Operations Electrode size in Arc current Minimum*
1/32 (0.8mm) protective
shade
Shielded metal
arc welding < 3 < 60 7
3 - 5 60 - 160 8
5 - 8 160 - 250 10
> 8 250 - 550 11
Gas metal arc welding
and flux cored
arc welding < 60 7
60 - 160 10
160 - 250 10
250 - 500 10
Gas tungsten
arc welding < 50 8
50 - 150 8
150 - 500 10
Air carbon (light) < 500 10
Arc cutting (heavy) 500 - 1,000 11
Plasma arc welding < 20 6
20 - 100 8
100 - 400 10
400 - 800 11
Plasma arc cutting (light)** < 300 8
(medium)** 300 - 400 9
(heavy)** 400 - 800 10
Torch brazing 3
Torch soldering 2
Carbon arc welding 14
Filter Lenses for Protection Against Radiant Energy
Operations Plate thickness Plate thickness Minimum*
inches mm protective
shade
Gas welding:
Light < 1/8 < 3.2 4
Gas welding:
Medium 1/8 - 1/2 3.2 - 12.7 5
Gas welding:
Heavy > 1/2 > 12.7 6
Oxygen cutting:
Light < 1 < 25 3
Oxygen cutting:
Medium 1 - 6 25 - 150 4
Oxygen cutting:
Heavy > 6 > 150 5
Source: 29 CFR 1910.133(a)(5).
* 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.
** These values apply where the actual arc is clearly seen. Experience
has shown that lighter
Sorry the cut and paste didn't work too well, but you can get the gist of it.
