Tesla coil UV eye protection?

[Michelle_]

Any suggestions? Is just clear polycarbonate enough?

[Mads Barnkob]

I believe you can find answers for all safety related issues here: https://www.pupman.com/safety.htm

[Michelle_]

I believe you can find answers for all safety related issues here: https://www.pupman.com/safety.htm

I believe not in fact, I’ve already read that page and basically all it says is don’t look directly at the spark gap. I want to know what kind of eye protection people are using to look at the coil when it’s running, don’t tell me nobody is looking at it when it runs. I’m talking about regular sparks or protection from flash over or other unexpected arcs. Or maybe people aren’t using any protection, I guess I wouldn’t know since nobody wants to share. I’ll just figure everything out on my own.

[alan sailer]

Clear polycarbonate will stop the majority of harmful shortwave UV. That is what you have to worry about.

I want to also note that not every question that gets asked on this forum gets an answer.
I've had this happen more than once...my feeling is that the site is doing me a favor and does not owe me anything.

I've never checked into the levels but with some coils (flame tesla  in particular) ozone, nitrous oxides
and metal vapor can be an issue.

Another claim I've run into is nervous system damage. So far all my nervous system damage has been from loud
noises and aging...

Cheers.

[Twospoons]

Any hard plastic sheeting rated for use outside will have a UV blocker added that absorbs anything shorter than about 400nm.  Without that sunlight will rapidly degrade hard plastics like PC, PMMA and PVC.

[MRMILSTAR]

The danger area is the spark gap due to the UV radiation. The UV radiation is caused by the extremely hot spark gap. Mine is shielded from direct view. As far as the streamers are concerned, I don't think there is any eye danger from viewing those. Those aren't nearly as hot as the spark gap. The colors that you see are just nitrogen and oxygen emission lines. I have looked at streamers of various types for years with no ill effects.

[Michelle_]

Thanks, I've been reading some conflicting information and I just wanted to double check from some more experienced people so I don't accidentally go blind or whatever.

[Twospoons]

N₂ emission at 337nm and 357nm is classed as UVA, so what you really need is sunscreen.  Or long sleeves. UVA causes skin damage.
Its worth noting that the UV in the arc is a lot brighter than it appears as your eye sensitivity drops off rapidly below 400nm.  The 337nm and 357nm peaks are 3-4 times brighter than the 400nm  you can see, and your eye is roughly 1/10th as sensitive to 400nm as it is to green light around 550nm.

Anyone own a light meter than covers the UV end of the spectrum?

[MRMILSTAR]

As previously mentioned, the spark gap is dangerous to look at because its so hot. The extreme temperature causes it to emit copious amounts of UV radiation. I have attached two pictures which graphically show this. The pictures are of the bottom portion of the secondary coil for my large SGTC. When in place, this portion was about 12 inches away from my rotary spark gap firing point. The brown area shows the effect of the UV radiation on the PVC tube. It has significantly degraded the surface. This was only after a total of about one hour of operation. The other picture shows my repair. I covered the exposed spot and other parts visible to the UV radiation with aluminum tape.

[Michelle_]

Yeah I think the spark gap is the most worrying thing. Hopefully my PETG will hold up to it for a while, should be better than PVC in that regard. I'll take care to shield it more though. Besides that I'll wear polycarbonate safety glasses in case. I burned a hole in my secondary and the spark was really bright so I guess things like that can happen too.

[klugesmith]

>> Anyone own a light meter than covers the UV end of the spectrum?

Somewhere lost in my sandbox is a photodiode with sensitivity (and clear solid window) that extends below 254 nm.
I got it as a sample from some vendor, long ago, for playing with atomic absorption by mercury vapor.

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Wandering off thread here:
On videos that show UVC shadow of a Hg vapor plume in air, would-be debunkers like to say the heavy vapor should move downward.  Nope.  We are visualizing, with incredible sensitivity, Hg concentrations in air that are only a few parts per million even if saturated. The maximum density increase from Hg could be offset by a temperature rise much less than 1 degree.