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Nitrogen oxides
Hello all:
Been watching the messages about spark gap fumes for a while and decided
to jump in. An electric discharge in air will form a number of
different compounds. A hot arc favors the formation on various nitrogen
oxides. Nitric oxide (NO) is colorless and odorless, it reacts quickly
with oxygen to form the highly toxic nitrogen dioxide (NO2/N2O4), this
is the brown, odorous gas. It is doubtful the much nitrous oxide (N2O)
is formed, and if it is, its basically harmless. Nitrogen pentoxide
(N2O5) may also be formed, but its a solid. The formation of ozone (O3)
is favored by a corona discharge. Ozone is also formed by the action of
short wave UV light on oxygen, and forms an equilibrium (2O3<-->3O2).
It is quite toxic, but is very reactive and unstable, and doesn't
persist. It is also possible that small amounts of metal are
vaporized, but these would be quickly oxidized to the metal oxide, which
for the most part are pretty harmless (unless of course you are using
thallium, mercury, arsenic or some other highly unlikely metal in your
electrodes). The brown cloud that has been seen is not vaporized copper
but likely NO2. And no, you can't form any metal carbonyls in a spark
gap. In my opinion, the sensible operation of a TC spark gap does not
constitute a health risk, at least not from any of the gases formed (I'd
be more concerned about the pole pig you are using to power it!). I
wouldn't suggest running a large spark gap in a small, enclosed room for
long periods of time, but outside or in a well ventilated garage for the
several minutes a TC is running, is not a problem. Hope this helps.
--
Have a good day!
Eric Davidson
edavidson-at-icva.gov