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Re: PCB Question
Original poster: "Bert Hickman by way of Terry Fritz <twftesla-at-qwest-dot-net>" <bert.hickman-at-aquila-dot-net>
David and all,
Your concerns are very justified!
Some history: There are actually over 200 different singly and
polychlorinated biphenyls collectively referred to as PCBs; about 75
of these were used in various commercial applications. PCB's were initially
introduced in 1929 by Monsanto, and were first used in 1930 by GE in PFC
capacitors for utilities. PCB capacitor oils are typically quite viscous
at room temperature with the viscosity decreasing markedly at elevated
temperatures - capacitors were impregnated while hot. The first PCB oil
was 1476 Pyranol in 1930, consisting of pentachlor diphenyl. Approximately
95% of all PFC capacitors manufactured prior to the mid-70's contained
And most of these are FAR from being odorless... :^)
PCB's used in transformers present a more complicated situation, since
were typically blends of chlorinated benzenes and chlorinated diphenyls.
However, the resulting mixture has a marked sweetish, solvent-like aromatic
odor, a marked yellowish tint, and relatively low viscosity (comparable
to mineral oil based transformer oil). As with other PCB's the density was
considerably higher than water (~1.5X). Since these PCB transformer oil
contained volatile elements (trichlor benzenes), its use required that the
transformer be sealed to prevent loss through evaporation.
Voluntary reduction of PCB's began in 1971 when Monsanto (the largest
manufacturer) restricted its use to closed dielectric systems. Only about
5% of all transformers used it, primarily at locations that demanded a fire
resistant dielectric. The US Environmental Protection Agency (EPA) banned
the manufacture of PCB's and regulated their use in 1978.
>From your description, it sounds as though your transformer contains
PCB's... and not at a ppm level, but most likely ~100%. Try the specific
gravity test or burn test. If the sample sinks in water or refuses to burn,
you'll have a sure-fire indication. Some of the previous posts contained
excellent information on other ways to detect oil containing significant
levels of chlorinated compounds.
However, if you want to measure down to the 50 ppm level, there are
commercial testing labs that will do this for you (for many $$$).
Fortunately, there are commercially available testing and spill kits that
will also do the job for you at considerably less cost. These are used by
utilities, hazardous materials teams, etc. to support rapid determination
of whether an unknown oil sample contains low levels of PCB's. Some of
these kits detect the presence of PCB's in oil down to 20 ppm or 50 ppm.
The tests typically only require 10-15 minutes to perform, and can be done
on-site. Examples include Dexsil's Clor-n-Oil, and GE's Kwik-Skrene kits:
The cost of using one of these kits has got to be lower than testing via a
You may be able to obtain a single kit by contacting your local fire
department or hazardous materials team, or by doing a web search for the
Best regards, and safe transforming to you!
-- Bert --
Web Site: http://www.teslamania-dot-com
Tesla list wrote:
> Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> Hi all,
> I have an old (circa 1945) x-ray transformer that I strongly
> suspect has PCBs for the dielectric fluid. I have ran across
> this same type of oily fluid before in another old transformer.
> It looks like oil, but has a different odor than plain transformer
> oil. However, the dictionary definition of PCB states that it is
> in the from of a "toxic, colorless, odorless, vicous liquid form-
> erly used as an insulator in electrical equipment" I was won-
> dering if it was usually mixed with petroleum in electrical euip-
> ment and thus the definite odor. And yes, I have gotten a little
> bit on myself before when I took them apart to facilitate an in-
> ternal repair :-(( Hopefully, my hair won't start falling out tomor-
> I've read that you can drop a drop of the fluid in question into
> some water and if it floats, then in isn't PCB, as PCBs have
> a higher specific gravity than water. However, I personally do
> NOT suscribe to this as a sure-fire way to detect the presence/
> absnece of PCBs as they may very well be mixed in with petro-
> leum oil, which of course has a lower specific gravity than water.
> Maybe some of the resident chemistry majors could comment
> on this?
> David Rieben