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Re: Photo of my mystery transformer



Original poster: Jim Lux <jimlux@xxxxxxxxxxxxx>

At 02:09 PM 12/2/2006, Tesla list wrote:
Original poster: Daniel Hess <dhess1@xxxxxxxxxx>


Josh;

PBCs in liquid form is not really hazardous. It's the smoke it gives off when heated that's toxic, much like fabric and plastic upholstery or carpet does in a fire. So why my sofa isn't on the EPA's top ten list is beyond me.

Uhh. no..
PCBs (poly chlorinated biphenyls) were used in electrical equipment because they are non-flammable and relatively inert (so they don't breakdown with heat, age, ozone, etc.). Post WWII, where major fires occurred from insulating oil fires after bombing raids, there was a LOT of interest in non-flammable insulating materials (also SF6, by the way). The problem is that there inevitably contaminants from the mfr process, and one of those is dioxin, which is particulary troublesome even in part-per-billion concentrations. Because the pcbs (including dioxin) are so durable, they hang around forever, and accumulate in fatty tissues, wreaking their havoc forever, even in ppb concentrations). Phenyl grops are benzene rings hanging off some other thing (a biphenyl is two benzene rings linked together) Almost everything with a benzene ring is persistent and toxic (benzene, toluene, xylene) and if you halogenate it (which makes a variety of useful things: DDT (based on toluene), 2,4,6-T, etc) it's worse... durable molecules that don't break down that cause troubles in living organisms.

http://en.wikipedia.org/wiki/Biphenyl

The problem with PBCs used in transformers or capacitors is when they overheat and/or vent/explode, they spew out a bunch of flaming, smoking PBC oil and that truly is a heath concern if you happen to be in the vicinity of such an event. Just not to the extent that the safety Nazi's have made it.

PCBs won't flame, nor are they oil, nor do they smoke. And the concern is not with a failure situation, but because they are so longlasting, that when you'd drain a transformer and need something to do with the leftover oil, it would get used for things like "road oil" to keep the dust down. Spraying a long lived toxic substance like dioxin is a recipe for disaster.

http://en.wikipedia.org/wiki/Times_Beach,_Missouri

I agree with the consensus of the list; keep mum and enjoy. A cool find.

Indeed.. most PCB insulated stuff has little or no carcinogen (most PCBs are non-toxic), it's the potential for contamination that's the risk. And, the fact that the making of PCBs inevitably results in a mixture of compounds, and nobody wants to do expensive analysis on every suspected widget, so they treat them all as hazardous.


Be safe,

Daniel Hess