PCB was/is a good insulating oil, in that it was least flammable. The
replacement oils now are more flammable. In capacitors, and transformers. I
have seen numberous GE 4 uF 45 kV capacitors rupture and spit flames at work
about 5 years ago, when they were at end of life. These were in pulsed power
energy storage application. They used either Geconal or Dielektrol, GEs own
names for their oils. Succcessively later vintage oils burn even easier. Some
high power oil-filled capacitors are now using a mixture containing rape seed
oil (canola) which is also flammable.
PCB is not good to drink or bathe in, but documented accounts of harm from it,
were from laboratory rat experiments. If you take in sufficient dose of any of
the transformer oils, you can get all sorts of effects. I know technicians who
developed sensitivity to Diala, Shell's transformer oil used in many
substation-sized units. Heating the oil, such as in use, causes volatile
materials to vaporize and are easily injested when you breathe.
Diala also has a pungent almost disgusting odor, like PCB and some others. So
the test for pungent or stinging vapor isn't enough to ID PCB oil. I happen to
like the smell myself, but I wouldn't sit in it for long.
Now for beryllia. It is used in SOME power tubes, not LOTS of them. Eimac had
to include a disclaimer about it with every tube, although most air-cooled and
water-cooled tubes use alumina, not beryllia. It is also in beryllium-copper
metal used for EMI gasket material in some many things. Also in the bottom
insulating material under some high power RF transistors. (not the top white
cap but underneath the device). But to injest it, you have to grind up or cut
and breathe the dust. Again, exposure of one time is not horrible, but repeated
exposure, such as doing this for a job, like a mechanic working on automotive
brakes all his career, is unhealthy.
It would be reasonable to say that many billions of dollars have been wasted
world-wide freaking out about PCB or that ceramic material, whereas the danger
of HV, of getting scaled by too hot water, by automobile accidents, is much
more heinous. However, keeping things in context to ham radio, its best not to
drink PCB oil or cut up and grind BeO2 into dust and breathe this. Incidental
usage of these materials in amplifiers, however, is NOT harmful to humans.
Over-regulation have pushed these materials as safety/environmental concerns in
business world. The companies who remediate and remove them are making plenty
of money now.
John
K5PRO
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