[BC] PCB and other hazards

[Mark Humphrey]

On Jan 15, 2008 2:45 AM, Milton Holladay <miltron at mindspring.com> wrote:
> Once you have smelled PCBs, you probably won't ever forget the distinctive
> odor.

I've probably smelled PCBs without realizing they were the source of
the odor.  Richard said, "basically, if it smells, it may contain
PCBs" but I would like to know how many of the substitutes are also as
smelly.

The reason I ask (some of you may have encountered the same
situation):  A couple of years ago, I acquired a Bird 1 kW air-cooled
dummy load, maybe 35 years old, which had been damaged by overheating.
 It had been exposed to 1.5 kw for an extended period and the
resistance had gone over 10% high, so the station just decided to buy
a new one.

In the course of rebuilding it, I drained the oil, which was dark
green, rather thick, and very smelly.  Orange sludge had been
deposited in the bottom, around the resistor and the conical shield
surrounding it, perhaps some kind of copper compound.  According to
Bird's website, they have never used PCBs in any of their products, so
I'm just curious to know what this stuff was.  I did carefully drain
it into a bottle and took it to a hazardous waste disposal center.

After doing some research, I determined that Bird currently uses a
silicone-based oil.  There a distributor in Philadelphia that sells a
similar product at a discount price, although the minimum order is 5
gallons.  I only needed about half of that, so I split the order with
a local ham who was also doing a dummy load rebuild.  Info:

http://www.clearcoproducts.com/specialty_silicones.html#2

The new oil doesn't have any appreciable odor.  With cleaning and some
adjustment of the resistor termination, I got the resistance down to
52 ohms, so the load is now doing a adequate job again.

Mark