Monday, March 01, 2021

Tin Cans With Strings to You


You will have to excuse the title. It kept coming to mind as a lot of old radio engineers refer to these capacitors as "tin cans."  In the USA, Pyranol caps, like all other PCB-containing (polychlorinated biphenyl) capacitors were banned in 1979.  Also called "Arochlors",  you will still see them at swap meets, and on eBay often without proper health warnings. But companies still do get fined for selling them, even at liquidation. Railside LLC got a tiny $250 fine from the EPA back in 2009 for selling PCB-containing capacitors without proper labeling or storage. [SOURCE] Nonetheless I easily found 8 different listings on eBay today without any warning whatsoever.

In 1865, the first "PCB-like" chemical was discovered, and was found to be a byproduct of coal tar. In 1881, German chemists first made PCBs synthetically in a lab. The Swann Chemical Company began making them for electrical use on an industrial scale in 1929. Monsanto bought their Anniston, AL plant in 1935 and took over production. Monsanto built a similar plant in Sauget, IL in 1955. (More HERE) The toxicity of PCBS was well documented even before the 1940s, so their continued use was inexcusable arguably criminal. Post PCB-ban, most liquid-filled capacitors use mineral oil or  rapeseed oil today

The law that prohibits the sale of PCBs is the Toxic Substances Control Act (TSCA) of 1976. It went without an update until 2016, thank you President Obama.  The original 1976 law in addition to PCBs included lead, radon, asbestos, and formaldehyde to name a few. But on that list PCBs are special They are more immediately toxic than the other substances and can be absorbed through the skin. Similar to dioxin, they have no taste or smell which can exacerbate exposure. And they're not just in old capacitors, they were also in transformers, voltage regulators, switches, light ballasts and innumerable other electrical components. Then there is the bumping. It is estimated that between 1946 and 1977 General Electric dumped about 1.3 million pounds of PCBs into the Hudson River. Mom was right, don't swim in the Hudson. More here.

But as toxic as it was, they made great capacitors. PCBs are non-flammable, a superior dielectric and very stable because of their superior heat transfer properties. They were ideal in high voltage, high capacity designs. When you can find them, you are most likely to encounter the wound-film capacitor variety. In the case of metalized film capacitors, also prevented arcing between the two plates. But if arcing did occur, the oil would reseal the burn hole. For that reason, this type capacitors were sometimes referred to as self-healing capacitors. They were used often with high-wattage radio transmittters. More here.

Below I have collated a good-sized list of PCB-containing trade names listed on numerous different brands of capacitors. There is an even bigger list in the book Paradigms Lost by Daniel Vallero. The EPA has a list here as well. But PCBs have been used for over 150 years and many early manufactureers have gone out of buisness. The 1979 EPA Final Rreport seems to have disspeared from their website. But it's still on the way back machine here. I've noted some common spelling variants in parentheses.

Trade Name
Apirolio -
Aroclor (Arochlor) Monsanto
Ascarel (Askarel)
ESCO, Ferranti-Packard etc.
Asbestol American Corp.
Aerovox Aerovox USA
Chlophen -
Chlorextol Allis-Chalmers USA
Chlorinol - USA
Chlortol -USA
Clophen BayerGermany
Delor-Czech Republic
Diaclor SangamoUSA
DK (Decachloro-diphenyl) -
Dykanol Cornell Dubilier
Elemex Line Material
Eucarel -USA
Hyvol (Hydol)-
Kennechlor (Kanechlor)MitsubishiJapan
Montar -
Noflamol (No-flammol)
Phenoclor Prodolec France
Pyralene Prodolec France
Pydraul -
Pyranol (Pyrenol) GE
Pyroclor -
Saf-T-Kuhl Kuhlman
Santotherm (Santothern) -
Santovac Monsanto
Sovol (Sovtol) -
Therminol (Therminal) Hints


No comments:

Post a Comment