Recycling of oil-filled transformers

[RogerWalker]

'morning all. Over the years, I have acquired a number of 'potted' transformers from mainly XWD equipment. Typically, they are about 6"/150mm cube and I suspect, filled with oil that probably contains nasty PCBs.

In the process of downsizing, I need to know how best to dispose of them, if possible without incurring massive reprocessing charges and, ideally being able to extract and sell the kgs of copper they contain to supplement my pension. I have read much about the potential toxicity of the oil - from 'never let it near you' to 'handle with great care, wearing gloves and mask'.



Has anyone on here ever successfully drained a potted transformer, safely and legally disposed of the oil, and lived to tell the tale, please?

[Ed_Dinning]

Hi Roger, Many transformers were potted in a basic mineral oil as PCB based oils were good but very expensive (so a possibility in Mil equipment, but maybe only post war).
The oil is normally disposed of by high temp incineration, not something to do on a DIY basis; the whole transformer needs to be done as it is all contaminated
Are there any chemists on the forum that can think of a simple test for these compounds ?

Not just the copper that is worth weighing in, there is probably a sale for the cores id they are the "C" type for use in Hi Fi amps

Providing sensible precautions are used and they are sealed/bagged there should be little risk.
Local councils may then dispose of small quantities of complete transformers, but that will depend on local policies

Ed

[GrimJosef]

Strictly speaking off-topic, I accept, but is there a good reason for not selling them as working transformers to people who could use them ? The Parmeko Neptune ones sell for large sums on eBay. I'll be taking some to RetroTech.

Re-use comes above recycling on the 'how to be green' priority list .

Cheers,

GJ

[woodchips]

From limited reading about the PCB oil, apparently used in just about any electronic device as a very stable high conductivity coolant, it seems that the oil isn't inherently poisonous or similar like mercury or cadmium.

The problem with it is that it is very stable, why it was used in the first place, and stays in the environment for decades. Apparently the oceans have measurable amounts floating around. It accumulates in the body fat but not clear what problems this causes.

Is high temperature incineration below or above 1083C, the melting temperature of copper, so smelting will automatically get rid of it. No scrap is used as is, it is always smelted to create something new.

I must say that in many decades of taking things to the scrappy they have never asked about the presence of PCBs in the transformers, capacitors etc. But they do ask about lithium batteries, apparently they cause the furnaces to explode if left in with other metals. Last year I gave away many large transformers, some were oil filled by Parmeko etc, but the recipient didn't seem bothered by them. In fact the comments were that these were expensive transformers and giving them away was really generous.

Make of that what you will.

[David Simpson]

If they are electrically safe, working, and not leaking - flog them via VMARS if they are exWD.
If they are rusty & seem ready to leak - take them to your local recycling depot & put them in the "hazardous WEEE" box.
DO NOT try stripping them out - possibility of Phenol contamination.

Regards, David (ex WEEE Certificate holder)

[GrimJosef]

Originally Posted by woodchips

... Is high temperature incineration below or above 1083C, the melting temperature of copper, so smelting will automatically get rid of it. No scrap is used as is, it is always smelted to create something new ...

The devil is in the detail with incineration. The ultimate temperature might be high, but if the temperature rise is slow then volatiles will be driven off early in the process, while everything is still quite cool, and may not be fully burnt down to CO2, H2O and whatever happens to the chlorine.

The real problem with PCBs is that relatively low temperature chemistry, including incomplete heating/burning, can convert them into dioxins (see https://en.wikipedia.org/wiki/Polych...of_destruction), some of which are very unpleasant indeed. This is why disposing of them has to be such a specialist business.

Cheers,

GJ

[RogerWalker]

Thanks everybody for such rapid and constructive replies. I would love to sell them as-is, but wonder what market ther is for 500-0-500V 200mA transformers, except for builders of homebrew transmitters? Some are even higher voltage, ex-oscilloscope etc and some are just low voltage high current filament transformers. Being heavy [up to 8kg] the cost of packing and sending anywhere would be prohibitive and [being located here in mid Wales] the chances of someone collecting them shrinks the market opportunities somewhat.
I had considered all that before deciding to go the salvage route: draining off the coolant oil and then incinerating at a temperature just low enough not to melt the copper but hot enough to decontaminate residual oil [ie; big bonfire temp!], then remove cladding and then break open the lams to get a bobbin and copper. Best offer I have had so far is 30p/kg, but a friend on here reckons he can get £1/kg as-is and up to a fiver/kg semi-stripped down.

Anyone any experience selling such items for salvage please?

I even have a homebrew PSU with 730V dc at 150mA and multiple 6.3V and stabilised bias supplies that I can hardly lift off the ground!

[GrimJosef]

Originally Posted by RogerWalker

... but wonder what market ther is for 500-0-500V 200mA transformers ...

Seriously, just check eBay Sold Listings. I wouldn't be surprised if that fetched a 3-digit price, and less than a tenner for shipping (courier collected). It's true that the CRT ones (kilovolts, milliamps) are less attractive. But they will still be worth something.

Cheers,

GJ

[Goldie99]

Originally Posted by RogerWalker

Has anyone on here ever successfully drained a potted transformer, safely and legally disposed of the oil, and lived to tell the tale, please?

I have no personal experience with pcb's, but if you are interested in "safely and legally" disposing of pcb contaminated oil, the following reference may be of interest:

https://www.gov.uk/guidance/polychlo...osal-labelling

Burning them in any kind of bonfire is not on the list.

Alan

[kalee20]

Transformer oil certainly exists, as distinct from PCB's, it's basically highly distilled, deionised mineral oil.

Paraffins are chemically very unreactive, except for burning; they're non-polar so have low dielectric losses, and are non-conductive so make excellent insulators. Transformer oil is expensive the reason being to get to that level of purity, for a niche market, rather than just burning in boilers and engines.

The problem is, as I see it, how to know whether it really is just mineral oil or the much more insidious PCB's sloshing around. I can't help unfortunately, but it's certainly the case that not every transformer that sloshes is automatically hazardous.

[David Simpson]

Roger, you're not that far from Hack Green in Cheshire which used to hold(prior to Covid) large ARS junk sales. I think VMARS had some connection too. You could also put out a sale post on the Golborne Forum Site.

Regards, David

[RogerWalker]

Thanks for the futher messages and useful links and suggestions. I will digest fully and revert.

[Peter F4VSA]

Hi Roger, could I add my few words. From experience high quality oil filled transformers up to around 500v at a few hundred mA do have a high resale value and are fairly cheap to ship by courier etc rather than the Post Office. These are aimed at the crazy valve amplifier market, it would be a shame to see them destroyed. I have bought them during my 50 years in this game and still use them as the gold standard of transformers.

Peter F4VSA/G8BZR

[CambridgeWorks]

Just be aware about all carriers t&c regarding sending anything containing liquid.
I had one who specifically excluded oil filled transformers in the quote.
Rob

[turretslug]

I agree that these transformers can fetch surprisingly high prices when they have outputs suited to valve power amplifier use - but be very careful to thoroughly protect the ceramic post type terminals if using a courier, e.g. with drilled off-cuts of plywood or the like with greater depth than the terminals well-taped to the case, then thorouhly enveloped in sturdy corrugated cardboard within generous outer packaging to guard against the woes of transit. I've had otherwise commendably well-packed transformers turn up with severely bent M5 studs, which takes some doing!

[woodchips]

On the other hand I recently listed the pair of transformers from a HP 628A sig gen, all valve, made in 1990 so no PCBs, and no interest whatever.

I did notice that the high voltage caps were marked NO PCB, except one with a 70's date code which was before the banning of PCBs. Not very good HP!

11 Feb 2021.

[factory]

Well you would have needed to advertise them elsewhere to get some interest, they are of no use to me as I don't own a 628A, probably unlikely to fail anyway, shame you recycled them, can't imagine many are left in the UK now.

David

[factory]

Originally Posted by woodchips

I did notice that the high voltage caps were marked NO PCB, except one with a 70's date code which was before the banning of PCBs. Not very good HP!

It's very unlikely HP made the capacitors, they would have bought them in from Sprague, Sangamo, Mallory, CDE etc.

David

[Al (astral highway)]

I made an original, detailed snd extensive study of copper refineries’ dioxin and furans smokestack emissions after US smelter Chemetco was found guilty of felony pollution offences. I am an expert in this field after I spent five years investigating this case and the entire secondary (scrap) copper refining industry, during which process I corrected some US EPA data by pointing out that test rigs were tampered with and data otherwise manipulated by the refinery concerned.

Although the kinds of oils you mention are supposed to break down harmlessly with incineration, I’m afraid the evidence is that they do not do so sufficiently even in a refinery furnace. Instead, they leave the smokestack emissions and can be carried many thousands of miles, ‘grasshoppering’ their way. Dioxin and furans from a point source in southern Illinois was traced all the way to the high Arctic, where it accumulated in lichen. Caribou ate the lichen and it entered the human food chain and particularly of concern, breast milk.

Persistent Organic Pollutants (POPS) have gone down the agenda since the 2000’s as other priorities have increased.

But unfortunately, these transformer oils are likely ‘forever’ materials.

You will not be paid the price for clean, bright copper wire if you produce pcb-contaminated wire from a transformer. Even if there is in fact no safe way of incinerating the oil, a scrap merchant will act as if there is and will deduct a penalty. ‘Irony copper’ is a price category for transformers with lams and windings and it doesn’t pay very much.


There is one major copper refinery in Europe. The others are largely in China and India. There is an unquantified but large risk that if you sold your scrap, someone here would burn it in an oil drum, releasing dioxins and furans, or that it would be shipped to China with the same effect - release of dioxin and furans into the atmosphere.

This really becomes a moral problem as much as anything. You are almost certain to produce hazardous wastes by any attempt to process the transformers, and if you don’t, likely someone else will. Nobody was thinking about disposal when these products were manufactured.

[David Simpson]

Al has summed up the situation really professionally, and his advice should be adhered to.
Although we've left the EU, I think that the EU Directive on WEEE still stands at the moment. All I used to have was a Paragraph 47 Exemption Certificate, but the penalties for incorrect disposal were draconian.
If folk aren't prepared to flog decent transformers on this Forum, or VMARS Forum, or Golborne Forum - then take them to Retrotech, or one of the BVWS Swapmeets, or a local ARS Junk Sale. If you don't want to get off your arris & attend one of these venues - then as I said before - take them to the WEEE Disposal Container at your local Council's Skip Site. Taking them to a "Scrappy" for "cash in hand" risks your local community breathing in "God knows what" when Paddy O'Tool lights his bonfire or copper crucible late at night !

Regards, David