Somewhat OT - Transformer oil

Is steam cleaning an option, if you can drain off the usable oil. It sounds like the gunk may still cause problems later, and reduce the efficiency (slightly).

Joules

I've got 5 gallon in sealed tin

-- Regards,

John Stevenson Nottingham, England.

It's ever so tempting to hose the electrical bits down with my little mickey mouse pressure washer, but I fear it could be a mistake. It's difficult for me to tell whether the sludge on the works is some sort of oil/water emulsion, or not. It's certainly got oil in it.

I have removed about a gallon of watery, rusty, cr*ppy sludge from the bottom of the tank but I wasn't surprised to find that.

I don't believe the deposits on the transformer were *causing* a problem, more concerned that they could be a symptom of one, especially the green tinge, & that's putting me off returning any of the old oil to the tank.

Cheers Tim

I can sympathise with Tim on this one, as we have a honking great Canning & Co Ltd plating tranny in the old factory that we have to move out, and nobody knows what is inside.

Cannings appear to have shut down, they used to be one of the biggest companies in plating gear in the UK, so we can't find out if we have a PCB type of oil or something safer.

We are tempted to take it to the scrappie who has relevant safety kit to drain it and not get involved ourselves. Specialist companies charge huge sums to come along and drain it and 'make safe', but not this time I feel.

Peter

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Isn't one of the 'benefits' of PCBs that they don't burn easily? If that is the case, try soaking a bit of rag with it & putting a match to it. If you need a blowlamp to ignite it, it's probably a PCB (my guess, don't stake your life on it ) Of course, you'll need to be very careful with it if you think there's a serious chance of it being nasty.

Cheers Tim

IIRC most copper salts are blue; copper oxide is black (or red in the rarer form of cupric oxide), copper carbonate is green but I wouldn't expect it to form under oil. Martin

The problem is that once you officially 'know' it's a PCB oil, then you are into reams of paperwork and specialists and MONEY!!

Better talk to the scrapyard I feel, as at least they have the equipment to play with it.

Haven't got the new van yet so can't move it until that arrives.

Peter

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Wouldn't a blue salt combined with yellow oil or brown 'rust' tend to look greenish?

Cheers Tim

PCBs were mainly used in capacitors and sometimes in high voltage transformers because their ability to withstand high voltage stresses and their slightly higher dielectric constant(K).

A 240v welding transformer is not in this class. The oil is there as a cooling agent and the use of a PCB is extremely unlikely. I once had PCB impregnated capacitor that leaked. The leakage had a strange unfamiliar smell quite unlike any of the oils that we normally encounter.

For cooling use, the exact oil type is not important as long as it's not higher viscosity or, a cutting oil with aggressive additives.

Jim

I never remotely thought my welding transformer might have PCB in (That was Peter's concern over his plating unit), it was more a question of what might be in the oil which has allowed the green sludge to appear/be deposited.

Are you saying that, for instance, light machine oil would do, at half the price (to me) of transformer oil?

Cheers Tim

The presence of water in the oil would allow some corrosion of the copper to take place, particularly if the water had become either acidic or alkaline from breakdown products of the oil, so I suggest the green colour definitely comes from the copper.

Cliff.

No you definitely NEED that drum of transformer oil I have for sale :-)

-- Regards,

John Stevenson Nottingham, England.

Yes you can. The special thing about transformer oil that it is a very pure simple oil which is able to withstand high voltage stresses. It is processed to have particularly low levels of chlorine impurities and is extremely thoroughly vacuum dried to remove even the tiniest trace of adsorbed water.

None of this should matter for your welding transformer. The oil is there as a coolant because it's a professional class item intended to withstand relatively long periods of operation at full power. For non- professional use with only occasional periods at full power you could get away with a partial fill or even none at all!

Jim

Really John - you should be more careful - someone will start calling you a cynical Trader!

Jim

Hello all. I have heard of people using vegetable oil (cooking oil, sunflower oil) in transformers and welders. I understand this is relatively unreactive, and performs the task perfectly adequately without causing corrosion. I would think think that light machine oil or any other mineral oil may melt away the insulation on the windings, as will any detergent-containing oils. I'd clean the transformer with diesel (using parrafin gun or similar), drain or dry thoroughly, re-assemble, and then fill with nice cheap sunflower oil, available in my local tescos in 25 litre drums! Hope this helps. Joe landy Peterborough UK. p.s PCB fluids are pretty nasty, and apparently cause birth defects or similar if contacted, so I'd recommend asking some old pensioner or someone who is sure they don't want any (more) children to do all the decanting for you. Keep well away! It can be disposed of in small quantities contained in plastic though. See local authority or environmental agency websites for sull details. I had to deal with some PCB filled capacitors some time ago, and it wasn't as much of a problem as I thought. bye.

Well AFAIK 'ordinary' transformer oil *is* a mineral oil

Interesting idea, though I think I'd want confirmation from another source that it would be OK (simply because I'm ignorant as to whether it's OK, never heard it suggested before)

As I've tried to say before, the welding transformer in question doesn't/didn't & I never remotely thought it might contain PCB fluid!! It's had ordinary transformer oil which seems to have become acidic or contaminated in some other way.

Thanks

Tim

Transformer oil IS a mineral oil and is less aggressive to the common insulants than diesel

Vegetable oil could work short term but long term performance is dubious because of poor resistance to oxidation - look at the inside of your chip pan or the rubbery gunk that forms on an oily utensil left unwashed for a few weeks. Acid content is unknown.

The compatibility with residual transformer oil is uncertain. Some combinations can result in something like thick black treacle. Adding mineral oil to Castrol R (which is castor oil based) can instantly ruin an engine!

Jim

Shell sells a transformer oil called Dailia (?sp).

Worked in the X-RAY field design, service etc. Found many old transformers filled with pcb's

Various companies sell filter / exchange kits to remove pcb oil and load transformer with new oil.

Please properly dispose of pcb as on this side of the pond you now have to have tested and certify that property (land) for sale has no haz mat on it and the seller has to clean it up at his expense.

One note any oil filled xformer that has been out of it's oil bath will / should be de-gassed after it is back in the oil. In the med x-ray industry we attached a small vacum pump to the tank for a day or two and tilted the tank to aid in clearing the air in the coils. Our oil was used as an electricial insulator not for cooling.

Hugh

Hi Hugh:

Diala :-))

That's the oil we have been giving away to the guys for their welders.

Peter

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