Transformer Oil - Page 1
Forum section: electronics / projects

author: jord4231
author_rank: Regular Contributor
timestamp: July 09, 2025, 11:21:40 am
content: Hi all,Looking for some knowledgeable people in regards to PCB oils, I have an old 1950s transmitter.It's got a sizable oil-filled transformer, probably around 100 kg, with a vent on top.There is a small amount of residual oil visible particularly around the folded metal lips on the transformer.My concern is that this transmitter is in a small room (Ham shack). Is this residual oil a safety concern? I'm thinking vapor / smell etc. I'm not talking about direct contact...Just to add to this I'm not even sure its PCB oil... There is not really enough to collect a sample its a very small amount

author: BILLPOD
author_rank: Frequent Contributor
timestamp: July 09, 2025, 01:39:35 pm
content: Good Morning Jord4231, Polychlorinated Biphenyls, (PCBs), exibit potential adverse human health effects of low-level environmental exposure to PCBs are probable, but not definite, but it is always best to consider them toxic.Disposeof this capacitor according to your local disposal methods. It will probably be expensive to find modern capacitors that are a proper substitute. What is the labeled capacitance, and what is the measured capacitance, (if you can get a reading with any LCR you have access to). The approximate weight of 100kG has me curious, and if you can post a photograph of it, I'm sure everyone watching this thread would appreciate seeing it, (I know I would). Thanks, and be safe.In animal studies, commercial PCBs elicit a broad range of toxic responses including:Acute lethality,Body weight loss,cCarcinogenesis,Dermal toxicity,Fatty liver,Genotoxicity,Hepatomegaly,Immunosuppressive effects,Neurotoxicity,Porphyria,Reproductive and developmental toxicity,Thymic atrophy, andThyroid hormone-level alterations.

author: moffy
author_rank: Super Contributor
timestamp: July 09, 2025, 01:41:01 pm
content: From the age it probably is a PCB oil and definitely something you don't want in a bedroom. I don't think I would want any type of oil filled transformer in a bedroom because of fire risk in the case of a fault and venting, let alone toxicity issues.

author: themadhippy
author_rank: Super Contributor
timestamp: July 09, 2025, 02:21:17 pm
content: Quoteand wot about the transformer the op was asking about?

author: mikerj
author_rank: Super Contributor
timestamp: July 09, 2025, 04:22:13 pm
content: Quote from: BILLPOD on July 09, 2025, 01:39:35 pmDid you copy paste this straight from an AI by any chance?

author: paul@yahrprobert.com
author_rank: Regular Contributor
timestamp: July 09, 2025, 04:58:46 pm
content: One distinquishing thing about PCB fluid is that it doesn't burn. So perhaps you could soak up enough of it with a Q-tip, take it outside, stand upwind, and put a lighter to it.The PCB's I've been near also were much lower viscosity than regular transformer oil and smelled very strongly of dry cleaning fluid or carbon tet.

author: Gregg
author_rank: Super Contributor
timestamp: July 09, 2025, 05:38:02 pm
content: From my experience in the US Navy, PCBs become paint removers if left on most painted surfaces. 1950's vintage is fairly early for PCB use in things not specifically made for military use.

author: BILLPOD
author_rank: Frequent Contributor
timestamp: July 09, 2025, 06:12:30 pm
content: Yes Mikerj, yes, most of it is AI generated, which Google gives automatically on ALL searches. I thought the AI information was very good and better than much of the AI content that Google supplies. I was wondering if anyone would notice. Good eye Mikerj.

author: jord4231
author_rank: Regular Contributor
timestamp: July 09, 2025, 07:45:33 pm
content: The problem is this thing is full of oil filled capacitors transformers etc and this photo is just the start of it.It stands around 6 ft tallIf I was to dispose of all oil filled caps and transformers I would be scrapping a working bit of history, perhaps I need to pop it in the shed and get it out of the house.

author: Perrold
author_rank: Contributor
timestamp: July 09, 2025, 08:00:58 pm
content: It's fine. The big selling points for PCB fluids were higher temperature operation, higher thermal conductivity, and being nonflammable. These came at a higher price tag so unless absolutely required conventional transformer oil or plain mineral oil would be used. Most of the hysteria comes from PCBcontaminationthatcouldbe present. Same facility fills transformers with mineral oil and PCB fluid? There's a potential that a bucket that once held PCB fluid was filled with transformer oil that went into your transformer. A 100kg plate transformer for a transmitter is not a high power density device that runs particularly hot. Hydrocarbon oil would be cheaper and work just as well. A PCB fluid fill was typically a premium selling point and would be advertised as such. Capacitors labeled with one of the trade names for PCB fluids and so on.

author: MadTux
author_rank: Frequent Contributor
timestamp: July 09, 2025, 08:22:26 pm
content: Quote from: paul@yahrprobert.com on July 09, 2025, 04:58:46 pmBurning that stuff at low temperature is exactly what you wouldn't/shouldn't want to do, unless you want to look like Viktor Yushchenko afterwards, if you inhale the decomposition products.Partial burning/oxidation makes all the dioxines, for which that stuff got banned for.Apparently you can decompose PCBs with solid NaOH/KOH pellets at room temperature, which should give biphenyl and Na/K chloride as products.Green flame test is also very sensitive for halogens, i.e. put a very slight amount of oil onto tip of litz copper wire and put it into a alcohol flame outside, if flame gets green, you have halogens, i.e. likely PCBs in you oil.

author: Whales
author_rank: Super Contributor
timestamp: July 09, 2025, 08:36:28 pm
content: QuoteI tried digging into individual PCB compounds (eg CAS 27323-18-8) but I am not smart enough to see obvious evidence relating to their volatility (evaporation).Intentionally manufactured PCB compounds are not the only thing to think about. There will likely be precursors (such as biphenyl) and products from the slow decomposition of the oil + additives mixed in there.Question: is there a cap or lid on top you can remove, and does this cap have an oily residue under it? Assuming the device has never been inverted or sloshed then this oil film must have gotten there through evaporation & condensation. Perhaps as a long-term experiment you could try cleaning the bottom of the cap, waiting a month and then inspect it again.I would assume the oil contains volatile toxic compounds unless proven otherwise. Would not recommend storing in your bedroom.Side story: my dad drives a vintage car with vinyl seats. Over time the inside of all the windows develops a super-greasy layer and the seats eventually crack. The suspicion is that these two things are linked. Not sure.

author: pardo-bsso
author_rank: Frequent Contributor
timestamp: July 09, 2025, 08:39:43 pm
content: If you ever decide to dispose of this wonderful piece of equipment my bedroom is in dire need of something like that.

author: jord4231
author_rank: Regular Contributor
timestamp: July 09, 2025, 08:48:11 pm
content: The large Plate / HV transformer in the picture has a vent on the top (in the Large picture top left hand corner).I'm going to assume it has been on its side at some point in its life but who really knows..Just to clarify this is not in my bedroom where I sleep but a ham shack (about the size of a bed room) spare room down the back of the houseI will see if I can get out a decent camera and take some pics of the residue I can see

author: radiolistener
author_rank: Super Contributor
timestamp: July 09, 2025, 09:02:36 pm
content: these old-age oil capacitors and transformers often contains very toxic poison inside. So this is definitely very bad idea to have it at home.

author: Zero999
author_rank: Super Contributor
timestamp: July 09, 2025, 09:03:32 pm
content: Quote from: jord4231 on July 09, 2025, 07:45:33 pmSerious question: what's it doing in your bedroom? Is it powering anything? It sounds like a strange place to store it. I agree. Keep it in your shed, away from people. It's much less of a hazard if it burns there.

author: jord4231
author_rank: Regular Contributor
timestamp: July 09, 2025, 09:10:37 pm
content: Quote from: Zero999 on July 09, 2025, 09:03:32 pmIts in a ham shack about the size of a bed room not an actual bedroom sorry I will edit the original post to avoid confusion!In answer to your other question Yes I use it on air on the 160m amateur band

author: radiolistener
author_rank: Super Contributor
timestamp: July 09, 2025, 09:56:30 pm
content: The Titanic was equipped with a radio transmitter, and as far as I know, there were plans to recover it for historical preservation. However, the idea of raising the section containing the transformers and capacitor batteries was rejected, as moving these components could compromise the structural integrity of their casings. This, in turn, might result in the release of toxic insulating oil into the ocean, posing serious environmental risks.In the photo, this block containing the oil-filled components is located in the lower right corner.

author: moffy
author_rank: Super Contributor
timestamp: July 09, 2025, 10:35:47 pm
content: The OPs photos look to be in a lot better condition than those from the Titanic, is that a metal enclosure that the OPs equipment is all built into?

author: jord4231
author_rank: Regular Contributor
timestamp: July 09, 2025, 11:18:58 pm
content: Quote from: moffy on July 09, 2025, 10:35:47 pma little better shape than the Titanic transmitter. Yes it's all built in to a rack cabinet with doors.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: July 10, 2025, 12:03:08 pm
content: These PCB (https://en.wikipedia.org/wiki/Polychlorinated_biphenylNothttps://en.wikipedia.org/wiki/Printed_circuit_board) oils were very common, also in power transformers (those Giga Watt things used by power companies). I have some vague memories this type of transformer oil was phased out somewhere in the '80-ies or '90-ies. Modern transformers use another type of transformer oil, and I think that back then all the old transformers got some kind of a revision job, in which also the oil was replaced.

author: CaptDon
author_rank: Super Contributor
timestamp: July 10, 2025, 06:01:55 pm
content: Basically if you don't stay in long contact with it by simply wearing gloves while cleaning the surfaces you will be fine. We ran 20 kilowatt transmitters to this very day with PCB capacitors and transformers. We were required to mark the transmitters as "Contains PCB hazards" and the fire department required the pre-printed placards on the entry doors to the transmitter room which had something like "This facility contains PCB hazards". Too many Chicken Little posters blowing the actual hazard way out of proportion. AND YES, PCB transformer oil WILL BURN but with a higher ignition temperature. It even smells like kerosene. They actually incinerate it in a normal gun style oil burner with a fire brick liner designed to operate at high temperatures to get rid of the stuff that has been recovered from old transformers and capacitors. There is still a lot of the stuff around!! I can lay my hands on Inerteen 50% PCB oil in a heartbeat.

author: amyk
author_rank: Super Contributor
timestamp: July 11, 2025, 03:07:27 am
content: Quote from: radiolistener on July 09, 2025, 09:56:30 pmAlmost certainly no PCBs there. The Titanic predates PCB production and use by over a decade.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: July 11, 2025, 11:36:33 am
content: @CaptDon has a more realistic view of this stuff. It's true, you don't want it moving up the food chain, but the actual risk has been blown out of proportion. People in the industry got covered with the stuff with little ill effect. Toxicity studies usually involve gross overexposure and long time periods. I'd certainly avoid exposure and use good industrial hygiene, but I wouldn't panic and dispose of anything.

author: Gyro
author_rank: Super Contributor
timestamp: July 11, 2025, 12:46:47 pm
content: Possibly obvious, but try increasing the ventilation (extractor fan). Not only will it reduce volatile compounds in the air but the transformer might run cooler, reducing the amount it vents in the first place.From the look of it, feeling cold is unlikely to be one of your problems. You don't need many air changes per hour anyway if the fan is carefully placed [Ed:or ducted].

author: Haenk
author_rank: Super Contributor
timestamp: July 11, 2025, 02:09:10 pm
content: Still the main issue is with accumulating in your* (*someones) body, causing cancer. I would assume the current state of being a bit oil-wet is not worrying, as that oil will mainly stay where it is.I'd either take care of very good ventilation, or cleaning and sealing (with boat sealant).If you can gather a bit (with a filter paper; put into sealed clean container), you can have it analyzed - XRF should not be too expensive. Just to be sure, what you are dealing with...