Oil for a leaking Tinsley standard resistor - Page 1
Forum section: electronics / general

author: tggzzz
author_rank: Super Contributor
timestamp: October 30, 2019, 01:13:56 pm
content: I've got a Tinsley 1659 oil-filled 10ohm standard resistor, and some of the oil has leaked out. The datasheet indicates that "the standards are not filled with oil when supplied. The recommended oil is Castrol Whitemor WOM14 or if it is not obtainable any high-quality non-corrosive oil can be used such as Transformer Oil".Firstly I have to clean the leaked oil off the outside, then decide whether or not to top up or refil the oil. The latest calibration markings are from 1995, so I think it is reasonable to assume there are no PCBs in the oil!Thereafter I could just leave the remaining oil in the resistor with a 1-2cm airgap at the top, or drain the oil. Either would imply not putting 1A(!) through the coil, but I don't see any real problem with that.Alternatively I could drain the oil and replace it. I've looked for Castrol Whitemor WOM14 (now called optileb wom 14), which turns out to be a "medicinal white oil" available in 208l drums - i.e. about 103times too much!Fleabay has sellers of Shell Diala B "transformer oil", but it isn't clear that it is suitable. In particular it contains potassium hydroxide and (unsurprisingly) the electrical properties are changed if stored in non-airtight containers. The standard resistor will never be airtight! Having said that, in my application I'm more concerned about any corrosive properties of the KOH.I'm aware of Ralf Richard Ohmberger's 1659 teardown athttps://www.amplifier.cd/Test_Equipment/other/Tinsley-1659-Standard-Resistor.html, but he is careful to avoid claiming that oil is suitable.I'd appreciate any comments on sources of Whitemor/Optileb oil, or alternatives that areknownto be suitable.

author: Gyro
author_rank: Super Contributor
timestamp: October 30, 2019, 01:51:36 pm
content: "medicinal white oil" sounds a bit like medical grade liquid paraffin - used as a laxative (among other things).

author: tggzzz
author_rank: Super Contributor
timestamp: October 30, 2019, 03:24:30 pm
content: Well, it is a "food grade lubricant", tasteless, and "complies with all of the purity requirements ... for Liquid Paraffin"!https://www.kernow-oils.co.uk/food-grade-lubricants/castrol-whitemor-wom-14-medicinal-white-oils-6920/c-6920/

author: Gyro
author_rank: Super Contributor
timestamp: October 30, 2019, 03:40:03 pm
content: I certainly remember hearing that Liquid Paraffin was used to lubricate the blades of industrial bread slicing (as in sliced loaf) machines... with slight laxative effect if you ate enough! It looks as if they've found a fancy brand name substitute.

author: picburner
author_rank: Frequent Contributor
timestamp: October 30, 2019, 05:08:13 pm
content: If it were not for the addition of perfume and Isopropyl palmitate, you could use Johnson's baby oil which is exactly liquid paraffin in even 500ml bottles.I don't know how much these additives can affect electrical properties.

author: Gyro
author_rank: Super Contributor
timestamp: October 30, 2019, 05:53:52 pm
content: You can get medical grade liquid paraffin on Amazon (best to pick your seller with care).Edit: Well veterinary grade anyway.

author: Diabolo
author_rank: Regular Contributor
timestamp: October 30, 2019, 06:00:31 pm
content: Hello,http://www4.total.fr/pdf/lub-indus/ISOVOLTINE.pdfDiabolo

author: PartialDischarge
author_rank: Super Contributor
timestamp: October 30, 2019, 06:22:22 pm
content: Either Shell diala B or paraffin oil are totally fine for that application

author: IRFP
author_rank: Contributor
timestamp: October 31, 2019, 10:10:25 am
content: Bonjour,Même avis que diabolo, de l'huile pour transformateur haute tension. J'ai fabriqué une référence de tension dans ce même type d'huile.Cordialement,

author: tggzzz
author_rank: Super Contributor
timestamp: October 31, 2019, 10:57:22 am
content: Quote from: Diabolo on October 30, 2019, 06:00:31 pmFortunately google translate exists!Thanks (and to IRFP). I can't see any source of less than 20l, which is a bit of a problem.

author: tggzzz
author_rank: Super Contributor
timestamp: October 31, 2019, 10:59:21 am
content: Quote from: MasterTech on October 30, 2019, 06:22:22 pmI have no reason to doubt that, but can you point to any supporting evidence?I note (without conclusion) that both Diala B and Isovoltine have similar levels of KOH.

author: tggzzz
author_rank: Super Contributor
timestamp: October 31, 2019, 11:26:41 am
content: Quote from: tggzzz on October 31, 2019, 10:59:21 amOn looking further, I see that indicates a gross misunderstanding of the specification.The mgKOH/g value does not indicate how much KOH isinthe oil, it indicates how much KOH would have to beaddedto neutralise any acid in the oil.Hence a lower mgKOH/g is desirable, but not very relevant.

author: ArthurDent
author_rank: Super Contributor
timestamp: October 31, 2019, 12:45:04 pm
content: Do you know what the correct oil level is? Filling the case with no air gap could result in expansion problems and cause leaks, especially dissipating up to 10 watts.

author: tggzzz
author_rank: Super Contributor
timestamp: October 31, 2019, 03:59:46 pm
content: Quote from: ArthurDent on October 31, 2019, 12:45:04 pmNo, but that doesn't worry me because:I don't plan on dissipating anywhere near 10Wit isn't hermetically sealed; if it is upended it will leakthere's a strange piston-like device for manually circulating the oul. That would move out if necessaryBut thanks for the caution; in other circumstances it might have been very valuableOverall the oil may not even be necessary: the resistors are normally delivered unfilled, and Ralf Richard Ohmberger's teardown claims cal labs use it unfilled.Currently I'm moving towards either liquid paraffin BP (medical grade, no additives) or draining it and not refilling it.

author: mzzj
author_rank: Super Contributor
timestamp: November 01, 2019, 10:32:05 am
content: Ask your local pharmacy/drug store for white oil/paraffin oil. Even hardware stores should have food grade paraffin oil for oiling kitchen countertops.

author: tggzzz
author_rank: Super Contributor
timestamp: November 01, 2019, 10:40:12 am
content: Quote from: mzzj on November 01, 2019, 10:32:05 amI tried a single pharmacy last night. Even after reflection and checking, they looked blankYou used to be able to get things like IPA and potassium permanganate at pharmacies here, but not any more.

author: mzzj
author_rank: Super Contributor
timestamp: November 01, 2019, 10:53:02 am
content: Quote from: tggzzz on November 01, 2019, 10:40:12 amSame here, anything more complex and they suspect that you are making bombs or drugs. But paraffin oil they have for sure at least around here, sold as laxative and skin ointment.Back in the day you could buy fuming nitric acid, sulfuric acid and ammonium nitrate from the farmacy(that was 25 years ago when I was 15.. )

author: Magnificent Bastard
author_rank: Regular Contributor
timestamp: November 01, 2019, 02:19:55 pm
content: Here in the USA, it is called "mineral oil", and it is sold over-the-counter (that means without a doctor's prescription). You can find it in CVS, Walgreens, Walmart, etc. It's pretty common stuff, and chef's use it to oil their cutting boards (butcher blocks) also. It is "pharmaceutical grade", which means it is about at pure as your going to find at ordinary prices.

author: Bud
author_rank: Super Contributor
timestamp: November 01, 2019, 02:40:24 pm
content: The other source of mineral oil are livestock/farm supplies places. Apparently mineral oil is used to feed animals to treat constipation. I'd imagine they use it in big quantities and it is a no additives product. I learned it when was looking for oil replacement for a RF dummy load.

author: Gyro
author_rank: Super Contributor
timestamp: November 01, 2019, 02:44:16 pm
content: Quote from: mzzj on November 01, 2019, 10:53:02 amI think it's only used as a horse and cattle laxative these days (although it is still the base of pretty much all of human skin emollient creams).A sad story, my Grandfather saw his father die of bowel cancer (that would have been back in the early 1900s) and dosed himself daily with liquid paraffin (Edit: from the pharmacy). Sadly he died at about the age of 70... of bowel cancer, a bit ironic. It's probably best reserved for the vet and external use these days.Quote from: Magnificent Bastard on November 01, 2019, 02:19:55 pmJust as well that you included the USA bit, I was just going to make a crack about buying it in blocks in Antarctica. We know where to find you now.

author: Bud
author_rank: Super Contributor
timestamp: November 01, 2019, 04:17:27 pm
content: BTW i ended up using mineral oil from the pharmacy for my dummy load and i can tell the dielectric constant was very close to the original oil . I measured the load impedance with a VNA without oil and the Return Loss was way off the dummy load manufacturer specs. I then filled it with mineral oil and re-measured and the Return Loss was almost spot on with the specs across the frequency range. All things being the same, it would indicate the dielectric constant of the mineral oil was a good match to the originally used oil.

author: IRFP
author_rank: Contributor
timestamp: November 01, 2019, 11:35:13 pm
content: Good evening,Get closer to a maintenance company for high voltage substations, I got a few liters that way.

author: mzzj
author_rank: Super Contributor
timestamp: November 03, 2019, 11:42:05 am
content: Quote from: Gyro on November 01, 2019, 02:44:16 pmDunno how often its used but its certainly still sold for human use in most? countries. Apparently maybe not UK.Also here in Finland its sold for human use but pharmacy website says that "commonly used earlier for constipation, nowadays modern alternatives are available"From wikipedia:"Liquid paraffin is primarily used as a pediatric laxative in medicine and is a popular treatment for constipation and encopresis. Because of its ease of titration, the drug is convenient to synthesize. It acts primarily as a stool lubricant, and is thus not associated with abdominal cramps, diarrhea, flatulence, disturbances in electrolytes, or tolerance over long periods of usage, side effects that osmotic and stimulant laxatives often engender (however, some literature suggests that these may still occur). The drug acts by softening the feces and coats the intestine with an oily film. Hence, reduces the pain caused by certain conditions such as piles (haemorrhoids). These traits make the drug ideal for chronic childhood constipation and encopresis, when large doses or long-term usage is necessary.Consensus has not been entirely reached on the safety of the drug for children. While the drug is widely accepted for the management of childhood constipation in North America and Australia, the drug is used much less in the United Kingdom. The drug is endorsed by the American Academy of Pediatrics and the North American Society for Gastroenterology and Nutrition, with the latter organization outlining it as a first choice for the management of pediatric constipation. The drug is suggested to never be used in cases in which the patient is neurologically impaired or has a potential swallowing dysfunction due to potential respiration complications, though normally the airways tolerate this medicine quite well, and some go as far as saying that it should never be used with children"

author: drussell
author_rank: Super Contributor
timestamp: November 03, 2019, 12:29:00 pm
content: Thehypo-allergenicversions of "Baby Oil" sold under various brand names is pure mineral oil and works fine for this kind of application or home chemistry. The versions marked as hypo-allergenic should be well refined / distilled, although some brands like Johnson's still annoyingly add a small bit of smell back into it, so best to stick with the cheap generic brands and double check the ingredient list for things like added "perfume" like it says on the Johnson's bottle.NurdRage looked into this while developing his alcohol-catalyzed magnesium + sodium hydroxide + mineral oil metallic sodium production process for the amateur home chemist.He figured out about needing a very pure mineral oil source as described in this video:https://youtu.be/oiZf-O6vvbE?t=260Watch the next 90 seconds from the linked start marker...

author: Gyro
author_rank: Super Contributor
timestamp: November 03, 2019, 05:57:49 pm
content: As I noted previously, pure Liquid Paraffin BP can easily be purchased on Amazon (or ebay) in the UK.

author: Magnificent Bastard
author_rank: Regular Contributor
timestamp: November 15, 2019, 06:25:30 am
content: Quote from: Gyro on November 01, 2019, 02:44:16 pmMcMurdo StationYou are welcome to come and visit!-MB

author: tggzzz
author_rank: Super Contributor
timestamp: November 15, 2019, 09:13:39 am
content: Thanks to everybody that has replied.I've tried finding mineral/paraffin oil in more than half a dozen pharmacists and traditional hardware shops, completely without success. Most reactions are bafflement or "no". The better reactions include "oh yes, we have some paraffin here" and "I should have some here, oh no it is gone"Hence it looks like the most probable source would be online, which is a bit of a shame.However, Real Life has intervened and so this is now on the back burner.Currently (ho ho) I'm only likely to use the resistor to calibrate DMMs. In most cases they would pass 1mA, which equates to a 10uW dissipation; the worst case is 10mA / 1mW.Given the size and surface area of the resistance wire, I doubt (without doing calculations!) that would result in a large temperature rise. In that case the principal value of any oil would be to stabilise the temperature and allow the temperature to be measured with a mercury thermometer inserted into the top hole. Hence I may just call it a day and use it without oil.Nonetheless, the discussion has been interesting and I have learned a lot; thanks.

author: Freerthy
author_rank: Newbie
timestamp: November 20, 2019, 08:57:56 am
content: Do you know correct oil level?

author: tggzzz
author_rank: Super Contributor
timestamp: November 20, 2019, 09:57:22 am
content: Quote from: Freerthy on November 20, 2019, 08:57:56 amNot explicitly, but there is no point in a partially submerged resistance wire.Why do you ask?

author: GigaJoe
author_rank: Frequent Contributor
timestamp: November 22, 2019, 01:56:13 am
content: does anyone knows if it will work ? I'm about in the same state for resistor ....https://www.rona.ca/en/paraffin-oilUPD: On the other hand, Paraffin oil, known as kerosene in Australia and the United States and stove oil in Canada, is an flammable liquid hydrocarbon burned as fuel.seems it not ....

author: Gyro
author_rank: Super Contributor
timestamp: November 22, 2019, 11:18:48 am
content: No, that says lamp oil, ie. Kerosene. It will contain quite a lot of water and be acidic.You want medical grade Liquid Paraffin BP, for internal use.

author: GigaJoe
author_rank: Frequent Contributor
timestamp: November 22, 2019, 07:01:57 pm
content: will that thing work ? :https://www.amazon.ca/Swan-Mineral-Oil-16-oz/dp/B001B2RG1C

author: Gyro
author_rank: Super Contributor
timestamp: November 22, 2019, 07:59:29 pm
content: Yes, that looks like the stuff.I notice that it contains 0.1% 'mixed tocopherols' as a non active ingredient stabilizer. You might just want to read up on those, but I suppose you want the oil to be stable anyway...https://en.wikipedia.org/wiki/Tocopherol. I suspect that they all might all contain some.

author: drussell
author_rank: Super Contributor
timestamp: November 28, 2019, 11:54:44 am
content: Quote from: GigaJoe on November 22, 2019, 07:01:57 pmThat looks rather expensive...You can get a larger container (591 mL) of the Equate brand (Wal-mart's house brand) stuff at any Wal-Mart for $3.97 Canadian...

author: tggzzz
author_rank: Super Contributor
timestamp: August 11, 2021, 11:24:19 am
content: ManateeMafia noted inhttps://www.eevblog.com/forum/metrology/precision-resistors-general-thread/msg3624927/#msg3624927"I came across this document from IET in regards to the oil filled SR-1030 series. Chapter 6 talks about their recommended oil and how to test if it is contaminated enough to warrant doing an oil change.https://www.ietlabs.com/pdf/Manuals/SR1030_im.pdf"

author: Gyro
author_rank: Super Contributor
timestamp: August 11, 2021, 11:56:40 am
content: That section reads just like a Haynes manual (DIY auto manual for non UK), including glossing over the messy bit.

author: leighcorrigall
author_rank: Frequent Contributor
timestamp: August 11, 2021, 12:50:48 pm
content: FYI, the topic of resistance standard oil has been briefly discussed in the General Precision Resistor thread too.https://www.eevblog.com/forum/metrology/precision-resistors-general-thread/msg3623623/#msg3623623

author: CalMachine
author_rank: Frequent Contributor
timestamp: August 11, 2021, 06:11:09 pm
content: Food-grade white mineral oil is the way to go

author: pico61
author_rank: Contributor
timestamp: August 11, 2021, 07:29:30 pm
content: On Ebay Italy 20 liter can!https://www.ebay.it/itm/255002905357?var=0&mkevt=1&mkcid=1&mkrid=724-53478-19255-0&campid=5338822678&toolid=10029Agip ITE 600 is an excellent transformers and rheostats oil.

author: TimFox
author_rank: Super Contributor
timestamp: August 11, 2021, 08:16:06 pm
content: For a different application (insulating the high-voltage power supply for 450 kV x-ray tubes), we used "Diala" oil from Shell, which is a "transformer oil", mostly used in power-distribution transformers.It is basically a purified "motor oil" (I used to know the SAE number) without the usual detergent additives, etc. designed for car engines.It contains a small amount of "anti oxidation" agent, which I remember being either BHA or BHT, common preservatives found in food or cosmetic products.

author: Gyro
author_rank: Super Contributor
timestamp: August 12, 2021, 10:26:21 am
content: Just a note that tggzzz necroposted his own thread yesterday. The discussions on pharmaceutical mineral oil etc, happened a couple of years ago (and I suspect he already topped it up, or decided that he didn't need to).

author: tggzzz
author_rank: Super Contributor
timestamp: August 12, 2021, 11:55:37 am
content: Quote from: Gyro on August 12, 2021, 10:26:21 amThe latter; see reply #26.I added the cross reference for the benefit of any reader that comes along in the future with a similar question.

author: Gyro
author_rank: Super Contributor
timestamp: July 27, 2024, 04:49:51 pm
content: I was lucky enough to pick up a 1k Ohm Tinsley 3504D Standard resistor a couple of days ago (photos...https://www.eevblog.com/forum/chat/what-did-you-buy-today-post-your-latest-purchase!/msg5584307/#msg5584307), in nice condition.I was cleaning it up today and took the opportunity to open the filler screw, and found that it was empty. Looking at the rubber seal and inside with an endoscope, it appears that it has never been filled. I can't see the actual winding, all that is visible inside the casting is a brass cylinder.Now I know that later resistors (as the OP's, presumably) they used Castrol Whitemor WOM14 (aka food grade Liquid Paraffin BP) and presumably the same would be applicable.My question is, after 50+ years being empty and as far as I can measure, only 10-20ppm low in value, do I fill it at this stage of just leave it empty? I was somewhat thrown by seeing the brass cylinder inside rather than the winding, I have no way of seeing if this assembly is sealed itself, or the winding construction. It forms a double concentric chamber anyway, so nothing like the current model.I would be grateful for opinions, and particularly any 3504D specific data. All I can find is a couple of listings on ebay and the datasheet for the current 5685 standard resistor (which comes pre-filled).P.S.I've just found a second, larger, filler port under the identification plate. Initially I wondered if it went into the inner cylinder, but it goes into the same outer space as the other one, odd. It's certainly a heavy casting. Images attached, the edge of the brass cylinder is visible...

author: Gyro
author_rank: Super Contributor
timestamp: July 27, 2024, 09:01:01 pm
content: It occurred to me that I hadn't tried the endoscope through the larger filling port. Winding located, it is closely wound around the brass (actually copper) cylinder, all but invisible under the varnish also hampered by the few mm distance from the fixed focus lens. I managed to image the wire terminations to the horns too, extremely short - I would certainly have snapped them if I had succeeded in removing the lid. Maybe the larger port is an access way for specially trained Imps!So I guess the question remains. To fill or not to fill?

author: Overspeed
author_rank: Frequent Contributor
timestamp: July 28, 2024, 07:42:30 pm
content: HelloA crucial problem is oil mixing compatibility if you change oil you need to clean the tank several times to remove all possible '' old oil '' and also avoid possible strange chemical reaction with the newI warm oil to 50 deg C , fill , shake , empty the tank I do that 3 times and let the tank open in a upside down several hours before filling with teh new oilRegardsOS

author: Gyro
author_rank: Super Contributor
timestamp: July 28, 2024, 08:46:50 pm
content: I should have made clear that my Reply #42 was a necro-post of tggzzz's old thread. He is now sorted I think. In my case, the resistor has never been filled for some reason.I agree though, mixing of different oils can cause issues, particularly if they are of different composition, eg. mineral and Silicone. [Edit: Or the original oil has decomposed and become acidic.]Thanks for the heads up - a messy procedure!

author: Gyro
author_rank: Super Contributor
timestamp: July 31, 2024, 12:36:00 pm
content: Quote from: Gyro on July 27, 2024, 09:01:01 pmSo, any thoughts before I pour in the Laxative this evening? (I've even bought human grade rather than veterinary).

author: tggzzz
author_rank: Super Contributor
timestamp: July 31, 2024, 03:57:50 pm
content: Quote from: Gyro on July 31, 2024, 12:36:00 pmTrouble is, I suspect nobody will be able to give a solid answer for several years.It sounds as if - whether or not it has the desired effect inside the resistor - it is having the designed effect inside you

author: Gyro
author_rank: Super Contributor
timestamp: July 31, 2024, 04:41:48 pm
content: Haha, I know I got it cheap, but yes, it is tweaking the bowels a bit.I guess if it is designed to be filled, filler, seals etc then it should be. It's a normal thing for reference resistors (as you know). It's just so damned pristine inside!I just wish I could find something that says 'fill on receipt'.EDIT: 200ml brought the level to within 5mm of the top leaving a small expansion volume... for better or worse.

author: Gyro
author_rank: Super Contributor
timestamp: August 03, 2024, 02:01:16 pm
content: After leaving to settle for a couple of days, I thought I had better check the insulation resistance of the Liquid Paraffin - now that's something that Ireallyshould have done before I poured it in!.Using my Kewtech KT35 insulation tester, I went up through the voltage ranges, on the highest 2GOhm scale, and am pleased to find that it reads over-range on the maximum 1kV setting, applied between one terminal and outer casing for 30 seconds.Whilst not a definitive test for moisture content (as the winding itself is lacquered) the terminations to the horns, their mounting nuts etc. are exposed to the liquid. It is certainly enough to establish that the filling will have no measurable shunting effect on the winding resistance. I intend to repeat the insulation test every few months to check that nothing suspicious is happening.For reference, this is the Liquid Paraffin that I used...https://www.amazon.co.uk/Bells-LIQUID-PARAFFIN-BELLS-150ML/dp/B00433YP3IThis was the only one I could find that specified for human consumption rather than veterinary use, so purity is hopefully a bit better. The label indicates active ingredients: Liquid Paraffin 100%, which hopefully means no additives, it is clear, colourless and odorless anyway. The manufacturing date on the bottles that I purchased was Mar 23, with expiry date (medicinal presumably) of Mar 28.The remainder will almost certainly end up being used (sparingly and only!) on kitchen chopping boards.

author: tggzzz
author_rank: Super Contributor
timestamp: August 03, 2024, 04:37:22 pm
content: Quote from: Gyro on August 03, 2024, 02:01:16 pmYour resistor will get lonely, so you should keep the spare oil for its siblings.

author: Gyro
author_rank: Super Contributor
timestamp: August 03, 2024, 05:33:41 pm
content: Well they did have a couple of old Cambridge Instruments ones, with brass tops and nice shiny Copper horns. From the leaks and loose bits though, they had already drunk more than was good for them!They were definitely pre-1948*too. No model numbers or current rating markings either. That's why I picked out the dull looking Tinsley.EDIT:*For the casual reader, before 1948 the 'International Ohm' definition was artifact based, based on a Mercury column of standard area / length and mass, at 0'C. After 1948, the 'Absolute Ohm' was adopted. Hence OHMS (ABS) on the Tinsley unit.

author: Alex Nikitin
author_rank: Super Contributor
timestamp: August 08, 2024, 10:47:24 pm
content: Quote from: Gyro on August 03, 2024, 02:01:16 pmMy curiosity won and I've ordered a bottle of the same Bell's Liquid Paraffin BP. A "quick but not dirty" experiment with two bare wires in a polyethylene cap showed that without oil the leakage of the setup was about 50fA at 100V (the box fixture with the BNC connector, cable and BNC/Triaxial adapter leaks less than 10fA at 100V so there was some added leakage), or 2Pohm , with the cap filled with the oil, as on the photo, the resistance dropped to ~300Tohm. Not perfect but good enough for most purposes.CheersAlex

author: Gyro
author_rank: Super Contributor
timestamp: August 09, 2024, 06:06:12 pm
content: That's somewhat better than I had expected, especially just out of the bottle without specific drying, although that's probably part of the product preparation [Edit: or just the distillation]. Certainly enough to allay any remaining fears around normal value standard resistor filling (thanks). You now appear to have a little more laxative remaining than I do.I wonder about using it for creating a more isothermal, and stable, environment for voltage reference, nulled circuits etc. It's certainly a lot easier to handle and clean up than Silicone oil.