Oil bath reference for the oil quality used in Tinsley  - Page 1
Forum section: electronics / general

author: Overspeed
author_rank: Frequent Contributor
timestamp: October 12, 2024, 08:42:21 am
content: HelloThis oil is in use in Tinsley resistor ( folowing Tinsley doc ) : Castrol WOM14RegardsOS

author: mendip_discovery
author_rank: Super Contributor
timestamp: October 12, 2024, 10:36:48 am
content: It can be bought for ~150EUR for 20L.

author: HighVoltage
author_rank: Super Contributor
timestamp: October 12, 2024, 10:44:27 am
content: In Germany, thisCastrol WOM14oil is mainly used in medical equipment, because it is so clean.Should be good for resistors as well.

author: tggzzz
author_rank: Super Contributor
timestamp: October 12, 2024, 11:42:27 am
content: Cross-reference to earlier thread...https://www.eevblog.com/forum/metrology/oil-for-a-leaking-tinsley-standard-resistor/msg2761572/#msg2761572I'm unconvinced that using a "clean oil" otherwise used in "medical equipment" is asufficientpre-condition for use in a Tinsley resistor. However, it is probably a good starting point, and I don't have a better alternative.

author: Overspeed
author_rank: Frequent Contributor
timestamp: October 12, 2024, 12:08:01 pm
content: HelloI'm unconvinced that using a "clean oil" otherwise used in "medical equipment" is a sufficient pre-condition for use in a Tinsley resistor. However, it is probably a good starting point, and I don't have a better alternative.HelloThis oil reference is provided by Tinsley on the Tinsley doc , see the linked picRegardsOS

author: Gyro
author_rank: Super Contributor
timestamp: October 12, 2024, 01:43:46 pm
content: Quote from: Overspeed on October 12, 2024, 12:08:01 pmCastrol WOM 14isa pharmaceutical grade oil....https://www.thelubricationstore.com/product/castrol-optileb-wom-14/As described in the other thread. If possible, go for a human grade laxative oil rather than a veterinary grade one.

author: tggzzz
author_rank: Super Contributor
timestamp: October 12, 2024, 02:19:09 pm
content: Quote from: Overspeed on October 12, 2024, 12:08:01 pmAgreed.However, just because all crows are black birds, it does not mean all black birds are crows

author: EC8010
author_rank: Frequent Contributor
timestamp: October 12, 2024, 02:55:44 pm
content: Fluke used to have a document about oil bath fluids that recommended white oil, but for the life of me, I can't find it.

author: Gyro
author_rank: Super Contributor
timestamp: October 12, 2024, 04:44:44 pm
content: It's the same stuff. From my link...Castrol Optileb WOM 14 is a Medicinal White Oil which are highly refined mineral oils which comply with the purity requirements of the various national Pharmacopoeias for Liquid Paraffins.

author: Overspeed
author_rank: Frequent Contributor
timestamp: October 12, 2024, 05:13:21 pm
content: Agreed.However, just because all crows are black birds, it does not mean all black birds are crowsHelloYou are right because Tinsley specified oil is OK for Tinsley resistors so compatible with Tinsley material so that not because that works for Tinsley that that mandatory works for other material as plastic , rubber ....An important parameter for oil is the hydrophobic performance so oil shall be sealed in a airtight container to avoid water contaminationRegardsOS

author: EC8010
author_rank: Frequent Contributor
timestamp: October 12, 2024, 05:59:16 pm
content: Quote from: Gyro on October 12, 2024, 04:44:44 pmYes, I looked up your link. What I meant was that it was not just Tinsley recommending white oil. I've made oil baths using BP white oil and was concerned about what it might do to things. I found that after about six months it dissolves flux from solder joints, so it's perhaps not a bad idea to flush after six months. I was worried that it might attack the Paxolin tag boards I used, but after three years, the test board (just inspected) looks fine.

author: Gyro
author_rank: Super Contributor
timestamp: October 12, 2024, 06:00:58 pm
content: Useful info.I don't know how the moisture content holds up in open oil baths, potentially they had a replacement schedule (I've never seen a reference to desiccators being built into the baths).Quote from: Overspeed on October 12, 2024, 05:13:21 pmAlex Nikitin did some electrical leakage testing, in addition to my 1kV testing, of the same Bells Liquid Paraffin that I purchased and it held up very well. The reason that I recommended human grade rather than veterinary was that the purity is possibly higher, or at least better controlled. There are no additives listed.The Tinsley 5685 datasheet claims hermetic sealing, but the photo shows a filler screw. On my earlier Tinsley 3504D (supplied empty), the filler screws are sealed by heavy black rubber O rings. Probably good enough to avoid any significant moisture ingress over a long period though.As @tggzzz says, we haven't come up with a better alternative for manageable quantities (for filling resistors anyway).

author: Bud
author_rank: Super Contributor
timestamp: October 12, 2024, 07:06:28 pm
content: For my RF dummy load (which contains a low inductance resistor, in case someone does not know what it is) i used clear mineral oil from laxative section of a drug store. The measured RF performance of the dummy load filled with that oil was very close to specification, which means the dielectric constant of the mineral oil was close to the original transformer oil.

author: Overspeed
author_rank: Frequent Contributor
timestamp: October 12, 2024, 07:36:16 pm
content: HelloA cheapest and easiest product to locate in small quantity can be the silicon break fluid dot 5 as used on race car , I use this on my oil bath for aluminium testing I have never try on resistor but that shall / can workDot 5.1 handle temp from minus 30 C to 250 deg CRegardsOS

author: tatel
author_rank: Frequent Contributor
timestamp: October 13, 2024, 03:42:09 pm
content: Quote from: Overspeed on October 12, 2024, 07:36:16 pmDOT-5 and DOT-5.1 == brake fluid for my Citroen car?https://www.startmycar.com/citroen/guides/brake-fluid

author: Overspeed
author_rank: Frequent Contributor
timestamp: October 13, 2024, 04:40:02 pm
content: DOT-5 and DOT-5.1 == brake fluid for my Citroen car?https://www.startmycar.com/citroen/guides/brake-fluidHelloYes that the cheapest silicone fluid available , far cheaper than silicone fluid use in lab thermal bath and available from a lot of suppliers in small can as that a car maintenance product , only 5.1 is silicone base all other are not silicone base .RegardsOS

author: mzzj
author_rank: Super Contributor
timestamp: October 13, 2024, 05:06:27 pm
content: Quote from: Overspeed on October 13, 2024, 04:40:02 pmHelloYes that the cheapest silicone fluid available , far cheaper than silicone fluid use in lab thermal bath and available from a lot of suppliers in small can as that a car maintenance product , only 5.1 is silicone base all other are not silicone base .RegardsOSOther way around. Dot5 is silicone base.I’d be wary of using any brake fluid, even the silicone ones can contain unwanted additives for corrosion protection, wear or moisture absorption. Without extensive testing it is hard to say if the possible additives are for bad or good.Medical grade white oil is quite safe bet that it doesn’t contain ”artificial additivies”

author: Overspeed
author_rank: Frequent Contributor
timestamp: October 13, 2024, 06:28:12 pm
content: Quote from: mzzj on October 13, 2024, 05:06:27 pmOther way around. Dot5 is silicone base.I’d be wary of using any brake fluid, even the silicone ones can contain unwanted additives for corrosion protection, wear or moisture absorption. Without extensive testing it is hard to say if the possible additives are for bad or good.Medical grade white oil is quite safe bet that it doesn’t contain ”artificial additivies”HelloI have provided this fluid ref as a cheap alternative for DIY resistor / experiments and nothing more.I use this fluid as oil bath fluid for metallurgy light alloy sample since years without problems at temp up to 150 deg C5.1 is a mix ofTris[2-[2-(2-methoxyethoxy)ethoxy] ethyl] orthoborate which a triester so a thermal fluid you can also have in '' oil heating system '' as electrical radiator but also hydraulic fluid ...minodipropan-2-ol so a stabilizer to adjust viscosityBrake fluids are safety products and homologated by car brakes company for corrosion , seal compatibility ...Changing oil of a reference resistor ( and probably the seals ) is a very rare operation regarding the price of a Tinsley resistor and the fact that a quite rare equipment too so no reason to try to save pennies on the oil specification and avoid to use the specified oil from Castrol.A last point , mixing oil can be a risky trial as not all oil are compatible so that far better to stay with the original specificationAnother technical fact to know :Engine oils are full of additives and shall be avoided for any experiments.RegardsOS

author: Gyro
author_rank: Super Contributor
timestamp: October 13, 2024, 07:01:14 pm
content: Quote from: Overspeed on October 13, 2024, 06:28:12 pmIndeed. Specifically, engine oils are hygroscopic, designed to absorb moisture in cold engines to prevent condensation and maintain lubrication in cold engines. They only release this moisture at normal engine operating temperature, which of course a reference resistor will never reach.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: October 14, 2024, 07:10:19 pm
content: I think people overthink this. Go to the farm store and get a gallon of mineral oil for horses or whatever. No matter what you use, you should change it out every couple few years.

author: Overspeed
author_rank: Frequent Contributor
timestamp: October 15, 2024, 08:44:10 am
content: Quote from: Conrad Hoffman on October 14, 2024, 07:10:19 pmHelloI agree there is no ''magic voodoo'' in this product . Another important point is the shape of the seal , changing oil is one thing , check the shape of the seal ( rubber ? cork ? ) is also very important , but also possible internal corrosion due to aging .RegardsOS