Oil bath reference for the oil quality used in Tinsley

[Overspeed]

Hello

This oil is in use in Tinsley resistor ( folowing Tinsley doc ) : Castrol WOM14

Regards
OS

[mendip_discovery]

It can be bought for ~150EUR for 20L.

[HighVoltage]

In Germany, this Castrol WOM14 oil is mainly used in medical equipment, because it is so clean.
Should be good for resistors as well.

[tggzzz]

Cross-reference to earlier thread...

https://www.eevblog.com/forum/metrology/oil-for-a-leaking-tinsley-standard-resistor/msg2761572/#msg2761572

I'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.

[Overspeed]

Hello

I'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.

Hello

This oil reference is provided by Tinsley on the Tinsley doc , see the linked pic

Regards
OS

[Gyro]

Hello

I'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.

Hello

This oil reference is provided by Tinsley on the Tinsley doc , see the linked pic

Regards
OS

Castrol WOM 14 is a 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.

[tggzzz]

Hello

I'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.

Hello

This oil reference is provided by Tinsley on the Tinsley doc , see the linked pic

Regards
OS

Agreed.

However, just because all crows are black birds, it does not mean all black birds are crows

[EC8010]

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.

[Gyro]

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.

[Overspeed]

Agreed.

However, just because all crows are black birds, it does not mean all black birds are crows

Hello

You 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 contamination

Regards
OS

[EC8010]

It's the same stuff. From my link...

Yes, 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.

[Gyro]

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).

...
An important parameter for oil is the hydrophobic performance so oil shall be sealed in a airtight container to avoid water contamination

Alex 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).

[Bud]

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.

[Overspeed]

Hello

A 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 work

Dot 5.1 handle temp from minus 30 C to 250 deg C

Regards
OS

[tatel]

Hello

A 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 work

Dot 5.1 handle temp from minus 30 C to 250 deg C

Regards
OS

DOT-5 and DOT-5.1 == brake fluid for my Citroen car?

https://www.startmycar.com/citroen/guides/brake-fluid

[Overspeed]

DOT-5 and DOT-5.1 == brake fluid for my Citroen car?

https://www.startmycar.com/citroen/guides/brake-fluid
[/quote]

Hello

Yes 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 .

Regards
OS

[mzzj]

DOT-5 and DOT-5.1 == brake fluid for my Citroen car?

https://www.startmycar.com/citroen/guides/brake-fluid

Hello

Yes 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 .

Regards
OS
[/quote]Other 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”

[Overspeed]

DOT-5 and DOT-5.1 == brake fluid for my Citroen car?

https://www.startmycar.com/citroen/guides/brake-fluid

Hello

Yes 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 .

Regards
OS

Other 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”
[/quote]

Hello

I 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 C

5.1 is a mix of
Tris[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 viscosity

Brake 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 specification

Another technical fact to know : Engine oils are full of additives and shall be avoided for any experiments.

Regards
OS

[Gyro]

Another technical fact to know : Engine oils are full of additives and shall be avoided for any experiments.

Indeed. 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.

[Conrad Hoffman]

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.

[Overspeed]

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.

Hello

I 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  .

Regards
OS