[volt-nuts] Resistance standard

Tue Aug 23 08:54:21 UTC 2011

Hi,
The troublesome part is the "cyclo-parraffinic" oil, that means you do have some benzene rings in there that may react or dissolve other plastic bits in the bath.Medicinal paraffin is suitable, but possibly a higher viscosity than you want. "Natural gasoline" is fairly parraffinic and does smell a bit like kerosene, so it could be that?

> Date: Tue, 23 Aug 2011 10:47:21 +0200
> From: rob.klein at smalldesign.nl
> To: volt-nuts at febo.com
> Subject: Re: [volt-nuts] Resistance standard
> 
> I have an L&N 10k oil-bath standard which is filled with something that 
> smells a lot like kerosene.
> 
> The stuff I am going to use is *not* a synthetic oil but, as I mentioned 
> earlier, a mineral oil. According to the manufacturer, it is made up of 
> "paraffinic and cyclo-paraffinic hydro-carbons"
> 
> http://www.kroon-oil.com/en/products/catalogue/seg_ind/krmp/200/industry/kroon-oil-maintenance-products/sewing-machine-oil/
> 
> 
> Rob.
> 
> Op 23-8-2011 8:33, Robert Atkinson schreef:
> > I investigated this and both NIST (NBS) and NPL use refined mineral oil A.K.A liquid paraffin for room  to medium temeperature baths. This is a food/pharmaceutical  grade oil. It is a clear white oil, pretty much non-toxic and no disposal concerns. The materials in older standards will have been intened for immersion in this, not modern synthetic oils. A commercial food or confectionery supply house should be able to supply larger quantities at resonable cost.
> >   
> > Robert G8RPI.
> >   
> > --- On Mon, 22/8/11, Mitch Van Ochten<mitch at vincentelectronics.com>  wrote:
> >
> >
> > From: Mitch Van Ochten<mitch at vincentelectronics.com>
> > Subject: Re: [volt-nuts] Resistance standard
> > To: "Discussion of precise voltage measurement"<volt-nuts at febo.com>
> > Date: Monday, 22 August, 2011, 23:50
> >
> >
> > Hi Rob,
> >
> > ESI recommended "Drakeol 9 LT mineral oil" in their literature which I couldn't find in small
> > quantities.  I investigated a synthetic oil replacement called SpectraSyn PAO and Exxon offered
> > to send a sample.  After checking with a chemist at work I decided not to.
> > He said over many years of immersion the "long chain parrafin" as Mike mentioned would be the best, and
> > less likely to deteriorate the insulation than the synthetic replacement.
> >
> > I have attached a chart he sent me for the group's observation.
> >
> > Mitch
> >
> >
> > ----- Original Message ----- From: "Rob Klein"<rob.klein at smalldesign.nl>
> > To: "Discussion of precise voltage measurement"<volt-nuts at febo.com>
> > Sent: Monday, August 22, 2011 8:10 AM
> > Subject: Re: [volt-nuts] Resistance standard
> >
> >
> >> Hi Mike and Charlie,
> >>
> >> For the oil, I have decided on the stuff that is sold locally as "sewing machine oil". This is a highly refined light mineral oil, guaranteed to be acid free.
> >>
> >> As explained in my previous message, things haven't been progressing over the last 18 months, but I'm going to pick it up again soon, so stay tuned.
> >>
> >>
> >> Best regards,
> >> Rob.
> >>
> >> Op 23-7-2011 19:14, Charles Black schreef:
> >>> Hi,
> >>>
> >>> The traditional oil for standard resistors and oil baths is Mineral Oil. The cheapest source of Mineral Oil USP  for small quantities is out local grocery store at about $5.50 per pint. It is a highly purified paraffin oil. If you need a large quantity then check out Exxon Marcol 72 which is available for about $12 per liter from Measurements International. I am trying to find a much better price since I could potentially use 157 liters if I am able to get a used bath that I know of.
> >>>
> >>> Charlie
> >>>
> >>> On 7/23/2011 3:03 AM, m k wrote:
> >>>> Hi,
> >>>>
> >>>> I only recently joined this group, but in answer to rob, the best oil would be a long chain parrafin, can be purchased for vacuum pumps, also a solid encapsulation will shift as it ages, and that would put strain on the resistors, so they would need an initial wrap in a silicone perhaps? definately a very compliant cover of some sort to isolate the strain.
> >>>>
> >>>> Mike
> >>>>
> >>>> PS I am shortly going to set up some LTZ's for a small family of references to age and compare. Doing the sums a difference measure between each one and graphed will tell me which ones are the most stable, then after a year or so splash out and get one calibrated against a known source.
> >>
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