[volt-nuts] Resistance standard

[J. Forster]

You can buy NuJol at any drug store. Look in the laxative area. It's so
oure, people drink it.

-John

==================


> 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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