[volt-nuts] Resistance Standard Oil - Plain Mineral Oil?

J. L. Trantham jltran at att.net
Sat Nov 26 14:31:44 UTC 2011


That may well be it!.

If plain old mineral oil from the drug store is OK, I'll use it.  But first,
I'll wait to see if I get any reply from my emails to the suppliers of
Drakeol 7 since it was recommended by Ohm-Labs.

Joe

-----Original Message-----
From: volt-nuts-bounces at febo.com [mailto:volt-nuts-bounces at febo.com] On
Behalf Of Robert Atkinson
Sent: Saturday, November 26, 2011 3:54 AM
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] Resistance Standard Oil - Plain Mineral Oil?


Hi,
"industrial" transformer oil tends to be golden brown in coulour and may be
part synthetic. Older oils may contain PCBs that are toxic and expensive to
dispose of. You should avoid these at all costs. The more highly refined USP
(United States Pharmacopeial) or BP (British Pharmacopeia) food / medical
grades are preferred for laboratory applictions. The additional cost over
transformer oil is off-set by the ready availabilty in small quantities. The
only disadvantage I know of is that when used for a long time in high
temperature baths (not our application), it can suffer sudden
polymerisation. It expands and turns to a gell and is hard to clean up.
Transformer oil has additives against this and oxidisation  but they can
have other problems such as smell and toxicity. I've used medical grade  oil
in many work applictions from insulation through temperature calibration
baths to keeping air away from anerobic bacterial cultures and never had any
issues.

Robert G8RPI.



________________________________
 From: J. L. Trantham <jltran at att.net>
To: 'Discussion of precise voltage measurement' <volt-nuts at febo.com> 
Sent: Saturday, 26 November 2011, 3:48
Subject: Re: [volt-nuts] Resistance Standard Oil - Plain Mineral Oil?
 
I wondered about the oil in the other two.  They come from very different
sources and one was NOS, including the calibration certificate, original box
and packing, etc., and both seem to have the same oil although one is GRAY
Industries and the other is Leeds & Northrup.

Joe





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