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Re: Polystyrene and oil?

Aric,

Transformer oil is not the same as petroleum. Mineral oils are highly
refined light distallates derived from petroleum. Most mineral oils used
for transformer application tend to be naphthenic because refiners and
utilities have found that these tend to exhibit somewhat better
longer-term characteristics than parafinnic transformer oils,
particularly under light corona bombardment. Common napthenic oils
include Shell Diala-X or AX, Exxon Univolt 60, N61, 33, Tulco LUBSNAP
100, etc. BTW, one notable exception to the above is r-TEmp which,
although being paraffinic, is an excellent insulating oil. Most
[non-synthetic] lubricating oils are paraffinic. 

Best bet would be to test some samples at elevated temperature before
committing for a whole capacitor. It's beginning to sound as though some
mineral oils may work satisfactorily with some polystyrene for some
coilers! However, your mileage may vary! :^)

Personally, I'd still stick with LDPE or PP since both are considerably
less brittle and there's no potential long-term solvent worries...

-- Bert --

Tesla List wrote:
> 
> Original Poster: Aric_C_Rothman-at-email.whirlpool-dot-com (Aric C Rothman)
> 
>      I, too, am using styrene in a capacitor (stack, not rolled, however).
>      I've been concerned with styrene's resistance to oil.  I found a site
>      at
> 
>      http://nunc.nalgenunc-dot-com/scripts/nalge/nunc/surface/chem.asp
> 
>      that provides information that is both useful and cryptic.  If one
>      requests chemical resistance information on styrene for all chemicals
>      in the database, you'll be told that styrene is resistant to paraffin
>      oil and mineral oil, but not petroleum oil!  Can anyone clarify the
>      difference?  Is petroleum naphthinic(sp?) vs. paraffinic for mineral
>      and (obviously) paraffin oil.  Should a product like Diala-AX (Shell's
>      transformer oil) be considered petroleum oil or mineral oil?
> 
>      I'm tempted to get a five gallon jug of corn oil and use that!  I
>      don't want to dissolve my precious capacitors!
> 
>      Aric
<SNIP>