Re: stopping leakage of mineral oil from wire feedthroughs? (fwd)

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---------- Forwarded message ----------
Date: Thu, 11 Nov 2004 08:01:46 -0800
From: Jim Lux <jimlux@xxxxxxxxxxxxx>
To: High Voltage list <hvlist@xxxxxxxxxx>
Subject: Re: stopping leakage of mineral oil from wire feedthroughs? (fwd)

> ---------- Forwarded message ----------
> Date: Thu, 11 Nov 2004 08:47:29 +0200
> From: Kristian Ukkonen <kristian.ukkonen@xxxxxx>
> To: High Voltage list <hvlist@xxxxxxxxxx>
> Subject: Re: stopping leakage of mineral oil from wire feedthroughs? (fwd)
>
> High Voltage list wrote:
> > From: Jack Vandam <snotoir7674g@xxxxxxxxxxxxxx>
> > I have been working on a project that requires a small, high frequency
> > transformer, not too much unlike a flyback, in mineral oil.  I am using
a
> > small plastic container to hold the transformer and have the input/
output
> > wires passing through the plastic container at several points.  However,
> > just after completing my first immersion of the transformer, I
discovered
> > that oil was leaking through one of the feedthroughs.


> metal to make oil-tight seal.. The metallic tank is much
> better from RFI point of view as well.
>
>    Kristian Ukkonen.
>



If your container is polyethylene, nothing will stick well enough to seal
against mineral oil. There are pretreatments you can use on PE, but they're
tedious, and don't always work the first time. You can weld PE fittings.
Why not use "Liquid Tite" type conduit fittings if you must.

The other thing to think about is to run all your wires out through the lid
of the container, with the circuitry hanging from the lid.  That way the
bottom is just a seamless/holeless tank.  You might have a PE container with
non-PE lid and a gasket that will seal well enough.

Although, I heartily agree with Kristian.... metal box & epoxy is really the
way to go.

And, of course, ALL oil insulated equipment leaks a little.  The temperature
and atmospheric pressure changes cause it to "breathe" and ooze out the oil.
Except, perhaps, welded metal cans with a crimped seal (like oil insulated
capacitors).