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

[<sroys@xxxxxxxxxxxxxxxxx>]

---------- Forwarded message ----------
Date: Thu, 11 Nov 2004 13:19:25 +1300
From: Malcolm Watts <m.j.watts@xxxxxxxxxxxx>
To: High Voltage list <hvlist@xxxxxxxxxx>
Subject: Re: stopping leakage of mineral oil from wire feedthroughs? (fwd)

Hi Jack,

On 10 Nov 2004, at 15:26, High Voltage list wrote:

> Original poster: <sroys@xxxxxxxxxxxxxxxxx>
> 
> 
> 
> ---------- Forwarded message ----------
> Date: Wed, 10 Nov 2004 14:37:08 -0500
> From: Jack Vandam <snotoir7674g@xxxxxxxxxxxxxx>
> To: High Voltage list <hvlist@xxxxxxxxxx>, hvlist
> <hvlist@xxxxxxxxxxxxxxxxx> Subject: stopping leakage of mineral oil
> from wire feedthroughs?
> 
> 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.  Originally before adding the oil, I thought I had
> sufficiently sealed around the feedthrough holes with plastic weld
> epoxy.  However, apparently not.  What a mess I had today draining out
> the oil and starting over again.  Getting rid of the oil residue
> required both mineral spirits and finally acetone.  Now I have to
> reapply a sealant around the wires/ feedthroughs.  What is recommended
> so I don't have this happen again?  I'm thinking of trying to dispense
> a generous amount of silicone around the areas, but would this be
> better or should I stick with the epoxy?

Silicone rubber won't work well with oil if I remember correctly (I 
had to deal with the same problems as well). Epoxy doesn't weld the 
plastic so it isn't ideal either and forget hotmelt. Only a true weld 
works. However, your real problem might be oil wicking through the 
tiniest of gaps in the feedthroughts by capillary action. I remember 
it wicking right through a stranded cable once. Not being able to see 
what you're doing means I don't have a useful answer sorry. 

Malcolm
 
> Thanks,
> Jack
> 
> 
>