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Re: [PSUBS-MAILIST] Pressure compensation
Hi Jon,
You wouldn't need to have a rotational shaft going through an O-ring in the
method I described. But there is a problem for deeper depths, I didn't think
of and that is, a magnetic coupling that is commercially available, may
require a flat face in between the magnets, inside and outside and of
course, being flat, unless you equalize the inside pressure, it would buckle
under pressure unless it was very thick and that I imagine would make the
drive less effective. So yup, looks like there are a good many reasons for
using the correct oil and like you say, keeping it simple.
Thanks for the URLs. I will check them out.
Regards,
Karl.
----- Original Message -----
From: Jon Hylands <hylands@ibm.net>
To: <personal_submersibles@psubs.org>
Sent: Saturday, August 12, 2000 3:49 PM
Subject: Re: [PSUBS-MAILIST] Pressure compensation
> On Sat, 12 Aug 2000 14:22:29 -0400, "Karl Fuller" <fullerk@voyager.co.nz>
> wrote:
>
> > Fish oil is used a lot as a corrosion inhibitor, works very well and can
be
> > obtained in a deodorized version. Seems like the last thing you would
want
> > to use in an electric motor though, much too viscous. Not too expensive
and
> > good for those hard to paint and protect spots on a steel vessel.
> > Surely, if you are using a magnetic drive, you can make a pressure proof
> > vessel for the motor that does not need the oil as well. O-rings, fitted
> > correctly, are good for 1000's of PSI.
>
> Well, for anything going down, say, 12,000 feet, I don't believe an o-ring
> on a rotation joint would work all that well.
>
> You can build an air-filled chamber that will withstand 6000 psi, but its
> pretty hard to build one that will do both that and fit a motor inside,
> with a magnetic coupling, and have a through-hull for the electrical. Its
> probably 100 times cheaper to just use a regular aluminum cylinder for the
> housing, and fill it with oil.
>
> For *full* ocean depth, which involves 36,000 feet, forget it. You don't
> have any choice.
>
> Check out:
>
> http://www.tecnadyne.com/thrusters.htm
> http://www.deepseasystems.com/thl404-8d.htm
>
> for a couple of examples...
>
> Later,
> jon
>
> --------------------------------------------------------------
> Jon Hylands Jon@huv.com http://www.huv.com/jon
>
> Project: Micro Seeker (Micro Autonomous Underwater Vehicle)
> http://www.huv.com
>