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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