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Re: [PSUBS-MAILIST] Pressure compensation

On Fri, 11 Aug 2000 22:00:37 -0700, "Gary R. Boucher" <protek@shreve.net>
wrote:

>      The trick is having the pressure inside the motor the same as the 
> outside pressure, or at least close.  If you set the pressure inside the 
> motor at a certain value and ascended the pressure inside is greater than 
> outside.  If you dove beyond the set pressure you have more pressure 
> outside.  One method of pressure compensating a motor is to place a rubber 
> bladder with air in the water close to the motor and run a tube from the 
> bladder to the motor housing.  As the sub dives the pressure on the bladder 
> increases and so does the inside motor pressure.

Just as a point of interest...

In deep professional-quality thrusters, they typically fill the thruster
housing (and thus the motor) with oil, which makes the whole deal basically
non-compressable. Instead of using a seal, they use a magnetic coupling to
turn the propeller. This gives a thruster that can be used to full ocean
depths.

Later,
Jon

--------------------------------------------------------------
   Jon Hylands      Jon@huv.com      http://www.huv.com/jon

  Project: Micro Seeker (Micro Autonomous Underwater Vehicle)
           http://www.huv.com