[PSUBS-MAILIST] motor oil compensator

[Alan via Personal_Submersibles]

Brian,
there is this military de-classified 1972 document on pressure compensating.
https://apps.dtic.mil/dtic/tr/fulltext/u2/894795.pdf
I printed it out & had it bound.
I found that the rotation of the motor was throwing the oil out of the motor
housing & up in to the compensating tube. If you dived there would be added
pressure to keep the oil in the motor housing, but this wouldn't happen transiting
on the surface. As the oil also keeps the Motor cool, there may be a danger of
the motor overheating in this instance.
As you will find in the linked manual, a minimum of 5psi over pressure is the norm.
I am going to use the same system as Cliff, with the relieving regulator dialled
up to 5psi to give an overpressure. However my system has oil in it so I get it's 
cooling advantages & eliminate large air volume changes.
Alan

> On 25/03/2020, at 11:19 AM, Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> Seawater gets compressed up the hose, so never goes above the highest point of the hose.  When oil heats up it spills into trap and cannot escape to the sea. 
> 
> Brian
> 
> 
> --- personal_submersibles at psubs.org wrote:
> 
> From: Øystein Skarholm via Personal_Submersibles <personal_submersibles at psubs.org>
> To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
> Subject: Re: [PSUBS-MAILIST] motor oil compensator
> Date: Tue, 24 Mar 2020 22:21:15 +0100
> 
> You should avoid contact between the seawater and the oil. The oil will contaminate quickly and it will no longer be dielectric. 
> Just the hose from the motor to the tee is enough to compensate. You do not have to have a large volume of oil. Fill the hose with oil and cap it off, done. or make a neat yet more sophisticated solution. 
> Make the end lid of the motor as a flange assembly and instead of a lid, use a rubber diaphragm. This will then act as a compensator. You can even install a light spring pushing down on the diaphragm  if you want a slight internal overpressure. 
> <image.png>
> 
> tir. 24. mar. 2020 kl. 21:28 skrev Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org>:
> Here is a drawing for my oil compensator
> 
> 
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> 
> -- 
> Vennlig hilsen
> Øystein Skarholm
> 91369599
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