[PSUBS-MAILIST] right side up compensator

[Øystein Skarholm via Personal_Submersibles]

I think you are going about this a little too complicated. The compensator
is there for two purposes.
1: Compensate for any oil expansion
2: Compensate for any leaks ie. supply oil to feed the leak, preventing
water ingress.
There is NO NEED for large comps for the motors unless you planning to
continue to operate with a leak ongoing.
Also, if you go for a hard compensator shell, then you should make it from
transparent acryl, enable you to see the amount and color of the oil.
A small rubber bladder with a transparent hose is a good solution. It
provides an overpressure at all times and is cheap and easy to make.

Further, the amount of air in the compensator does not really matter, it's
the amount of air inside the compensated housing that matters because the
compensator needs to replace that decreasing air volume with oil. In fact,
your whole compensator could consist of air, the downside is it would give
you variable buoyancy - but if the comp is small and the vessel large that
would matter much either.
I saw somebody was writing that the air volume would compress to half the
volume for each ATM of pressure, which is not correct.
The pressure must be doubled to decrease the air volume by half. So from
0-10m depth - the pressure doubles (from 1 to 2 Atm) and the volume halves.
But to half that volume again, we will have to go to 30m where the pressure
is 4 Atm (or bar if you prefer) Now the air will be 1/4 of its original
surface size. The next half volume from here would occur at 70m - 8Atm =
1/8 of the original volume. This is off course do not take into account the
temperature, but you get the picture.

[image: image.png]
[image: image.png]If you want to include the temperature use T in kelvin
0K=-273,15Celcius => 20Celcius = 293,15K

fre. 27. mar. 2020 kl. 20:21 skrev Brian Cox via Personal_Submersibles <
personal_submersibles at psubs.org>:

> Here it is right side up hopefully
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-- 
Vennlig hilsen
Øystein Skarholm
91369599
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