[PSUBS-MAILIST] Yet another compensator method

[Alan via Personal_Submersibles]

James,
ideal is to have a system that pressurises to 5psi above ambient as this is
the figure that professional compensators try to achieve.
Compensating as Cliff does with a relieving regulator does this. He was
air compensating, but if you oil compensate with his system you have the 
Cooling plus added security that if all the oil leaked out you would still have
air compensation.
With your bellows, I would reduce the air volume a lot. The oil expansion
won't be much & you can run your motors out of water till they get hot to
check that if you like (but don't overheat them). If you lost oil then the bellows
could compress in to the affixed tube & rupture; so less air volume will give
you a bit more of a reserve of oil.
I would have also put the bellows on the bottom side. If they rip or deteriorate
with the oil & leak, then oil being lighter than water will flow out & be replaced
with sea water.
You could rectify that by swapping the thrusters from one side to the other.
If you enclose them for protection, then maybe in an acrylic tube so you can
keep an eye on the oil level.
Alan.


> On 7/07/2020, at 1:31 AM, James Frankland via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> Hi All
> 
> Getting Jodie B ready for diving in the next week or so.
> I have changed the motor compensator yet again as the last enclosed one didnt really have a proper flexible part and I think the oil expanded a bit over time and leaked out through the seals.  Just a tiny bit, but enough to put some air back in the pipe.
> 
> Anyway, the new method is simply a tube with belows.  These are from a toilet flush and have been sitting full of oil for a couple of weeks to see if anything happens.  They seem good, so i have installed them. The motor is completely filled with oil and the bellows have a small amount of air.  They compress easily, so should provide pressure compensation while also allowing the oil to expand if required.
> 
> The bellows will be covered with an open ended tube for protection.  Just got to make a strap for those.
> 
> Any comments?
> Thanks
> James
> 
> <20200704_142240.jpg>
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