[PSUBS-MAILIST] oil compensation

Tue Jul 22 04:51:23 EDT 2014

But wait there's more....below is a summary by Jim of advice for oil compensating & Carsten's cynical 
additional points.
Alan
	* o: <personal_submersibles at psubs.org>
	* Subject: Re: [PSUBS-MAILIST] illustration is this what you mean sort of?? pressuriz...
	* From: MerlinSub at t-online.de
	* Date: 05 Dec 2010 09:43 GMT
	* Reply-to: personal_submersibles at psubs.org
	* Sender: owner-personal_submersibles at psubs.org
________________________________

9. Run the motor a half hour with the boat in the water and see may how the hot oil gets out of the weakest point by internal overpressure.. 
10. Switch of the motor and let the boat still in the water for two hours or so.  Open the engine the next weekend in you shop and found partly water in it because of the underpressure creates as the oil cool down.. The best for the seal is if it see no pressure differtial doesnt matter from which side. So logical the bladder has the same high as the motor. 
A deeper installed bladder indicates a leak by oil getting out in the water, A higher install may not. 
A higher installed bladder indicates maybe allready a leak onshore - and thats maybe the better solution.  The best solution is that the hose work between using device and bladder is from clear material and has a loop higher than the user and the bladder. So air in the system can be easy spotted.  See here: http://www.euronaut.org/content/upload/notes/IMG_3321a.jpg Euronaut has seven bladders on:
- Stern Thruster (oil)
- Bow Thruster (oil)
- Anchor winch motor (oil)
- Propeller shaft (oil)
- Void space frame cave between fwd.ballast tank and pressure hull (coolant water)
- Void space frame cave between aft.ballast tank and pressure hull (coolant water)
- One bag for all three fix rudder skegs (coolant water)
- Side Rudder and Stern deeprudder are also filled with c.water but without bags. See also the other mail I just send.  vbr Carsten 
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------------------------------------------------------------------------------ <JimToddPsub at aol.com> schrieb:
> All,
>  
> I'm having difficulty understanding the need for the bladder,  and it seems 
> like an additional complication and an additional point of  vulnerability 
> along with the line.  How would this work:
>  
> 1. Install a bleed valve at the uppermost point of  the motor housing.
> 2. Install a fill valve at the bottom of the motor  housing.
> 3. Attach a fill line (equipped with a pressure gauge) to  the fill valve. 
> Purge all air from the fill line prior to attaching it to the  valve.
> 4.  With the bleed valve open, fill the motor from the  bottom until oil 
> discharges from the bleed valve.
> 5.  Turn the motor shaft by hand and vibrate the motor to  release any 
> trapped air bubbles.  Close the bleed valve and allow the motor  to sit for a 
> couple of days undisturbed.
> 6.  Open the bleed valve and add more oil to drive any  residual bubbles 
> out.  Close the bleed valve while pressure is still being  applied to the fill.
> 7. Adjust the pressure from the oil pump to the desired  pressure, then  
> close the fill valve.
> 8.  Release the pressure on the oil pump/fill line, then  disconnect the 
> fill line.
>  
> This seems logical to me, but I'd like to hear from the voice  of 
> experience.  Does 14 lb. seem like a reasonable differential pressure  for set up?  I 
> expect to start with new Minnkota motors, and I haven't  addressed sticking 
> with the factory seals vs retrofit seals.  My intended  operational depth 
> is 300 feet.
>  
> As always, comments  and criticisms are eagerly  invited.
>  
> Thanks,
> Jim

________________________________
 From: Alan James via Personal_Submersibles <personal_submersibles at psubs.org>
To: psubs.org <personal_submersibles at psubs.org> 
Sent: Tuesday, July 22, 2014 8:28 PM
Subject: [PSUBS-MAILIST] oil compensation

I found some comments that Carsten made about oil expansion & compensation.
Someone was interested in hearing them if I found them. The thread was 5 Dec 2010.
Alan
Alan and the other gentlemens,  our expierence with oil filled motors, batterys or even propeller shafts is that the oil expand if the motor is runing longer time. 
Simple because its warm up. We had that problem on Eurosub on the first dives. 
And on Euronaut we filled the bladder complet up and the get pretty hard in the hot summer just by sun heating the sub. 
A full filled bladder with over pressure creates a lot of interal 
pressure in the wrong direct - a lot of force for the bladder itself and hose work.  Therefore our bladder are only half expand during the filling. But still free of any air. 
An other point is that the bladder has to be not to small. To create a slightly overpressure on the motorseal you just install the bladder below the motorcasing. 
But we found out that on trolling motor (electric outboards) this is not nessesary. There seals are good for some 
douzend feets at least - so you can install the bladder else were. 
Filling is simpler if the bladder is slightly over the motor - you can vent the system direct on the filling point. Another point is that we install now one bladder per motor  - in the earlier sub (Sgt.Peppers) we install a central
one for all motors. Hard to find a leak after a dive with all the T-crossing piepings and motorseals..  vbr Carsten

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