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Re: [PSUBS-MAILIST] illustration is this what you mean sort of?? pressuriz...
Thanks Carsten for all that information & experience.
that's given me a lot more clues about how to do this.
I never knew you did your motors that way.
Regards Alan
----- Original Message -----
From: <MerlinSub@t-online.de>
To: <personal_submersibles@psubs.org>
Sent: Sunday, December 05, 2010 10:43 PM
Subject: Re: [PSUBS-MAILIST] illustration is this what you mean sort of?? pressuriz...
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@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
In a message dated 12/4/2010 10:07:34 P.M. Central Standard Time,
alanjames@xtra.co.nz writes:
Hi Lawrie,
from what I can understand of the explanation on oil compensating a motor
on the ROV site is this....
If you have a motor with half pie reasonable seals, you just fill it with
a suitable low viscosity oil.
You have a drain nipple in to the bottom of the motor casing & a nipple
for attachment of a hose
on the top of the casing. You attach a tube from the top nipple to a
bellows or as they suggested
something like the bladder in a football. This is filled with oil &
pressurized to about 15 psi so there
is always an external pressure of the motor oil over the internal pressure
of the sea or lake water of
15 psi no matter what depth you are at. You can use the one bladder for
all your motors.
The other option they mentioned was in the case where the motor might not
be designed for underwater
applications & the seal not so good. In this case you can make an
enclosure, put a suitable shaft seal
in the enclosure & do the same as the first option with the nipples tube &
bladder but on the enclosure
not the motor. The motor inside would need to be filled with oil & have an
opening in it. There shouldn't be
any air in these systems.
The idea of the seals back to back seems to be an additional option as a
safe guard.
I bought a couple of trawling motors that I couldn't easily change the
seals on so will be trying the oil
bladder method & if I'm going through too much oil then maybe air
compensation or buying some better motors.
Regards Alan
----- Original Message -----
From: _lawrie-psubs@environics.com.au_
(mailto:lawrie-psubs@environics.com.au)
To: _personal_submersibles@psubs.org_
(mailto:personal_submersibles@psubs.org)
Sent: Sunday, December 05, 2010 2:53 PM
Subject: [PSUBS-MAILIST] illustration is this what you mean sort of??
pressurized oil compensation bladder for motors
Jim I created an illustration based on your concept as in outer oil
housing and internal air housing for eletric motor.
I have shown the location for a pressure sensor within the closed stem at
the top of the outer housing and at the bottom a stem for the
drain/fill/pressure up component not shown.
Is this sort of what you mean with regards to seals and using oil to
indicate you water passing the seal and increasing the differential pressure
between the two housings? Lawrie
On Fri, 3 Dec 2010 22:48:55 -0500 (EST), JimToddPsub@aol.com wrote:
Great sites, Alan. Thanks!
Lots of supplies/components when you click on the COMPANIES button.
Jim
In a message dated 12/3/2010 8:29:18 P.M. Central Standard Time,
alanjames@xtra.co.nz writes:
Dan Fjellroth's website is a good resource for home builds.
Go to _http://www.ROV.net_ (http://www.rov.net/) then ROV FAQ and look
for 'Build your own ROV'.
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