[PSUBS-MAILIST] motor oil compensator

Fri Apr 3 16:17:51 EDT 2020

Thanks guys, the vacuum,  i was thinking would be for the motor only. The
end of the tube would have an air bubble that i could determine how big i
wanted it to be without guessing what was hidden in the thruster. In the
mean time I'm using the same set up for air compensation as a starting
point. Valve system still to be determined.
David

On Fri, Apr 3, 2020, 1:03 PM Sean T. Stevenson via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> This is exactly why compensators should never be filled to capacity. You
> need capacitance in both directions. Kink your tube to create a collapse
> initiation site, and leave room for expansion as well.
>
> Sean
>
>
>
> -------- Original Message --------
> On Apr. 3, 2020, 13:57, Alan via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
>
> David,
> another problem you may have is that if the oil expands & there is no air
> in the system then the wall of the tube will be relied on to take up the
> expansion. The wall won't have a lot of give & you may end up getting oil
> leaking out the shaft seals while the sub is in storage.
> I know Emile & Carsten had problems with this.
> Alan
>
> On 4/04/2020, at 4:52 AM, David Colombo via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Hank, I've been thinking about this oil compensatation issue. On the
> seaQuestor, I did not want to side tap my thrusters, but wanted to have the
> ability to go with oil compensatation in the future. So I designed a
> coupler made out of uhmw. I had it machined to thread into the 1" thruster
> shaft location, and to have threaded in the opposite direction a seaconn
> wet mate  connector and that would plug into the pressure hull via what
> ever cable lenght I need. In the coupler there are other side taps that are
> for other sensor wires( ie: temp, pressure). One tap is reserved for future
> use as the port for oil compensatation. The average lenght from my
> thrusters to hull body is about 48". My future plan would be to fill the
> thruster thru the largest port of the coupler. Take the thruster, place in
> a plastic bag so that the seal seams have a way to sealed temporarily and
> place the unit into a vacuum chamber. Pull a vacumm like we do with epoxy,
> remove the unit, cap off the end of the 5/8"x 48" tube,  and install in the
> sub. My assumption is there is no hidden air now in my thruster, and I have
> 48" long bellows to compensate should the oil expand. Do you see any issues
> with my thoughts?
> David
>
> On Fri, Apr 3, 2020, 5:26 AM hank pronk via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
>> James, you could have the bellows attached to the bottom side of the
>> motor and a fill plug on top.
>> Hank
>>
>> On Thursday, April 2, 2020, 10:21:56 AM MDT, James Frankland via
>> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>
>>
>> Hi All who replied to me.
>>
>> Many thanks, i am investigating what I can find.  I want to keep it
>> really simple.  Ideally just oil compensated, sealed with a suitable
>> bladder.  Im nearly there with my existing setup, I think i just need some
>> sort of bellows or super soft bladder in the line.  The accordian bladder
>> Cliff mentioned looks good but i need one with a connection at both ends so
>> I can run a tube to my filling valve.
>>
>> I will keep searching.
>>
>> On Thu, 26 Mar 2020 at 21:21, Alan via Personal_Submersibles <
>> personal_submersibles at psubs.org> wrote:
>>
>> James,
>> If you go with the regulator method make sure it is a relieving regulator
>> that
>> can let overpressure out on assent.
>> In general in the relieving regulators there is a hole in the valve
>> spindle portion
>> that allows an overpressure down line to escape, & also allows water
>> pressure at
>> ambient depth to maintain the set pressure above ambient. You need to
>> mount with
>> the handle down or water will ingress through the valve.
>> If you set it for say 5psi pressure, the down stream pressure ( in the
>> motor housing)
>> may jump a lot higher when relieving due to the fixed overpressure
>> setting. I oiled
>> the regulator piston with silicone & this helped make the differential
>> just a few psi.
>> I bought a number of regulators & pulled them apart looking for a cheap
>> plastic option
>> with view of changing out parts in the handle that are exposed to water,
>> but too
>> much work & Hugh found that regulator that Cliff referenced.
>> The system below is filled with 5 cst silicone oil. The oil runs down the
>> wiring tube
>> to the T & continues up to within a couple of inches of the regulator.
>> This gives room for any oil expansion but leaves only a couple of inches
>> of air that
>> will be compressed when diving.
>> Even if all the oil leaked out there would still be air compensation.
>> Alan
>> [image: image2.JPG]
>>
>>
>>
>> On 27/03/2020, at 6:53 AM, Cliff Redus via Personal_Submersibles <
>> personal_submersibles at psubs.org> wrote:
>>
>> James, the pressure reducing/relieving regulator I used for pressure
>> equalization of my thrusters until recently was the Parker - PR364-02BSS -
>> Regulator Port size 1/4" NPT, stainless steel body.  Parker has a number of
>> PR364 regulators that show up on ebay all the time .  Make sure you get the
>> SS version.
>>
>> Would be similar to this one
>> https://www.ebay.com/itm/PARKER-R364-02B-1-4-MINIATURE-REGULATOR-NEW-IN-A-BOX-0-60-PSI/252360167538?hash=item3ac1d69072:g:EckAAOSwubRXFSSP
>> but his one not SS.
>>
>>
>> Hugh Fulton was the the first in the Psub group to adopt this pressure
>> compensation device for his Q-Sub.
>>
>> I used this regulator quite successfully to pressure compensate my Minn
>> Kota 101s for many years.  I abandoned the regulator about 8 months ago and
>> switch to oil pressure compensation.  The reason I switched is that I did
>> not like the amount of air it used in my HP air bank on repeated deep dives
>> to 300 to 400 ft.  I ran these with 4 psi differential positive pressure.
>> I left the lip seals in my 101's oriented as per the original manufacturer
>> ( oriented to withstand external pressure).  I don't have enough run time
>> on my new oil compensation method which is WD-40 with small accordion
>> plastic bladders I got from Alec to argue which technique is better.
>>
>> Best Regards
>>
>> Cliff
>>
>>
>>
>> On Thursday, March 26, 2020, 12:15:51 PM CDT, James Frankland via
>> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>
>>
>> Also interested in Cliff's compensator regulator that was mentioned.  Any
>> info on that.
>>
>> Many thanks
>>
>> On Thu, 26 Mar 2020 at 17:08, James Frankland <
>> jamesf at guernseysubmarine.com> wrote:
>>
>> Hi Alan,
>>
>> Im using silicone oil.
>>
>> I deliberately kinked the hoses for the very reason you say.  I initially
>> used silicone hose which is much softer and flexible, but it reacted with
>> the oil and expanded, quite a lot.
>>
>> I think I might see if i can get some thinner walled tube (but not
>> silicone) and wrap it around the motor a couple of times, to give it a
>> bigger compensator.
>>
>> Can other people confirm that a small amount of air in the tube is
>> acceptable?  I have been constantly trying to remove every bubble.  If a
>> small amount is ok, im pretty good to go.
>>
>>
>> Also I will be making some progress on my new sub pretty soon.  Just
>> getting a heavy hoist sorted, which at the moment is difficult as all the
>> shops are shut.
>>
>> Regards
>> James
>>
>>
>>
>>
>>
>>
>>
>> On Wed, 25 Mar 2020 at 21:38, Alan via Personal_Submersibles <
>> personal_submersibles at psubs.org> wrote:
>>
>> James,
>> that method with the hose wrapped around has come under criticism
>> previously.
>> Fortunately you have a kink in the hose which initiates a collapse of the
>> hose to
>> provide some equalisation. We calculated that the hose may take over
>> 100psi
>> external pressure before it collapsed to provide equalisation. So at
>> depth water
>> would push past the seals before there was any compensation.
>> I don't know whether you are still getting trapped air in the system
>> coming out
>> or whether expansion & contraction when out of the water is sucking air
>> in.
>> But for air to get in, oil would have to get out. Maybe oil expands out
>> through the
>> seals when you transit & it heats up, & then causes a vacuum when you
>> take the sub
>> out of the water & the motors cool down, thus sucking air in.
>> Perhaps you could run the motors out of the water for a while untill they
>> feel
>> hot, & see if any oil comes out. Another thought is that if you are using
>> WD40
>> or similar, perhaps it is pushing past the seals with the hot cold
>> variation over
>> each day, & evaporating away so that there's not much evidence of a leak.
>> Alan
>>
>>
>>
>> On 26/03/2020, at 1:35 AM, James Frankland via Personal_Submersibles <
>> personal_submersibles at psubs.org> wrote:
>>
>> Hi All,
>> This is a really interesting topic for me.  I have been meaning to ask
>> this for a while but been a bit busy with other stuff.
>> I need to modify my motors again somehow.  I have a simple tube coming
>> from the top of the motor with a valve that i can shut, so i can seal the
>> motor and close it off.
>>
>> No matter what i do, i always seem to end up with a small amount of air
>> in the tube.
>>
>> This picture is the only one i can find.
>>
>> The tube comes out the top, around to a valve secured underneath.  Thats
>> it.  There is no hole on the underside any more.
>>
>> I fill it, it seems fine.  The next day there are a few bubbles, which i
>> would expect from just sticking to things.  So i clear that.  However,
>> after either a dive or some time, a small amount of air gets in the tube.
>>
>> There appears to be no leaks and no seawater in the motor.
>>
>> What am i doing wrong?  Its such a nuisance and worry to me.
>>
>> I have heard that some people put the prop shaft seals in backwards?  I
>> didnt do that, they are just standard.
>>
>> I suspect im getting pressure differences and its sucking air past the
>> seal.  Maybe some sort of 5 psi pressure system is required, as per cliffs
>> method?  Any more info on that?
>>
>> Thanks,
>> James
>>
>> <image.png>
>>
>> On Wed, 25 Mar 2020 at 08:43, Alan via Personal_Submersibles <
>> personal_submersibles at psubs.org> wrote:
>>
>> Brian,
>> not sure of your depth but if you are going to 300ft, the air will be
>> compressed to
>> 1/12th the volume, so the oil overflow reservoir is going to be
>> problematic because
>> It's large volume could mean the seawater would come a long way up the
>> tube on
>> the seaward side. Also using it as an overflow would create the problem
>> of "how do
>> I get the oil back in the motor" & " how do I monitor it".
>> I have had rubber perish in WD40 so I would watch that if you are
>> considering using
>> a rubber compensator.
>> Have a look at the PDF I referenced as that has several options.
>> Alan
>>
>>
>>
>> On 25/03/2020, at 5:40 PM, Brian Cox via Personal_Submersibles <
>> personal_submersibles at psubs.org> wrote:
>>
>> Alan,
>>                So do you see any issues with the way I have my
>> compensator set up?   I've been trying to see a scenario where it wouldn't
>> work, but I don't see one.  One reason I like it is because there in no
>> over or under pressure in the system.
>>
>> Brian
>>
>>
>>
>> --- personal_submersibles at psubs.org wrote:
>>
>> From: Alan 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: Wed, 25 Mar 2020 17:28:21 +1300
>>
>> Brian,
>> I wouldn't read a lot in to that experiment as far as heating goes, as
>> when
>> the motor is under load it will be drawing a lot more amps & develop a
>> lot more heat.
>> But people run the Minnkotas with air compensation & get away with it.
>> Alan
>>
>>
>> On 25/03/2020, at 2:09 PM, Brian Cox via Personal_Submersibles <
>> personal_submersibles at psubs.org> wrote:
>>
>>  Alan,
>>                    In my case my motor pod contains about 8 gallons of
>> WD40   .  I ran the motors the other day , all day long for about 10 hours
>> straight .  The temp outside was around 60 F  so it sort of simulated our
>> water temperature here.   I was surprised to discover that the expansion of
>> the oil was not as much as I thought it would be , it was about 1/2
>> gallon.  It reached a point where it stopped expanding, so I guess it
>> reached a point of equilibrium with respect to the temperature.    One
>> problem I have is in the summer the oil actually expands more than when the
>> motor is running just sitting there heating up from the
>> ambient temperature.    I think in the summer I'm going to disconnect the
>> hose and put it into a bucket when sitting.
>>
>> Brian
>>
>>
>>
>> --- personal_submersibles at psubs.org wrote:
>>
>> From: Alan 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: Wed, 25 Mar 2020 13:25:53 +1300
>>
>> 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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