[PSUBS-MAILIST] motor oil compensator

Fri Apr 3 18:39:36 EDT 2020

Alan, thats what I thought I would be doing.  I cant imagine it would use
to much air from the hp tanks. I think I might try to put together a
pressure tank to test the amount of air would be used on a typical thruster
thru a typical dive to 500ft. Maybe Hank could do it for me with his
pressure cylinder.

David

On Fri, Apr 3, 2020, 1:47 PM Alan via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> David,
> a simple air compensation system that Karl Stanley was using was to use
> a first stage regulator with the spring removed. This gives ambient
> pressure,
> however in my testing the pressure varied within 11 psi of ambient, as the
> mechanism
> was a bit sticky. The over pressure on ascent he let force it's way out
> the motor shaft seals.
> A much better way ( in my opinion) is Cliffs regulator which can be used
> for air & oil compensation, gives you a set pressure above ambient that can
> be adjusted, & the system can be turned off to help stop the overpressure
> causing oil to come out on
> your driveway.
> I have a number of cheap plastic "Festo" relieving regulators which may be
> a good
> non corrosive option with a few parts changed in the spindle.
> Alan
>
> On 4/04/2020, at 9:17 AM, David Colombo via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> 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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>> <Image8053679313664869058.jpg>
>>
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