[PSUBS-MAILIST] motor oil compensator

Thu Apr 2 12:21:21 EDT 2020

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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