<div dir="ltr">A Little air in the compensator does not matter at all. As long as your compensator is closed, no water will ingress.<div>Remember, the only need you have for an oil reservoir is to take up any expansion in the oil caused by heat or change in the compensated volume (like pushrods going in an out of a compartment) To cerate a slight overpressure you can use a soft rubber ballow and inflate it a little with oil so it stretches just enough create an overpressure in the system. To inflate the bellow - make T connection in the system with a check valve and insert oil through it. </div><div>I use that principle on my ROV where all the electricity is inside an oil compensated apartment. </div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">ons. 25. mar. 2020 kl. 13:36 skrev James Frankland via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>>:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr">Hi All,<div>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.</div><div>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.</div><div><br></div><div>No matter what i do, i always seem to end up with a small amount of air in the tube.</div><div><br></div><div>This picture is the only one i can find.</div><div><br>The tube comes out the top, around to a valve secured underneath. Thats it. There is no hole on the underside any more.</div><div><br></div><div>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.</div><div><br></div><div>There appears to be no leaks and no seawater in the motor.</div><div><br></div><div>What am i doing wrong? Its such a nuisance and worry to me.</div><div><br></div><div>I have heard that some people put the prop shaft seals in backwards? I didnt do that, they are just standard.</div><div><br></div><div>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?<br><br>Thanks, </div><div>James</div><div><br></div><div><div><img src="cid:ii_k87b37s60" alt="image.png" width="387" height="516"><br></div></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, 25 Mar 2020 at 08:43, Alan via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="auto"><div></div><div>Brian,</div><div>not sure of your depth but if you are going to 300ft, the air will be compressed to</div><div>1/12th the volume, so the oil overflow reservoir is going to be problematic because</div><div>It's large volume could mean the seawater would come a long way up the tube on</div><div>the seaward side. Also using it as an overflow would create the problem of "how do </div><div>I get the oil back in the motor" & " how do I monitor it".</div><div>I have had rubber perish in WD40 so I would watch that if you are considering using</div><div>a rubber compensator.</div><div>Have a look at the PDF I referenced as that has several options.</div><div>Alan</div><div><br></div><div><br></div><div><br>On 25/03/2020, at 5:40 PM, Brian Cox via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a>> wrote:<br><br></div><blockquote type="cite"><div><div style="font-family:Arial,sans-serif;font-size:10pt"><font size="2" style="font-family:Arial,sans-serif">Alan, </font><div><font size="2"><font face="Arial, sans-serif"> 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.</font></font></div><div><font size="2"><font face="Arial, sans-serif"><br></font></font></div><div><font size="2"><font face="Arial, sans-serif">Brian</font></font></div><div><font size="2"><font face="Arial, sans-serif"><br></font></font></div><div><font size="2"><font face="Arial, sans-serif"> </font><br></font><br><span style="font-family:Arial,sans-serif;font-size:10pt">--- <a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a> wrote:</span><br><br><span style="font-family:Arial,sans-serif;font-size:10pt">From: Alan via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a>></span><br><span style="font-family:Arial,sans-serif;font-size:10pt">To: Personal Submersibles General Discussion <<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a>></span><br><span style="font-family:Arial,sans-serif;font-size:10pt">Subject: Re: [PSUBS-MAILIST] motor oil compensator</span><br><span style="font-family:Arial,sans-serif;font-size:10pt">Date: Wed, 25 Mar 2020 17:28:21 +1300</span><br><br><div style="font-family:Arial,sans-serif;font-size:10pt"></div><div style="font-family:Arial,sans-serif;font-size:10pt">Brian,</div><div style="font-family:Arial,sans-serif;font-size:10pt">I wouldn't read a lot in to that experiment as far as heating goes, as when</div><div style="font-family:Arial,sans-serif;font-size:10pt">the motor is under load it will be drawing a lot more amps & develop a</div><div style="font-family:Arial,sans-serif;font-size:10pt">lot more heat.</div><div style="font-family:Arial,sans-serif;font-size:10pt">But people run the Minnkotas with air compensation & get away with it.</div><div style="font-family:Arial,sans-serif;font-size:10pt">Alan</div><div style="font-family:Arial,sans-serif;font-size:10pt"><br></div><div style="font-family:Arial,sans-serif;font-size:10pt"><br>On 25/03/2020, at 2:09 PM, Brian Cox via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a>> wrote:<br><br></div><blockquote style="font-family:Arial,sans-serif;font-size:10pt"><div><div style="font-family:Arial,sans-serif;font-size:10pt"><font size="2"><font face="Arial, sans-serif"> Alan, </font></font><div><font size="2"><font face="Arial, sans-serif"> 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. </font></font></div><div><font size="2"><font face="Arial, sans-serif"><br></font></font></div><div><font size="2"><font face="Arial, sans-serif">Brian</font></font></div><div><font size="2"><font face="Arial, sans-serif"><br></font></font></div><div><font size="2"><font face="Arial, sans-serif"> </font></font><br><br><span style="font-family:Arial,sans-serif;font-size:10pt">--- <a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a> wrote:</span><br><br><span style="font-family:Arial,sans-serif;font-size:10pt">From: Alan via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a>></span><br><span style="font-family:Arial,sans-serif;font-size:10pt">To: Personal Submersibles General Discussion <<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a>></span><br><span style="font-family:Arial,sans-serif;font-size:10pt">Subject: Re: [PSUBS-MAILIST] motor oil compensator</span><br><span style="font-family:Arial,sans-serif;font-size:10pt">Date: Wed, 25 Mar 2020 13:25:53 +1300</span><br><br><div style="font-family:Arial,sans-serif;font-size:10pt"></div><div style="font-family:Arial,sans-serif;font-size:10pt">Brian,</div><div style="font-family:Arial,sans-serif;font-size:10pt">there is this military de-classified 1972 document on pressure compensating.</div><div style="font-family:Arial,sans-serif;font-size:10pt"><a href="https://apps.dtic.mil/dtic/tr/fulltext/u2/894795.pdf" target="_blank">https://apps.dtic.mil/dtic/tr/fulltext/u2/894795.pdf</a></div><div style="font-family:Arial,sans-serif;font-size:10pt">I printed it out & had it bound.</div><div style="font-family:Arial,sans-serif;font-size:10pt">I found that the rotation of the motor was throwing the oil out of the motor</div><div style="font-family:Arial,sans-serif;font-size:10pt">housing & up in to the compensating tube. If you dived there would be added</div><div style="font-family:Arial,sans-serif;font-size:10pt">pressure to keep the oil in the motor housing, but this wouldn't happen transiting</div><div style="font-family:Arial,sans-serif;font-size:10pt">on the surface. As the oil also keeps the Motor cool, there may be a danger of</div><div style="font-family:Arial,sans-serif;font-size:10pt">the motor overheating in this instance.</div><div style="font-family:Arial,sans-serif;font-size:10pt">As you will find in the linked manual, a minimum of 5psi over pressure is the norm.</div><div style="font-family:Arial,sans-serif;font-size:10pt">I am going to use the same system as Cliff, with the relieving regulator dialled</div><div style="font-family:Arial,sans-serif;font-size:10pt">up to 5psi to give an overpressure. However my system has oil in it so I get it's </div><div style="font-family:Arial,sans-serif;font-size:10pt">cooling advantages & eliminate large air volume changes.</div><div style="font-family:Arial,sans-serif;font-size:10pt">Alan</div><div style="font-family:Arial,sans-serif;font-size:10pt"><br>On 25/03/2020, at 11:19 AM, Brian Cox via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a>> wrote:<br><br></div><blockquote style="font-family:Arial,sans-serif;font-size:10pt"><div><div style="font-family:Arial,sans-serif;font-size:10pt"><font size="2">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. </font><div><font size="2"><br></font></div><div><font size="2">Brian</font></div><div><font size="2"><br></font><br><span style="font-size:10pt">--- <a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a> wrote:</span><br><br><span style="font-size:10pt">From: Øystein Skarholm via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a>></span><br><span style="font-size:10pt">To: Personal Submersibles General Discussion <<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a>></span><br><span style="font-size:10pt">Subject: Re: [PSUBS-MAILIST] motor oil compensator</span><br><span style="font-size:10pt">Date: Tue, 24 Mar 2020 22:21:15 +0100</span><br><br><div dir="ltr" style="font-size:10pt">You should avoid contact between the seawater and the oil. The oil will contaminate quickly and it will no longer be dielectric. <div>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. </div><div>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. </div><div><div><image.png><br></div></div></div><br><div style="font-size:10pt"><div dir="ltr">tir. 24. mar. 2020 kl. 21:28 skrev Brian Cox via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org" target="_blank">personal_submersibles@psubs.org</a>>:<br></div><blockquote style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div style="font-family:Arial,sans-serif;font-size:10pt"><font size="2">Here is a drawing for my oil compensator</font><div><font size="2"><br></font></div><div><font size="2"><br></font></div></div>_______________________________________________<br>
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</blockquote></div><br clear="all"><div><br></div>-- <br><div dir="ltr" class="gmail_signature"><div dir="ltr"><div>Vennlig hilsen<br>Øystein Skarholm</div><div>91369599</div></div></div>