<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/><title></title></head><body><p style="margin: 0px;"><span style="font-family:arial,helvetica,sans-serif;font-size:10pt;color:#000000;text-decoration:none">The glue of the permanent magnets can be affected. </span></p>
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<p style="margin: 0px;"><span style="font-family:arial,helvetica,sans-serif;font-size:10pt;color:#000000;text-decoration:none">I use silicone oil with a low ct around 1 after bad expierence wir air compensation. </span></p>
<p style="margin: 0px;"><span style="font-family:arial,helvetica,sans-serif;font-size:10pt;color:#000000;text-decoration:none">But oil compensation needs also an compensator.bag. </span></p>
<p style="margin: 0px;"><span style="font-family:arial,helvetica,sans-serif;font-size:10pt;color:#000000;text-decoration:none">Siliconeoil is inherend to metal and plastic. (But prevent re-glueing) </span></p>
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<p style="margin: 0px;"><span style="font-family:arial,helvetica,sans-serif;font-size:10pt;color:#000000;text-decoration:none"><a href="https://silikon-profis.de/ELBESIL-SILIKONOEL-B-1-1-cSt-500-g">ELBESIL SILIKONÖL B 1 (1 cSt) - 500 g - SILIKON-PROFIS</a></span></p>
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<p style="margin: 0px;"><span style="font-family:arial,helvetica,sans-serif;font-size:10pt;color:#000000;text-decoration:none">vbr Carsten</span></p>
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<p style="margin: 0px;">Betreff: Re: [PSUBS-MAILIST] Thruster Reliability</p>
<p style="margin: 0px;">Datum: 2023-07-26T14:36:40+0200</p>
<p style="margin: 0px;">Von: "Cliff Redus via Personal_Submersibles" <personal_submersibles@psubs.org></p>
<p style="margin: 0px;">An: "River Dolfi via Personal_Submersibles" <personal_submersibles@psubs.org></p>
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<div dir="ltr" data-setdir="false">These reports look good. I am in the process of digesting them. Is this the Univolt transformer oil you use? Kinematic viscosity is low at 2.3 cSt. <a href="https://www.mobil.com/en-us/industrial/pds/gl-xx-univolt-n-61-b" rel="nofollow">https://www.mobil.com/en-us/industrial/pds/gl-xx-univolt-n-61-b</a></div>
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<div dir="ltr" data-setdir="false">Good point compatibly issues and need for testing. The good news on the MK 101's is there are only a few parts to evaluate, lips seals, brushes, wire insulation and for my case, a Subconn connector. The other parts are metal. I don't think the permanent magnet would be affected.</div>
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<div dir="ltr" data-setdir="false">Cliff</div>
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<div>On Tuesday, July 25, 2023 at 07:07:54 PM CDT, River Dolfi via Personal_Submersibles <personal_submersibles@psubs.org> wrote:</div>
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<div dir="ltr">Cliff,
<div>Those sound like signs of an incompatible fluid to me. Especially considering the length of time that the thrusters were filled with WD40 compared to the hours they have run in the field.</div>
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<div>The US Navy created a bunch of technical reports on various aspects of deep submergence systems design, and distributed them among defense companies and researchers as part of the "Deep Submergence Systems Project" in the 60's and 70's. All of the documents are now approved for public release and readily available online. This one is particularly interesting and relevant to this conversation. I consult it often enough that I have a physical hard-copy on my office shelf.</div>
<div>"<span style="color: #333333; font-family: Helvetica, Arial, sans-serif; font-size: 14px;">Handbook of Fluid-Filled, Depth/Pressure-Compensating Systems for Deep Ocean Applications"</span></div>
<div><a href="https://apps.dtic.mil/sti/citations/AD0894795" rel="nofollow">https://apps.dtic.mil/sti/citations/AD0894795</a></div>
<div>There is also:</div>
<div><span style="color: #333333; font-family: Helvetica, Arial, sans-serif; font-size: 14px;">Handbook of Fluids and Lubricants for Deep Ocean Applications</span></div>
<div><a href="https://apps.dtic.mil/sti/citations/AD0866350" rel="nofollow">https://apps.dtic.mil/sti/citations/AD0866350</a></div>
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<div>I suspect that the bushing wear is caused by the low viscosity of the WD40 making it a poor choice for lubrication. I've always been told WD40 is a penetrating oil, not a lubricating oil.</div>
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<div>I maintain and operate a small fleet of ROV's and AUV's that routinely work at a depth of 6000m. All of them use motors that are compensated with either univolt transformer oil where high voltages are involved, or a silicone oil. The caveat being that all of these are brushless electric motors, so don't have the complications of carbon fouling of the fluid.</div>
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<div>We have been evaluating fluids that can serve as both a hydraulic system oil and an electrical system compensation oil, as we currently run two separate oils for each function. The problems we are running into are material compatibility with existing components. Things like wiring, heat shrink, seals, adhesives, etc. We know what not to do with Silicone and Univis, but the only way to determine the compatibility of a particular oil with a particular off the shelf or proprietary component, like a Minn Kota or any other motor, is testing.</div>
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<div>Thanks,</div>
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<div dir="ltr">-River J. Dolfi
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<div>412-997-2526</div>
<div><a href="mailto:rdolfi7@gmail.com" rel="nofollow">rdolfi7@gmail.com</a></div>
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