[PSUBS-MAILIST] Penetrator materials

Wed May 17 08:02:52 EDT 2017

Alan,That is not correct, the epoxy will not stop the water past 1,000 psi completely.    If the wires are stripped back further so the sealant creates an extra layer against the conductor, that will certainly help.  I tested my penetrators by screwing them into a pipe and applying air pressure inside the pipe and the  low pressure side in water.  There were super tiny bubbles coming out of the wire ends past 1,000 psi.  That means the air got past the epoxy and escaped between the conductor and the jacket.    Hank 

    On Tuesday, May 16, 2017 8:03 PM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

 Alan,If the other end of the cable is not perfectly sealed the water will migrate making the silicone useless.  Hank 

    On Tuesday, May 16, 2017 7:01 PM, Alan James via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

 Hank,Juries not out on how I want to do that.I don't think I'll have the glue on the conductor, I will just embed the conductor & insulation& a portion of the cable sheath in the epoxy & then go over the aluminum fitting & cablewith the glue & then encapsulate it all in polyurethane potting mix.Alan

      From: hank pronk via Personal_Submersibles <personal_submersibles at psubs.org>
 To: Personal Submersibles General Discussion <personal_submersibles at psubs.org> 
 Sent: Wednesday, May 17, 2017 12:37 PM
 Subject: Re: [PSUBS-MAILIST] Penetrator materials

Alan,Your idea to use a silicone or similar to back up the epoxy is a good idea.  My epoxy multi wire connector will let teeny tiny air bubbles through when I exceed 1,000 psi.  You will have to strip the wire back far enough for the silicone to stick to the conductor.Hank 

    On Tuesday, May 16, 2017 6:18 PM, Stephen Fordyce via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

 Hi Alan,I'd be interested to see what you come up with on cable.  My research indicated a polyurethane outer sheath was the way to go (and it's held up extremely well to the punishment my caving lights have seen) but that's also really expensive and hard to get.  I previously used PVC and it held up well enough, slightly different application though.
The China stuff - yep there's a lot of good stuff, but also a lot of bad stuff.  Your experience is pretty bad though, usually they are a lot better than that.
Cheers,Steve
On Wed, May 17, 2017 at 10:03 AM, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Thanks Steve,I found some in a local sports shop. I'll see how it likes themarine environment!   Have changed tack a bit as I thought I should be nailing downexactly what cable I'm going to use so I know what material I amgluing to. G.L. wants self extinguishing sheathing / insulation& halogen free. Also can't be hydroscopic.    Got my pressure sensors back from China (again) they now havethe right fitting but still a sloppy fit. They sent them out with an over-sized o-ring that wouldn't fit, even though I supplied them a first stage regulator for testing. I am thinking that your originalsuggestion of an adapter would have been a better way to go!Alan 

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On 17/05/2017, at 10:54 AM, Stephen Fordyce via Personal_Submersibles <personal_submersibles at psubs. org> wrote:

Hi Alan,Try searching for Shoe Goo - I gather it's the same stuff. I've got some off ebay in Australia and used with good success on wetsuit gloves for caving. Liquid Electrical Engineering Tape is also good if you brush it on in thin layers.
Cheers,Steve
On 17 May 2017 6:50 am, "Alan via Personal_Submersibles" <personal_submersibles at psubs. org> wrote:

Hank,thanks, I feel I am getting somewhere.I can't find Goop in N.Z. but have been looking at other marine products.You are right about the silicone not being ideal. 90 % of the marine adhesivesI looked at are polyurethane based products.  Although the outer mouldedsection will be polyurethane, sometimes mouldable products lose a bit of theiradhesion with their "bulking" additives.Keith Gordon gave me a link to a product he has used for splicing underwatercables. You squirt the glue in to heat shrink tubing that is around the cables, thenheat the ends of the heat shrink tubing to close it. I will do a bit more research on that today.Alan

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On 17/05/2017, at 12:11 AM, hank pronk via Personal_Submersibles ed <personal_submersibles at psubs.o rg> wrote:

Alan,Got it, there is a way better option than silicone for that.  The product is call Goop or shoe goo.  This stuff is amazing, it sticks much better than silicone and is super tough.  I patch my waders with it, and you can not peel it off, no way no how.Hank 

    On Tuesday, May 16, 2017 4:25 AM, Alan via Personal_Submersibles <personal_submersibles at psubs.o rg> wrote:

 Hank,I see you can't sleep again!Thanks for the offer on the windshield polyurethane. My thought process went like this.... I had seen Doug's video where hehad several failures using just the epoxy, so I was going to coat the epoxywith silicone to seal it better. On my Subconn connectors I noticed theyhave a thin layer of rubber vulcanised for about an inch up the wire casing;I wanted to mimic this but with silicone. Then the polyurethane outer was,as I have said, a cable support, protection for the silicone & to make it looktidy. It didn't necessarily have to adhere to the silicone. I need a material that will compress at a similar rate as the cable I amusing, so that one surface doesn't pull away from the other.I might test the silicone against the polyurathane to see what adheres bestto my wiring & aluminium light housing, & go from there.I will have at least 50 through hull fittings to do & am open to playing aroundwith a few variations to get it right.Cheers Alan 

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On 16/05/2017, at 9:38 PM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.o rg> wrote:

Alan,There is really no need for the silicone layer, in fact it might cause you grief trying to get another material to stick to it.  If you need some testing done on the windshield stuff, let me know, I have some left over.Hank 

    On Monday, May 15, 2017 7:10 PM, Alan via Personal_Submersibles <personal_submersibles at psubs.o rg> wrote:

 Thanks, I will have a look at that it sounds like it would have theadhesion that's needed.This stuff is designed for encapsulating electronics in marineenvironments. I was going to use it over a thin layer of silicone butmight not use the silicone now. Alan

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On 16/05/2017, at 12:06 PM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.o rg> wrote:

Alan,I have good luck with windshield adhesive (poly urethane)  I used it as a liquid rubber.  It is super tough and cheap.Hank 

    On Monday, May 15, 2017 5:40 PM, Alan via Personal_Submersibles <personal_submersibles at psubs.o rg> wrote:

 Ended up ordering this encapsulating 2 part flexible polyurethane,  that is suitable for a marine environment.http://nz.element14.com/robnor /el110h-bk-250/encapsulant-2k- flex-pu-gp-marine/dp/1891122Will see how it goes!Alan

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On 16/05/2017, at 3:43 AM, Alan via Personal_Submersibles <personal_submersibles at psubs.o rg> wrote:

Thanks Hank,I need the two wires to angle off to the sides as they are soldered onto the corners of the LED.Yes I could thread the outside of the nozzle & put on a blue globe cable gland,I have some. Even though Carsten & Emile are advocates of the Blue globe,they do fit two on each penetration; one on the outside, one on the inside &I can't do that with the light fitting.   I have come across a few likely candidates for the outer covering in the wayof a mouldable polyurethane for marine applications......https://www.aeromarineproducts .com/product/urethane-75a-enca psulating-compound/This is an American product I can't locate here in N.Z.. Have found a localproduct ...http://www.electrolube.co.nz/p roducts/encapsulation-resins-p olyurethane/ur5118/polyurethan e-potting-compound/Cheers Alan 

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On 15/05/2017, at 11:59 PM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.o rg> wrote:

Alan,In an effort to keep it easy and clean looking, I would extend the penetrator body at the wet side to allow for  threading on a compression fitting.   Slide your cable into that and snug the nut and it is done and clean looking.   Also from my experience, I would not angle the wires, I would make it strait through and strip as much of the jacket as possible.  I am sure your drawing is not representing the actual amount to be stripped, but it should be more significant.  Keeping it strait will make it a lot easier, I have done over 20 wires in one penetrator with a strait threaded bore.  Hank 

    On Sunday, May 14, 2017 9:40 PM, Alan James via Personal_Submersibles <personal_submersibles at psubs.o rg> wrote:

  Hi,I have a number of penetrators to do on my lights & other items, & I'mlooking for the best materials for them.My design is as below. It is the base of my light housing.I have stripped a small section of wire that runs through the epoxy. I am not sure of the best material on the next 2 layers.I am looking at this marine silicone, to seal about an inch up the wiring jacket.http://www.selleys.co.nz/car-c are/sealants/marine/Am thinking I will apply this silicone with a brush & then tidy things up & both protect the silicone & support the cable with a molded rubberized outer layer.I am not sure of a suitable moldable material for a marine environment.Am guessing I will need about the same hardness as a standard o-ring.Any suggestions on the material or comments on the design thanks.Alan
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