[PSUBS-MAILIST] Penetrator materials

Wed May 17 17:28:10 EDT 2017

If you machine the hole through the penetrator as a conical cavity rather than cylindrical, and then use a potting epoxy with some compliance / flexibility, the pressure acting to push the potting compound into the hole will also develop some increased compressive force around the electrodes.

Sean

On May 17, 2017 1:55:51 PM MDT, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>Hank,
>If I cover everything with the glue & then the polyurethane, I won't
>need to rely on
>the epoxy for sealing. If the cable was cut then the system would rely
>on the epoxy
>as a back up. At that stage I could put up with a temporary dribble;
>the electrics would
>be shorting out as well. I will be wary of stripping back enough of the
>wiring sheath,
>but failure can also occur between the epoxy & wall of the penetrator.
>Cheers Alan
>
>
>Sent from my iPad
>
>> On 18/05/2017, at 12:02 AM, hank pronk via Personal_Submersibles
><personal_submersibles at psubs.org> wrote:
>> 
>> 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 & cable
>> with 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 the
>> marine environment!
>>    Have changed tack a bit as I thought I should be nailing down
>> exactly what cable I'm going to use so I know what material I am
>> gluing 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 have
>> the 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 original
>> suggestion of an adapter would have been a better way to go!
>> Alan 
>> 
>> 
>> Sent from my iPad
>> 
>>> 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
>adhesives
>>> I looked at are polyurethane based products.  Although the outer
>moulded
>>> section will be polyurethane, sometimes mouldable products lose a
>bit of their
>>> adhesion with their "bulking" additives.
>>> Keith Gordon gave me a link to a product he has used for splicing
>underwater
>>> cables. You squirt the glue in to heat shrink tubing that is around
>the cables, then
>>> heat the ends of the heat shrink tubing to close it. 
>>> I will do a bit more research on that today.
>>> Alan
>>> 
>>> 
>>> Sent from my iPad
>>> 
>>>> 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
>he
>>>> had several failures using just the epoxy, so I was going to coat
>the epoxy
>>>> with silicone to seal it better. On my Subconn connectors I noticed
>they
>>>> have 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 look
>>>> tidy. 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 am
>>>> using, so that one surface doesn't pull away from the other.
>>>> I might test the silicone against the polyurathane to see what
>adheres best
>>>> to my wiring & aluminium light housing, & go from there.
>>>> I will have at least 50 through hull fittings to do & am open to
>playing around
>>>> with a few variations to get it right.
>>>> Cheers Alan
>>>>  
>>>> 
>>>> Sent from my iPad
>>>> 
>>>>> 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
>the
>>>>> adhesion that's needed.
>>>>> This stuff is designed for encapsulating electronics in marine
>>>>> environments. I was going to use it over a thin layer of silicone
>but
>>>>> might not use the silicone now. 
>>>>> Alan
>>>>> 
>>>>> 
>>>>> Sent from my iPad
>>>>> 
>>>>>> 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/1891122
>>>>>> Will see how it goes!
>>>>>> Alan
>>>>>> 
>>>>>> Sent from my iPad
>>>>>> 
>>>>>>> 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 on
>>>>>> to 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 way
>>>>>> of 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 local
>>>>>> product ...
>>>>>> http://www.electrolube.co.nz/p roducts/encapsulation-resins-p
>olyurethane/ur5118/polyurethan e-potting-compound/
>>>>>> Cheers Alan
>>>>>>  
>>>>>> 
>>>>>> Sent from my iPad
>>>>>> 
>>>>>>> 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'm
>>>>>>> looking 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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