metal cable gland potting

**jmurba** · 22nd September 2006, 09:58

Hi all,

has anyone successfully potted a cable gland to prevent gas to go throught the cable from the loop to the oxygauge case without using a lumberg or a fisher or whatever connector?

I am thinking of doing it that way :

1/ removing the plastic jackets of the small wires in the cable

2/ getting the cable in the gland and tightenning it gently

3/ injecting epoxy resin with a hypodermic needle deep in the cable as long as the resin gets out of the cable in the gland

4/ pourring epoxy resin in the cable gland to drawn the small cable and expecialy their part with removed plastic jacket ?

5/ letting the resin hardenning

6/ tightenning completely the cable gland....

What kind of resin should I use ?
should I use rigid or sligth flexible resin ?

I think that in the lumberg cable and connectors they use flexible resin...not sure.

regards

thanks in advance for our help

jean mi

**Dave Sutton** · 22nd September 2006, 14:20

Don't make it more complex than needed. Just stick the wire thru the gland, tighten it normally, and then pot it. Just place the gland in a vise so that the exposed wire side is up and pour a little two-part potting compound into the gland. Let it harden and go diving. Potting compound is a a VERY thin epoxy, ike water, and it can be bought to harden "hard" or "soft" (flexable). I use the soft stuff. I bought a 1 litre can of it with the hardener yearts ago at an electronics place for about $30 and have most of it left. It is thin enough to run right down thru the wire for a reasonable distance, so after the pour "top it up" with more compound as it runs into the wires.

Dave

Dave

Genesis · 22nd September 2006, 22:03

Yep - any decent epoxy will work as well. It will wick up quite a ways, and water isn't going anywhere through that stuff.....

rdmmdr · 22nd September 2006, 22:22

in the refineries we use a product callled chico for sealing conduits against explosive gases it is good for 150 psi as i remeber and can be had at any good electrical wholesaler
rick

bgpartri · 23rd September 2006, 01:57

Just make sure you don't get a quick-dry epoxy. You want something that takes about 24 hours to dry. Usually, the drying time is inversely proportional to the shrinkage. To get a good seal, you want it to dry slowly and not shrink.

Although it doesn't apply in your case, you also want slow drying epoxy for potting electronics. Quick dry can actually shrink enough to pull surface mount components off the board. They can also be very exothermic.

Bruce

rdmmdr · 23rd September 2006, 03:08

good point the slow drying urathans for casting are good for this.
rick

**jmurba** · 26th September 2006, 20:58

hello,

Don't make it more complex than needed.

++++++I did not felt like to.

Just stick the wire thru the gland, tighten it normally, and then pot it. Just place the gland in a vise so that the exposed wire side is up and pour a little two-part potting compound into the gland.

++++++will the cable drink the epoxy ? without having to inject it ?

Let it harden and go diving. Potting compound is a a VERY thin epoxy, ike water, and it can be bought to harden "hard" or "soft" (flexable). I use the soft stuff. I bought a 1 litre can of it with the hardener yearts ago at an electronics place for about $30 and have most of it left. It is thin enough to run right down thru the wire for a reasonable distance, so after the pour "top it up" with more compound as it runs into the wires.

+++ do you performe a test to be sure the gas does not pass through the cable ? or do you simply assume that this potting methode is 100% sure ?

regards

jean mi

Dave

Dave[/quote]

**Dave Sutton** · 27th September 2006, 00:22

The cable will take the potting compound by "wicking" like a candle, exactly like you use the word "drinking". Yes, it will do this reliably if you use the correct potting compound.

I do not test them, as (1): I already use cable that has a solid core and (2) they don't 'seem' to leak, and my guess is that if the *do* leak the rate is so slow as to make it unimportant. It's important to use a cable that is manufactured with the individual wires embedded in a material of some sort, not loose in the outer sheath. This way you are just sealing the end, not trying to make a plug on the end of a cable that is essentially a hollow tube with some wires threaded thru it. Those types are impossible to seal.

Dave Sutton

22nd September 2006, 09:58	#1 (permalink)
jmurba wet bear Current Rebreather/s: Home Build Other Rebreather/s: Home Build Join Date: May 2006 Location: cannes france Posts: 920	metal cable gland potting Hi all, has anyone successfully potted a cable gland to prevent gas to go throught the cable from the loop to the oxygauge case without using a lumberg or a fisher or whatever connector? I am thinking of doing it that way : 1/ removing the plastic jackets of the small wires in the cable 2/ getting the cable in the gland and tightenning it gently 3/ injecting epoxy resin with a hypodermic needle deep in the cable as long as the resin gets out of the cable in the gland 4/ pourring epoxy resin in the cable gland to drawn the small cable and expecialy their part with removed plastic jacket ? 5/ letting the resin hardenning 6/ tightenning completely the cable gland.... What kind of resin should I use ? should I use rigid or sligth flexible resin ? I think that in the lumberg cable and connectors they use flexible resin...not sure. regards thanks in advance for our help jean mi
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22nd September 2006, 14:20	#2 (permalink)
Dave Sutton Diveshop of Horrors Current Rebreather/s: Sport Kiss MK 15.X rEvo Other CCR Azimuth Home Build Other Rebreather/s: Evolution Megalodon rEvo Other CCR Azimuth Home Build Join Date: Jun 2006 Location: Narragansett, Rhode Island and Hackettstown, New Jersey Posts: 2,907	Re: metal cable gland potting Don't make it more complex than needed. Just stick the wire thru the gland, tighten it normally, and then pot it. Just place the gland in a vise so that the exposed wire side is up and pour a little two-part potting compound into the gland. Let it harden and go diving. Potting compound is a a VERY thin epoxy, ike water, and it can be bought to harden "hard" or "soft" (flexable). I use the soft stuff. I bought a 1 litre can of it with the hardener yearts ago at an electronics place for about $30 and have most of it left. It is thin enough to run right down thru the wire for a reasonable distance, so after the pour "top it up" with more compound as it runs into the wires. Dave Dave __________________ "Silent Diving with No Bubbles and No Politics".... www.nobubblediving.com
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22nd September 2006, 22:03	#3 (permalink)
Genesis Bubbless Box of Death Current Rebreather/s: Home Build Other Rebreather/s: Home Build Join Date: Oct 2005 Location: Sunny Florida Posts: 1,453	Re: metal cable gland potting Yep - any decent epoxy will work as well. It will wick up quite a ways, and water isn't going anywhere through that stuff..... __________________ "A venturesome minority will always be eager to get off on their own, and no obstacles should be placed in their path; let them take risks for Godsake, let them get lost, sunburnt, stranded, drowned, eaten by bears, buried alive under avalanches - that is the right and privilege of any free American." http://www.denninger.net http://www.diversunion.org/liability.htm - Fix the Diving Cert racket
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22nd September 2006, 22:22	#4 (permalink)
rdmmdr designer of death Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Mar 2006 Location: kerman,california Posts: 372	Re: metal cable gland potting in the refineries we use a product callled chico for sealing conduits against explosive gases it is good for 150 psi as i remeber and can be had at any good electrical wholesaler rick
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23rd September 2006, 01:57	#5 (permalink)
bgpartri CEO-Shearwater Current Rebreather/s: Megalodon Other Rebreather/s: Inspiration Classic Sport Kiss Classic Kiss Titan Join Date: Apr 2005 Location: Vancouver, Canada Posts: 423	Re: metal cable gland potting Just make sure you don't get a quick-dry epoxy. You want something that takes about 24 hours to dry. Usually, the drying time is inversely proportional to the shrinkage. To get a good seal, you want it to dry slowly and not shrink. Although it doesn't apply in your case, you also want slow drying epoxy for potting electronics. Quick dry can actually shrink enough to pull surface mount components off the board. They can also be very exothermic. Bruce __________________ http://www.shearwaterresearch.com Good judgment comes from experience. Experience comes from bad judgment. Last edited by bgpartri : 23rd September 2006 at 02:00.
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23rd September 2006, 03:08	#6 (permalink)
rdmmdr designer of death Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Mar 2006 Location: kerman,california Posts: 372	Re: metal cable gland potting good point the slow drying urathans for casting are good for this. rick
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26th September 2006, 20:58	#7 (permalink)
jmurba wet bear Current Rebreather/s: Home Build Other Rebreather/s: Home Build Join Date: May 2006 Location: cannes france Posts: 920	Re: metal cable gland potting hello, Don't make it more complex than needed. ++++++I did not felt like to. Just stick the wire thru the gland, tighten it normally, and then pot it. Just place the gland in a vise so that the exposed wire side is up and pour a little two-part potting compound into the gland. ++++++will the cable drink the epoxy ? without having to inject it ? Let it harden and go diving. Potting compound is a a VERY thin epoxy, ike water, and it can be bought to harden "hard" or "soft" (flexable). I use the soft stuff. I bought a 1 litre can of it with the hardener yearts ago at an electronics place for about $30 and have most of it left. It is thin enough to run right down thru the wire for a reasonable distance, so after the pour "top it up" with more compound as it runs into the wires. +++ do you performe a test to be sure the gas does not pass through the cable ? or do you simply assume that this potting methode is 100% sure ? regards jean mi Dave Dave[/quote]
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27th September 2006, 00:22	#8 (permalink)
Dave Sutton Diveshop of Horrors Current Rebreather/s: Sport Kiss MK 15.X rEvo Other CCR Azimuth Home Build Other Rebreather/s: Evolution Megalodon rEvo Other CCR Azimuth Home Build Join Date: Jun 2006 Location: Narragansett, Rhode Island and Hackettstown, New Jersey Posts: 2,907	Re: metal cable gland potting The cable will take the potting compound by "wicking" like a candle, exactly like you use the word "drinking". Yes, it will do this reliably if you use the correct potting compound. I do not test them, as (1): I already use cable that has a solid core and (2) they don't 'seem' to leak, and my guess is that if the do leak the rate is so slow as to make it unimportant. It's important to use a cable that is manufactured with the individual wires embedded in a material of some sort, not loose in the outer sheath. This way you are just sealing the end, not trying to make a plug on the end of a cable that is essentially a hollow tube with some wires threaded thru it. Those types are impossible to seal. Dave Sutton __________________ "Silent Diving with No Bubbles and No Politics".... www.nobubblediving.com Last edited by Dave Sutton : 27th September 2006 at 00:31.
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