Looking after wet electronics^

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Jon Wood
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Looking after wet electronics^

Post by Jon Wood » Sat Apr 01, 2006 11:47 am

I have just purchased a hand-held Icom VHF.
It is JIS grade 7 (1m/30 min) watreproof rated.
The manual simply recommends washing in fresh water and making sure the antenna is securely fixed
From past threads I see that storing it in an Aquapac may cause as many problems as it prevents.

Is there any merit in using silicone grease on the contacts to prevent corrosion, or any other precaution that should be taken beyond giving a good rinse at the end of the day? The same advice also required for the new WP type cameras etc.

(I have attached a decent lanyard)

gizmo
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Post by gizmo » Sat Apr 01, 2006 1:48 pm

Hi Jon - I bought an Icom Vhf about a month ago and as recommended I've washed it in clean water after use and everything seems fine. I wonder whether doing anything else might not void the warranty??
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Canuck
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Post by Canuck » Sat Apr 01, 2006 8:51 pm

Silicone on the battery contacts sounds like a great idea. I try and keep a pencil w/eraser handy for polishing the corrosion off, and a little grease will likely go a long way as an ounce of prevention.

Thanks for the tip.

John W
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Post by John W » Sat Apr 01, 2006 9:07 pm

Both my GPS and VHF spend their lives afloat in Aquapacs and are both still like new after many years use. The Aquapac also helps them float much better and stops them getting scratched; however it does make the VHF a little bulky for BA pockets. Condensation on a sunny day can make the GPS a little difficult to read sometimes but it is not a big problem.

I have seen a number of VHF rotary channel/volume controls corrode to point of unserviceability over time, where they have been used without any protection.

I know there is a school of thought that trapped water vapour in the Aquapac could work its way past the seals but I'm not convinced by this. I can't see that vapour at atmospheric pressure can get past a seal that is designed for 30min at 1 metre, but I may be wrong...

JW

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ChrisS
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Silica gel - do not eat

Post by ChrisS » Sat Apr 01, 2006 9:40 pm

I keep a small sachet of silca gel sachet in my aquapac to remove water vapour. It needs to be dried out occasionally, something I haven't yet bothered to do. When I do get round to it I'll just give it couple of minutes in the microwave.

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Pelagic
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Post by Pelagic » Sat Apr 01, 2006 9:41 pm

I know there is a school of thought that trapped water vapour in the Aquapac could work its way past the seals but I'm not convinced by this. I can't see that vapour at atmospheric pressure can get past a seal that is designed for 30min at 1 metre, but I may be wrong...
Neither am I John, and a little sachet of silica gel inside the Aqapac solves the fogging problem.
It cost quite a lot in dead electronics before we stopped believing manufacturers claims to be waterproof. I have used Aquapacs for years now with no problems with dead or corroded electronics, of course eventually the Aquapac fails, normally round the lanyard eyelets or the clamp seam. cheaper to replace than a VHF or GPS anyway.
As a final thought, silicone grease should also be smeared thinly over any "o" ring or gasket seals as well as the contacts themselves, make sure its the fine stuff and dont do it on the beach! A very thin film is sufficient.

Phil

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Post by John W » Sat Apr 01, 2006 10:22 pm

Phil

I have had 2 Aquapacs fail now, just wear and tear really. But both times I have contacted their customer services and had replacements provided without any hassle. How customer service should be.

Dave Thomas
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Post by Dave Thomas » Sat Apr 01, 2006 10:33 pm

what is a good source of suitable silicone grease?

Dave Thomas

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Robert Craig
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Post by Robert Craig » Sat Apr 01, 2006 10:47 pm

Maplin.
Though can't find my catalogue to check.

Steve B
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Post by Steve B » Sat Apr 01, 2006 11:16 pm

http://www.maplin.co.uk/Search.aspx?cri ... &source=15

or RS Components - http://rswww.com - and search for silicone grease (poorly designed web site doesn't provide a direct link).
Steve Balcombe

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Post by Canuck » Sun Apr 02, 2006 5:11 am

Dow Corning makes an excellent product they call R4 electric insulating compound for use on automotive wiring. Check your auto/marine electric stockist's for silicone dilectric

Dow also makes a silicone grease valve sealant #111 which would likely be ideal for the gasket/o ring application mentioned by Pelagic.

I've had two Garmin e-trex failures in as many years. I'm guessing the water made it's way past the gasket on account of the pressure differential when the gps slid off the hot black spray deck into the cold water. The latest replacement has a small hole in the back of the body. I'm presuming there is some kind of bladder behind it to offset any sudden change in pressure.

Dave Thomas
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Post by Dave Thomas » Sun Apr 02, 2006 9:02 am

Thanks for those suggested sources!

Dave Thomas

Chris Bolton
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Silicone grease is an insulator?

Post by Chris Bolton » Sun Apr 02, 2006 9:34 am

Looking at those links, silicone grease is described as an insulator. Putting it on contacts would stop them corroding, but wouldn't it introduce a resistance?

Maybe a thin film is OK as the resistance will be small? Any electrical experts who can clarify the position?

Chris

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Pelagic
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Post by Pelagic » Sun Apr 02, 2006 12:45 pm

Putting it on contacts would stop them corroding, but wouldn't it introduce a resistance?
Im no expert Chris, however.The actual contact surfaces should be clean and bright. It obviously depends on the individual design of gizmo. I personally dont grease battery contacts in GPS or VHFs apart from one radio which uses rechargable AAs. I do however liberally grease the brass contacts in my Petzl Duo then carefully clean the actual (raised) contact area it stops that green verdigris look. Geoff and I are both pretty liberal with the stuff on so-called waterproof switches as well (we use electric pumps) It certainly seems to help with that "atmospheric corrosion" that most things in a sea-environment are prone to.

The crucial thing is that gaskets and "o" rings need to be greased, it is normal to get a small sachet with cameras, headtorches, waterproof housings etc, but strangely not with GPS or radios. However the principle is well documented.

Damn useful stuff silicone grease!
Try a thin film around the rim of a weepy hatch. Dead good. Also flare tubes and the threads on gas canisters............possibilities are endless.
Nearly as useful as self-amalgamating rubber tape!

Phil

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MikeB
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Post by MikeB » Sun Apr 02, 2006 1:34 pm

Should it also be used on the seals on a camera? (33WR for instance??)

Mike.

David P
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Post by David P » Sun Apr 02, 2006 1:38 pm

I don't see any reason why not ... The golden rule has always been the merest film of grease - typically applied between fingertips (hence you can feel any imperfections, grit, hairs etc on an o-ring).

The only problem is knowing which type of grease to use! See eg the "Cameras Underwater" website. In practice, the only product I've used that needs "funny grease" are the Olympus camera housings - all the other housings/o-rings etc I've come across are black rubber ones where silicone grease should be just fine.

Good luck!
David P

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Pelagic
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Post by Pelagic » Sun Apr 02, 2006 2:20 pm

Hi Mike,
cant add anything to Daves reply, except to say the Pentax is water resistant, this is manufacturers double-speak for "not waterproof" so no guaruntees!

I remember a friend of mine telling me that greased "o" ring seals, as well as helping to prevent "vapour transmission", whatever that is, also help to prevent the rubber seal puckering as its being closed. Makes sense really, its more slippy. I remember he explained it as being "relaxed in its seating" such a nice turn of phrase! The main cause of leaks apparently after sand and grit etc.

Phil

Steve B
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Re: Silicone grease is an insulator?

Post by Steve B » Sun Apr 02, 2006 3:00 pm

Chris Bolton wrote:Looking at those links, silicone grease is described as an insulator. Putting it on contacts would stop them corroding, but wouldn't it introduce a resistance?
No, the amount of grease which actually remains between two contacts when they are closed is too tiny to be of consequence. A thin film of corrosion, on the other hand, forms an insulating layer which is bonded to the metal.
Steve Balcombe

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Robert Craig
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Post by Robert Craig » Sun Apr 02, 2006 9:53 pm

The wee breathing hole on the back of a eTrex doesn't have a bladder behind it. There's a small disc of Goretex, which keeps the water out but lets air in and out. Clever!

Chris Bolton
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Silicone grease

Post by Chris Bolton » Sun Apr 02, 2006 10:24 pm

Thanks to those who clarified the purpose of the grease for me; I shall make a point of getting some. My fairly ancient Garmin GPS leaked through the battery compartment while in a (non-waterproof) deck bag in Greece. I suspect thermal effects, but grease would probably have helped. (I stole its Aquapac for my mobile phone....)

Chris

andreadawn
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Post by andreadawn » Sun Apr 02, 2006 10:45 pm

MikeB wrote:Should it also be used on the seals on a camera? (33WR for instance??)
Nikon used to supply a tube of silicone lubricant for the seals on the Nikonos and my new Canon underwater housing was also supplied with some for the seals.

Andrea.

David P
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Post by David P » Sun Apr 02, 2006 11:47 pm

Hence, Andrea, my point about the right grease fot the job. Yes, I've got the Nikon grease too (came with my Nik III) - but be careful about assuming you can use the Canon grease on the Nikonos or vice versa... They may be using quite different o-ring materials. But I'm sure you know that :-)
David P

Graham T
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Re: Looking after wet electronics^

Post by Graham T » Mon May 21, 2012 3:28 pm

Does any one know if something like the lubricant for a Tizip dry suit zip is good for such lubrication?

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immunogirl
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Re: Looking after wet electronics^

Post by immunogirl » Tue May 22, 2012 11:35 pm

I've been using dow corning vacuum grease on my electronics (including camera doors) for years:
http://www.amazon.com/CONQUEST-INC-Vacu ... B003NV2LPK

My pentax optio w60 is 4 years old now and is still waterproof. I just leave it clipped on to my pfd. It never gets rinsed.

Vacuum grease is used in labs for experiments where you need airtight seals in apparatus and it has to be inert so as to not influence the experiments.

No idea whether it's necessarily better than any other silicone grease.

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JohnA
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Re: Looking after wet electronics^

Post by JohnA » Fri Jun 15, 2012 6:47 am

immunogirl wrote:I've been using dow corning vacuum grease on my electronics (including camera doors) for years:
http://www.amazon.com/CONQUEST-INC-Vacu ... B003NV2LPK

My pentax optio w60 is 4 years old now and is still waterproof. I just leave it clipped on to my pfd. It never gets rinsed.

Vacuum grease is used in labs for experiments where you need airtight seals in apparatus and it has to be inert so as to not influence the experiments.

No idea whether it's necessarily better than any other silicone grease.
They use higher molecular weight or chemically modified hydrocarbon groups attached to the silicon atoms. The idea is just to reduce the volatility. At low pressures (under vacuum) boilling points are reduced and you don't really want your grease to evaporate/boil off, adding vapour to a space you're trying to pump all the gas out of and of course once the grease is gone, the joints will leak. It's usually used on ground glass joints in glassware.

With respect to lubricating O-rings, the grease should be chemically compatible with the elastomer. Some hydrocarbon's will actually soften and swell the o-ring material which can then result in the shape being permanently distorted after being loaded. Either in cross-section or longitudinally. i.e. it can stretch making the o-ring difficult to put back into it's housing. So as mentioned above, some lubrication can be good but it's worth making sure that it's the right grease for the material.

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