Monday, February 10, 2014

Re: [Electric Boats] Encapsulating Electronic Components

 

To be honest, I have not been following this thread very closely.
Has anyone mentioned paraffin (wax) coating?
I know some underwater ROV and camera people use it to encapsulate and keep water out at depth.
Might be something to google.
 
mattelderca


On Sunday, February 9, 2014 7:22:33 PM, Peter Verralls <pverralls@verralls.net> wrote:
 
Nice one Arby,
http://www.gore.com/en_xx/products/venting/protective/index.html
Makes perfect sense.
Also beware of those encapsulants/sealants that smell like vinegar.  That is acid and the fumes will start to corrode anything within the enclosure.
Peter


On 8 February 2014 22:23, Roger L <rogerlov@ix.netcom.com> wrote:
 

I agree on the silicone sealer. There are two different silicone chemistries that are commonly sold. The first one is the common one at hardware stores and is distinguished by a strong fruity & acidic odor - it's far less expensive and is the one that's easiest to find. 
This first type will corrode electronic connections, so if you use it be sure to protect all connections and any vents as the silicone cures.
 
The other chemistry is a water curing silastic, more durable, more temperature resistant, and more sticky too. It is waterproof - though how it is used is what determines if the application will be waterproof. It is good for doing potting of electronics. This is the good stuff and it's easy to spot because it has absolutely no odor at all. This is the one you want if you can find it. My own favorite silicone is this second type: Dow Corning's 3145 (grey) RTV. It's probably the favorite throughout the instrument industry. The 3145 caps well; a tube lasts years. Sometimes you can find it at McMaster.
 Roger L.
  
 
 
----- Original Message -----
From: Bob Noble
Sent: Saturday, February 08, 2014 12:08 PM
Subject: Re: [Electric Boats] Encapsulating Electronic Components

I haven't tried to waterproof anything, but have some experience working for the old HP in a Reliability Physics lab, where I did a lot of work seeing how water entered things in very tiny parts.
 
Most silicones are not conductive so it could help make it resistive to water.
 
The real problem with trying to make something water proof is this little catch.
 
If there are any air pockets at all, even little ones, this is what happens.
Let's say the air in those air pockets is at ambient temperature. When the part hits the water, it's much colder, which causes the air in the air pockets to cool down fast, which causes a suction. Since the part is in the water, it causes water to get sucked into the parts. It's very hard to stop this action, the greater the temp difference, the greater the suction.
 
When people try to waterproof a box, they try to seal it, but, there is a big air space in there and the seal usually won't hold for any length of time when submerged in cold water.
There is also a problem with condensation in a sealed box. If any water at all gets into it, it can't get out and will eventually fail because there is no place for the water to get out of the box.
 
It's actually easier to make something water resistant, than it is to waterproof something.
I think the silicone would make your part at lease water resistant with a good job of applying the silicone, if there are no moving parts on the part, which I don't see?
Since the part is only sixty bucks, it's worth a try and I think the part would last longer this way, than not doing it.
 
 
Sent: Friday, February 07, 2014 3:32 PM
Subject: [Electric Boats] Encapsulating Electronic Components
 


I am thinking of getting a "Watts Up" meter to use on my solar canoe project. I can't seem to find a waterproof meter? So I am wondering if its possible for me to encapsulate the Watts up meter in lets say Sylgard 184 Silicone Elastomer ? I have access to it for free from a friends solar panel build.

Does anyone have any experience to share on waterproofing circuit boards etc. ???

Watts Up meter:

http://www.amazon.com/Watts-Meter-An...watts+up+meter



--
Kind regards 
Peter Verralls  PO Box 71, Caribbean Villas, San Pedro, Ambergris Caye, Belize.  International Cell Phone:  +501 610 3155  Guatemala Cell Phone:     +502 490 46237   Satellite Phone:                 +8816 316 53280  E Mail:                               pverralls@verralls.bz  Satellite E Mail:                 881631653280@msg.iridium.com (160 characters max).  or use free messaging at  http://messaging.iridium.com/, to 881631653280 (no spaces).


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