Interesting moisture effect

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avrcandies
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Posted by avrcandies: Tue. May 7, 2019 - 01:43 AM
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I was looking at connectors & came across this...shows an interesting way moisture can creep into your enclosure---even when you think it is all sealed up with top-dog waterproof grommets!

 

http://www.dsmt.com/products-and-services/moistureblock/

 

Wicking draws up liquid through the interior of the power cord, bypassing any exterior seals and bariers [sic].

 

 

DSM&T has created and developed MoistureBlock® Technology to stop water, oil and other fluids from migrating in either direction through a power cord, preventing damage to involved internal circuits.

This patented process adds additional protection from moisture by sealing the conductors at the micro level –down to the individual copper strands themselves! Ensuring your product is protected from the elements.

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

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Learning and Information, General Electronics
Last Edited: Tue. May 7, 2019 - 01:44 AM
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Kartman
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Posted by Kartman: Tue. May 7, 2019 - 01:50 AM
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Then there's migration through the sealing gasket.  This tends to be a problem where you have large variations in temperature from day to night. When the internal air cools, it sucks in the external moisture laden air. During the day it turns to vapour. 

Last Edited: Tue. May 7, 2019 - 01:52 AM
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ka7ehk
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Posted by ka7ehk: Tue. May 7, 2019 - 03:20 AM
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Also barometric pressure variations can result in a lower pressure inside compared to outside. This will tend to pull air in, and that usually means moisture.

 

There are MANY routes for moisture into "sealed" enclosures. That is one reason for adding packets of desiccant gel in spaces that must stay dry.

 

Atmospheric environment is almost harder than underwater. There, you have water pressure pressing on seals in a way that makes them seal better. There it tends to be either good or catastrophically bad.

 

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

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Kartman
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Posted by Kartman: Tue. May 7, 2019 - 06:30 AM (Reply to #3)
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Mos def. i’m surprised i never got pulled up in airports with the amount of silica gel i carried!

On a slightly similar note, there’s a specific type of cable used in north america that is rubbery and stinky. The rubber has been vulcanised with a sulphur based compound. Ok you say, but what happens is the cable outgasses and along with atmospheric moisture forns sulphuric acid. This attacks anything metallic in an enclosed or semi enclosed area. Smd leds are prone as well as pcbs and straingauges. It takes 6 months or so to see the effects.

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ki0bk
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Posted by ki0bk: Tue. May 7, 2019 - 01:13 PM
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I always use this stuff in/around my connectors to fill gaps to keep moisture out! smiley

Jim

 

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avrcandies
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Posted by avrcandies: Tue. May 7, 2019 - 04:34 PM
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 but what happens is the cable outgasses and along with atmospheric moisture forns sulphuric acid. This attacks anything metallic 

Interesting...years ago we had a $4000 (roughly) unit with a high end plastic (glass-filled something) handle that screwed into the unit (like 3/4 inch, very beefy).

However, more than a few customers complained --they'd be carrying their almost brand new unit & the handle would snap at the threads & the $4000 unit crash to the ground...not happy!

Finite Element Analysis showed the handle was strong enough the hold 10 elephants...so made no sense.  The big-wigs ordered an all-hands immediate investigation.  

After a while, it was noted the ones breaking were warehoused in brand NEW transit cases (industrial locking style with custom foam insert shaped to the unit).   

Mysteriously, cases using inserts that had sat in the warehouse for a year seemed to cause no issue. 

Turned out, the outgassing from fresh foam inserts caused some sort of degradation to the handle plastic.  

 

 

 

When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

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