Electronics tube Condensation example


#1

Hi,

After leaving the ROV sealed up and running at my desktop for a couple of hours I was amazed about how much condensation had formed. I do live in a very humid climate (Hilo, Hawaii 105cm of rain so far this year) so I'm not surprised.

I couldn't find any individual silica packs at my local hardware store so I ended up making my own using some refill of bulk moisture absorbent and coffee filters. The coffee filters are good to use because they don't break down when they get wet.

After making a little absorber packet and putting it in the ROV I have not seen condensation forming again. Even if you don't live in a super humid environment I'd still recommend putting in some sort of moisture absorbent just to be on the safe side.




#2

Hi Marcus,

Good idea. I had the same problem. I was putting electronics tube together in my basement with 70% RH. I needed a new dehumidifirer (old one iced up all the time so I bought a new one). Now the RH is 45% and the electronics tube shows no condensation. If the water temp is cold it may require a lower RH, I can achieve that by mounting a box in front of the dehumidifirer's output to capture low RH air and place the open electronics tube in the box for a 1/2 hour or so. Then put the end caps on the tube to capture the low RH air.

Frank


#3

Hi Marcus,

please excuse my revival of an old(ish) thread here. My kit hasn't arrived yet, but that doesn't stop my mind from wandering - and condensation is a topic I've been considering. Especially when a unit assembled, in a more or less humid climate, is flown into the sea at some depth, I'm guessing the drop in temperature might cause condensation issues.

I'm glad to hear the absorbent solution worked out for you. A different solution would be to purge the electronics tube with nitrogen. Nitrogen does not carry moisture the way air does, so if you replace the air with nitrogen then there should be no moisture that can condense either.

In a previous job I worked with oceanograhic measurement systems (mostly buoy mounted), and this was the go-to solution for electronics enclosures - or even large instrument containers. This purging does of course require some inlet for nitrogen and some outlet for air, that will open when they should and close when they should. We used spring loaded one way pneumatic fittings. This equipment was not submerged though; but I guess this is just a question of pressure ratings of the fittings used. Where the fittings would be exposed to surf and spray they were covered by a lid - I guess this lid could also be sealed relatively easily for a submerged application.

Though I realize such a setup might not be for everybody, I just wanted to mention it in case anyone found this useful.

-håvard