Condensation problem fixed. Got a dive with air?

Build
1

Hello, I wanted to share my solution to getting rid of that nasty condensation inside the electronics enclosure that builds up on the dome cap. I live in west coast of Florida and its really really humid here and I’m on the water which makes it worse. So I had to come up with an easy and practical way to get rid of all that damm humidity.

First and foremost make sure the inside of the dome is cleaned. I cleaned it like I clean my telescopes main mirrors with with 60% isopropyl alcohol aka rubbing alcohol and distilled water and use cotton swabs since it wont scratch the dome that will remove any oil that will cause dew to form.

Then use anti-fog spray on the inside and use a lint free cloth. I used two applications.

Then the fun part. I powered up my ROV since the rasberry pi runs warm I wanted to heat the air inside and then I put 20mg of silica packs inside the electronics and closed the acrylic from the back and left the dome off and I installed the vent plug. I also put the dome cap on but barely on so the orings would not engage the housing and went and grabbed a beer and waited a while until the enclosure got warm ( about 15 minutes)

Go to the dollar store and get some ballons. I happen to be a diver and I have several dive tanks filled and ready to go. An interesting side note (Dive air is desicated and humidity is at 67pmm which is pretty dry so it will not rust the inside of tanks… keep that in mind). Fill one of the balloons with the dive air. I like Nitrox so I used the 32% tank. Then I used the nice plastic vinyl tube that Rusty sent with the ROV and the vent adapter and connected it to the ROV and the other end to the balloon and let the ballon fill the enclosure and just barely allowed the air to escape from the dome. When the balloon was empty I quickly pushed the dome into place and replaced the vent plug.

Then I did a vacuum test and filled another balloon. After my ROV passed the vacuum test I used once again the nice vinyl tube that Rusty send with ROV and connected it to the vacuum pumps port to replace the air that was vacuumed out therefore I replaced the removed air with more dry tank air. and then quickly closed the vent plug.

Tested the ROV for hours after that and not a sign of moisture on the dome cap and now my ROV is moisture free and Nitrox certified 32%

Heinz

2

Thanks for sharing that Heinz. I’ll just add that there are some other things you can do to avoid moisture inside a housing:

  • replace the air in the housing with Nitrogen gas
  • be sure you're working in a room that has a dehumidifier
  • use extra desiccant packs
anyone else have suggestions to share?
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@Heinz and @undersearobotics,

We’ve had excellent luck with a desiccant pack of the moisture-indicating desiccant. We’ve used it in pretty humid environments and it can handle it.

-Rusty

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@Heinz,

If you don’t mind saying, where on the west coast of Florida do you live?

I live in Ft. Lauderdale, but like to get over to Sanibel/Captiva to run my ROV. I run out of Jensens Landing on Captiva.

Regards,

TCIII AVD

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Hi Rusty, I had some silica packs inside the enclosure the first time and it failed and there was still dew on the dome. With all the water vapor around here and the fog we’ve been having I took this extreme measure to get rid of it. I did a test dive in a pool today and after the end of the dive there was no dew on the dome at all.

TCIII Im in Treasure Island about two hours north of you, I have a lot dives planned around here and with all the friends with boats the next few months should be very interesting in getting some good video.

Heinz

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@Heinz,

Okay. Do you know exactly what type of desiccant packs you were using? Were they fresh and sealed from the atmosphere before you put them in the enclosure? I think we use about 20 grams or so inside the ROV at a time and we make sure it’s fresh, which is easy with the moisture-indicating version.

-Rusty

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Hi Rusty, yes they were opened from the sealed air proof bag and immediately into the enclosure but during that brief moment they were exposed to ambient air. I was not in a de-humidified room and although it’s not the high humidity of summer it was still pretty humid. That’s why I put the dry air from my dive tanks in order to expel the ambient air out of there. I dove the ROV and it worked really well and I used the color indicating descant packs as well.

Heinz

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Heinz,

Okay, sounds good. Glad it worked!

-Rusty