Pool Testing...Chlorine? What should be done before and after dive?


#1

We tested our ROV last week in water for the first time...the pool at our school. We are wondering about the affect of chlorine if we do most of our test dives here. As well, what should be done before and after the dive...silicone spray to what parts? drying methods? preventative maintenance? Also plan to put a silica pack in before the dive as we had condensation after the dive last time...any other suggestions?


#2

Hey Ashley,

Congratulations on your first dive! I've done a bunch of testing in chlorine pools without any post-dive maintenance. So far as I've observed, there are no particular noticeable effects from chlorinated water on the ROV.

To keep the ROV in its best condition, I'd recommend removing the motor bells after each dive and rinsing the bearings with fresh water and then alcohol. Fresh water will dilute and absorb chemicals that were in the water you flew in (which can expedite corrosion), and alcohol will then displace the water and evaporate away.

Condensation inside the main tube is a problem we've been working on finding a good solution for for quite some time. Silica (and other desiccant) packets may work well, but be sure they have not already been saturated and note that you'll need to have them inside the sealed tube for several hours before they'll work. The reason for this is that they absorb water slowly, so the humidity in the tube will remain close to ambient until they've had time to work.

We've also experimented with filling the tube with dry gases like helium, nitrogen, or (and this is the most easy to find), canned air like what you'd use to clean your computer keyboard.

As a final trick for mitigating condensation (although this is more of a band-aid rather than a solution), you can put pieces of felt above and below the camera so if you move the faceplate up and down, it will work like a sort of internal windshield wiper.

At some point, we hope to put together a formal operating manual for the ROV. If you guys come up with your own tricks and practices that you think might be good to put in something like that, let us know.

Once again, congratulations on your first dive. Keep us posted with your progress, and enjoy your ROV flying!

Eric


#3

I use desiccant packs in several of my U/W camera housings. They work well, but as Eric stated, they work slowly. You need to put them in to the housing an hour or so before the dive.


#4

Thanks guys for the tips...still had condensation after our second dive with a little water in the camera tube? We used silicone spray on the o-rings and also placed a silica pack inside the camera tube 2 hours before the dive. We got to have a better look at sealing the ROV...o-rings as well as the wiring going into camera tube before our next dive. Also getting some rust on the motors...need to figure our how to remove them and prevent the rust from forming.

Back to the classroom to further research and examine the ROV. Here are some pictures taken after our last dive...

172-Condensation.jpg (380 KB) 173-rust.jpg (537 KB)