Sealment of main tube


Good morning!

I have a OpenROV V.2.7 (fully assembled) from 2015, which was not used for approximately one year. Now I want to make it going again.
This worked quite well in the beginning, but when I was updating the software and had look on the main tube after approx. 30min, I realised the O-ring on one side came loose despite the black strings were attached with high tension.

Is this a common problem? And do you have any suggestions to fix this problem? Is this caused by the air expanding inside the tube, as it is heated?
I attached some pictures to make my case more clear.
The condensation on the inside of the tube comes from old, maybe humid dessicant pouch which will be replaced.

Thank you for your help!

Cheers- Nicolas


Yes it is due to the air expending inside the tube. What I do is I take the syringe out a few times while the air warms up, and then firmly press down on the end cap while putting the syringe back in. I do it as long as I hear pressure drop when I take it out. I do this as a pre dive procedure. Once the air is well warmed up you can shut down the rov and let the tube cool down until your dive. Be carefull if you want to take the syringe out though cause a negative pressure will have formed and the syringe might be hard to pull out. You don’t want the syringe stick to break leaving the rubber part stuck in the end cap.


I can add that you have the same issues when traveling and diving between different heights as here also the pressure differences between tube and environment will change. As long as you are diving it should not be a problem, because the water pressure will just about always be greater than the pressure within the (warm) tube and the water cools the tube.

Just be careful when handling the ROV between water and air, and long heat times. Before every dive, briefly take out the syringe, and make a pressure adjustment.