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Where are these leaks coming from?

I have the 4 inch enclosure and i have all my electronics in there but sometimes im getting leaks in there. I tightened everything and made sure that all the flanges and penetrators have O rings and i put a lot of silcone greese just to make sure that no water could get in but every now and then i get a leak. What should i do and how should i fix it?

I’d be tempted to backfill all the penetrators and see if that helps.

I found the leak I had by putting slight positive pressure through the vacuum test port using a hand pump while the ROV was in a water tank. Turned out to be a leaky temperature sensor.

Great to see you again corndog! i know that the perpetrators are properly sealed but i was thinking that it could be one of the O rings.

Haha you too Jay. I’ve been going through my own issues with leaks on a new build and am just now feeling like I have a grip on what all had been influencing those leaks. One is that I’m pretty sure the power jumper is leaking through the jacket because there was much less of a drop when testing both bottles together versus one bottle at a time, very repeatable. Second was that I tested with an electric vacuum pump and had much less leakage than with the hand pump, which told me that the hand pump wasn’t sealed tight, but I also think that what little leakage is left is probably from the other cable jackets in the penetrators, which is why I’m curious about backfilling them. BR also recommended the same as what k.deboer had mentioned, maybe just a few pounds so it’s not enough to blow off the end caps and either dunk it or use soapy water.

Spent a lot of time troubleshooting a leak that turned out to be the vacuum pump.

I would recommend testing it before and after a test…

really! so all the penetrators could be fine but the vacuum plug penetrators. im wondering how the water passes the two o-rings and the screw thread inside the vacuum plug

Our robotics team uses a mighty-vac to test for leaks in our 4 inch enclosure. The procedure calls for pumping down the enclosure through the test port and holding for 30 seconds without the needle moving at all. If the needle moves at all there is a leak. Sometimes, our leaks have been so bad that we can’t use the mighty vac to find them. Autozone will rent an electric vacuum pump for free that will let you hear the leak,

We use a thin coat of silicone grease for the enclosure’s double o-ring seal. We use a thin coat on the penetrator o-rings. We don’t over compress the o-rings on the penetrators to avoid causing cracking in them.

We have never had an issue with an o-ring seal that wasn’t caused by a foreign object in the seal. In the past we have had issues with insulation on the wiring. We used to use CAT5 UTP (CAT 6 is less flexible), but water can quickly and easily travel down the length of the CAT5 insulation. To avoid this, you can use vacuum to pull RTV silicone sealant into the cable sheathing. In one case, the leak was in an external camera and traveled down the wire insulation into the main tube. In another case, the problem was with the expoxy job on the penetrator. Someone had not stripped the jacket off of the CAT5 when passing it through the penetrator. That just let water travel down the insulatiion and right through the penetrator.


Not only the plug but the pump itself.

Especially with the T hose barb fitting.