[solved] Leaking Electronics Tube

water-proofing
solved
sos

#1

Hello Everyone!

I wanted to share some photos and gather other people's valuable input into a problem that I am having trying to seal the electronics tube. I have a 2.5 version ROV and end caps. After going through the forums and looking at a how-to video on how to properly seal the end caps, my electronics tube is still leaking.

My test setup is the empty tube, plunger in one side and vacuum pump on the other, just as Eric describes on this discussion I pull a vacuum 50-60 kPa on the vacuum pump and then submerge it in a container.

I started with just a single layer of teflon tape and then in followings tests increased to three layers, but I am still getting leaks in the tube :(

In my last test, it looks like the water is coming in between the teflon tape and the end cap. I'm wondering if the cracks on the end cap are allowing water in via capillary action.


Above: Two leaks at the top


Above: Another leak on the side


Above: Cracks in the end cap


Thoughts? Comments?

Thanks,

Mike


#2

Hi Michael
I am using silicone grease around the gasket area. This seems to seal any small gaps.

Dave


#3

Hi Dave,

Thanks for the response. I put silicone grease on the o-ring itself. You you apply the grease before the teflon tape? Do you need to use teflon tape on your ROV for a better seal?

Thanks,

Mike


#4

Hey Mike,

I'm not a fan of the teflon because the overlap at the end of the tape almost always seems to create a hairline path for the water to travel at depth. The upgrade kit to the 2.6 end caps that has the fatter o-ring is highly recommended.

If you think the rough cut on the laser cut tracks is allowing water to travel, I have successfully smoothed out the track by coating the inner track with the acrylic cement. Might help.

-B


#5

Thanks Brian! I did a combination of what you said and Dave. On one end with the potted wires, I did the silicone grease-teflon tape-o-ring (w/ Si grease) combination and on the other, like you said, applied some acrylic cement to fill the cracks.

I was satisfied with the vacuum test and had my first dive today! I think I will add the acrylic cement to the other end cap to build up some confidence. I also have the 2.6 end caps as well, but I wanted to get some use out of the 2.5s and also figure out if I needed to pot additional wires when I do the 2.6 end caps.

How do you check for tightness on the battery caps? The spring is quite strong, so the battery caps don't fit all the way in, even with the large o-rings holding them in place. I saw that the small o-rings on the battery caps had ~1mm width of contact and assumed this was alright just for flying in the pool.


#6

Hi Michael



I didn’t use Teflon tape on mine. As for the battery caps, I, like you didn’t feel comfortable with the strength of the rubber to hold on the caps. What I did was to epoxy 4 stainless steel threaded bolts to the tubes. So I use 4 stainless steel nuts to hold on the battery caps. This works well and makes it quick to change out the batteries. No chance of them springing out. I also used a little silicone grease on these gaskets.



Dave


#7

That's a great idea Dave! I will have to implement that on my ROV!

Thanks!


#8