Leaking electronic housing


#1

I have a problem with a leaking electronic housing. I have used teflon tape behind the orings to get a good seal. Without the teflon tape the o-ring is barely touching the tube (this was before sanding down the seal area). Have also sanded down the seal area according to this post: http://openrov.com/forum/topics/laser-imperfection-leading-to-water-leaking

I still have a leak, I have also tried to lubricate the oring with grease to try to get a better seal without any luck.

Any good suggestion how to fix the leak?


#2

Hey Kjetil,

What version of end caps/OpenROV are you using? I had a similar problem with the 2.5 end caps (which I am still using) and also posted on the forums. The problem I had was that the water was leaking in underneath the teflon tape as seen in my post.

http://openrov.com/forum/topics/leaking-electronics-tube

I just took acrylic cement and applied it around the groove without any sanding (I tried to keep a somewhat smooth finish), added the teflon tape back, and then applied the o-ring with the silicone grease. I always test the electronic tube's integrity using a vacuum pump before diving.

Hopefully this helps. I know it can be frustrating but you need to hang in there!


#3

I have the 2.6 version end cap. I will try to remove the teflon tape and use silicon grease instead


#4

http://openrov.com/forum/topics/laser-imperfection-leading-to-water-leaking

check that out and see if it helps


#5

I read that post, that was the reason why I sanded the seal area. I will try differet seal grease and see if that helps.

The last test show that the pressure i leaking from -25mmHg vacum to -15 during 8 hours


#6

Place an elastic band underneath the o-ring instead of teflon tape. This worked very well for me for my 2.4 rov. I used a balloon, since my o-rings were not as loose as yours seem to be, but Walt used a wide elastic band and that worked for him.


#7

I tried with a rubberband that I cut to the correct width. Used Hylomar flange sealing behind the rubber bang and on the O-ring. Have only held the vacum for 1 hour in water without any water leak into the housing. I will have a longer water test tomorrow.


#8

1 hour is pretty long. how much water gets in after one hour?


#9

I also have leaks, both in the electronic housing and in one of the battery tubes. After a few minutes of diving (to around 10 meters depth), there is so much moisture in the tube that the camera image becomes blurred. The o-rings seem to touch the tubes quite well, especially after I added some teflon tape.

After close inspection, I found some laser imperfections in both endcaps. There were small cracks on both the o-ring facing sides. So I guess the water first seeps in below the o-rings in a crack, then flows around the perimeter in the inside corner until it finds another crack that leads to the inside of the tube.

Without teflon tape, I measured the vacuum in the e-tube (in an air environment) to drop from -20 inHg to -15 within 10 minutes and to -10 within 20 minutes.

I have now bought some Acrifix 116 acrylic cement to fill the cracks and replace the teflon tape. This seems to be the European equivalent of Weld-On 16. Hope to report positive results soon.

FT


#10

The moisture that you are seeing could also be due to the moisture in the air in the E-tube. Since usually the water that you are running the ROV in is colder than the surrounding air, the moisture in the air condenses thus fogging up your E-tube. This can easily be solved by adding a desiccant packet into the tube. However, I also could be entirely wrong and you could have an actual leak in your end cap.


#11

There was definitive water in the housing and not only moisture.

Have fixed the leak. What I do now is that I have made a special tool that I use to pump vacuum in the housing before I insert the plug to remove as much air as possible from the inside.



But there is still some fog on the inside after the ROV have been in the water for a while. I have ordered some silica gel that I plan to install inside to see if that helps.


#12

That's a very clever design. If I understand how it works correctly, you pull a vacuum in the tube, and then while it is still at a negative pressure you release the plunger which gets sucked into the syringe keeping the housing at a negative pressure? Does this system work well?


#13

You have the correct understanding of the system. The design is not 100% pressure tight most likely due to the tape between the tool and hose. The system works very well. The only thing, you should expect that the plunger will get sucked into the syringe. I do actually need to push it downward even with a 25 mmHg vacuum.