Leak outside of syringe. OpenRov2.8


#1

Yesterday I had a dive with my OpenRov 2.8. Went down to only 20m this time. When I got the ROV to surface, it turned out there was water inside the electronic tube. After some trouble shooting with vacuum pump and water, it turned out that the water came in on the outside of the syringe. I suspect that different material types between the epoxy and syringe, making different expansions at different temperatures can have caused this. My initial plan was to mold a plug with RTV silicone (I have equipment and silicone for molding), making a seal from the outside. But I’m also concerned that if this syringe get loose, it could pop into the tube, since there is nothing physically stopping it from moving in, it’s just glued to the hole in the endcap. Was thinking of using a piece of plastic and cement it to the backside of the endcap (have some leftovers after HD Pro camera upgrade), with just a small hole for the syringe, making a support and preventing syringe from moving in. Any thoughts about this? Or should I simply order new endcap and syringe? Am I the only one experiencing this?


#2

@rune_soldal,
According to the Non-Pass-Through assembly instructions the first three acrylic disks (assuming inside to outside) center holes are welded to the outside circumference of the syringe with the acrylic cement which should provide a watertight seal between the syringe and the disks center holes. This also assumes that the mating surfaces of the first three disks have been properly welded together with the acrylic cement. Therefore even if there is unequal expansion between the syringe outer circumference and the epoxy on top of the third disk, the acrylic cement seal between the outer circumference of the syringe and the center holes below the epoxy should have prevented water from traveling along the syringe body into the WTC?

I have been able to pull a 540 mm Hg vacuum on the WTC, without the controller board installed, for over two hours without a loss of vacuum.
Regards,
TCIII AVD


#3

I know, and I did the “welding” as per instructions, but maybe I didn’t manage to do it good enough. I’ve been diving with it a year, before it suddenly started to leak. But I’ll try to fix it, and strengthen it, just to be safe :slight_smile:


#4

@rune_soldal,
Since it just started leaking, it might be the O ring?
Is the O ring in good shape? Have you tried to remove it, clean it, silicone lube it, check the O ring seating surface on the Non-Pass-Through Disk, then reinstall the O ring just to be sure?
Regards,
TCIII AVD


#5

Thanks for the tip, TCIII, but the leak is identified, as I explained. Used vacuum and water, the cap wasn’t even mounted on the tube :slight_smile: Could actually see the water “bubbling” along the outside of syringe, almost looked like it was boiling. But a fix is ongoing now, both to seal it, and strengthen it to prevent it to move inwards if it should get loose. I’ll attach some pictures when the fix is completed. But you’re right about the welding, I probably did a poor job welding the syringe to the discs.


#6

@rune_soldal,
Glad to hear that you can implement a satisfactory fix.:slight_smile:
Regards,
TCIII AVD