On my ROV setup, we have 8 penetrators (with the 16/2 BR cable) connected to 8 bilge pumps (Tsunami 1200GPH). The team has noticed that it did leak air slowly when a mild vacuum was applied to the tube, but after discussing it on this forum concluded that it probably wouldn’t be an issue (see: https://www.bluerobotics.com/forums/topic/waterproofing-penetrators/ ). Today we ran a simulated test to 40ft for 15 minutes and found one of our two tubes to be nearly filled with water .
All of the o-rings are in place and were covered with dielectric grease before being fastened to the 1/2" acrylic plate. Submersion testing while applying a vacuum to the setup confirmed that the leaks were through the cables/wires and not through the o-ring seals. The wire seals were made by soldering the individual wires in line, then applying two layers of liquid electrical tape to the joint, followed by covering that with adhesive lined heat shrink.
Are there any other recommendations for sealing these wires off?