Deep Pressure Equalization


I have been thinking about ways to reduce the leak possibility on the dry portion of my ROV. One thought is to pressurize the dry chamber before the dive. If I took the internal pressure to 150psig, then at 330’ it would be equal to ambient pressure. Has anyone experimented with this before?

A second thought is to install a strong bladder such as a hot water bottle inside the dry chamber and plumb it to the wet side. This would allow equalization at all depth.

The concept is so simple, I am sure that I am missing something obvious that would not allow it to work.



If your bladder is filled with seawater then the buoyancy of the ROV will be reduced by the weight of the water. You will never keep it trimmed. Also if you bladder pressurized the chamber to 150 PSI (10 atmospheres) it would have to occupy 90% of the chamber volume.

Pressurizing with air gives you a potential explosion hazard at the surface. Probably a bad idea. Also you would need a different way to secure the endcaps as the current method assumes negative internal pressure.

Also note that O rings seal best with significant pressure across them. When there is little pressure, or worse yet alternating positive and negative pressure the O rings work back and forth in their slot and tend to leak.


Excellent points! I have been around long enough to know just how little I do know and to appreciate the fact that there are always smarter people in the room. THANKS for the input.