I keep reading that oil compensation would allow for most housings, even PVC pipes, be (theoretically) rated for full-ocean depth. But I’ve seen notes that some components would not function at these pressures inside of an oil-filled housing. Naturally, I could see how some capacitor types, relays, and batteries, components that are hollow but sealed, and cannot be oil-filled, would fail. And that eventually, some integrated circuits would crack, or that the solder joints on the PCBs would shrink and snap. What I’ve yet to see is a “straight” answer on when any of this would happen.
To those who have used oil-compensated housings in the past, what has your millage been? How deep could they go, what components were housed in them, and what components had to be housed in non-compensated 1-atm housings?
This topic isn’t one I have much experience with, so am unfortunately not able to go into depth about specific details and expectations. That said, from a theoretical standpoint component failures in an oil-filled component would be dependent on the crushing strength of the materials and structures involved.
I imagine many of those who have used oil-filled components won’t have had reason (or the necessary equipment) to test them to failure, so you may find limited information as to what doesn’t work. I would at least expect integrated circuits and solder joints to withstand much higher pressures than “can” capacitors, or other hollow components. That kind of thinking can perhaps guide you as to which information is most important/relevant to what you want to achieve (i.e. only the weakest component matters, and validation beyond a particular point stops providing useful results).
Do you have a use-case or some limitations in mind (e.g. can X components withstand Y pressure), or are you mostly putting out feelers for gotchas/limitations that others have found that you’ll need to look out for if pursuing an oil compensation approach?
My experience is with work class ROVs and oil filled electronic boxes is very common with PCB and control electronics immersed in the oil for intelligent hydraulic valve operation. Have a look at this link:
I know that crystal oscillators can fail under pressure. I have built some oil-filled servos (commercial R/C servos in my own waterproof case) that had crystal oscillators that failed at about 400 meters. You may be able to fix that by putting a blob of hard epoxy over the oscillator to protect it from the pressure. Of course, that technique requires careful surface preparation and a sufficiently hard epoxy.
All the other components in these servos did fine up to 600 meters. If your device needs a motor, try to use a brushless motor instead of a brushed motor.
Hi everyone,
I know this is an old post, but I´m looking into oil compensation aswell.
I was wondering if anyone has experience with some sort of “hybrid” system. What I would like to do is to use a 5" enclousure and fill it with Shell Diola or silikon oil, without a hydraulic compensator. This would not necessary increase the depth rating, but also not increase the pressure on single components like in conmpensated systems. The enclosure would still be absorbing the pressure.
Now why fill it with oil in the first place? I had alot of struggle with condensation, and want a different solution then silika gel.
The oil would prevent condensation, increase heat transfer from electronics to the alluminium enclousure and also prevent leaks.
Now I am wondering what you guys think about that!
Hi @michaelsloschek -
While that approach would help heat transfer, it may not make too much of a difference when it comes to leaks. If you’re able to fill the tube entirely with the oil, with no air present after sealing things up, the enclosure will transfer the external pressure to the internal fluid, by deforming the enclosure tube. As the oil is not very compressible, this is likely to help your depth rating, but will expose internal components to potentially significant external pressure…
Condensation is quite easy to manage - to me, keeping desiccant recharged with a toaster or microwave is vastly easier than dealing with large quantities of oil - this is quite messy!
