[PSUBS-MAILIST] Yet another compensator method

[Sean T. Stevenson via Personal_Submersibles]

One thing to note about air in compensation systems is that the oxygen can dissolve into the oil, and just as with aqueous solutions, solubility is greater at lower temperatures, so if you have your compensating oil exposed to atmosphere for a length of time at surface conditions, the dissolved oxygen will reach an equilibrium at that temperature, and then in service if your oil heats up (in the case of light or motor housings, or other compensated volumes where the heat input is greater than cooling through the enclosure walls), once you take the pressure off that heat drives the gas out of solution, which you notice when you bleed the system post dive. Also, not every little bubble is going to make it to the high point bleed during pre - gas trapped in other areas (not necessarily due to design - small bubbles can adhere to vertical surfaces due to their own surface tension) may dissolve into the oil initially, and then evolve off when you bleed the system later.

Sean
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