hydraulic cylinders

there are several methods for removing air in the commissioning of a system, depending on its use and other requirements, I have vacuumed to 25 inches several times on certain cylinders used in elevators, but for the most part the entrained air is eventually cycled back to tank , just depends on the nature of the equipment

I had this problem when I set up my hydraulic press.

Just topped up the tank and ran the thing back and forth a few times.

Then it was fine.

I would assume that the compressed air "dissolves" in the oil and once it gets back to the tank, it just kind of bubbles off.

DOC