Actually I think it happens the other way around. I think the nitrogen passes through the diaphram slowly as a leak and is dissolved and passed to the unpressurized section and out of the system.
What I am not sure about is how the pounding eventually drives all the fluid from the system (my own image). In these cars the shocks are wimpy and the car is low and they seem to recuperate with the replacement of the accumulators.
Bosch Master, ASE Master, L1
33 years MB technician