Thanks you for the good presentation I would like to emphasize on the function of separation seal is to prevent lube oil leakage from bearings into seal faces. That's why nitrogen pressure of about 8 psi is start permissive for lube oil pump
As the seal gas leaks to the inboard side and forms the barrier, it has to pass through the labyrinth; what's the pressure drop within the zig-zags of labyrinths? How much pressure drop are we having till the seal gas finally reaches the process side and form the barrier?