A method to control an axial separation between a rotating ring and a stationary ring of a dry gas seal. The dry gas seal restricts leakage of a gas or other fluid to or from a rotating device. At least one property of the gas or other fluid is sensed. At least one of the axial separation between the rotating ring and the stationary ring, and a time rate of change of the axial separation, is sensed. A stiffness of a film between the rotating ring and the stationary ring is estimated. A field strength of at least one magnetic device is adjusted based on at least two of the sensed axial separation, the sensed time rate of change of the separation, and the estimated film stiffness. The axial separation between the rotating ring and the stationary ring is adjusted.