A pressure balanced shaft seal assembly that allows a seal to dynamically
respond to angular or radial misalignment of a shaft is disclosed. The
pressure balanced shaft seal assembly includes a fixed stator, a floating
stator, and a labyrinth seal. In one embodiment, the floating stator and
labyrinth seal are mounted within an annular groove formed in the fixed
stator such that the floating stator and labyrinth seal may move a
predetermined amount in the radial direction with respect to the fixed
stator. A spherical interface between the labyrinth seal and floating
stator may allow the labyrinth seal to pivot with respect to the floating
stator during angular misalignment of a shaft around which the pressure
balanced shaft seal assembly is mounted. A pressure balancing annular
channel formed in the floating stator allows pressurized seal fluid to
balance the axial pressure exerted on the floating stator by the process
fluid.