Abstract: A pressure gradient rotary sealing system is described with an additional configuration which uses and externally mounted pressure-reducing piston with a differential area to create a pressure differential across the system to reduce the pressure×velocity (PV) value to extend seal system life and provide early indication of impending seal failure. This invention is another embodiment of this previous invention offering using a separate externally mounted pressure reducing piston therefore the main body of the wash-pipe top-nut is lighter weight, the system has more fluid capacity, is simpler to assemble, operate and monitor and has a longer service life than previous configurations.

Abstract: A pressure gradient rotary sealing system is described which uses a pressure-reducing piston in several configurations with surface area differentials thereby reducing the pressure times velocity (PV) value for each of the sequential seals to extend seal system life and provide early indication of impending seal failure.