US Patent 7296622 Labyrinth seal for pumping system

A seal section for a downhole pumping system includes a fluid exchange pathway and a rotatable gravity separator. The rotatable gravity separator preferably includes a chamber, a backwash inlet connecting the chamber to the fluid exchange pathway and a backwash outlet connecting the chamber to the fluid exchange pathway. The rotatable gravity separator further includes a weight that causes the rotatable gravity separator to remain in a substantially constant orientation with respect to the force of gravity.