Abstract: A pump (1) has a rotor (4) and a stator (3) disposed closely adjacent to and biased towards it, but spaced apart from a surface of the rotor. The stator (3) or rotor (4) has recesses (30) on its surface facing the rotor or stator respectively, and an inlet to and an outlet from each recess to provide for the supply of fluid to and from the recess. Rotation of the rotor (4) about its axis is arranged to cause fluid to be pumped from the inlet to the outlet as a result of the viscous drag on the fluid resulting from rotation of the rotor relative to the stator (3). The force biasing the rotor (4) and stator (3) together is provided at least in part by fluid pressure feedback from the pump (1) in order to control the clamping or biasing pressure between the rotor and stator automatically.

Abstract: A mechanical face seal adapted to withstand a pressure differential across its sealing faces, includes a bellows unit of monolithic construction, comprising a plurality of corrugations, the crowns of the convolutions directed towards the high pressure side of the seal being of greater radius of curvature than the crowns of the convolutions directed towards the low pressure side of the seal.