Stator of a moineau-pump

A Moineau stator, comprising:

• a tube (10) having lobes (3) arranged in a configuration which is adapted to interact with a rotor, the tube (10) is thin-walled with walls (2) that are sufficiently thin as to be subjected to elastic deformation in response to interfacial seal forces imposed by interference with the rotor and is surrounded by a supporting structure (201) in the form of a support housing having walls able to resist pressure, torque, and axial loads experienced in its intended operating environment, discrete pressurized axial cavities (203) are positioned in an annulus (202) between the tube (10) and the support housing (201) and fluid passages (206) are provided to equalize pressure in the axial cavities (203) with pressure within the interior (5) of the tube (10) by allowing fluids from the interior (5) of the tube (10) to communicate with the axial cavities (203).