Positive displacement pumps, such as the helical rotor pump, are typically used to pump highly viscous materials and for dosing or metering of fluids. They transfer fluids through a series of cavities, the spaces between a moving, helical rotor and a fixed stator. As the rotor turns, these spaces traverse axially along the pump, eventually depositing the fluid at the pump’s outflow. Available in many materials to assure compatibility with a range of process fluids, progressive cavity pumps are also used to preserve shear sensitive biologicals, or to move fluids consisting of more than one phase (e.g. oil water mixtures). Helical rotor pumps can be used to achieve flows up to 200 cubic meters per hour and pressures up to 20 bar. These pumps have excellent pressure stability, are excellent when accurate volumetric measurement is required and have the ability to operate with the flow reversed.