∃hasComponentPartAtAllTimes.RotaryDisplacementMechanism ⊓ ∃lacksComponentPart.SeparateInletValve ⊓ ∃lacksComponentPart.SeparateOutletValve
Contains a chamber with gears, cams, screws, vanes, plungers or similar elements actuated by relative rotation of the drive shaft or casing, and lacks separate inlet and outlet valves.
The differentia captures the two key distinguishing characteristics from the definitions: (1) the rotary displacement mechanism with specific types of elements (gears, cams, screws, vanes, plungers), and (2) the absence of separate inlet and outlet valves. These conditions are necessary and specific to rotary pumps among positive displacement pumps.