A system and related apparatus and method for delivering fluid to and from a bottom center of a floor-operation pad on a rotary-motion flooring machine while the pad is rotationally operating on a horizontal underfoot surface, the system comprising a fluid-delivery hub comprising: a plurality of fluid entry openings disposed on an outside circumferential surface thereof; an equal plurality of fluid flow channels commencing at the fluid entry openings, angling downward and inward from the fluid entry openings toward a center of the fluid-delivery hub, and terminating at an equal plurality of fluid exit openings proximate a bottom center of the fluid-delivery hub; and a floor-operation interface at a bottom of the fluid-delivery hub configured to directly or indirectly attach a floor-operation pad thereto, for operating on a floor.