(under the class definition) Apparatus wherein the impeller* comprises a blade* projecting radially outwardly from a hub or shaft or a flow passage which wholly confines the working fluid while in working engagement therewith, the blade or flow passage extending circumferentially at least substantially one complete flight around the hub or shaft and the peripheral edge of the blade or flow passage defining a spiral path about the hub or shaft axis.
SEE OR SEARCH CLASS
198, Conveyors: Power-Driven,
625, and 657+ for similar impellers especially adapted for moving other- than-fluid materials.
