(under subclass 151) Device comprising two blade* rows which each add energy (i.e., "pump"* blade rows) to working fluid* and further comprising means to selectively configure the device to direct the working fluid from a device inlet to an outlet either (a) along one path proceeding through the two blade rows in sequence (i.e., in-series flow path) or (b) along separate paths, a proceeding alone different ones of the through only one of the blade rows (i.e., in-parallel flow paths).
