A fan blade is disclosed comprising a lightweight metallic airfoil portion and a high-strength sheath portion. In the system, when spent sulfuric acid that is discharged or collected at a discharge source is transported by a carrier unit and used at a user office a concentration of the spent sulfuric acid is measured andor adjusted at least at one of the discharge source, the carrier unit, and the user office. That common insert is, in turn, detachably located in, or on a lateral frame of the printing machine.