Abstract: A solid or screen bowl decanting-type centrifuge comprising: a rotatable bowl; a helical scroll conveyor which rotates coaxially within the bowl at a different rotational speed, the helical scroll comprising a hub carrying a plurality of flights whose radially outer edges lie close to an inner wall of the bowl such that, in use, solids are scrolled by the conveyer to solids discharge ports at one end of the bowl, with separated liquid being discharged from liquids discharge ports at the opposite end of the bowl. The conveyor hub carries a plurality of nozzles in a wash zone for supplying wash fluid to solids being scrolled by the conveyer towards the solids discharge ports. The conveyor hub also carries a blade in the region of the nozzles and intermediate adjacent flights of the conveyor for directing fluid droplets from the nozzles over said solids.

Abstract: A method of controlling a centrifuge of the type having a rotating perforated basket on whose inner peripheral wall a liquids/solids slurry is caused to collect in use, with separated liquid being collected via the basket perforations. The method comprising taking depth measurement of the material in the rotating basket continuous or at repeated intervals, over a basket cycle from commencement of slurry feed to discharge of solids, using at least one laser unit adapted to direct a beam of coherent light energy towards said inner peripheral wall of the basket of solids. The depth measurements can be made using at least one laser unit (30) adapted to direct a beam of coherent light energy towards said inner peripheral wall of the basket.