Abstract: A centrifugal microstrainer includes a closed cylindrical vessel with a cylindrical screen within, both rotating about a hollow shaft forming a common central axis. Liquid-solid admixture introduced through the shaft is flowed radially outward subjected to centrifugal acceleration, and forced back through the screen under pressure with particles too large to pass the screen remaining on its outboard side. The centrifugal force applied by the rotation of the vessel acts on these larger particles pushing them away from the screen thus preventing clogging and permitting substantially continuous operation. The device may be operated as a classifier by providing a plurality of concentric screens of decreasing mesh size spaced outwardly from one another in conjunction with properly sized chokes.