A system for processing a workpiece includes a head attached to a head lifter. A workpiece is supported in the head between an upper rotor and a lower rotor. A base has a bowl for containing a liquid. The head is movable by the head lifter from a first position vertically above the bowl, to a second position where the workpiece is at least partially positioned in the bowl. The bowl has a contour section with a sidewall having a radius of curvature which increases adjacent to a drain outlet in the bowl, to help rapid draining of liquid from the bowl. The head has a load position, where the rotors are spaced apart by a first amount, and a process position, where the rotors are engaged and sealed against each other. For rapid evacuation of fluid, the head also has a fast drain position, where the rotors are moved apart sufficiently to create an annular drain gap. Fluid is rapid evacuated by spinning the rotors with the head rotors slightly apart and unsealed, causing the fluid to flow our quickly under centrifugal force.