Patent ID: 6235537
Filing Date: 2001-05-22
Classification: B04B,G01N,Y10T

Abstract:
A method of replacing contaminated liquid in a particle suspension with uncontaminated liquid, said particle suspension containing first particles having a first sedimentation velocity and second particles having a second sedimentation velocity, said first sedimentation velocity being greater than said second sedimentation velocity, comprising the steps of:a. placing a predetermined fixed volume of a contaminated particle suspension in a test tube shaped receptacle;b. placing the receptacle on a resilient stopper, said stopper having multiple integrated conduits, the stopper so positioned as to enclose within said receptacle the contaminated particle suspension and a volume of air;c. rotating the receptacle about an axis of symmetry with a predetermined RPM and time duration so that particles with a greater sedimentation velocity are driven by centrifugal force to an interior wall of the receptacle but with insufficient RPM and time duration for most particles having a lesser sedimentation velocity to have reached the interior wall of the receptacle;d. introducing an uncontaminated liquid at a predetermined flow rate into the receptacle at a bottom of the receptacle and at substantially the axis of rotation of the receptacle;e. allowing the uncontaminated liquid to flow over the particles located at an interior wall of the receptacle and displace the contaminated liquid containing said second particles towards the stopper;f. removing the contaminated liquid from the receptacle through said conduits in the stopper;g. delivering the removed contaminated liquid to a waste container;h. stopping the flow of uncontaminated liquid into the receptacle and stopping the flow of contaminated liquid out of the receptacle resulting in a predetermined volume of uncontaminated liquid and the particles remaining in the receptacle; andi. resuspending the particles in the receptacle with the uncontaminated liquid.