Particle analyzing system

Abstract

A particle analyzing system of the type having an aperture retaining member for obtaining signals from microscopic particles suspended in a fluid which passes through a scanning aperture. The aperture opens on one side thereof to the fluid suspension and on the opposite side to a passageway in the aperture retaining member; the passageway is connected at an entrance end thereof to a source of clean electrolyte and at an exit end thereof to a waste collecting container or isolator and a vacuum source. A vacuum from the source is applied to the collecting container to cause the clean electrolyte to be drawn through the passageway and wash or sweep behind the aperture simultaneously with passage of the suspension through the aperture. A sealed sweep flow isolator drip chamber or tank is interposed in the fluid conduits between the source of clean electrolyte and the passageway with a respective restriction in the fluid conduit on either side of the tank to enable filling of the tank with clean electrolyte to a predetermined desired level below the sealed top of the tank thereby to prevent electrical connection between the electrolyte supply and the passageway. The waste isolator is provided with a second aperture retaining member disposed in the wall thereof. Sample which has been sensed in the scanning aperture and diluted with the sweep flow clean electrolyte mixed therewith in the passageway is accumulated in the isolator to be tested with low coincidence correction required by passing the same through the second aperture into a secondary isolator. Alternatively, diluted sample present in the fluid conduit between the exit end of the passageway and the waste isolator may itself be forced back through the scanning aperture by applying pressure to the waste isolator; the diluted sample thereby is tested with low coincidence correction required.