Abstract: An aperture module for obtaining signals from microscopic particles suspended in a sample blood solution which passes through a scanning aperture. A module housing including an aperture holder is mounted on a container or bath containing a body of the particulate liquid suspension to be tested. The aperture holder with aperture formed therein extends into the vessel to permit passage of the sample through the aperture to an outlet chamber immediately behind the aperture. The chamber is connected to a source of clean electrolyte and has a narrowed or reduced dimension portion positioned immediately behind the aperture. A vacuum is applied to the chamber to cause the sample to be drawn through the aperture for testing thereof. An optical hemoglobinometer is positioned in association with the bath to measure the hemoglobin content of the solution to be tested.

Abstract: A pneumatically controlled liquid transfer system for delivering a liquid from a source to a delivery location, said liquid source being provided with a pneumatic cylinder for driving the liquid from said source, a pneumatically operated pinch valve of the make-before-break type and flexible conduit paths leading through the valve to the delivery location. The make-before-break pinch valve comprises a valve shell having two pistons movable laterally therein. The shell has a window. One piston has a yoke, each arm thereof having a passageway, one aligned with the other. A stop extends between the arms of the yoke. One of the flexible conduits is arranged through the window between the first piston and the yoke and the other flexible conduit is arranged also through the window but within the aligned passageways and between the piston and post. The second piston is spring biased to bear against the second conduit to place same in a normally closed condition. The first conduit is normally open.