A blood cell counter having a purging system.

摘要

A blood cell counter has sensing electrodes (12 and 16) which detect the passage of a cell through an aperture (80). A purge system serves to purge the aperture (80) and the surrounding portions of the blood cell counter of dirt, debris, and previous sample liquid. A sample tube (10) extends from a source of either sample liquid or cleansing solution to a small gap (35) between the aperture (80) and a housing (40). A purge line (34) is connected between an annulus (33) surrounding the gap (35) and a pump (86) which supplies negative pressure. Due to the geometry of the sample tube (10), gap (35), annulus (33) and purge line (34), a high pressure drop occurs across the gap (35) and the liquid flows ar relatively high velocity past the aperture (80) to facilitate cleaning.