To obtain a particle counting apparatus which delays a drop in the filtration effect of a semipermeable membrane and which extends the life of a filter part by a method wherein, inversely to a case in which a reagent is filtered in the filter part, the reagent is pressurized from a reagent outflow port at the filter part and particles such as bacteria or air bubbles which are stuck to the reagent inflow side face of the semipermeable membrane are removed.
A filter part 4 is provided with a group 13 of many hollow fiber membranes as semipermeable membranes. A flow cytometer 7 measures particles, e.g. bacteria, in a sample liquid, e.g. urine which is fluorescence-stained. At a stage at which thier measurement is finished, a solenoid valve 19 is opened, a three-way selector valve 22 is changed over, a pressurized air source 25 is operated, a reagent on the side of a low pressure which is partitioned by the group 13 of the hollow filber membranes at the filter part 4 is pressurized reversely, clogged particles at the group 13 of the hollow fiber membranes are exfoliated to the side of a high pressure, and the exfoliated particles and a gas which floats near them are discharged to a liquid discharge chamber 7 via a discharge passage 18. When the clogged particles at the group 13 of the hollow fiber membranes are exfoliated and removed, the life of the filter part 4 can be extended.
FUKUDA MASAKAZU
TANAKA YASUSUKE
