Classification apparatus and fine particle measuring apparatus

Abstract

A classification apparatus for classifying and separating particles having particle sizes within a predetermined range is disclosed. In a preferred embodiment of the classification apparatus, a center electrode () and an outside electrode () generate an electric field for classifying charged fine particles according to electric mobility. In the upper part of a housing (), a sheath gas supply portion () is provided. An aerosol supply portion () has an introduction port () provided on the outside electrode () side in a classification region (), and supplies a charged aerosol at a constant flow rate through the introduction port (). On the downstream side in the flow of a sheath gas in the classification region (), a larger-size particle discharge portion () is provided. The larger-size particle discharge portion () has a discharge port () provided on the outside electrode () side, and discharges charged fine particles, which are contained in the classified charged aerosol and have particle sizes larger than a predetermined particle size, together with part of the sheath gas at a constant flow rate. A detector () is provided downstream of the housing () to detect the number of remaining charged fine particles contained in the sheath gas introduced thereinto as the quantity of electricity.