主权项 |
1. A cascade impactor comprising:
a series of concentrically-arranged collection stages and a terminating filter or filter adapter stage, each of said collection stages comprising an elongated structure with a cylindrical shape, each of said elongated structure having an open top end and a bottom end containing at least one orifice through which aerosol-containing air flows, the walls of each of said elongated structure having an inner surface and an outer surface and further characterized by a raised portion inside each of said bottom ends, each of said raised portions sized to establish an orifice-to-collection surface distance, wherein, for each of said elongated structures, the outer diameter is sized to fit within and slidably seal within the inner diameter of the elongated structure of the next stage in the series, and wherein particles entrained in the sampled air are collected on the inner surface of the bottom end of the stage opposite said at least one orifice. |