Aerosol Instrumentation (Inertia-Based)

:: Section 4

Cascade Impactor

A cascade impactor is operated by arranging several impaction stages in series in order of decreasing cutoff size with the largest cutoff size first. The cutoff size is reduced at each stage by decreasing the nozzle size (thus a higher flow velocity and an increased inertia). Each stage is fitted with a removable impaction plate for gravimetric (or chemical) determination of the collected particles. The last stage is usually followed by a filter that captures all particles less than the cutoff size of that stage.

Figure 2. Schematic diagram of a cascade impactor