Theory of Operation B–3
Figure B-1
Classifier Shown with Impactor Installed on Inlet
Figure B-2
Cross-Sectional View of an Inertial Impactor [Hinds, 1982]
The impaction plate deflects the flow to form a 90° bend in the
streamlines. Particles with sufficient inertia are unable to follow the
streamlines and impact on the plate. Smaller particles follow the
streamlines, avoid contact with the plate and exit the impactor. The
impactor is used in the SMPS system to remove particles larger
than a known aerodynamic size due to their contribution to
multiply charged aerosols. The aerodynamic particle size at which
the particles are separated is called the cut-point diameter. The