Measurement of particle deposition in industrial ducts

A new method was developed to measure particle deposition in industrial ducts. Greased wire grids were used to capture particles in situ by impaction upstream and downstream of a duct bend. Particles were recovered from the grid using a hexane extraction procedure. Cumulative mass distributions of the recovered particles were determined with a sedimentation pipette; these distributions were then used to compute particle deposition by size. As these procedures were compatible with solid particles only, the interior surface of the bend was coated with grease to eliminate solid particle bounce so that results obtained here could be compared to published models for droplet deposition in bends. In a 20.3-cm-diameter, 90° bend at an air velocity of 27.4 m s−1, deposition increased from approximately 35% at 15 μm to nearly 100% at 100 μm. These data generally agreed with models developed for small sampling tubes.