Katie Bland - MSENV Technical Report Final Oral Defense

Impactors have been used since 1860 to collect and analyze particles in the air. A cascade impactor uses a series of impactors to separate particles according to size. While most jet plates in cascade impactors have round or rectangular jets, the Linear Orifice Impactor (Lori-10), a cascade impactor developed by BGI, contains two stages designed with annular rings (d50 cutpoints of 10 and 4 <m), and two stages designed with round jets (d50 cutpoints of 2.5 and 1 <m). The performance of this impactor was evaluated using a series of tests with both a liquid and a solid particulate aerosol. Tests measured the efficiency of each stage to collect particles at its designed cutpoint. Impactor performance was also evaluated by comparing mass size distributions found using an aerodynamic particle sizer that sampled simultaneously with the lori-10 impactor. Tests indicated that impactor design was effective for collection of the liquid aerosol, but was less effective for collection of the solid aerosol at sizes intended by the design. several different collection substrates were used in measuring efficiency with the solid particles, but particle bounce was a problem for all substrates evaluated. mass size distributions calculated after weighing substrates from the impactor did not agree well with mass size distributions determined using the aerodynamic particle sizer. results indicated that the design of the lori-10 impactor should be improved.

Committee:
Advisor David Leith
Readers Greg Characklis
Mike Flynn

For further information please contact Rebecca Riggsbee Lloyd by email at Rebecca_Lloyd@unc.edu