Potential application of a single-particle aerosol spectrometer for monitoring aerosol size at the DOE filter test facilities

At each of the three Department of Energy (DOE) filter test facilities (FTF), a commercial single particle aerosol spectrometer, the LAS-X, was used to demonstrate that the test aerosol produced by each of the Q107 high efficiency particulate air (HEPA) filter test systems was polydisperse with a geometric standard deviation greater than 1.35, and a geometric mean diameter less than 0.2 ..mu..m. These results confirm the work of others that the OWL (mechanical analyzer) is inadequate for assuring that these test aerosols are monodisperse with a mean diameter of 0.3 ..mu..m. Use of the LAS-X for monitoring aerosol size was evaluated. The LAS-X is relatively insensitive to changes in aerosol concentration and refractive index over the range of interest for filter testing. It appears that the LAS-X would provide a better instrument for monitoring aerosol size, and would permit the FTF test operator to adjust the test aerosol to approximate the size characteristics currently recommended for this test.