A Versatile Flat-Deposit Impactor-Type Aerosol Collector Part 2: Calibration and Quantitative Study

The SPAL collector is a versatile impactor-type aerosol collector with rotatable substrate plates and radially aligned slot orifices. The airflow, controlled with a critical orifice at the last stage, becomes choked for an exit pressure of 0.5 atm or less. Monodisperse latex and methylene blue aerosols sampled on coated and uncoated aluminum foil substrates were used to determine the particle cutpoint diameters of each stage (9.0-0.07 mu m aed), loss on walls (3-7% for 0.054 mu m particles), and overall efficiency (97% from 0.3 to 7 mu m). Quantitative measurements were made with a spectrophotometer after recovering aerosols with a water and surfactant solution and with a semiautomated particle counting system using phase contrast microscopy. The experimental cutpoints and mea sured interstage pressures compare well with theory.