Development of a system to rapidly measure sampler penetration up to 20 mum aerodynamic diameter in calm air, using the aerodynamic particle sizer

Although the use of monodisperse aerosols to measure penetration through sa mpling devices results in accurate measurements, it is time consuming and e xpensive. Measurement methods using polydisperse aerosols are orders of mag nitude faster, but tend to be restricted to smaller particle diameters. Thi s is particularly the case with systems using the Aerodynamic Particle Size r (APS) in calm air, which are limited by poorly characterised aspiration e fficiency and low detection efficiency above approximately 10 mu m. By meas uring the aspiration of such a system in calm air, and introducing a virtua l impactor to act as an aerosol concentrator above 10 mu m, we have develop ed an APS-based penetration measurement system that may be used successfull y up to 20 mu m. Experimental errors (+/- 1 S.D.) are typically less than 2 0-25% at 20 mu m, reducing to below an estimated 10% at 15 mu m. Errors bel ow 10 mu m are of the order of a few percent. The system is ideally suited to the rapid and inexpensive development of size selective aerosol samplers with cut points below 15 mu m, and is capable of quantifying the performan ce of such samplers under calm air conditions. Crown Copyright (C) 1999 Pub lished by Elsevier Science Ltd. All rights reserved.