Facility for aerosol monitoring instruments (ManDust): design and fabrication of a versatile diffuser tower with isokinetic sampling probes

Abstract There is a growing demand for a flexible, precise calibration facility for aerosol monitoring instruments. This study investigated ManDust1, an aerosol calibration facility that is compatible with a variety of different operating principles. The facility comprises four systems: (a) a clean air supply system, (b) an aerosol generator system, (c) a diffuser tower, and (d) a sampling system. A compact and modular diffuser tower provides turbulence flow to homogeneously mix the injected aerosol before collection by custom-made isokinetic sampling probes. The velocity profile in the diffuser tower was computed and measured to be turbulent, generating a well-mix aerosol condition with spatial homogeneity of 4.38% across all sampling locations. A computational fluid dynamics (CFD) simulation conducted to confirm the dimension of the facilty was able to generate turbulence flow and mixing. The facility stably provided aerosols from 0 to 10 µm with variable concentrations from a few µg/m3 to 1000 µg/m3. The uncertainty budget in this study was calculated to be 5.98% when the facility was operated at 600 µg/m3 (95% confident level), and span drift was calculated to be 3.15% after 120 h of measurement.