Facility for calibration of optical and condensation particle counters based on a turbulent aerosol mixing tube and a reference optical particle counter

In this study, we present a custom-made facility developed for evaluating the measurement efficiency of optical particle counters and other common aerosol instrumentation. The facility consists of an aerosol generation setup, a turbulent flow tube for particle homogenization, isokinetic sampling ports, and a home-built particle counter that serves as a reference instrument. Stable and reproducible aerosols of polystyrene latex particles can be produced in the size range 100 nm–10 μm and at concentrations between 0.5 cm−3 and a few thousand submicron particles per cm3 or a few tens of 10 µm particles per cm3. The flow characteristics in the homogenizer were investigated with laser Doppler velocimetry measurements and computational fluid dynamics simulations indicating a plug (turbulent) flow at the aerosol sampling location. The particle mixing characteristics were determined experimentally at various heights of the flow tube by parallel measurements with two condensation particle counters. A spatial homogeneity within 1.1% was found across the sampling area. The measurement uncertainties in the determination of the particle number concentration have been evaluated in detail and amount typically to 5.4% at 1 cm−3 and 2.1% at 100 cm−3 (95% confidence level).In this study, we present a custom-made facility developed for evaluating the measurement efficiency of optical particle counters and other common aerosol instrumentation. The facility consists of an aerosol generation setup, a turbulent flow tube for particle homogenization, isokinetic sampling ports, and a home-built particle counter that serves as a reference instrument. Stable and reproducible aerosols of polystyrene latex particles can be produced in the size range 100 nm–10 μm and at concentrations between 0.5 cm−3 and a few thousand submicron particles per cm3 or a few tens of 10 µm particles per cm3. The flow characteristics in the homogenizer were investigated with laser Doppler velocimetry measurements and computational fluid dynamics simulations indicating a plug (turbulent) flow at the aerosol sampling location. The particle mixing characteristics were determined experimentally at various heights of the flow tube by parallel measurements with two condensation particle counters. A spatial homog...