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

Stefan Horender,Kevin Auderset,Konstantina Vasilatou

doi:10.1063/1.5095853

Stefan Horender, Kevin Auderset + Show 1 more

Open Access

https://doi.org/10.1063/1.5095853

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Abstract

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).

Highlights

Optical particle counters (OPCs) are increasingly used in cleanrooms for monitoring the number concentration of airborne particles
It can be seen that the characteristics of the mean velocity and its fluctuations were captured well in the simulations for all three positions downstream of the mixing jets
By comparing panels (b) and (c) of Fig. 3, it can be seen that the boundary layer thickness increases with downstream position, the boundary layer being defined as the distance from the wall to the point where velocity reaches 90% of its centerline value

Summary

Introduction

Optical particle counters (OPCs) are increasingly used in cleanrooms (e.g., in semiconductor industries and medical and pharmaceutical environments) for monitoring the number concentration of airborne particles. A cleanroom is an enclosed and highly controlled space in which airborne particles, contaminants, and pollutants are kept within strict limits. Cleanrooms are used in manufacturing and servicing of hardware, such as integrated circuits and hard drives. In biotechnology and pharmaceutical sciences, cleanrooms are used to minimize the presence of bacteria, viruses, and other pathogens. Contamination can compromise severely the quality of the (manufactured) products or processes, lead to disease spreading in hospital environments, or aggravate the health of industry workers.. The development of accurate calibration procedures for OPCs is highly important Contamination can compromise severely the quality of the (manufactured) products or processes, lead to disease spreading in hospital environments, or aggravate the health of industry workers. the development of accurate calibration procedures for OPCs is highly important

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