Development of an automatic beta gauge particulate sampler with filter cassette mechanism

Abstract

A beta gauge particulate sampler for measuring the aerosol mass concentration in the ambient air is described. The instrument is automatically calibrated with two self-calibration mass standards during each sampling period, while it samples particles continuously with minimum sampling dead-time loss. Key design features of the instrument based on the attenuation of beta radiation include filter cassette mechanism, auto-calibration system, low sampling dead-time, high sensitivity, and straightforward audit procedures. The instrument consists of three main components: PM10 inlet, mechanical filter movement system, and control and data processing system. The mechanical filter movement system includes particle collection system with filter cassette magazine, β-ray measuring module and particle sampling module, auto-calibration system, and flow control system. The control and data processing system performs filter cassette movement control, sampling pump control, and data analysis. The instrument has been tested in the field to compare the measurement results with those by gravimetric mass measurement. The developed beta gauge instrument has been proved to be an efficient measuring gauge for the ambient particulate mass determination.