Development and testing of an automatic Beta gauge particulate sampler with filter cassette mechanism
A new beta gauge particulate sampler with filter cassette mechanism instead of conventional filter roll has been developed for automatic measurement of mass concentration of PM{sub 10} particles in the ambient air. By utilizing filter cassette mechanism the instrument can be automatically calibrated with two self-calibration mass standards during each sampling period and sample particles continuously without any dead-time loss. New design features of the beta gauge particulate sampler include filter cassette mechanism, auto-calibration system, very low sampling dead-time, high sensitivity, and straightforward audit procedures. The beta gauge particle sampler consists of three main components: PM{sub 10} inlet system, mechanical system, and control and data processing system. A PM{sub 10} inlet was designed based on a particle trap impactor operating at a sampling flow rate of 25 l/min. The mechanical system includes particle collection system with filter cassettes and movement control system, auto-calibration system, and flow control system. Movement of filter cassette is controlled by three stepping motors in the x, y, and z directions. The filter carrier is designed to accommodate up to twenty filter cassettes including two calibration films. Optoelectronic sensors mounted on each floor of the filter carrier are used to verify the existence of the filter cassette. The beta radiation measurement section consists of a 100 {micro} Ci{sup 14}C source and a solid-state semiconductor detector having a count rate greater than 10{sup 5} counts/sec. Two calibration mass standard foils of known mass are used to the auto-calibration purpose in order to minimize the effect of long-term drift. The sampling flow is controlled by a critical orifice to a volumetric flow rate of 25 l/min. The control and data processing system software performs filter movement control, sampling pump control, and data analysis.
- Research Organization:
- Kwangju Inst. of Science and Technology (KR)
- OSTI ID:
- 20002080
- Report Number(s):
- CONF-990608--
- Country of Publication:
- United States
- Language:
- English
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