Abstract
A β-ray attenuation type dust monitor was developed for continuous measurement of mass concentration of stack dust. The dust monitor has the isokinetic sampling system using microcomputor, the abatement system for dust deposition inside of the sampling nozzle by in jection of heated sheath air, and the compensation system for gas adsorption. Comparison of mass of dust collected on the filter between β-ray attenuation type dust monitor using Pm-147 and microbalance showed a good agreement with little error. Dust deposition inside of the 90 degree bend of sampling nozzle was decreased from 15 to 5% by heating sheath air from 25 up to 110°C and also decreased from 10 to 2% by flow rate of increasing sheath air from 7 to 12l/min. The measurements by the, β-ray attenuation type dust monitor showed a good agreement with those by the manual gravimetric method by JIS Z 8808, especially in the low concentration range below about 100mg/m3N.
