抄録
The portable Digital Dust Indicator was improved. The size of improved apparatus was 204 × 130 × 84mm, and its weight was about 2.5kg. As the electric power, 6 dry cells were used for the required power of 1.5 watt.
The response of one pulse per minute corresponded to the dust concentration of 0.05mg/m3 for usual mineral dusts. It was possible to estimate by this apparatus the dust concentration from 0.05mg/m3 to 500 mg/m3.
The relation between the response of apparatus and the dust concentration was expressed by the equation R= AC/p0.6
Some different points of this equation from the expression derived for the other type of Digital Dust Indicator (Type A or S) were discussed.
The optical maze provided at the position of air-inlet of this apparatus truncated the particles larger than 20μ in Stokes diameter.
The estimating method of the mass concentration of dust particles under 5μ in Stokes diameter was demonstrated.
