Abstract
Characteristics of the Digital Dust Indicator were examined, and the following equation was derived to express the response R of it, R=Kσ(C/P)exp.[-θ(C/P)] where K is the constant, σ is the relative scattering coefficient of dust, p is the dissipa-tion coefficient of dust particles, θ is the linear function of the extinction coefficient of particles and C is the mass concentration of dust.
And usefulness of this equation was examined experimentally.
It was found that values of p were proportional to product of density and meandiameter of particles. Regarding values of θ, almost the same values were obtained for all samples tested regardless the difference in particle size and colour or dusts.
Calculated values of Kσ obtained for various dusts vary with colour of dust.
From these experiments, it was proved that the equation was sufficiently useful toexpress the relation between the dust concentration and the response of the Digital Dust Indicator.
The practical method to evaluate the dust concentration in air by the Digital Dust Indicator was discussed.
