Simplified Measuring Method of Particle Size Distribution by Using Cascade Impactor

Hongo Syozo, Ohata Tsutomu, Suzuki Masashi, Yanagi Yoshiro

doi:10.4164/sptj1964.8.3

In order to establish a practical method of measuring the aerodynamic size distribution of any aerosol sample collected by a 4 stages cascade impactor, the theoretical consideration and calculation of collected proportion of particles by using a computer were attempted on the basis of the theory of Ranz & Wong and the assumption on the log-normal distribution for aerosol samples, for 345 kinds of particle size distributions having 23X15 paramaters.<br>In the calculation, the approximation to the partial collection efficiency for each stage of cascade impactor was introduced for simplifying the calculation and for applying the method easily to any type of cascade impactors.<br>The result from the calculation was arranged by relative quantities of collected particles on each stage and indicated as a ready-reckoner. In practice, we can obtain the geometrical-mean-diameter (Da₅₀) and the geometrical standard deviation (σ) of a given sample of aerosol, by measuring the collected quantities of the aerosol on each stage of cascade impactor (particle number, mass, activity etc, of the collected sample) and by searching the best fitness of the values to the one among 345 kinds of size distribution which were calculated by the computor in advance. This procedure could be easily accomplished by using the ready-reckoner above-mentioned.<br>As actual size distribution of many aerosols are said to be subjected to the log-normal distributions, the method above-mentioned is considered to have enough accuracy in practical used and to obtain better approximation for particle size distributions in general.

Simplified Measuring Method of Particle Size Distribution by Using Cascade Impactor

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