Kyo Suda

Correlation between the concentrations of polynuclear aromatic hydrocarbons and those of particulates in an urban atmosphere.

The new technique for preparation of gases of a known concentration presented here makes it possible to prepare gases for environmental measurements and studies. The apparatus and operations of this technique are simple. The stability of the concentration of gas generated from the generator is excellent and the generation sustains for several hours a t least. The concentration varies to a smaller extent with changes in temperature and air flow rate than with the permeation tube technique. The prepared gas contains some water vapor which is preferred for experiments meant to simulate the real atmosphere. In this paper, SOz, NO, NOz, HCN, HzS, and NH3 gas generation was described, but other gases such as hydrogen fluoride and carbon dioxide can also be prepared by the same technique.

Instrumentation for the size determination of submicron particulates systems by sideway light scattering method

A new submicron particle counter using a low output He–Ne laser (unpolarized, 8 mW) is proposed for in situ measurement of particulates. The design is based on calculations and experimental checks of factors governing the signal‐to‐noise ratio. Right angle scattering is found to be the most suitalbe optical system for eliminating miscellaneous noise and fundamental noise components derived from the carrier gas. The present version of the instrument with nine channels is constructed so as to minimized the noise level by reducing the sensing volume. This instrument can actually measure correct size distributions from 0.1 to 10 μm without detectable coincidence loss, at environmental particulate concentrations of up to 5×104/cm3.

Portable optical particle (0.06 μm) counter

An improved portable optical counter, using a He–Ne laser with 8 mW output, measures particles ranging in size from 0.06 to 10 μm in diameter in situ.

Characterization of smokes from flame-retarded plastics on the basis of the size distribution of particulates

Abstract The characterization of the behaviour of smokes from several flame-retarded or slow-burning plastics was pursued on the basis of the size distributions of particulates in the smokes or their time-dependent changes. The sizing instrument was a Hitachi TSI 500 type optical counter with HeNe laser as the light source, and the range of the size fractions was from 0.1 to 10 μm in terms of channel isolation by nine steps. Halogens from the flame retardant seemed to decelerate the coagulation of smokes accimulated in the smoke box, while they worked as an accelerator to produce bigger particulates in the nascent state. Phosphates acted as a strong accelerator for the coagulation of smokes from phenolic laminates. It was recognized on the basis of the pattern in the size distribution that the thick smokes from polyurethane and ABS resin came from the formation of the bigger diameter particulates by the coagulation of the sooty particulates owing to the lack of oxygen in their combustion. In addition, the time-dependent changes of the turbidities of smokes were pursued in terms of the volume surface diameters of their size distributions.

Size determination of submicron particulates by optical counter using laser and characteristics of smoke from polymerized materials

Abstract A handy and transportable submicron level optical counter was developed for the in situ measurement of aerosol systems even at high concentrations. The counter has a low output HeNe laser light source (unpolarized, 8 mW), a sideways light scattering system at right angles with a solid angle of light collection of 0.5 steradian, and a 9-channel counting system which can cover the particle size range from 0.07 μm to more than 10 μm at m = 1.60. A high concentration measurement can be achieved up to 1 × 10 13 particulates/m 3 on the basis of an equation derived for the first order correction of the coincidence loss and cross-channel sensitivity due to the counting loss, while the critical concentration of the instrument with a low coincidence loss can ordinarily reach 5 × 10 10 particulates/m 3 . When applied to the measurement of polypropylene smoke, a good coincidence was obtained between the scattering cross-sections from the observed turbidities and those calculated from the size distribution after the correction of the coincidence loss etc. On this basis, the turbidities of several smokes and their stepwise coagulation are characterized by the change in their size distributions.