Abstract
For development of an on-line system to monitor the quality of ultra-pure water, a new technique is proposed and experimentally studied. In the technique, water is atomized and promptly evaporated using hot (70°C) and clean (filtered to remove d> 0.1μm particles) air. Then the particles derived from the evaporated water droplets in the clean air are counted by a laser dispersion-type air-borne particle counter. In this way, the concentration of impurities (T : total solid) is obtained using the volume of measured particles.
The results are summarized as follows.
(1) By using NaCl as a simulated impurity, residue after evaporation could be measured satisfactorily by this technique.
(2) Water qualities in an ultra-pure water production line could be estimated by using this technique.
(3) Relationships between the TS value determined by the new technique and resistivity, TOC and SiO2 values obtained by a conventional technique were satisfactory, and TS provided a good estimate of total impurities.
