Sizing Technique of Water and Salt-water Solution Droplets: NGB (Dye)-gelatin Film Method

Abstract

A Naphthol Green B (NGB) dyestuff gelatin film, coated on a slide glass, can be used for determining the size distributions of water or salt-water solution droplets. The stain sizes that remained after the evaporation of droplets that impacted a slide glass, are calibrated by using the solid particle tracer method, the silicone oil film method and the two-stages cascade impactor. The following results are obtained experimentally: 1) The calibration results using these three different methods agree well with each other, and the diameter of the droplets are 0.54 times the diameter of the stains, on the average; 2) The value 0.54 is almost independent of the droplet diameters, the concentration of NGB dyestuff and the velocity of the approaching droplet velocity within the experiment range; 3) The value of the ratio for 4% salt-water solution droplets is almost the same as that of water droplets; and 4) The best composition of gelatin sol is 10ml of distilled water, 0.5g of NGB dyestuff and 0.6g of dried gelatine.