Miscellaneous Items

Abstract

The volume median diameter (vmd) of a spray deposit is normally found by converting the drop diameters to their cubes, finding the total volume of the drops and thence the cumulative percentage volume of the drops. The results are plotted against drop diameter to determine the drop size corresponding to the 50% volume. Using the most concise mathematical method such an operation takes half an hour. Using a simple graphical method the vmd can be estimated with the same accuracy in approximately five minutes. The method of drawing the necessary cube curves and their subsequent use are described. Ways of avoiding unnecessary measurement of small drops are also discussed.