(70b) New Measurement of Particle Size Distribution by Bouyancy Weighing Method

The principle of the Bouyancy weighing method as well as the sedimentation balance is the determination of the rate at which particles settle out of a homogeneous suspension. It is not easy to make a handmade product of the sedimentation balance, but easy to make a handmade weighing bar for measuring the particle size distribution (PDS). Five weighing bars were made of stainless-steel, copper, aluminum, glass and PMMA. The measuring bars were 9 mm diameter and 200 mm length. The weighing data obtained via an electronic balance can be controlled by connecting a personal computer with RS232C terminal. Except for the bar of PMMA, the PSD by four kinds of bars agreed well with the data obtained by the Andreasen analyses and the sedimentation balance. The samples of test powder were Sample No.4(Talc), Sample No.10(Flyash), Sample No.3(Silica sand) and Sample No.16(Calcium carbonate, Heavy) standardized by Japanese Industrial Standards. NaPP and NaHMP were used as dispersing agents.