For the purpose of measuring particle size distributions, we have developed a new apparatus consisting of an imbalance measuring unit with a rotor and a personal computer.
The imbalance of the rotor caused by the centrifugal sedimentation of the particles in the cell installed in it was detected with the mechanism of the balancing machine and gave the particle size distribution with the aid of the computer.
Some test measurements were carried out with this apparatus under the following condition. The rotation of the rotor was increased linearly before a set time Tc, After Tc it was set at a constant revolution during the operation.
This was done in order to shorten the settling time of the particles and to extend the measuring size range.
The result obtained with the changing rotation gave similar distributions to those with a constant rotation using the same method previously reported by the authors.
Finally, a comparison with other measurements showed that the results were in good agreement with the sedimentation balance and were finer than the electric resistance and the photo extinction method.