Particle size measurement with an improved sedimentation balance method and microscopic method together with computer simulation of necessary sample size

In order to confirm reliable particle size measurement and to prepare stand ard reference particles, experimental and theoretical studies have been con ducted on the particle size measurement of three kinds of spherical glass b eads. Revised-type sedimentation balance and microscopic methods with sampl e sizes greater than 10 000 were used for the measurement. The particle siz e distributions obtaine using the improved sedimentation balance and micros copic methods are nearly equal for the three kinds of glass beads. However, in the case of large particle diameters, particle sizes measured by the im proved sedimentation balance method are larger than those obtained by the m icroscopic method. The reason for this is due to the fact that particles gr eater than about 50 mum settle too fast in a sedimentation bath. In the cas e of the microscopic method, variation of the evaluated mass median diamete r decreases with the increase in sample size. The results of numerical simu lation agreed with the analytical solution propose by Masuda et al. For the improved sedimentation balance method, it is desirable to disperse particl es completely. At the beginning of measurement, it is recommended that a di spersing agent is pasted on the test particles directly and then the slurry solution is mixed in a dispersion bath with supersonic vibration.