The authors, in 1975, developed the Chain System Sedimentation Balance for the analysis of particle size distribution of powder. They later developed the Electromagnetic Sedimentation Balance (ESB) which is an improved version of the above apparatus. The present paper describes the outline and reproducibility of measurement by the ESB.
(1) The ESB has a maximum weighing load of about 5g and weight detection sensitivity of 0.1mg, and equiped with a small, light weighing pan for the particle size distribution analysis.
(2) Since the weighing pan is small, the buoyancy acting on it in suspension is correspondingly small.
(3) In order to prevent the effect of the room temperature variation, heat transfer from the room to the balance box was cut off by covering the apparatus with a styrene resin plate containing air bubbles. The zero point of the balance was maintained constant for a long period during the measurement.
(4) Particle size distribution analysis of quartz powder was repeated 10times. The particle size distribution curves obtained by the ESB and the Chain System Sedimentation Balance agreed with each other very well.
(5) For high reproducibility of the measurement, a reduction of the variation of the measurement in the large particle size region is advisable. This purpose could be attained by making the falling distance of the particles long enough in order to enable the obtention of a straight line at the begining of the sedimentation curve.
(6) The ratio of the weight of the suspended solids which actually settled on the weighing pan to that of the ideal weight was calculated. This ratio,
n%, was 77.0±3.3 and 66.0±3.0% for short (8cm) and long (24cm) falling distances of the particles respectively. It would therefore mean that about 11% of the particles missed settling on the weighing pan in the case of the long falling distance.
抄録全体を表示