くさり天秤を用いた粉体粒度分布測定法における測定の再現性について

抄録

The authors, in 1975, developed the chain system sedimentation balance for the analysis of particle size distribution of powder. The present paper discusses the accuracy of measurement by this apparatus.
(1) The influence of room temparature variation appeared as a variation of the weight. It was revealed that this phenomenon is caused by air convection around the hanging wire of the weighing pan in the balance box. In order to prevent this effect, heat transfer from the room to balance box was cut off by covering the apparatus with a styrene resin plate containing air bubbles. The zero point of the balance is maintained constant for a long period of measurement.
(2) By using heavy and light types of the weighing pan, particle size distribution analysis of quartz powder was repeated 10 times for each type under the same conditions. The particle size distribution curves obtained by the two type pans agreed with each other very well. For better agreement of the results, it is better to reduce the discrepancy between the distribution curves in the large particle size region.
(3) The ratio of the weight of the suspended particles which will actually settle on the weighing pan to that of the ideal weight was calculated. This ratio (n%) represents the index of accuracy of the measurement. In this experiment, n% was obtained as 79.6±1.9 and 76.7±3.3% for the Heavy type and Light type weighing pans respectively.