Mass frequency undersize determination

3 DuPont/Brookhaven scanning x-ray disc centrifugal sedimentometcr (DI-XDC) (S constant, r variable, I varh 

This instrument was developed as a centrifugal version of the Allen and Svarovsky s [13] x-ray gravitational sedimentoineter in order to reduce the analysis time and measure down to smaller sizes [14,1.5]. fhe x-rays are generated by an air cooled low power x-ray tube and, after passing through the suspension, they are detected by a scintillation counter. The signal is 

This instrument was designed [16] to fill a need for fast, reproducible sedimentation analyses in the sub-micron size range. The heart of the instrument is a hollow, x-ray transparent, disc which, under normal operating conditions, contains 20 ml of suspension at a concentration of around 0.2% by volume. The centrifuge speed is selectable in the range 750 to 6000 rpm. The default condition is for the source and detector to remain stationary for 1 minute at a radial position of 48.00 mm and then to scan towards the surface. Total run time is normally 8 min. 

A computer controlled particle size measurement device with veiy high resolution was presented by Foerdeneuther [18] based on the Brookliaven optical and x-ray disc centrifuges. 

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Centrifugal sedimentation methods 415 8.6.4 Mass frequency undersize determination... 

Follow a procedure similar to that of Example 2.4, in order to elaborate a histogram, a frequency curve, and an undersize cumulative percentage graph, and determine the median size of the powder (note that the particle size distribution obtained will be by number, while in Example 2.4 the particle size distribution obtained was by mass). 

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