Line-start cumulative gravitational sedimentation

If the powder is initially concentrated in a thin layer floating on the top of a suspending fluid, the size distribution may be determined by plotting the fractional weight settled against the free falling diameter. 

Marshall [77] was the first to use this principle. Eadie and Payne [78] developed the Micromerograph, the only method in which the suspending fluid is air. Brezina [79,80] developed a similar water based system, the Granumeter, which operated in the sieve size range, and was intended as a replacement for sieve analyses. 

The Werner and Travis methods [81,82] also operate on the layer principle but their methods have found little favor due to the basic instability of the system a dense liquid on top of a less dense liquid being responsible for a phenomenon known as streaming in which the suspension settles en masse in the form of pockets of particles which fall rapidly through the clear liquid leaving a tail of particles behind. 

The line-start technique has also been used to fractionate UO3 particles by measuring the radioactivity at the bottom of a tube, the settled powder being washed out at regular intervals without disturbing the sediment [85]. 

1 Allen, T. (1990), Particle Size Measurement, Chapman Hall, 4th ed., 360, 388 

---

Line-Start,incremental, gravitational sedimentation Line-Start,cumulative, gravitational sedimentation... 

Figure 6 Line Start, Cumulative Gravitational Sedimentation...

---