Line start sedimentation

Fig. 2.6 Principles of differential sedimentation (line-start technique) and integral sedimentation (homogeneous technique) the former is employed for disc centrifuges, the latter for cuvette centrifuges below the corresponding time-curves of local particle concentration...

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

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]. 

Figure 30. Typical particle sedimentation pattern in line-start and homogenous gravitational sedimentation tests.

F. 2.8 Impact of diffusion on the concentration profiles in sedimentation experiments for a monodisperse particle system left homogeneous technique, right line-start technique... 

Two basic suspension systems, the line start system (or the two-layer sedimentation system) and the initially homogeneous system are employed in the gravity sedimentation technique. In the Kne start system, a thin layer of particles is placed at the top of the sedimentation column, and its settling behavior is analyzed by different techniques. In the initially homogeneous system, the column is homogenized first and its settling pattern is subsequently studied. 

Line Start Methods of Sedimentation Fineparticle Size... 

Figure 4.7. Stokes diameter distribution data obtained for line start sedimentation of a glass powder performed at various concentrations, a) Data for a water suspension floated onto a water column, b) Data for a water suspension placed on a brine column.

Figure 4.9. The Micromerograph system uses a short burst of pure nitrogen gas to create a well dispersed cloud of the sample powder which forms what is essentially a line start sedimentation system, a) Appearance of the Micromerograph system, b) Comparison of several system with data for the Micromerograph.

The first line start sedimentation procedure based on centrifugal sedimentation was described by Marshall [46], who was aware of the problems involved in floating a layer of suspension onto a column of clear fluid because of reported difficulties with the Werner sedimentation tube discussed in the previous section. He attempted to achieve a stable suspension system by using a suspension of lower density than the liquid column through which the fineparticles were to be sedimented. He used a sucrose solution for the column fluid and a water-based suspension of fineparticles. This strategy as discussed earlier only eliminates gross inversion of the layer of suspension. 

Figute 4.10. A basic photocentxidisc, as used to perform line start sedimentation smdies, has a thin layer of suspension added onto the free surface of the fluid in the spinning disc, a) Appearance of the photocentridisc. b) Side view of the equipment showing the suspension layer, c) Typical signal output from a photocentridisc. 

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