Particle size measurement sedimentation balance

CAHN RG ELECTROBALANCE/SEDIMENTATION ACCESSORY. This app produces a continuous, visible chart record of the sediment weight collected on the balance pan. It has been evaluated for measuring particle size distributions of the primary expls Lead Styphnate, Lead Azide, Tetracene by Hutchinson (Ref 41). 

The hydrostatic pressure results from the weights of the continuous and dispersed phase and can, thus, serve as a measure for the particle mass or volume concentration. In the context of analytical sedimentation, it was already utilised by Ostwald and Hahn (1922), who quantified the rate of sedimentation of flocculated suspensions by means of a hydrostatic pressure gauge. More recent papers report on the manometric determination of the hydrostatic pressure in analytical cuvettes centrifuges with electronic pressure transmitters (Bickert 1997 Beiser 2005). In contrast to the detection systems portrayed above, these manometer centrifuges do not measure a local particle concentration, but the total mass of all particles that are suspended above the point of measurement. The cumulative function of the volume weighted size distribution (gsfxstokes)) can be, thus, computed liom the time derivative of the hydrostatic pressure. In that regard, the manometric detection shows similarity to the sedimentation balance. 

The interaction of fineparticles in a suspension has been reviewed in detail in Reference 1 B. H. Kaye and C. R. G. Treasure, The Thermal Stability of Sedimenting Suspensions Used to Measure Particle She.Distx sxdxotxd, Materiak Research and Standards, 5 11 (1965). R. Davies and B. H. Kaye, The Effect of Cluster Instability in Suspensions and Particle Size Analysis Measurements with the Cahn Balance Particle Size Analysis Conference 1970, Bradford University, British Society for Analytical Chemistry, London. 

Children. For particle sizes between 1 and 3 pm, deposition under ventilatory conditions of rest and light exercise was measured in 41 children by Bec-quemin et al. (212,213). Exercise caused per-breath deposition of 1-pm particles to decrease from about 20 to 15%, whereas the deposition of 2- and 3-pm particles was almost unaffected. Because the higher ventilatory demand under light exercise was accomplished mainly by an increase in breathing Irequency, respiratory flows were increased, but the residence time of particles in the respiratory system was shortened. This caused 1-pm particle deposition, which is mainly governed by sedimentation, to decrease. It appears that, for 2- and 3-pm particles, the decreased deposition probability by sedimentation was balanced by an increased effect of impaction, so that total deposition remained imaffected. Therefore, it may be speculated that regional deposition was affected with a partial shift in... 

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