Particle size instrumentation

J.G. Day D.R. Dillehay, ibid, 277-285 3.0) D.E. Middlebrooks, S.M. Kaye, D.J. Edel-man G. Weingarten, Preliminary Evaluation of the Coulter Counter Particle Size Instrument , PATM 1054(1963) 31) J.A. Freitag, Four-... 

Process Raman Particle size instruments 2000s Chemical/petrochemical... 

The major disadvantage of the laser diffraction and electrical pulse counting techniques is that they are only directly applicable to dilute emulsions or emulsions that can be diluted without disturbing the particle size distribution. However, many food emulsions are not dilute and cannot be diluted, either because dilution alters the particle size distribution or because the original sample is partially solid. For concentrated systems it is belter to use particle-sizing instruments based on alternative technologies, such as ultrasonic spectrometry or NMR (Dickinson and McClements, 1996). 

Particle size and distributions can be determined by a number of different methods. The technique described here is light scattering. Different measurement methods produce different results which can be correlated experimentally. The absence of distribution standards for light scattering particle sizing instruments precludes any determination of size accuracy. This is further complicated by particles of non-spherical shape which makes the concept of size very difficult to define. However, for particulate materials encountered in most industrial processes, the assumption that particles are spheres produces quite useful results that are repeatable and relate to important parameters of many processes. 

Particle Sizing Systems (PSS) is a designer and manufacturer of particle sizing instruments that are used for research and development, USP quality assurance, contamination and in-line monitoring. 

Brookhaven 90 Plus sub-micron particle size instrument is a dual-angle instrument with measurements at 15° and 90° to generate size distributions in the 10 nm to 1 pm size range together with zeta potential determinations. 

FIG. 21-21 A typical on-line application with a representative sampler (TWISTER) in a pipe of 150-mm, which scans the cross section on a spiral line, and dry disperser with particle-sizing instrument (MYTOS) based on laser diffraction. Courtesy of Sympatec GmbH.)... 

Mean hydrodynamic diameters of vesicles (liposomes, nanospheres, nanobeads) can be determined by dynamic laser light scattering, e.g. the NICOMP 380 particle sizing instrument, Particle Sizing Systems (Sta. Barbara, CA, USA). 

The advent of single-cell measurements in flowing cell suspensions, first accomplished in the Coulter particle sizing Instrument has revolutionized the experimental characterization... 

In any discussion of particle size analysis techniques, it is important to re-emphasize several points made by McCave Syvitski (1991). During the past several decades, advances in particle size instrumentation have been so rapid that most electronic instruments are outdated by the time they are purchased. Similarly, it must be realized that most of the sizing instrumentation used by Earth scientists today was designed for different purposes and different areas of investigation (e.g., pharmaceutical sciences, medical research, paint... 

Coulter Counter A commonly used particle-sizing instrument employing the principle of electrical resistance. 

Table 12.3 lists some of the more common particle size instruments, together ivith their ranges and can serve as a reference guide for instrument and range... 

Thermal FFF (ThFFF) is driven by a temperature gradient where the channel is positioned between two highly heat conductive metal blocks that allow introduction of rapid and controlled temperature gradients. Particles and molecules in suspension or solution are generally driven towards the cold wall by thermal diffusion. No commercial particle size instrument based on this technique is currently marketed. However, FF Fractionation, Inc. does produce a Model T-KX) ThFFF suitable for molar mass determinations. 

H. Ulmke, T. Wriedt, and K. Bauckhage Piezoelectric droplet generator for the calibration of particle-sizing instruments. Chemical Engineering and Technology, 24(3), 265-268 (2001). 

This approach to measuring cluster size distribution is analogous to (although less sophisticated than) the way that most commercial laser diffraction particle-sizing instruments extract the particle size distribution from measured scattering data - the only real difference being the model for a single scatterer that is used. ... 

Modern particle size instruments have been designed to be easy to use. However, considerable additional skills and understanding is required before reliable results can be obtained. These skills include subsampling and dispersion of aggregates. The understanding of how to transport all the sizes of particles to the measurement zone without introducing bias and the avoidance of introducing additional, unwanted, artifacts such as dirt and air bubbles is also needed. 

Table 1 Principal features of particle sizing instruments in common use...

N. Chigier, Comparative measurements using different particle size instruments, in liquid particle size measurement techniques, ASTM STP 848, eds. by J. M. Tishkoff, R. D. Ingelbo, J. B. Kennedy (American Society for Testing and Materials, Philadelphia, 1984), pp. 169-189. ISBN 0-8031-0227-5... 

For many techniques, particle sizes are best obtained by suspending the particles in a fluid in which the particles are insoluble. The fluid can produce a suspension that is homogeneous in concentration and fairly uniform in size for introduction to the particle sizing instrument. Fluid suspensions also disrupt any cohesive forces that could lead to coagulation or agglomeration of the particles. The fluids chosen must be chemically inert toward the materials contacted in the instrument. 

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