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How to pick a particle analyzer. (Lab Equipment).

Particle size analysis is an important tool in characterizing a wide range of performance factors. Selecting the most appropriate instrument for a given application depends on a number of variables. The user must determine those factors that are most important for their application when considering the multitude of alternative particle sizing techniques.

Particle size analyzers range from the historical sieve to modem automated light scattering instruments. The most appropriate selection for a particular application depends on a number of factors including the size range of interest, nature of the sample, the information required from the analysis, sample throughput, and price.

Modern light scattering instruments are becoming the particle analysis method of choice in most industries due to their analysis speed (approximately 30 sec), wide size range, ease of use, flexibility, and reproducibility. Their higher cost is balanced by their greater productivity than other methods and tighter control on production processes.

Developments in digital image processing analyzers have extended the measured size range to 30 mm or larger. These instruments offer the same benefits as light scattering, with the addition of particle count and shape information, which becomes a greater influence on product performance with larger particles.

Size analyzers based on a sedimentation principle continue to be sold, including both centrifugal and gravitational sedimentation. Due to the simplicity of the technique, the analyzers are generally lower priced, although the longer analysis times and limited range are offsetting factors.

Sieve analysis, the oldest particle sizing technique, remains very common, again due to lower cost and the simple approach. Limited resolution (determined by the number of sieves), reproducibility, and speed of analysis limit the capability, but it also has the benefit of separating the various size classes if necessary for further analysis.

Particle counting techniques, using either optical or electrical resistance sensing methods, are used where the number of particles in a given size range is important to the final product performance.

Particle Size Analysis: An analytical technique by which the distribution of sizes in a sample of particulate material is measured. Numerous analytical techniques exist for particle size analysis.


--Duncan Griffiths

Griffiths is product specialist at Horiba Instruments Inc.

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Author:Griffiths, Duncan
Publication:R & D
Article Type:Brief Article
Geographic Code:1USA
Date:Jun 1, 2002
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