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Particle Size: Exact Length and Breadth or just Equivalent Diameter?
Particle size analysis with the CAMSIZER XT records all the different particle characteristics. The example of cellulose fi bres shows that the distributions with regards to different dimensions of the particles can be analysed simultaneously. The graphic shows the results in relation to the thickness, the area equivalent of the circle diameter, and the length of the fi bres. Other measuring techniques, such as laser diffraction, only determine the equivalent diameter based on the assumption that the particle to be measured is spherical. By providing more detailed information on the particle, the CAMSIZER XT allows a much greater understanding of the particle.
homogeneous particle size distribution of round particles. In the granulation and coating processes, the formation of agglomerates is an unwanted side effect. Agglomerates can have a negative impact on product properties; they can lead, to changes in the release rate of the active ingredients. Therefore, the amount of agglomerates is usually strictly controlled for each product batch. The CAMSIZER is able to detect percentages of agglomerates as low as 0.05%. Neither laser diffraction nor sieve analysis are suitable methods to reliably determination of such small percentages. Particle shape is also an important factor in this context.
Elongated particles, for example, can’t be detected by either laser diffraction or sieve analysis.
Figure 3. Measuring cellulose fi bres with CAMSIZER XT Seeing is Believing: Analysis of Particle Shape
When measuring catalyst materials the amount of broken particles among the otherwise almost perfectly spherical particles is of interest. Broken particles can negatively infl uence the packing density of a catalyst and thus the fl ow characteristics in a chemical reactor. Non-round, broken particles can be easily detected with particle shape analysis. The width/length (b/l) aspect ratio or the symmetry parameters of broken particles differ considerably from those of spherical ones. The measurement sequence in Figure 4 shows how an increasing amount of broken particles is refl ected in the b/l diagram. The initial material is almost spherical with a b/l ratio of 0.95 (red curve). The increasing proportion of broken particles can be read off the amount at the threshold value 0.95.
Figure 5. The graphic shows the detection of oversized agglomerates by the CAMSIZER. Approx. 0.21 g of agglomerates, which is equal to about 10 particles, have been repeatedly added to a sample of 21 g to achieve mixtures in the range of 1% to 11%. The percentage of oversized particles at 0.7 mm exactly matches the calculated mixed percentages.
CAMSIZER XT: Dispersion Options and Modular Sample Feeding
The CAMSIZER XT is an advancement of the well-proven optical measurement system CAMSIZER for finer samples. In addition to the newly developed optics with a higher resolution it also features enhanced options for sample feeding. Fine particles tend to agglomerate which makes it difficult to detect the geometric dimensions of each individual particle. It is therefore beneficial to have various sample introduction options, to establish for each material, the best way to separate agglomerates without destroying the primary particles.
The CAMSIZER XT provides flexible solutions: The free fall X-fall cartridge, which provides the gentlest dispersion method for the material; the X-Jet air pressure dispersion cartridge with adjustable pressure and variable nozzle geometry; and finally, the X-Flow module in which particles are dispersed in liquids, optionally by an ultrasonic probe.
Conclusion Figure 4. Measuring catalyst materials with the CAMSIZER XT Every Grain Counts: Detection of Agglomerates in
the Production of Pharmaceutical Pellets The production of pharmaceutical pellets is typically done by granulation, extrusion with subsequent spheronisation or coating. The desired result is a narrow and
Instead of ‘calculating’ particle size distributions from indirect size measurements, the DIA method provides precise, direct information from each particle about its length, width and shape. In addition to the calculated and averaged numbers for the size distribution, the images of the particles are available to view the sample size and shape, like in a microscope.
Dynamic Image Analysis provides faster and more accurate information than the established methods and is therefore ideally suited for particle characterisation in research and development and quality control typical sample analysis times are between 1 and 3 minutes.
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New Quick 5-Point Flow Function Test Saves Time and Improves Quality
Brookfield is pleased to announce that the Quick 5-Point Flow Function Test is now integrated into Powder Flow Pro Software, version 1.3 (build 23). This quick new test can be accomplished in about 16 minutes as compared to the Standard 5-Point Flow Function Test which takes about 25 minutes to complete. This considerable reduction in time allows for more rapid QA/QC checks on production powder batches.
The predecessor to this test was the Quick Standard 2-Point Flow Function Test which only provided data for the lowest and highest consolidated stress values.
The 5-Point Test provides the operator with five predefined consolidation stress measurements. These five points of data are then used to provide a more accurate representation of the powder’s flow characteristics, through a hopper or feeder system. This allows manufacturers to predict potential flow problems before they occur and make necessary adjustments to improve production and product quality.
Free sample testing is available from Brookfield and authorised dealers to illustrate the comparative data from the Quick Test and the Standard Flow Function Test.
29957pr@reply-direct.com
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