Fisher Sub-Sieve Sizer

Refs 16, 28, 29 31) Microscope (Refs 20 27) Fisher Sub-Sieve Sizer (Refs 16 27) Cenco Photelometer (Refs 16 28) MSA-Whitby (Ref 25) Cintel Flying Spot Counter (Ref 20) Ro-Tap Siever (Ref 18) and Andreasen Pipette (Ref 31). The advantages most frequently observed were ... 

The detn of APD s between 100 and 500 microns can be made using a permeability app larger than the Fisher Sub-Sieve Sizer. This app, which was developed at PicArsn, uses a sample size of approx TO times the sample density (Ref 7a)... 

Permeability is another method for obtaining information about pcirticle diameters. If one packs a tube with a weight of powder exactly equal to its density, and applies a calibrated gas pressure through the tube, the pressure drop can be equated to an average particle size. The instrument based on this principle is called the "Fisher Sub-Sieve Sizer ". Only one value can be obtained but the method is fast and reproducible. The instrument itself is not expensive and the method can be applied to quality control problems of powders. Permeametry is usefiil in the particle range of 0.5 to 50 n. 

The volume-surface mean diameter, dsv, can be determined by permeamitry (e.g., Fisher Sub-Sieve Sizer) for a fine powder [41], It is given by... 

Allowable avg particle size range, detd in accordance with ASTM procedure B330 (Method of Test for Average Particle Size of Refractory Metals and Compounds by the Fisher Sub-Sieve Sizer) ... 

The average particle size of metal powders is determined by the Fisher sub-sieve sizer. The method uses air permeability to determine particle size. The method is designed for coarser metal powders having particle sizes in the range of 0.2 to 50 pm. The method should not be used for flakes or fibers. 

ASTM B 330-93. Average particle size of powders of refractory metals and their compounds by the Fisher sub-sieve sizer. 

Physical characterization of TBO includes particle size and size distribution measurement by laser diflraction (macroporosity) as well as specific surface area measurement (microporosity). Particle size measurement by FSSS (Fisher Sub-Sieve Sizer), as also sometimes used, is misleading, because of the porosity of the TBO particles. An empirical relationship between FSSS and particle size measured by laser scattering can, however, be detected if the microporosity of the samples is uniform (constant blueing conditions). 

Fisher Sub-Sieve Sizer. An air-permeability apparatus for the measurement of particle sizes between 0.2 and 50 pm. (Fisher Scientific Co., USA). 

Constant volume cells and the cell of the Fisher Sub-Sieve Sizer should be filled in one increment only. It is often advantageous to tap or vibrate such ceUs before compaction but if this is overdone segregation may occur. With other ceUs the powder should be added in four or five increments, each increment being compacted with the plunger before another increment is added so that the bed is built up in steps. This procedure largely avoids non-uniformity of compaction down the bed, which is likely to occur if the bed is compacted in one operation. To reduce operator bias a standard pressure may be applied (1 MN m-2). In order to test bed uniformity the specific surface should be determined with two different amounts of powder packed to the same porosity. Bed dimensions should be known to within 1 %. 

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