Sieve analysis

Table 4. Sieve Analysis for CaCl2 Commercial Grades, Mass %, Passing ...

In the United States, a number of physical tests are performed on siUcon carbide using standard AGA-approved methods, including particle size (sieve) analysis, bulk density, capillarity (wettabiUty), friabiUty, and sedimentation. Specifications for particle size depend on the use for example, coated abrasive requirements (134) are different from the requirements for general industrial abrasives. In Europe and Japan, requirements are again set by ISO and JSA, respectively. Standards for industrial grain are approximately the same as in the United States, but sizing standards are different for both coated abrasives and powders. 

Sieving Methods and Classification Sieving is probably the most frequently used and abused method of analysis because the equipment, an ytical procedure, and basic concepts are deceptively simple. In sieving, the particles are presented to equal-size apertures that constitute a series of go-no-go gauges. Sieve analysis presents three major difficulties (1) with woven-wire sieves, the weaving process produces three-dimensional apertures with considerable tolerances, particularly for fine-woven mesh (2) the mesh is easily damaged in use (3) the particles must be efficiently presented to the sieve apertures. 

The Sauter mean is often used in sieve analysis, and in situations in whieh the surfaee area is important, e.g. mass transfer ealeulations, ete. 

The resulting sieve analysis data are normally expressed initially as either... 

A quantity of sodium bicarbonate crystals has the following sieve analysis... 

Particle Size Distribution by Sieve Analysis , MIL-STD-1233 (1962) 22) S.M. Kaye, D.E. 

Powdered Teflon for use in pyrots is covered by US Mil Spec MIL-P-48296IPA) (1 May 1974), Polytetrafluoroethylene (TFE) . Three classes of material are specified (1,2 3). The requirements are purity, 99.4% min infrared spectrum, peaks consistent with figure shown color, TFE shall be opaque and the color shall range from white to gray moisture, 0.05% max ash, 0.1% max mp, 337° 10°C packing density, Class 1 — 1.18 0.13g/cc, Class 2 - 1.25 0.02g/cc, Class 3- 1.14 0.09g/cc particle size by sieve analysis, Class 1 — 95 15 microns, Class 2 — 237 27 microns, Class 3 — 200 30 microns particle size distribution by sieve analysis, as specified in Table 1... 

Table 4,16. Sieve Analysis on Powder Samples from Two Vendors for Details, see Text... 

The sieve analysis notation changed at some point in time, see batches 1, 23 and 24 in columns N-P, lines 19 and 21 The >45 y m value shifts from =92 to =7%. The customer had requested an additional specification <106 fim , which explains the row of dashes in line 19 up to column A an appropriate footnote should have been inserted. In connection with this, the specification in line 21 was changed from >45 to <45 correspondingly, all values had to be converted by hand, e.g., 93 = 100 - 7. (See table Step 1.)... 

In table Step 1 it becomes apparent that 8 rows of data contain no information or information that cannot be interpreted (TLC, heavy metals, chloride, residual solvents C, D, and E) and 4 where further clarification is needed (Sieve analysis (as above), HPLC impurities (changing LOQ )). 

Figure 4.41. Trend analysis over 12 batches of a bulk chemical. The sieve analysis shows that over time crystals larger than 250 /urn were reduced from a weight contribution in the range of a few percent of the total to about 1% in favor of smaller sizes. Impurity C appears to follow the trend given by the lead compound for the competing side reaction 1. The very low moisture found for sample 3 could be due to a laboratory error because during drying one would expect ethanol to be driven off before water. Methanol is always below the detection limit.

The classical approach for particle size determination, or more correctly for particle size selection - which is still used for solids like soils, sediments and other technical materials like coal, and also for biological materials - is sieving analysis. The raw material is milled, generally after drying, see Section 2.1, and if the required particle size is obtained, typically ranging from <0.1 to a few mm, it is allowed to pass sieves with different apertures to discard coarse particles and remaining materials. For materials consisting of numerous different particles microscopical inspection is used. 

Hunt G. and Nashabeh W., Capillary electrophoresis sodium dodecyl sulfate nongel sieving analysis of a therapeutic recombinant monoclonal antibody a biotechnology perspective, Anal. Chem. 71, 2390,1999. 

Various techniques and equipment are available for the measurement of particle size, shape, and volume. These include for microscopy, sieve analysis, sedimentation methods, photon correlation spectroscopy, and the Coulter counter or other electrical sensing devices. The specific surface area of original drug powders can also be assessed using gas adsorption or gas permeability techniques. It should be noted that most particle size measurements are not truly direct. Because the type of equipment used yields different equivalent spherical diameter, which are based on totally different principles, the particle size obtained from one method may or may not be compared with those obtained from other methods. 

Sieve analysis, based on either vibratory or suction principle, uses a series of standard sieves calibrated by the National Bureau of Standards. The method is generally used for screening coarse particles down to a material as fine as 44 pm (No. 325 sieve). Sieves produced by photoetching and electroforming techniques are now available with apertures from 90 down to 5 pm. 

Different methods are available for the determination of the particle-size distribution of powdered solids [30]. These are optical microscopy (usually combined with image analysis), sieve analysis, laser light scattering of suspended particles, and electrical zone sensing. 

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