Standard Sieve Sizes

Specifications and Analysis. R%-MaHc acid that is sold in the United States meets the specifications of the Food Chemicals Codex and National Formulary, which are Hsted in Table 5 (40,41). MaHc acid is available in the following U.S. standard sieve sizes ... 

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. 

The grain size distribution of spent foundry sand is very uniform, with approximately 85 to 95% of the material between 0.6mm and 0.15mm (No. 30 and No. 100) sieve sizes. Five to twelve percent of foundry sand can be expected to be smaller than 0.075 mm (No. 200 sieve). The particle shape is typically subangular to round. Spent foundry sand gradations are too fine to satisfy the fine aggregate standard specified in specification ASTM C33 Standard Specification for Concrete Aggregates. 

Classification3 Minimum Apparent Thickness, cm Formation Factor (F), cm Capillary Fringe Height,b cm U.S. Standard Sieve Size Rang... 

Wet Sieving by a Mechanical Flushing Procedure. The sieve residue is the portion of coarse particles that cannot be washed through a specified test sieve with water. The result depends on the mesh size of the sieve. For standards, see Table 1 ( Residue on sieve Mechanical method ). Apparatus Mocker s apparatus. 

After selection, the shale rocks were crushed, sieved, and divided into small samples by riffling. The shale samples weighed 2.5-3 g and were —6+10 U.S. Standard sieve size. The average composition of random samples chosen for chemical analysis is given in Table I. 

All of the tests conducted in the pilot plant were with a single batch of Colorado oil shale from the U.S. Bureau of Mines mine at Rifle, Colo. Mine run material was crushed to 1/4-in. size at the mine and sieved elsewhere into various fractions. We selected a —6+10 U.S. Standard sieve size material for most of these tests because it was the largest size which we could successfully feed with our existing equipment. This material had a Fischer assay oil yield in the 20-25 gal/ton range. 

The following tables give the relationship between particle size diameter (in pm) and several standard sieve sizes. The standards are as follows ... 

Table 9 shows the results of the sieve analysis obtained for a sample of a FCC1 powder. The values reported in the first two columns of the table are the standard diameters of the sieve apertures. From these the mean diameter dp is obtained for each two adjacent sieve sizes and the values are reported in the third column. From the mass fraction of powder in each sieve (values in the fourth column) the weight percentage is obtained and reported in the fifth column. Thus, the sum of the mass fraction over the mean diameter allows the calculation of the volume-surface mean particle diameter of the distribution using Equation (1) ... 

Note-. USS = United States standard sieve size. 

The starting materials are mixed in the molar ratio needed in the final product. In the case of ZnCr2C>4, 1 mol of ZnO and 1 mol of CdC would be needed. Fine powders of each would be used. Powders are normally sold with purity and mesh designations. The purity may read 3 N7, which means three nines followed by a seven 99.97%. Sometimes all the digits are nines 5 N means 99.999%. The mesh designation follows one of the standard mesh sizes. Sample U.S. standard sieve sizes include ... 

Plastic powder form used usually has a particle size of 35 mesh (74 to 2000 pm). The particle size of powders is usually quantified in terms of the mesh size. This relates to the number of mesh openings per inch in the sieve used to grade the powder that are defined in industry mesh size standards. 

In sieve analysis, standard screens with precise screen openings are arranged in a stack from the coarsest to the finest with a pan below the bottom sieve to collect the fines. The material is introduced on the top screen and the stack of sieves is vibrated such that the material will stratify by particle size through the sieves. 

Probability paper and linearization of the cumulative distribution curve In general, when calculating an average one uses the diameter d, at the midpoint of an interval times the number or weight of particles in that interval for the equations summarized in Table 3. However, there are situations where this is not possible e,g when one considers sieve data the midpoint of the interval for the largest sieve size is not defined, all that is known is how much material passes through the top sieve. Thus, to analyze this type of data one cannot use the standard methods illustrated in the previous examples. 

The size of particles is usually determined with a set of standard sieves the size designation referring to the range of sieve sizes which best describes those particles. For example, a 20-60 specification means that most particles pass through a size 20 sieve but are retained by a size 60 sieve (the larger the sieve number, the smaller the opening). 

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