Particle size diameter

Figure 6. Range of common particle sizes (diameter) over range of UF pore size.

The foregoing procedure is straightforward if all the particles are of the same diameter (d). However, if the solid particles cover a broad range of sizes, the procedure must be applied for each particle size (diameter dh concentration particle size to the pressure drop APsi, The total solids contribution to the pressure drop is then T,APSj. If the carrier vehicle exhibits non-Newtonian properties with a yield stress, particles for which d < To/(0.2g Ap) (approximately) will not fall at all. 

Particle shape plays an important role in particle size determination. The simplest definition of particle size diameter is based on a sphere, which has a unique diameter. In reality, however, many particles are not well represented by this model. Figure 1 illustrates the variety of shapes that may be found in particle samples [1]. As the size of a particle increases, so does its tendency to have an irregular shape [2], complicating statistical analysis. Particle shape coefficients have been derived for different geometries [3], and various equivalent diame-... 

Once manufactured, small particles present another challenge. At small particle size diameters, gravity ceases to be the major force exerted on the particles and interparticle forces become more prominent. The resultant increase in the cohesive and adhesive nature of the particles produces problems such as poor flowability, fillability, and dispersibility. These problems are typically minimized by blending with larger. 

Gliksman s approach The result of the conversion of equations into nondimensional ones is a set of dimensionless parameters (Froude number, velocity, particle size, diameter ratios, etc.) that should be matched in both small and large systems. It is not necessary for the values of the parameters to be equal in each system. Instead, the dimensionless number ratios have to remain the same. To achieve this, the particle size and/or the particle density of the solids have to be changed appropriately in the small unit. It usually results in a smaller particle size in the small unit compared to the large one. 

Fig. 3. Types of gas cleaning equipment versus particle size diameter s. (Stanford Research Institute)...

Exponents in the obtained equation reveal a remarkable effect of the feed moisture content and mean particle size diameter of the raw material on energy input for the increment of granule size. 

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

Figure 11.12 Particle size (diameter) of ground potatoes.

Figure 11.17 Particle size diameters after classification.

International Standards Organization is preparing a Standard, ISO/FDIS 9276-2 Calculation of average particle sizes/diameters and moments from particle size distributions. For a discussion of this draft Standard see Alderliesten [5]. 

Macromolecular or particulate samples fractionated by the FFF are usually not uniform but exhibit a distribution of the concerned extensive or intensive parameter [8] or, in other words, a polydispersity. Molar mass distribution (MMD), sometimes called molecular weight distribution (MWD), or particle size distribution (PSD) describes the relative proportion of each molar mass (molecular weight), M, or particle size (diameter), d, species composing the sample. This proportion can be expressed as a number of the macromolecules or particles of a given molar mass or diameter, respectively, relative to the number of aU macromolecules or particles in the sample ... 

Table 2 compares the estimated Mayer Stowe median particle size D with the corresponding median particle size diameter D50 measured by laser light diffraction... 

TABLE 3-3 Comparison of Particle Sizes (Diameters) of Various Porous Media (USDA System versus USCS)a... 

Moments Moments represent a PSD by a single value. With the help of moments, the average particle sizes, volume specific surfaces, and other mean values of the PSD can be calculated. The general definition of a moment is given by (ISO 9276, Part 2 Calculation of Average Particle Sizes/Diameters and Moments from Particle Size Distributions)... 

Example 2 The Sauter mean diameter and the volume weighted particle size and distribution given in Table 21-1 can be calculated by using FDIS-ISO 9276-2, Representation of Results of Particle Size Analysis—Part 2 Calculation of Average Particle Sizes/Diameters and Moments from Particle Size Distributions via Table 21-2. 

These diameters offer an extension over volume equivalent diameters to account for shape deviations from spherical. As with any other quality measure of size, many particles must be measured to determine distributions of these particle-size diameters. 

The conversion from an old to a new system is not always precise as far as particle size diameter is concerned, but knowing the old designation helps to... 

A continuous fixed bed reactor coupled on-line with a GC (FID/TCD) was used for the catalytic experiments. The amoimt of catalyst (particle size diameter 0.1 - 0.3 mm) loaded was 0.6 g. The catalytic behaviour of the catalysts was investigated in the total oxidation of methane and chloromethane (1 vol.% in air, feed stream 5 1/h) considering by-product formation. 

A = coefficient in empirical power-law size distribution function (number /xm Vcm ) dp = particle size (diameter basis) (/xm) di = diameter of Particle 1 (/xm) d2 = diameter of Particle 2 (/xm)... 

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