Sizing technique

The sieve test is probably still the most commonly used sizing technique both to characterize particulate distributions and separate them into fractions on the... 

Finally, it should be emphasized that in all these studies more than one particle characteristic should be determined and this will usually entail more than one method of measurement. These can include various sizing techniques and the value of microscopy should not be ignored. Often, however, end-use tests provide the most meaningful data e.g. sedimentation rates or filtrability. 

A frequent sizing technique, which is useful when the reaction kinetics and heat of reaction are not known, is to conduct small scale tests. Then scale up to large equipment is done by providing a vent with similar vent area per mass of contents. 

Sizing technique Description Size range (pm) Limitations Ref. 

The correct application of either sizing technique will result in a duct network that works well on air. It is equally important to ensure that each air flow is adequate to transfer all the particulates from the hood/enclosure to the collection and/or cleaning device. Unfortunately, many dust control systems have been designed and/or are being operated with little or no regard for what actually has to go through the hood-duct network. This can result in ... 

One of the newest particle sizing techniques is light scattering. This technique is used to measure particle size distribution, colloid behavior, particle size growth, aerosol research, clean room monitoring, and pollution monitoring. 

Hydrodynamic focusing and electronic cell-sizing techniques (with M.L. Shuler and H.M. Tsuchiya). Appl. Microbiol. 24,384-388 (1972). 

Suspensions contain micronized drug for proper delivery to and absorption in the respiratory system. Typical particle size of the micronized drug is from 2 to 5 microns [5], Aerodynamic mean particle size as measured by cascade impactor or direct method of microscopic analysis is usually from 0.5 to 4 microns [5], Additional particle-sizing techniques such as light scattering can be used [6],... 

In this chapter, the basic definitions of the equivalent diameter for an individual particle of irregular shape and its corresponding particle sizing techniques are presented. Typical density functions characterizing the particle size distribution for polydispersed particle systems are introduced. Several formulae expressing the particle size averaging methods are given. Basic characteristics of various material properties are illustrated. 

The book contains two parts each part comprises six chapters. Part I deals with basic relationships and phenomena of gas-solid flows while Part II is concerned with the characteristics of selected gas-solid flow systems. Specifically, the geometric features (size and size distributions) and material properties of particles are presented in Chapter 1. Basic particle sizing techniques associated with various definitions of equivalent diameters of particles are also included in the chapter. In Chapter 2, the collisional mechanics of solids, based primarily on elastic deformation theories, is introduced. The contact time, area, and... 

A particle or droplet-sizing technique in which the flow of dispersed species in a capillary, between charged electrodes, causes changes in conductivity that are interpreted in terms of the sizes of the species. Coulter is the brand name for the automated counter. See also Sensing Zone Technique. 

A general term used to refer to any of the particle or drop-let-sizing techniques that rely on (usually) conductivity or capacitance changes in sample introduced between charged electrodes. Also termed resistazone counter . 

System conditions often allow for the measurement of magma density, and in such cases is should be used as a constraint in evaluating nucleation and growth kinetics from measured population densities. This approach is especially useful in instances of uncertainty in the determination of population densities from sieving or other particle sizing techniques. 

Third, in selecting a particle sizing technique, one must consider the size of the material itself. Most techniques have effective upper and lower limits of detection. Laser diffraction, for example, can measure particles from approximately 0.01 pm to several millimeters. With optical microscopy and image analysis, it becomes very difficult to resolve features that are smaller than a 0.3 pm because of the wavelength of light used in conventional optical microscopes.1... 

TABLE 13.1 Comparison of Particle Sizing Techniques for Active Pharmaceutical Ingredients... 

This paper describes the development of a particle sizing technique utilizing the visibility parameter and the Mie scattering theory for spherical particles. The technique allows the measurement of size and velocity of individual particles and was tested in fuel sprays under both burning and non burning conditions. 

The mass versus particle size distribution of several polymer latices with diameters in the range of 30 nm to 1500 nm was determined in less than 20 minutes using an integrated hydrodynamic chromatograph. Distributions obtained were compared with those found by other particle sizing techniques such as electron microscopy to verify validity of the technique. The instrument employed was able to analyze latices re-producibly with different optical properties, even though some of the injected particles may have been trapped within the column. Latex properties were correlated with particle size distribution data to illustrate the benefit of this particle sizing technique. 

Hydrodynamic chromatography was originally described by Small (7) in 1974. A number of publications have appeared since then which describe the separation mechanism and sample detection methods used with HDC (5, 8-18). In addition, Van Gilder, et. al. (19) used HDC as the primary particle sizing technique in research on the particle size versus viscosity relationship of high solids paper coating latices. 

Fairs (1943) has criticized the method of linear measurements above described. He points out that the diameter so measured does not correspond with the Stokes or effective diameter det but is usually greater. The importance of avoiding some shape factor to convert d to de is obvious but over and above this lies the fact that a linear measure is of statistical interest only, as already inferred. A diameter to be useful must be related to measures of mass or surface. Schweyer (1942) in his comprehensive analysis of particle size techniques (about which more will be said later) has dealt with this subject in detail. 

Table 1 lists several Laplace inversion techniques together with the constraints that they place on the inversion. Details can be found in the cited references. The review of Stepanek [491 provides a good discussion of the difficulties encountered in comparing the sizing techniques in Table 1 and assessing their relative merits. Included are citations of some of the comparisons that have been made... 

For the extractive distillation results of Tables V and VI, the reboiler load for the above ethanol rate would be about 20.9 million Btu per hour. The ethanol product contains about 16 ppm of water and about 1.2 ppm of ethylene glycol. For an ethanol recovery of 99.99% ra, 46 total equilibrium trays are required with a reflux-feed ratio of 1.55+ and a solvent-ethanol ratio of 4.09" mole basis. The condenser load is about 13.1 million Btu/hour, and the tower diameter is about 5.3 feet, based on a Glitsch sizing technique. 

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