Particle size analysis, methods

TABLE 17-1 Particle Size Analysis Methods and Equipment... 

Table 13.1 covers general information for different particulates, liquids in gas, typical particles and gas dispersoids, behavior of particles in the human body, charging mechanisms, principles of particle size analysis, methods for particle size analysis, and an estimation of the general collection efficiency of available commercial particle removal equipment. 

Particle-Size Analysis Methods for particle-size analysis are shown in Fig. 17-34, and examples of size-analysis methods are given in Table 17-1. More detailed information may be found in Lapple, Chem. Eng., 75( 11), 140 (1968) Lapple, Particle-Size Analysis, in Encyclopedia of Science and Technology, 5th ed., McGraw-Hill, New York, 1982 Cadle, The Measurement of Airborne Particles, Wiley, New York, 1975 Lowell, Introduction to Powder Surface Area, 2d ed., Wiley, New York, 1993 and Allen, Particle Size Measurement, 4th ed, Chapman and Hall, London, 1990. Particle-size distribution may be presented on either a frequency or a cumulative basis the various methods are discussed in... 

Particle Size Analysis Many particle-size-analysis methods suitable for dry-dust measurement are unsuitable for liquids because of coalescence and drainage after collection. Measurement of particle sizes in the flowing aerosol stream by using a cascade impactor is one... 

Correlations with other particle size analysis methods... 

According to Heywood [1] sieving is the Cinderella of particle size analysis methods it does most of the hard work and gets little consideration. This was reiterated by Leschonski [119] who also quotes the chairman of the Institution of Mining and Metallurgy as stating, in 1903, that screening is not a scientific means of measurement. 

Though sieving analysis is a simple and reliable particle size analysis method, there are some data collection issues that one must be aware of and control in order to obtain reproducible results. Factors that may affect data accuracy include sieve properties, sieve motion and powder properties, sieve time and load, and errors of experimental method and environment. This section will discuss the effects and methods to reduce data collection errors. 

Since the reported diameter is an equivalent volume diameter, proper consideration must be taken when comparing the results with other particle size analysis methods. For instance, the equivalent volume diameter reported for any non-spherical shaped particle will generally be higher than the particle size reported by sieve analysis, as the equivalent volume diameter is based on the volume of a perfect sphere. This theory becomes apparent if one compares the equivalent volume diameter with the sieve diameter of a square that has dimensions of 2(X)pm by 200 pm by 200 pm and that passes through a U.S. ASTM sieve 70 (212 pm) and is retained on a U.S, ASTM sieve 80 (180 pm). In this case, the sieve diameter reported will be 212 pm but the... 

Bernhardt C (1988) Preparation of suspensions for particle-size analysis—methodical recommendations, liquids and dispersing agents. Adv Colloid Inter Sci 29 79-139... 

Appropriate particle size analysis methods with very low shear stress (free settling with particle image velocity, field emission scanning electron microscopy, fluidized bed or vibrating sieve feeding with laser diffraction) have been tested for their reproducibility and minimal dispersion energy. 

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