Particle sizes measurement

The surface mean diameter is the diameter of a sphere of the same surface area-to-volume ratio as the actual particle, which is usually not a perfect sphere. The surface mean diameter, which is sometimes referred to as the Sauter mean diameter, is the most useful particle size correlation, because hydrodynamic forces in the fluid bed act on the outside surface of the particle. The surface mean diameter is directly obtained from automated laser light diffraction devices, which are commonly used to measure particle sizes from 0.5 to 600 p.m. X-ray diffraction is commonly used to measure smaller particles (see Size TffiASURETffiNT OF PARTICLES). 

The electrical aerosol analyzer and the optical counter are used to measure particle size distributions. Describe the size range and resolution characteristics of each of these instruments. 

CAHN RG ELECTROBALANCE/SEDIMENTATION ACCESSORY. This app produces a continuous, visible chart record of the sediment weight collected on the balance pan. It has been evaluated for measuring particle size distributions of the primary expls Lead Styphnate, Lead Azide, Tetracene by Hutchinson (Ref 41). 

Figure 13. Comparison between measured particle size distribution for 2D2/380 latex (B) and that calculated at 254 nm (A)...

The phase-Doppler method is capable of accurately measuring particle size distribution and velocity J655] The most recent models ofphase-Doppler particle analyzer (PDPA) can generate data of droplet size and velocity simultaneously as a function of time, from that droplet drag can be calculated and clustering phenomenon can... 

This is a universally applicable instrument for determining particle-size distributions of all kinds of solids which can be analysed either in suspension in a measuring cell or dry by feeding through a solid particle feeder. In the Fritsch Analysette 22 laser diffraction apparatus the measured particle-size distribution is displayed on the monitor in various forms, either as a frequency distribution, as a summary curve or in tabular form and can be subsequently recorded on a plotter, stored on hard disk or transferred to a central computer via an interface. The time required for one measurement is approximately 2min. 

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. 

Other Measurements. Particle size distributions were measured by the Coulter Counter method. Absolute density measurements were made using the well known pycnometer method. 

On the average, the requirements for application of the statistical technique to filter data were met. Analysis of the 254 measured particle size distributions in 1979 indicates that the fine aerosol volume distribution preserved its shape. The measured sulfur mass distribution followed that of the total submicron volume. By difference, it was assumed that the organics did the same. The low relative humidity at China Lake minimized the formation of aqueous solutions due to water condensation on the particles. Therefore, it is expected that the statistical technique can be used with some success with the China Lake filter data. 

Electrical mobility analyzers Several types of instruments for measuring particle sizes in the atmosphere depend on the mobility of charged particles in an electric field (e.g., see Yeh (1993) and Flagan (1998) for a review and history of the development of this field). The electrical mobility analyzer developed by Whitby and co-workers at the University of Minnesota, in particular, has been used extensively to measure particles in the range 0.003 to 1 yum (Whitby and Clark, 1966 Eisele and McMuriy, 1997). 

Measured Particle Size (Micrometers)/Cubic Foot of Air... 

Particle size measurement is one of the essential requirements in almost all uses of colloids. However, our discussion in Section 1.5 makes it clear that this is no easy task, especially since even the definition of particle size is difficult in many cases. A number of techniques have been developed for measuring particle size and are well documented in specialized monographs (e.g., Allen 1990). Optical and electron microscopy described in the previous section can be used when ex situ measurements are possible or can be acceptable, but we also touch on a few nonintrusive methods such as static and dynamic light scattering (Chapter 5) and field-flow fractionation (see Vignette II Chapter 2) in other chapters. 

The competition between diffusion and sedimentation and how this is used to measure particle size, solvation of particles, etc. (Chapter 2)... 

Figure 27-1 Measured particle-size distribution of colloids formed when FeS04 was oxidized to Fe31 in 10 4 M OH in the presence of phosphate (POJ ), silicate (SiOJ ), or no added anions. [From M. L Magnuson. D. A. Lytle.

Snow, R.H. and T,. Allen Effectively Measure Particle-Size Classifier Performance, Chem. Eng. Progress, 29 (January 1993). 

Concerning aggregation kinetics and stabilization it was found in case of barium sulfate that barium ions adsorb more readily than sulfate ions [11], Thus, increasing the ratio R of barium to sulfate ions in the educt composition and thereby increasing the excess of barium ions after precipitation leads to high surface potentials and stabilization. Fig. 5 shows measured particle size distributions of continuously precipitated barium sulfate, measured based on quasi-elastic fight scattering (UPA 150 by Microtrac) within 3 min after pie-... 

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