Particle size determination Coulter counter

H.L. Stalcup (Ref 28) evaluated the instru- -ment for the particle size determination of HMX used in rocket formulations. He found that Coulter Counter distribution was similar to that obtained with the Micromerograph except at the large particle end, where the Micromerograph indicated particles over lOOp compared to 32 p for the Coulter Counter. Median values were 13.5p by Micromerograph and 16 p for the Coulter Counter. The samples for the Coulter Counter were run on an as received basis, ie, while still water-isopropanol wet ... 

The treatment of wastes and water supplies primarily involves the removal of particulates and, therefore, is accomplished by solid-liquid separation processes. However, present design procedures for such treatment systems do not utilize or even recognize the importance of the physical properties of particulates in solid-liquid separation. In fact, until very recently, eflForts at measuring particle size in wastewaters and raw water supplies have been very limited. Among early eflForts, the investigations at Rutgers University (3,4,5,6) are especially notable. Very recent renewed interests in particle size determinations have used Coulter, Hiac, and Zeiss Videomat particle counters (7,8,9). 

Multiple techniques can be used to measure the particle size distribution, for example electrozone sensing, sedimentation, laser diffraction, and microscopy. With the exception of microscopy, they all require calibration and the results depend on the technique. For example, in a round-robin study reported in Reference 4, the commonly used electrical sensing zone technique (Coulter Counter) was compared to microscopy and sedimentation. The average particle size determined by the electrical sensing zone method was by about 25%... 

Perhaps the most useful method for determining particle distributions is that of electrical conductivity, the most widely used instrument is the Coulter Counter (named after the Inventors), although there are now other similar instruments on the market. Originally, this instrument was designed to measure blood corpuscles which are 2-8 p in size. It has proven to be very... 

For a given bulk solid, determine particle size distribution, median particle diameter dv50 (e.g., using a Coulter Counter or a Malvern Laser Diffraction Analyser) and ps. 

The suspension produced had a wide range of particle sizes (as identified by optical microscopy) with an average size of 1 um, determined using a Coulter Counter (Model TAII). 100 g leg ... 

The general objective of this study was to determine the sample size limits of each of the above mills. Factors which affected mill efficiency and grind times were also evaluated. In some cases, the grind times required to reduce the sample particle size to less than three microns were determined as a function of grind media type, grind media charge and sample size. All particle size analyses were carried out on a Coulter Counter (Model TA II). 

Particle Size. After determining, with bottle tests, which systems easily produced stable oil-in-water emulsions, the droplet size distributions for the oil-in-water emulsions were determined with a Model TA II Coulter Counter. The quantitative results obtained with the Coulter Counter were verified by qualitative observations with an optical microscope. The droplet size distributions for several oil-in-water emulsions are given in Figure 5. A qualitative correlation between droplet size and emulsion stability was observed. The smaller the median droplet size, the more stable was the emulsion. The pore size distribution for a 300-md Berea sandstone core is given for comparison. 

Particle size distribution and classifier selectivity have been determined, using kernel density estimations, to data from (two) classifier flow streams. The procedure has been applied to hydrocyclones using platey particles whose sizes were determined with a Sedigraph 5100 and spheroidal particles whose size distributions were determine using the Malvern Mastersizer and the Coulter Counter [8] Svarovsky s equation was used [9,10]. 

The second method for obtaining the rate constant of flocculation is by direct particle counting as a function of time. For this purpose, optical microscopy or image analysis may be used, provided that the particle size is within the resolution hmit of the microscope. Alternatively, the particle number may be determined using electronic devices such as the Coulter counter or flow ultramicroscopy. 

To obtain a measure of the rate of crystal growth, the particle size distribution of the suspension is followed as a function of time, using either a Coulter counter, a Master Sizer or an optical disc centrifuge. Usually, the cube of the average radius is plotted versus time this gives a straight Hne from which the rate of crystal growth can be determined (the slope of the linear curve). 

The phase difference between he "particles" (which were detected by the Coulter Counter) and oil droplets of the same size was determined. This phase difference was large. This meant that the refractive index of the "particles" was different than the refractive index of the crude. The "particles" therefore were not oil droplets. This only leaves the possibility that they were micellar aggregates of surfactant. However, it is possible that there was some crude oil dissolved in the hydrophobic cores of the micelles that constitute these aggregates. 

The particle size distribution of the reagent CaC03 is given in Table II. It was determined by a Model TAII Coulter Counter using 0.18 M CaCl2 electrolyte with a 100 Urn aperture. 

We will not dwell further on this method since electrical conductivity, i.e.- Coulter Counter and optical methods, i.e.- Laser-Diffraction have totally supplanted all of the sedimentation methods for determining particle sizes. 

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