Counter Coulter

Coulter counter measmes the number and size of particles as they are caused to flow through an orifice. For this to happen, again a suspension of the particles is prepared. A tube containing a narrow orifice on its side near its bottom is kept standing in the suspension. One electrode is kept inside the tube. 

Result of sedimentation measurements using turbidity for two particle sizes in a solution Vf is terminal velocity. 

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Fig. 14. Simplified schematic of an electrozone stream counter, the Coulter Counter (Coulter Counter Electronics, Hialeah, Florida).

The principle of this zone sensing (Coulter Counter ) technique is as follows ... 

Comparison of the precision of the Sharpies Micromerograph with that of the Coulter Counter using standard glass bead sample, type XC-3... 

Comparison of microscopic particle size distribution with the average distribution of four identical runs made with the Coulter Counter... 

The performance of the Micromerograph has been of interest ever since its introduction because of its potential for a much needed improvement in the analyses of the important sub-sieve sized ingredients of Ordnance. It has been evaluated relative to several other instruments Coulter Counter... 

Tungsten Sample Lots Turbimeter Micromerograph Coulter Counter B.E.T. Burning Time sec/in... 

The specific surface being a gauge of the fineness of a powder, comparison of the result for M-10 and M-20 in Table 10 shows that the Turbidimeter yielded analyses which were consistent with the burning time data, that is, M-10 is a finer powder than M-20. The Micromero-graph showed a smaller difference between these two lots. The Coulter Counter gave results which were inconsistent with the burning times. It... 

A comparison of the distribution curves given by the Turbidimeter, Micromerograph and Coulter Counter for identical samples of tungsten is shown in Figure 20... 

COULTER COUNTER. This commercially available equipment utilizes the change in resistance of the system caused by the presence of a particle suspended in an electrolyte. The sus-... 

Micromerograph, Coulter Counter, Micromerograph Coulter Counter... 

Coulter Counter operational conditions Gain index 4 Aperture 100 microns... 

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 ... 

It was found essential to maintain cleanliness around the Coulter Counter at all times. Dust and moisture must be avoided or high background counts and instability will result. The Coulter Counter analysis was found to be more rapid than the Micromerograph, requiring approximately 15 minutes per analysis as compared to 90 minutes for high surface material on the Micromerograph. The use of a multichannel Coulter Counter would reduce the time per analysis to less than five minutes... 

J.G. Day D.R. Dillehay, ibid, 277-285 3.0) D.E. Middlebrooks, S.M. Kaye, D.J. Edel-man G. Weingarten, Preliminary Evaluation of the Coulter Counter Particle Size Instrument , PATM 1054(1963) 31) J.A. Freitag, Four-... 

Fig. 1.13 Principle of electronic particle counter Coulter counter. 

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... 

The Coulter Counter is particularly usefiil and unique in that steps as small as 1.0 micron may be used if so desired. Results by this author have demonstrated that some distributions which appear to Gaussian may actually consist of more than one subdivision where the peaks are separated by only a few microns, an example is given as follows ... 

Various techniques and equipment are available for the measurement of particle size, shape, and volume. These include for microscopy, sieve analysis, sedimentation methods, photon correlation spectroscopy, and the Coulter counter or other electrical sensing devices. The specific surface area of original drug powders can also be assessed using gas adsorption or gas permeability techniques. It should be noted that most particle size measurements are not truly direct. Because the type of equipment used yields different equivalent spherical diameter, which are based on totally different principles, the particle size obtained from one method may or may not be compared with those obtained from other methods. 

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