Coulter-counter particle size analyzer

The Coulter-counter particle size analyzer (larger than 0.5 pm) is used for measuring volumes of individual particles. Particles are suspended in a conductive fluid, into which electrodes are placed. As a particle passes through an aperture between the electrodes, it displaces its own volume of electrolyte, and there is a measurable change in the electrical resistance of the system. The change becomes a precise measure of particle volume. These volumes can then be put into size bins and the PSD can be constructed. 

E. J. Wynn, M. J. Hounslow, Coincidence Correction for Electrical-Zone (Coulter Counter) Particle Size Analyzers , Powder TechnoL, 93 (1997) 163—175 Information on the Coulter Counter is available from Coulter Particle Characterization Electronics Inc., R O. Box 169015, M/C 195-10, Miami, Florida, USA, 33116-9015. Information on Celloscope and Electrozone resistazone counters can be obtained from Particle Data, Inc., P. O. Box 265. Elmhurst, Illinois 60126. 

Although the Coulter counter detects and analyzes particles accurately and reliably, it has still many drawbacks bulky size, heavy weight, complexity, high power consumption, high cost, and no portability. Especially during outbreak of public diseases such as severe accurate respiratory syndrome (SARS) and influenza, there is urgent need for simple, low-power, low-cost, and portable particle counters. 

Figure 3. Pints of mean particle size versus standard deviation of two prepared mixtures of standards analyzed by selected automated electronic particle size analysers (from Syvitski et al 1991a). The expected value is shown with a black box. S SediGraph C. Coulter Counter M Malvern laser panicle. sizer G Galai CIS-1, L Lumosed photosedimentometer lA Image analysis (Syvitski et al.. 1991a).

Thus, when comparing particle size data, one should make sure they are obtained with the same technique. Generally, there are techniques to analyze particles whose size is below or above 1 xm. For instance, the Coulter counter covers the range from 0.4 to 800 (Jim the Coulter N4 from 10 to 3000 nm, and the Cilas from 0.1 to 600 xm. The following... 

---