Electrical resistance particle counter

ASTM F-662-86 (1992), Measurement of particle count and size distribution in batch samples for filter evaluation using an electrical resistance particle counter, 450... 

Figure 6. Basic electrical resistance particle counter (modified from Lieberman, 1996).

ASTM F662-86(1992)el Standard Test Mefliod for Measurement of Particle Count and Size Distribution in Batch Samples for Filter Evaluation Using an Electrical Resistance Particle Counter... 

R. Davies, R. Karuhn, L. Townsend, n e Efiect of Particle Shape on the Response of an Electrical Resistance Zone Counter, in Proceeding ofthe Symposium on Particle Size Analysis, Nuremhurg, Germany, i 75 publishedasDechemaMonographien,79(1589-l6l5), Teil B (1975). 

The Coulter Counter contains a capillary through which a suspension is pumped. The electrical resistance of the liquid column is measured and depends on the resistance of the liquid medium, the resistance of the solid phase and the proportion of solid material in the suspension. From the size of the change in electrical resistance, certain conclusion can be drawn about the dimension of the particles in a certain fraction. 

The single largest use for the phenol-formaldehyde resins is in adhesive applications for the production of plywood, chipboard, and particle board. The resin can comprise as much as one-third of the weight of the board, particularly of particle boards, which contributes to a total demand for phenolics in the U.S.A. of over half a million metric tonnes per year. They are also used as the matrix adhesives for the production of several types of grindstones. In combination with paper, woven cotton, glass fiber, etc., components, phenolics contribute to the production of engineering and decorative laminates in the form of rods, tubes, and sheets. The sheet products Arborite and Formica are familiar as the finished surfaces of furniture, bathroom, and kitchen counter tops and other areas where attractive patterns and water resistance are important characteristics. Molded products from phenolics are also important where heat or electrical resistance is required, such as saucepan and toaster handles, switches, and the printed circuit boards used in computers. Recent phenolics production in the U.S.A. has totaled over 500,000 metric tonnes per year, not including fillers [38]. 

Electrical Sensing Zone (Coulter Counter) As a particle passes through an orifice, the electrical resistance measured across the orifice changes as a function of the particle size (volume). This can be proved by considering Figure 37 and deriving the following relationships (7, 8) ... 

Coulter Counter A commonly used particle-sizing instrument employing the principle of electrical resistance. 

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. 

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