Electricity: measuring and testing – Determining nonelectric properties by measuring electric... – Particle counting
Patent
1991-02-26
1992-09-22
Heyman, John S.
Electricity: measuring and testing
Determining nonelectric properties by measuring electric...
Particle counting
377 10, 377 29, 73 1G, 73 2802, 324601, G01N 1502, G06M 1100
Patent
active
051500361
ABSTRACT:
A process and apparatus for calibrating a particle counter is described. The process comprises the steps of forming a vector gas flow by an aerosol of particles of the same grain size, developing ions in the vector gas with both sign by a bipolar charger, certain particles being electrically charged to a stationary charge state in which the distribution of the number of charges fixed to each particle follows a Gaussian law (Gunn or Boltzmann), passing the charge aerosol into a mobility selector to attract the charged particles to electrodes therein and classify them as a function of the numbers p of their elementary electrical charges e and allowing the electically neutral particles to escape, collecting the neutral particles and passing the neutral particles into the particle counter to be calibrated, the particles counter displaying a value N'.sub.o ; counting the values of N.sub.p and N.sub.p+1 of the number of particles of charges pe and (P+1)e fixed by the selector and calculating by the formula ##EQU1## the number N.sub.o representing the number of neutral particles supplied to the counter and comparing N'.sub.o with N.sub.p. An apparatus using above process to separately pick-up the charged particles with a view to count the numbers N.sub.p and N.sub.p+1 contains a particle counter in which particles of the same grain size are produced comprising a cylindrical case containing an annular cylindrical bipolar charge space and a mobility selector linked with the charge space and are superimposed manner within the cylindrical case.
REFERENCES:
patent: 3413545 (1968-11-01), Whitby
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patent: 4556849 (1985-12-01), Kalakutsky et al.
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"Equilibrium bipolar charge distribution of aerosols" by B. Y. Lui et al., in: Journal of Colloid and Interface Science, vol. 49, No. 2, Nov. 1974, pp. 305-312, (Liv et al.).
"Electrical aerosol analyzer: calibration and performance" by D. Y. Pui et al., in: Aerosol Measurement, D. Lundgren, 1979, pp. 384-399 (Pui et al.).
"Erzeuging von Prueaerosolen fuer die Kalibrierung von optishen Partikelmessverfahren nach VDI 3491" by C. Helsper et al., in: TM Technisches Messen, vol. 56, No. 5, May 1989, pp. 229-234, (Helsper et al).
Commissariat a l''Energie Atomique
Heyman John S.
Meller Michael N.
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