A Sensitive Monitor for Particles in Liquids

  • John Gregory


A new technique for monitoring low concentrations of particulate impurities in flowing liquids is introduced. The method is based on measurements of fluctuations in the intensity of light transmitted through the flowing sample. These fluctuations arise from variations in the number of particles in the probe volume and follow Poisson statistics, so that the root mean square value of the fluctuating signal depends on the square root of the particle concentration. Simple analysis indicates that, for particle sizes of around 1 μm or greater, the fluctuating signal provides a much more sensitive measure of particulate contamination than turbidity measurements (either by light scattering or transmission). A practical device based on the new technique is described, which provides a very simple means for continuous, flow-through monitoring of relatively clean liquids.


Latex Particle Fluctuate Signal Particle Number Concentration Turbidity Measurement Polystyrene Latex 
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Copyright information

© Springer Science+Business Media New York 1990

Authors and Affiliations

  • John Gregory
    • 1
  1. 1.Department of Civil EngineeringUniversity College LondonLondonUK

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