Abstract: A method and apparatus for simultaneously measuring the streaming potential of a fiber suspension and a filtrate thereof. A container is provided having an inlet and an outlet for the flow of fiber suspension therethrough, and a filter screen divides the container into an upstream compartment and a downstream compartment. Each compartment has an electrode pair disposed therein, each electrode pair including a cylindrical outer electrode configured for flow of fiber suspension therethrough and an inner electrode. Each electrode pair is connected to a differential amplifier, with the differential amplifiers connected to a microprocessor.

Abstract: A particle suspension from a process is introduced into a measuring vessel 1 and caused to rise above a screen 4 whereupon the streaming potential of the suspension is determined by measuring the voltage across the screen at alternately different, relatively low pressures. The measurements may be carried out continuously with the measuring vessel being rinsed between measurements. The apparatus comprises a vertical U-shaped measuring vessel 1 in which a horizontal screen plate 4 in one leg 3 defines a measuring chamber 9, the other leg 2 being supplied with the suspension. Valves V4-V8, V10 are provided to alternately subject the vessel to different measurement pressures, and to provide a high rinsing pressure. Adjacent its center the screen plate supports electrodes 5, 6 for measuring the voltages between particle suspension and filtrate, and an electrode 11 is associated with the screen plate for measuring the conductivity of the suspension.