Abstract: A consistency measuring apparatus and a method for determining fiber concentration of a pulp suspension, which utilizes a flow cell having a pair of parallel, light transparent side walls to allow the sample to be monitored to flow therethrough. A plane polarized beam of light is transmitted through the cell and received by a pair of detectors which have overlying plane polarized light analyzers, one having its axis of transmission crossed with and the other having its axis of transmission parallel to the plane of polarization of the transmitted light beam. The detectors provide electrical signals which are processed to give the consistency of the pulp suspension sample.

Abstract: An apparatus and a method for determining pulp quality by monitoring the rate of descent of the pulp-water interface of a uniformly intermixed stationary sample of pulp suspension, at a selected consistency, while it settles out.