Twin Wire Retention Tester, 2000 Papermakers Conference Proceedings

Seppo Sivén, Hannu Manner--The High Speed Retention Tester (HSR-Tester) is a new laboratory scale retention tester. It can be utilized also for drainage and formation evaluation. The uniqueness of the HSR-Tester is based on its operating principle. The HSR-Tester is the only laboratory scale retention tester with two-sided water removal. Two-sided drainage increases drainage rate and an adjustable forming pulsation can be set up to 200 Hz frequency. Such a fast alternating and dis-continuous drainage pressure exist in high speed gap formers. These forming characteristics depend upon the set up of forming section of a paper machine. These can be varied while operating with the HSR-Tester. Retention is influenced also by another prime factor which is adsorption characteristics of added chemicals. The easy modifications of chemical input make the tester a proper tool for an evaluation of the efficiency of retention aids. Adsorption characteristics are influenced mostly by the time delay and the mixing intensity during the time chemicals are involved with a pulp suspension. Those and the pulp consistency can be adjusted to the desired level in the HSR-Tester. The compact retention tester with easily made adjustments suits well for retention studies. Most advanced and practi-cable feature is a sheet production under different water removal conditions. Paper sheet carries a lot of information about sheet forming characteristics. This allows the estimation of retention, drainage and formation based on a single testing apparatus.