Schopper Riegler Freeness Testing Device - Applications:

The Schopper Riegler testing device is a precision Schopper Riegler grinding degree tester for professional determination of the freeness of solutions containing paper fibers in water. The test result will be comfortable according to the Schopper Riegler system and according to the test standard ISO 5267-1 and BS 6035-1 in Schopper Riegler degree listed.

The Schopper-Riegler test (SR test) This is a standardized procedure for determining the dewaterability of pulp suspensions and thus provides a direct indication of the fineness of cellulose fibers. In this test, a defined volume of diluted pulp is placed in a test chamber with a precision sieve. As soon as the sealing cone is lifted, the water can drain through the sieve, while the fibers form a temporary fiber mat. The rate at which the filtrate permeates this mat is a sensitive indicator of fiber disruption, internal fibrillation, and the proportion of fines.

During the test, the filtrate is split into two streams: one part flows freely into a measuring cylinder, while the other part is directed into the SR measuring chamber. The SR value corresponds to the volume retained in the measuring chamber, expressed in Schopper-Riegler degrees. A higher SR value indicates slower dewatering and thus finer pulp, while a lower SR value signifies faster dewatering and fewer milled fibers. This makes the SR method particularly well-suited for monitoring milling performance and the consistency of fiber treatment in both laboratory and production environments.

Engineers value the SR test because it provides a fast, reproducible, and sensitive measurement of fiber changes that correlate well with the subsequent behavior of the pulp in the papermaking process. Changes in the SR value reflect variations in fiber flexibility, specific surface area, fines content, and water retention capacity—all crucial parameters for sheet formation, strength development, and energy optimization during refining. The method is standardized in ISO 5267-1 and TAPPI T227, thus ensuring international comparability and high process reliability.