Grinding Fineness Tester SR 1

The Grinding Fineness Tester SR 1 serves to determine the dewatering rate of paper and wood grindings.

This tester allows you to reliably determine how quickly the cellulose is drained on the screen and permits a good assessment of the material fineness, as dewatering rate and degree of crushing of the fibre material are closely interrelated.

It gives numerical values for the otherwise relative and subjective assessment by the observer of the terms "crisp" and "smeary". The determinations can be carried out so quickly that it is possible to constantly monitor the effect of a beater or other crushing devices on the fibre material.

The test method

consists in 2 g of dry material finely dispersed in 1000 cm3 of water being dewatered through a screen. The screen forms the bottom of a chamber which is placed on a funnel with two discharge openings at different heights.

If the material is dewatered quickly, characterising a "crisp" state, a large proportion of the water flows out of the higher opening, with "smeary" substances only a small proportion. The amount of water under the discharge opening on the side is a measure of the dewatering rate and of the degree of grinding of the material. There is a scale on the measuring device which can be read off directly.


A funnel-shaped separation chamber with two discharge openings is placed into a stand. Arranged on the separation chamber is a filling chamber containing a mesh with a given mesh width and area. A sealing cone is placed into the filling chamber which seals the filling chamber from the separating chamber so that the material/water mixture can be poured in before the test.

The sealing cone is lifted out of the filling chamber by the force of a falling weight. For this purpose, a rack is attached to the cone which engages with a gear wheel. The gear wheel is connected to a roller over which a cord is placed and at the free end of which a weight is suspended. After tripping of a detent, the cone is always lifted out at the same speed.

Technical data

  • Dimensions: 450 x 250 x 1000 mm (length/width/height)
  • Weight: net 34 kg, gross 86 kg
  • Installation: The tester is placed on a table and aligned using adjusting screws