Dr. Dietmar Schulze Schüttgutmesstechnik

The Ring Shear Tester RST-01.pc provides computer-controlled measurement of the flow properties of powders and other bulk solid materials, under conditions which duplicate handling situations. Such properties are useful for many applications: Product development, product characterization, quality control, comparative tests, troubleshooting, or silo design.

Automatic measurement means that the test is performed following a well-defined procedure, which is executed computer-controlled. Further measurements provided by the tester are wall friction tests (friction between a powder and the surface of a solid, e.g. the wall material of a hopper) and compressibility tests. The tester can even be used to measure the attrition properties of materials such as granules, flakes and pellets.

The Ring Shear Tester RST-01.pc is extremely versatile. Materials which are free flowing, very poor flowing, or require large shear deformation can all be tested. The applied stress level can be varied over a wide range, consistent with how your material is being handled. Shear cells of different volumes allow the testing of limited quantities of your material.

The Ring Shear Tester RST-01.pc is controlled by the software RST-CONTROL 95. The software provides several test modes. Standard procedures can be used, where test parameters are entered once. Thus, the operator can start a test just with some mouse clicks. For special applications a semi-automatic test mode is provided. Here the operator observes the measured data on the screen and controls the test via the PC keyboard or the mouse. The software package additionally contains the program RSV 95 for the detailed analysis of the test data and for the output of the results, e.g. as diagram, table or report, with the possibility to export the data/diagrams to other applications (e.g. word processor, spreadsheet).

The Ring Shear Tester RST-XS.s is an easy-to-operate tester for the precise determination of the flow properties of fine-grained powders and bulk solids. The specimen volume can be varied from around 3.5 ml to 70 ml. Therewith, the RST-XS is appropriate especially for those industries and research institutions which deal with fine-grained materials or which have only small amounts of powders for testing, e.g. the pharmaceutical industry, food industry, chemical industry and many others.

The Ring Shear Tester RST-XS.s provides automatic, computer-controlled measurement of the flow properties (e.g. flowability, time consolidation and caking, bulk density) of powders and other bulk solid materials, under conditions which duplicate handling situations. Such properties are useful e.g. for product development, quality control, comparative tests, and silo design. Automatic measurement means that the test is performed following a well-defined procedure, which is executed computer-controlled. Further measurements provided by the tester are wall friction tests (friction between a powder and the surface of a solid, e.g. the wall material of a hopper) and compressibility tests. Furthermore, for attrition tests the bulk solid can be sheared under defined conditions thus simulating flow under defined stresses.

The tester is extremely versatile. Materials which are free flowing, very poor flowing, or require large shear deformation can all be tested. The applied stress level can be varied over a wide range, consistent with how your material is being handled.

The Ring Shear Tester RST-XS.s is controlled by the software RST-CONTROL 95. The software provides several test modes. Standard procedures can be used, where test parameters are entered once. Thus, the operator can start a test just with some mouse clicks. For special applications a semi-automatic test mode is provided. Here the operator observes the measured data on the screen and controls the test via the PC keyboard or the mouse. The software package additionally contains the program RSV 95 for the detailed analysis of the test data and for the output of the results, e.g. as diagram, table or report, with the possibility to export the data/diagrams to other applications (e.g. word processor, spreadsheet).

The test results of Ring Shear Testers are not only applied on flowability measurements, e. g.. for product development or quality control, but also on hopper design for flow. In this case, hopper slope angles and outlet dimensions are calculated in dependence on the measured flow properties, e.g., with the goal to achieve mass flow in the hopper, and to avoid cohesive arches. In case of funnel flow silos, the rathole diameter can be predicted. For both types of flow the influence of the time consolidation is taken into account. Time consolidation refers to the increase in the strength of a bulk solid when it is stored in a silo for a long time at rest.

The new hopper design software reads the data generated by the Ring Shear Testers to interactively tune the required graphs of unconfined yield strength, bulk density, internal
friction, and so on, and then to create a silo design from the selected data. Interactivity is important in order to allow a transparent approach, but also to be able to intervene in critical products, in order to avoid errors by a "stubborn" application of the design methods.

With the new software, time-consuming iteration cycles at stress-dependent friction angles are a thing of the past: All stress-dependencies specified by measured data are taken into account. Thus, e.g. the hopper slope angle can be specified as a function of the outlet size or local hopper cross section, respectively.

The results are output as a comprehensive pdf document, from which all steps of the interpretation can be understood in retrospect. This is indispensable for a complete documentation of a silo design.

In addition to the design of mass flow silos for conical, wedge-shaped, and asymmetric wedge-shaped hoppers, taking into account the time consolidation, the design of funnel flow silos is also included. In addition to newly calculated design parameters (e. g., flow factors, ff) based on Jenike's differential equations in Bulletins 108/123, other known approaches can alternatively be applied.

The software will be shown as a working development version at POWTECH 2019. It should be available later in 2019.