Scientific & Medical Products Ltd

Model The RST-XS - Ring Shear Tester by Dr Dietmar Schulze



This tester is compact and bench mounted. Designed for applications with powders of up to 1.5 mm in particle size. This tester is particularly well suited for small sample volumes.

There have been many methods developed over the years to characterise the flow properties of powders. However, there is only one method which is universally recognised as having the following attributes:

  • Based on solid theoretical science
  • Robust and Accurate
  • Producing data that relates to real physical properties
  • Simple to use

This method is called: Shear Testing. This method was developed by Jenike in 1965 and followed up by Carr and Walker. However, the first generation of testers using this method were awkward to use and labour intensive.

Schulze started to develop a tester for his own work. His tester was based on the Jenike principle, since this was the only true way of measuring powder flow, but, more importantly, he wanted a tester that was simple, practical and accurate to use.

As a result the first Ring Shear Tester was developed. This led to much outside interest and encouraged Dr. Dietmar Schulze to develop the method further which has given rise to the current range of products described below.


This tester is floor mounted and designed for handling powders wtih large sample sizes. This also includes coal, cereals, soil and other coarse materials.

The Ring Shear Testers can be used for simple determination of batch to batch variations and quality control. The RST-XS is particularly popular in the pharmaceutical industry for the detailed characterisation of drugs, excipients and formulations.

Beyond the fact that the Shear Test is the only method where the values have any understandable meaning, the key features of the tester are:

  • simple to use
  • very reproducible
  • able to charactersise small changes in flow behaviour
  • measurement of caking or time consolidation

A FURTHER unique aspect of the Jenike method is that the parameters measured by the shear method allow the user to either:

  • Design hoppers, silos and feeders to suit a particular powder’s properties (hopper angle, opening size and wall material). This will ensure mass flow and prevent effects such as: arching, funnel flow, flooding etc.
  • Check that a powder will flow through an existing processing line, by checking whether the powder flow properties are compatible against the exising plant set-up.

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