High-resolution tapped density analyzer – GranuPack

For powder characterization, the tapped or tap density, the Hausner ratio, and the bulk density measurement are well-known due to the rapidity as well as simplicity of the measurement. Furthermore, the capability of a powder to increase its density are significant parameters for transportation, caking, storage, and so on.

This simple test has three major disadvantages. Firstly, the measurement result depends on the operator. Undoubtedly, the initial volume of powder is influenced by the filling technique. Secondly, strong errors are induced in the results through volume measurements made by naked eyes. Lastly, the compaction dynamics between the initial and the final measurements are completely missed with this simple technique. Presently, these problems will not occur anymore with the GranuPack instrument.


The GranuPack instrument is an enhanced and automated tapped density measurement technique based on the latest results of fundamental research. Using an automatized device, the powder behavior submitted to consecutive taps is examined. The tapped density, the Hausner ratio (Hr), and the initial density are measured precisely (an accuracy of 0.4%). In addition, an extrapolation of the maximum density ρ(∞) and a dynamical parameter (n1/2) are extracted from compaction curves.

The powder is placed in a metallic tube with a stringent automated initialization process. Then, on the top of the powder bed, a light hollow cylinder is placed to maintain the air/powder interface flat at the time of the compaction process. The powder sample in the tube rises to a fixed height of ΔZ and conducts free falls. The height of the free fall is usually fixed to ΔZ = 3 mm or ΔZ = 1 mm. After each tap, the height (h) of the powder bed is measured automatically.

Key benefits

  • The intuitive software computes and reports physical data, and the results obtained under different conditions can be compared. All data are automatically collected and stored for post-processing. Data can be easily transferred and reports can be automatically generated.
  • Size compatible with confined enclosure or hood
  • The repeatability of measurements is increased by the recorded standard operating procedures
  • Measurement is rapid, intuitive, and simple
  • Closed system for safety requirements


  • The system is specifically robust
  • The sample cell can be easily cleaned and filled
  • It complies with the European Pharmacopeia
  • Offers information about the compressibility behavior and the trapped and released air


  • Powders flowability/compressibility classification can be easily achieved, thanks to its very high accuracy (0.6% for excipients and 0.4% for metals); this is the most accurate test for characterizing collective grains behavior
  • Ideal tool to underline the difference between one set of powder to another
  • The compaction kinetics enables the selection of the best powder for tableting/compaction process


  • Calibration kit
  • Additional measurement cells for small samples
  • Reduced-intensity tap
Granutools - Presentation of the GranuPack

Video Credit: Granutools

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