GranuTools instruments range for powder flowability measurement: The basic principles

Selected geometries

Different flow geometries are available to evaluate the rheological properties of a powder or a granular material. A consortium of French research groups called GDR Midi has studied these geometries carefully. In their publication dedicated to dense granular flows [1], the different geometries are analyzed: plane shear, annular shear, vertical-chute flows, inclined plane, heap flow, and rotating drum. 

Among these flow geometries, GranuTools has selected three configurations: the rotating drum (GranuDrum), the heap flow (GranuHeap) and the vertical-chute flow (GranuFlow). These particular geometries have been selected for two reasons. Firstly, there are very well known fundamentally. Secondly, there are easy to use. As a consequence, the instruments proposed by GranuTools are easy to operate and are based on a strong scientific knowledge [2].

Complementary tools

GranuHeap performs an improved measurement of the repose angle. Moreover, GranuHeap is able to measure quickly and precisely the powder cohesiveness. GranuFlow instrument measures the flow through a set of silo apertures. GranuFlow allows comparing easily the flowability of different powders. Our powder flowmeter GranuDrum allows measuring the powder rheology with deep details. The flowing angle and the powder cohesiveness are measured for different rotating speeds, i.e. for different flow rates. In addition to simple powder comparison, the analysis of the obtained curves allows to determine complex powder behaviors: shear thinning, shear thickening, fluidization, granulation, segregation. In addition to these instruments dedicated to flowability measurement, GranuTools proposes two specific instruments for density and electrostatic properties measurement. GranuPack performs an improved and automated tapped density measurement. Finally, our new GranuCharge instrument measures the ability of a powder to create electrostatic charges during a flow.

The wide range of instruments proposed by GranuTools allows solving the diversified problems encountered in industries processing powders and granular materials. As a function of the needs, GranuTools staff helps customers to select the right instrument, set up the appropriate measurement protocol and provide results interpretation. 

Instrument assessment

Our experience has shown that in most cases, customers need to compare precisely the flowability of a selected sample with the flowability of their reference material. In specific cases, a deep understanding of the sample is needed to improve a process or to solve a practical problem. Both approaches (simple comparative measurements or deep rheological analysis) are possible with GranuTools instruments.

[1] On dense granular flows, Eur. Phys. J. E 14, 341–365 (2004)

[2] Measuring the flowing properties of powders and grains, Powder Technology, Volume 224, page 19, 2012