It doesn’t always have to be expensive: bulk density and tap density as basic powder properties
How many tons of flour will fit in my silo? How does the weight of the packaging relate to the contents of the packaging? Has my material changed? Does this raw material or product meet our quality requirements? The bulk properties of powders depend both on the solid itself (density) and on the processing, treatment and storage. Small changes in certain parameters can lead to significantly different bulk densities, so that the determination of bulk and tap densities must be carried out under standardized conditions.
3P Instruments offers complete solutions for particle analysis. With the Bettersizer S3 Plus, particle size analysis by laser diffraction according to ISO 13320 and particle shape analysis by dynamic image analysis according to ISO 13321 can be performed in a single measuring system. This covers essential particle parameters that can be used for appropriate interpretations. However, the comprehensive particle size analysis is not always necessary or in other cases this is not sufficient:
a) There are powder heaps where a simple determination of bulk and/or tap density leads to a clear indication of changed powder properties. In these cases, simple measuring instruments as shown in Figure 1 may be sufficient.
Figure 1: From left to right: Bulk density meter for non-metallic powders (BeDensi B1), Scott capacity meter for bulk density determination of metal powders (BeDensi B1-S) and Hall flowmeter (HFlow-1) for the determination of the flowability of metal powders; compliant with ISO 3923-2 and ASTM B329-14.
b) Other powders need the determination of bulk density and/or tap density in addition, because in these cases the particle size analysis cannot answer relevant practical questions or only the combination of bulk density and tap density (Figure 2) with a particle shape analysis leads to certain correlations and further conclusions.
Figure 2: Affordable tap density meters of the BeDensi T series (left) and the PowderPro A1 (right), which is able to determine the tap density and 12 more parameters of powder heaps: Carr Angle of Repose, Carr Angle of Fall, Carr Angle of Difference, Carr Angle of Spatula, Carr Packed Bulk Density, Carr Compressibility, Carr Dispersibility, Carr Uniformity and Carr Cohesion, Voidage as well as Flowability and Floodability indices; according to ASTM D6393.
Of course, these measurement methods can also be carried in our LabSPA (Lab for Scientific Particle Analysis) as part of contract analysis. We are always surprised to find out what problems one has to encounter practice. We can also find some solutions through the complex use of complementary analysis methods. Therefore, feel free to discuss your tasks with us in order to find out the critical parameter and the optimal measuring method. And sometimes the inexpensive methods of bulk density and tap density determination actually lead to a solution.