The apparent densities of powdered, granular of flaked materials are highly dependent on the manner in which the particles are packed together.
During tapping, smaller particles distribute into the spaces between larger particles.
Gradually particles pack more efficiently, the powder volume decreases and the tap density increases, often by 50% to 100%.
For this measurement, Quantachrome has developed two instruments which conform to the British Pharmacopoeia method for apparent volume and ASTM standard test methods B527, D4164 and D4781 for Tap Density.
These two models, the Autotap and the two samples Dual Autotap, automate the required procedures to provide accurate, reproducible values.
If the material characteristic is unknown, tapping may be done continuously or step-wise by user specified numbers of taps, while noting or graphing the results until the volume becomes constant.
In either case the number of taps is displayed. Once the material characteristic is known the proper number of taps, typically thousands can be preset on subsequent runs thus freeing the operator for other work.
The new Autotap and Dual Autotap Tap Density Analysers are available from Scientific Solutions.