Determination of tap density and bulk density of powders
If a powder is loosely poured into a measuring cylinder the bulk density can be determined. Bulk density considers existing pores and the interparticular voids of a loose powder bed. The tap density of powders after defined tapping steps of the powder bed can easily be calculated. Tap volume and density also consist of pores and interparticular voids, which is not based on a loose powder bed but on a bed after a defined number of tapping steps. The method for tap density and bulk density determination requires an easy measuring arrangement but leads to important material properties for storage and transport applications of powdered and bulk samples.
Measuring method
Measuring instruments for the determination of tap densities are called tap volumeter, such as the BeDensi T series. This is a small device with one, two or three rotary plates. The cylinder can be used to determine the bulk volume before tapping the sample and therefore gives information how compressible the material is. The tapping number is set and automatically finished after that.
A tap starts with raising the rotary plate automatically including the filled cylinder followed by dropping it, which results in compacting of the powder bed. The volume of the sample decreases during the tapping procedure. Therefore the tap density is smaller than the bulk density.
Analyzer
