Tapped Density Tester for Powders: Series JV
The Tapped Density Testers Series JV have been designed to measure the tapped density of powders, granules and similar products in accordance with USP Chapter Method 2 and EP Chapter 2.9.34. This technique is particularly useful in powder flowability studies and also in determining the amount of settlement during transit to optimise pack sizes e.g., washing powders, etc.
Tapped density is achieved by mechanically tapping (raising the cylinder and allowing it to drop a specified distance under its own weight) a measuring cylinder containing the sample under test.
Two versions of the tester are available dependent on the number of test stations required (1 or 2).
Both of the instruments concerned are equipped with membrane keypads for setting the number of strokes or time and an LC display to set the appropriate parameters and monitor the progress of the test.
Mode of operation
The mode of operation is identical on both models:
- Weigh out a predetermined amount of the sample, say 100 g /- 0.1%, and place it in the graduated cylinder provided and note the unsettled volume. Secure the graduated cylinder to the test platform of the tester using the bayonet fitting provided for this purpose.
- Unless otherwise specified, set the number of taps via the touch sensitive keypad on the front of the instrument to 500 and operate the device making a note of the resulting tapped volume. Repeat this operation for a further 750 taps noting the volume once again.
- Continue repeating the test in increments of 1250 taps until the difference in tapped volume is less than 2%. Note the final reading.
- The tapped density in grams per ml can now be calculated by dividing the sample weight by the final tapped volume.
- Measures of the ability of the powder to flow and its compressibility can now be given in the form of the so-called Hausner ratio (Tapped Density/Bulk Density) and the Compressibility Index ((Tapped Density – Bulk Density/Tapped Density) x 100).
- In a free flowing powder, inter-particulate interaction is less significant and unsettled and tapped densities will be closer in value. In poorly flowing powders, the inverse is to be expected.
- It follows that the closer the Hausner ratio is to one, the better the flow. Powders with poor flow generally have a ratio of greater than 1.25.
The Tapped Density Testers measures 280 mm wide x 250 mm deep x 670 mm high.