Powder Flowability

Powder flowability is the ease with which the powder flows under a specified set of conditions. It's affected by a variety of factors, such as the equipment design, the powder properties and the environmental conditions.

Powder flowability testing helps to decide the best way to handle powder and granular solids across a range of industries. We undertake powder flow testing and a range of related powder characterisation tests.

Powder physical properties play a role in powder flowability, such as:

  • Size of the particles
  • Distribution size
  • Shape
  • Surface area
  • Density

To investigate the behavior of a powder, we can carry out Shear Cell and wall friction testing.

Shear Cell Testing

Shear cell testing aims to measure how much energy is required to initiate powder flow, for example, from a silo or hopper into a receptacle.

Using a Schulze Ring Shear Tester (RST XS), we slowly apply horizontal stress to the upper layer of powder when the bottom layer is restrained from moving – the test is complete when the powder bed "yields”.The force applied can be changed to mimic the scale of the process of interest and predict how the material flows from small hoppers to large IBCs.

The ring shear tester is very useful as it is able to test materials that are poor flowing, free-flowing or require large shear deformations. We use the results to predict how formulations will flow in process equipment e.g. tablet press hopper.

For more information about API characterisation or our powder testing service, get in touch today by completing our online contact form here, by emailing info@merlin-pc.com, or by calling +44(0)1509 860 222.

Wall Friction Testing

We can use the Shear Cell to measure the flow against a wall surface. The friction of the hopper walls is also an important factor in flow behavior and rate. Wall friction testing measures the change in flow from a polished surface.

The angle of friction measured can be used to design appropriate hoppers for problem materials.

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