A powder or granular material is fluidized when air is entrapped between the particles of the material and cause the material to behave like a fluid. As with many material flow properties, fluidization can be a benefit or a disadvantage to processing and handling materials. Easy fluidization improves material performance when materials must be pneumatically conveyed or sprayed. However, for material handling equipment, easy fluidization can lead to flooding, inconsistent feeding, and uncontrolled behavior as powder handling equipment is not made to control fluid-like materials. In essence. materials can simply flow too well.
The interesting point about this is that many materials are formulated to make sure they flow well from silos and totes and do not cake. Anti-caking and flow agents are mixed in to poorly flowing materials to improve their behavior. This solves the caking issues but can lead to processing problems caused by the samples flowing too well. Fluidization is one of these problems. Flow and anti-caking agents improve a materials ability to fluidize on handling. This can lead to handling issues as well as segregation problem. But few materials are tested to make sure they do not flow too well when exposed to flow energy.
The REVOLUTION Powder Analyzer tests the fluidization potential of materials by measuring their behavior in the RPA sample drum as the drum speed is increased to very high velocity. The action of the rotating drum creates air pressure that fluidizes the material.
Link to instrument-specific test pages: