A fixed container in which powder is suspended in a continuous stream of air. Preheated objects can be coated by dipping directly into a fluidized bed. The fluidized bed can also be used to facilitate transfer of powder materials to an alternate application site.
Finely divided powders can be made into a fluid-like state by passing air through a porous plate bottom of a powder hopper. This permits the fluidized bed of powder particles to be used in dip tanks and to be transported in a manner similar to liquids.
A medium bed which has become expanded during the backwash step or during "upflow" regeneration of an ion exchanger.