Classifying Flow Properties of Solids

The flow properties of solids are an indicator of the way a solid will move when allowed to freely flow through a system. Flow properties are measured using a series of indices known as the “Carr Indices,” invented by Ralph L. Carr in 1965. These flow properties fit into two different categories:


A solid’s flowability is the relative easiness with which the powder moves from a stationary to a moving condition. Essentially, it is a measurement of how easily the powder starts flowing when prompted to flow, either by vacuum, air current, or water current.


A solid’s floodability is its tendency to flood, or move in an unstable, liquid-like flow. The more floodable a solid is, the more likely it is to have an uncontrolled or undesired flow. This is important, as products with more floodability may flow in a way that is counterproductive to the processing of the solid.

If you wish to learn more about the classifying the flow properties of solids, be sure to watch the entire webinar.