In this column, we'll look at how to decide which pneumatic conveying system is best for conveying a powder. Even when a particular conveying system seems like a logical choice for your powder, it's important to study the material's characteristics and determine how they affect your system choice.
Powders are fine materials such as flour, plastic resins, cement, or pulverized coal. Powders are generally defined as materials with all particles being smaller than 700 microns (0.7 millimeters). No particles can be larger than this size because the larger particles tend to separate from the finer particles and cause a unique conveying problem in some conveying systems. Typically at least 25 percent of the particles in a powder are smaller than 75 microns (0.075 millimeters).