PREDICTING THE EXPANSION OF GRANULAR FILTER BEDS.

At present, the only methods available for predicting bed expansion are experimental procedures, although J. L. Cleasby has produced mathematical models for specific grain materials such as garnet, silica sand and coal. In this study the authors develop specific models for ballotini, anthracite, polystyrene and sand and, additionally, from such models a general mathematical model applicable to grains of any material.