Solids feeders are used to deliver powder, granular and other bulk solid materials along a process line, or to and from process units, storage bins, conveyors and product packaging.  Additionally, many styles serve to break down clumps or arches to allow for more uniform distribution.  There are a number of solids feeders designs: belt feeders, gravimetric feeders, screw feeders, vibratory feeders, volumetric  feeders, and valves.  These are not exclusive designs as it is common to find  volumetric screw designs, vibratory belts, etc. Solids feeders may also be classified based upon where there are placed within the process line: internal bin devices, feeders placed between the conveyance system and the storage container, or valves along the process line.