Volumetric Feeders
In principle, volumetric feeding is the simplest, most economical feeding solution available. Bulk material is held in a hopper and constantly fed into a process per unit of time. A gravimetric feed rate may be inferred through a calibration process where a timed sample is taken and weighed, and screw speed adjusted accordingly. Although there is no weight feedback to assure feeding accuracy over time, this may not be a concern for materials with consistent bulk density.