Ask an Expert: Can I Overfill or Underfill my Blender?

Regardless of what you’re blending, there are consistent and historically proven fill level recommendations for all vessel shapes, be they double cone, slant or v-shape.  While many blenders need to operate at the rated batch size, some have a batch size that deviates. Doublecheck with your vendor—and before purchasing a new unit, consider whether your needs will deviate between batches. One flexible blender can replace several different size blenders. 

Effective mixing and drying is a function of characteristics of both the blender and the materials to be mixed and using an agitator impacts minimum and maximum fills with all vessel types.

There’s a good rule of thumb based on historical data: A general blend working volume of about one half of the total internal volume will produce effective blend uniformity while optimizing production flexibility and productivity.

This fill level is often referred to as “100% of working volume.” Because the geometry of certain vessels provides effective particle mobility and cross mixing – even at different fill levels – the reality is that effective fill levels can be much broader and should be evaluated and confirmed on a case-by-case basis.

It is important to remember that the bulk density of the final blend must be used to approximate fill level. Fill level is a volume measurement, not a measure of weight.

Additionally, three critical characteristics of the materials to be mixed must be considered: (1) cohesiveness (2) angle of repose and (3) particle size distribution.