Weighing, Dosing & Loss-in-Weight Feeding calculator

Bulk Density Adjustment Calculator

Bulk density adjustment corrects a feeder's expected throughput when the material's packed density drifts from the reference value used at calibration. Loss-in-weight and gravimetric feeder engineers rely on it because a 5-10% swing in bulk density from a new lot of powder, a change in aeration, or a different flow aid will push a volumetric feeder off its setpoint even though the screw speed never changed. Getting this right keeps recipes in spec and stops silent over- or under-dosing on continuous lines. It is one of the first checks a process technician runs after a raw-material lot change.

What this calculator does

  • Bulk density adjustment corrects a feeder's expected throughput when the material's packed density drifts from the reference value used at calibration.
  • Use it when bulk density adjustment in weighing, dosing and loss-in-weight feeding needs a few factors combined into one defensible number for weighing, dosing and loss-in-weight feeding.
  • It multiplies a reference feed rate by the material's density factors and a feeder efficiency multiplier to give the density-corrected throughput.

Formula used

  • Bulk Density Adjustment = first factor × second factor × conversion factor × process multiplier
  • Use the multiplier for unit conversion or process efficiency

Inputs explained

  • Volumetric feed rate at reference density:
  • Reference bulk density of the material:
  • Density ratio correction factor:
  • Feeder efficiency / process multiplier:

How to use the result

  • Use it whenever a new material lot, moisture change, or aeration state shifts bulk density away from the density at which the feeder was last calibrated.
  • It assumes a linear density relationship and steady-state feeding; it will not capture pulsation, bridging, or flooding that break the volumetric-to-mass link entirely.

Common questions

  • How do you calculate a bulk density adjustment? Multiply the reference feed rate by the reference bulk density, the density-ratio correction factor, and the feeder efficiency multiplier. With 100, 4, 0.005 and 1 the result is 2 units, showing how a small correction factor scales a large nominal rate down to the real delivered amount.
  • What is bulk density in loss-in-weight feeding? Bulk density is the mass of material per unit of settled volume, including the air gaps between particles. It matters because a volumetric feeder meters volume, so any change in bulk density directly changes the mass delivered per revolution.
  • Why does bulk density change between lots? Particle size distribution, moisture, additives, and how aerated or compacted the powder is all shift bulk density. Even the same product from the same supplier can vary 5-15% lot to lot, which is exactly what this adjustment is designed to catch.
  • Bulk density vs tapped density: which do I use? Use the density state that matches how the material actually sits in the feeder hopper. Loose (aerated) bulk density suits free-flowing feed; tapped density better represents a compacted, vibration-settled hopper. Mixing the two is a common source of dosing error.
  • What is a good feeder efficiency multiplier? A well-tuned gravimetric feeder on a free-flowing powder often runs at 0.97-1.0 (a multiplier of ~1). Cohesive or bridging materials can drop below 0.9, meaning you deliver noticeably less than the volumetric math predicts.

Last reviewed 2026-05-12.