Bulk Bag Weighing

IBCs are typically used for loss-of-weight application. IBCs are suspended by load cells to weigh the material dispensed into receiving containers. Hardy 3010 Filler/Dispenser can either standalone or connect to host computers (PC), Programmable Logic Controllers (PLCs), Programmable Automation Controllers (PAC), or Distributed Control Systems (DCS), to open and close the discharge gates while weighing the loss of ingredients.

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Empty IBCs are often exchanged before the desired weight is met. A Hardy dispenser/filler retains the amount dispensed from the first IBC in memory so that it knows how much material is required from the second IBC to complete the desired weight. Without this feature, material is wasted by not completely emptying the IBC or by overfilling when switching.

Instrumentation and Control

Hardy filling and dispensing systems include weight or rate controllers connected to load points (load cells and mounting hardware) in either a standalone system or connected to PCs, PLCs, PACs, or DCSs. Total net weight can be tracked with Hardy's totalizer feature, keeping track of the total amount of the material that has been filled or dispensed. In addition to filling and dispensing, Hardy controllers can also be used to control or monitor the rate of flow of material.

Accuracy

High resolution and fast update rates in Hardy's controllers allow for precise cut-offs. The scale must be capable of updating faster than the rate that material is entering or leaving it.

Hardy controllers with their programmable preacts have the ability to account for the in-flight material that is not yet on the scale when the valve or gate is closed. A preact can stop the process earlier in order to compensate for the material in-flight, so it doesn't overshoot the desired weight.

If the final weight falls under the desired amount, Hardy's "jog" feature slightly opens the gate or valve for a selectable period of time to bring the weight into tolerance. The preact can be either user-selectable (Manual) or user selectable and self-adjusting (Reactive).

Speed

Accuracy of dispensing is increased even more using the dual speed capabilities of Hardy's controllers. A fast or bulk speed is used for the majority of the process cycle in which valves or gates are wide open to allow maximum flow coupled with a slow or dribble speed at the end of a cycle, where the valves or gates are nearly closed. The slow or dribble speed allows for higher accuracy of hitting the final desired weight without under or overshooting it. A reactive algorithm analyzes and automatically adjusts the fast cutoff to increase system throughput.

For more information, check out our Case Studies on inventory management and our Application Notes on loss-in-weight or gain-in-weight measurement systems.