The Basics of Bulk Weighing Systems

Load cells and mounts form the base of weighing systems. The mount helps ensure vertical forces align on the load cell for correct measurements while also ensuring any horizontal forces don’t damage the load cell. There are many different styles of mounts, and the application environment and requirements will determine the style used.

When a system uses more than one load cell, the signals are combined in a junction box to present one weight reading. The junction box is connected to a digital weight indicator or controller to display the weight or transmit the information to another area of production. Weight can be transmitted to a PLC or PC, and special software is used for batching systems, loss-in-weight dosing systems or belt scales. Connections through Profibus, Profinet, Ethernet and DeviceNet allow more data to be shared between a PLC and weight processor.

Static Weighing Systems

Static weighing systems are one of the most accurate ways to determine the net content of a bunker, drum, hopper or large bag in kilograms or tons. The type of load cell and mount used are determined by a variety of considerations including gross and net weight, vibrations, cleaning methods, exposure to corrosive substances, ATEX zoning and more.

Choosing an indicator or controller to pair with the system depends on your needs for functionality, communication to a PLC, where it will be located and how it will be mounted. Some controllers can be installed in production areas while others will be in a control office. Calibration can be performed with a premeasured amount of material in the container or with certified calibration weights. For Legal for Trade weighing, calibration weights must be used to verify weighing system accuracy.

Silo Weighing

Silo weighing systems are very similar to static weighing systems. However, when the silo is installed outside there are additional conditions to consider for the installation, including strong winds. Special load cell mounts can compensate for high wind forces while providing accurate weights. The mounts are fitted with anti-tipping features to help protect and prevent silos from tipping over.

For many larger silo weighing systems, it’s recommended that an indicator with an auto-calibration function be used to simplify calibration procedures. When load cell data can be entered and stored in the indicator, the calibration can be performed without weights or material.