Belt scales can be relatively easily calibrated, however, this is a manual exercise requiring plant downtime and personnel to attend the units and carry out the work.  Most belt scales will provide an accurate measurement immediately after calibration, however, the system performance can be prone to drift in time and so calibration maintenance is important.  One important aspect of the calibration which affects system accuracy is the zero value.  This means that if there is a way to allow automation of the re zeroing ie without the need for operator intervention, this would be a very useful feature.  Ultra-Dynamics Pty Ltd ultraWEIGH^TM Low Cost Beltscale now includes an automatic zero function.  This feature requires the unit to be provided with a “Material Available” signal which is used in conjunction with the speed sensor to indicate to processor that the belt is empty and moving.  Once this empty belt condition has been identified by the processor for a minimum period, the unit automatically carries out a zero (empty belt) measurement.  This feature allows the zero value to be updated based on prevailing plant conditions which might have changed since the last full calibration and set up procedure.