Sterlco SGBD Series Batch Gravimetric Blenders - Manual (Page 46)

BLN1-600A Chapter 3: Installation 46 of 116
Blender Calibration
The load cells on the blender are FACTORY CALIBRATED. Since the load cells can be
subject to shock loading during shipping, moving, etc., we recommend that they be
recalibrated.
The load cells monitor the weight of each ingredient added to the blender weigh hopper.
Since load cells are reading the actual material weight that is metered by the feeders, the
proper calibration of these load cells is essential for the correct operation of the blender.
The load cells should be checked once a month with a calibration weight and if
necessary recalibrated to ensure that they have not been damaged in the normal routine
of removing and replacing the weigh hopper for cleaning, color changes, etc.
The calibration of each load cell is accomplished by using two reference points on the output
of the load cell scale. The first of these points is known as the “Tare Weight”. This is the
weight of the empty hopper assembly on the load cell. This is also known as the zero weight
point (starting point) of the scale. This zero or starting point must be initialized with an empty
weigh hopper. There must be no binding or leverage put on the load cell.
The second weight point used in the load cell calibration procedure is a known amount of
weight for the weigh hopper. A calibration weight is provided with all Batch blending
systems. The calibration weight is stamped with its actual weight on top. If this is not
available, any object with a known weight accurate +/- 0.01 lbs. will suffice. (The weight
should be as close as possible to the maximum batch size you plan to run.) The weight will
be in pounds, unless the blender is provided for metric operation. In the case of a metric
blender display, the weight to be used is calibrated in kilograms.
Given the two weight points on the load cell scale, the controller should determine any other
weight on the load cell span. This is limited to the maximum capacity of the load cell. The
standard load cell used on these blenders has a span accuracy of 0.02%.
The maximum capacity of each load cell is clearly marked on top of the load cell. This value
will be indicated in kilograms (1 kg = 2.2 lbs.).
• The weight scale on a new blender comes pre-calibrated, but it is
recommended to periodically check the calibration to ensure that the
reported inventory levels are accurate.