Kistler-Morse KM L-Cell Bolt-On - Manual (Page 75)

Appendix D. System Calibration
D-1
Appendix D: System Calibration
This chapter describes general procedures for calibrating the
L-Cell system. Before calibrating, you must install a signal
processor. Refer to the signal processor manual for the procedures
to input calibration parameters.
There are two calibration methods:
•
Live Load calibration — set lo span and hi span while moving material into
or out of the vessel. This is the preferred method.
• Manual calibration — set scale factor counts, scale factor weight, and zero
calibration value without moving material. This method is less accurate
than Live Load calibration.
A Live Load calibration requires you to move a known quantity of material into
or out of the vessel while performing the procedure. The quantity of material
moved must be at least 25% of the vessel’s total capacity to provide best
accuracy. Live Load calibration is also based on the material weight currently in
the vessel.
Manual calibration allows you to start using the system as soon as L-Cells,
junction boxes, and signal processor are installed and wired, even if you cannot
move any (or enough) material now. Manual calibration values are based on
system parameters, including sensor sensitivity, vessel stress, and signal
processor A/D converter sensitivity. These values are known, can be calcu-
lated, or can be obtained from the signal processor. Manual calibration is also
based on the material weight currently in the vessel.
Note that manual calibration does not take into account the actual response to
changes in weight. Theoretically, a change in weight results in a proportional
change in digital counts. However, the structure’s actual response to load and
interaction with piping, catwalks, a roof, discharge chutes, etc. prevents the
system from achieving theoretical values. Manual calibration is a good start,
but to obtain the highest accuracy, perform a Live Load calibration when
scheduling permits you to move material into or out of the vessel.
The following sections provide procedures for performing Live Load and
Manual calibrations.