Sartorius DCU 3, Operator'S Handbook Manual

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Operators Handbook DCU3 – System
6., Main function „Control Loops“
BAEDCU3 - Rev. 4.6 - 0504 6 - 29
6.18 Weight Controller
Fermentation processes often require to keep the culture volume precisely constant, i.e. during con-
tinuous or „repeated fed batch“ operation. Compared to level control the weight control is another suit-
able, more precise method to control the vessel contents.
The contents of the culture vessel will be measured using balance platforms or load cells. The weight
controller in the DCU system is a PID controller and controls a harvest pump or a harvest valve via
pulse-width modulated outputs.
6.18.1 Operating Display
For a description of the tags, the physical units or entries, the displayed value or function
and of the required inputs see the table in section
6.3, Controller Operation in General.
6.18.2 Special Notes
To avoid unintended controller actions during manipulations at the culture vessel the weight
control mode should be set to „hold“ in the calibration routine for the balance system. This
will disable the weight control temporarily.
Since the level and the weight controller trigger the same control signal output, only one of
these functions can be implemented in one DCU system.
The dosing counters HARV and FEEDP will automatically be activated, whenever one of the
modes „auto“, „profile“ or „manual“ is selected.