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 - 10
6.7 Airflow Controller
The airflow is controlled via an external massflow controller. The airflow control function of the DCU3 -
system works as a setpoint controller. It supplies the analog setpoint signals to the external massflow
controller . The menu at the DCU-system is used for entering the setpoints and display of the flowrate
signal coming from the massflow controller. For pO
2
control the airflow controller can be switched over
to be servo controller in the pO
2
cascade control loop.
6.7.1 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.
6.7.2 Special Notes
In „manual“ mode, when entering the MIN/MAX output limits and entering data into OUT,
allways observe the permissible measuring range of the corresponding airflow rate:
– BIOSTAT
®
ED : 0 - 100 % = 0 - 20 l / min
For further information on the permissible airflow range of your fermentor check the preset
configuration of your DCU3 – system or refer to the configuration documentation of your fer-
mentor system delivered extra.
The basic airflow rate is entered via the MIN/MAX-output limits. If the airflow controller is
used as servo controller in the pO
2
cascade control, you can enter the maximum allowable
airflow rate here.
For standard laboratory scale fermentors the control valve of the external massflow control-
ler will be fully closed when the airflow controller is switched off.
When the pressure setpoint is rather high and the pressure controller is activated at this
time, the air supplied to the fermentor cannot be controlled up to its maximum aeration rate.