86
BioFlo/CelliGen 115
y
M1369-0050
User’s Guide
Figure 36: Setting Pump Setpoint
This sample
PUMP
screen shows Pump 1 assigned to Acid (
see Section 11.1 for
details on assigning a pump
). Instead of a Setpoint edit box, there is an “Out Mult”
(Output Multiplier) edit box. The output for this pump is calculated through PID.
It is common, when a batch is running, to see that pH remains steady at the setpoint,
yet the acid and/or base pumps are continually alternating in making additions. This is
an indication that the controller is overcompensating for minor fluctuations in pH.
Output Multiplier
is a feature that attenuates controller output to the acid and base
pumps and the CO
2
gas line, providing more nuanced control of additions to maintain
pH.
Contrary to the number shown in the Figure 36 Pump 1 Out Mult edit box, we
recommend that you begin by implementing a multiplier of 25%. This means that if
the controller’s output to the base pump, for example, is 100%, then the 25%
multiplier will reduce pump output to 25%. If the controller’s output to the pump is
50%, the 25% multiplier factor will reduce pump output to 12.5%.
If, after applying an Output Multiplier of 25%, you find the results are attenuated but
the controller seems unable to maintain the setpoint, increase the Multiplier by small
increments until the controller is able to maintain setpoint.
2. Press the Setpoint edit
box for Pump.
3. Use the touchpad that
opens to enter the desired
setpoint, then press OK to
save it and return to this
screen (or press Cancel to
return to this screen without
saving a setpoint.
