GE Xcellerex XDM Series Operating Instructions Manual page 267

pH control
The information presented in this section is relevant for XDUO mixer only.
Problem
pH is not coming
to equilibrium
even if the pumps
are running.
Xcellerex XDM 50-1000, XDUO 100-1000 mixers Operating Instructions 29251615 AD
Possible causes
The deadband is set to 0.
Acid/base supply is empty.
The pumps are not primed.
Feed line before or after the pump is
kinked.
Feed line before or after the pump is
clamped.
PID parameters are not appropriate for
the system.
9 Troubleshooting
Corrective action
pH control must use a deadband. If no
deadband is used, acid and base are
alternately introduced. Define a
deadband value appropriate to your
process.
Fill the acid/base supply vessel.
Prime the pumps.
Free the feed line.
Free the feed line.
Conduct a study to verify the control
parameters. The following factors have
been identified as important:
Quantity of media
•
The pump type
•
Concentration of acid and base
•
Mapping strategy
•
Buffering capability of media
•
Mixing of the mixer vessel contents
•
(weight and viscosity dependent).
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