9.5
pH equilibrium
Corrective action
Possible causes
Problem
A deadband must be used for pH con-
trol. If no deadband is used, acid and
base are alternately introduced. Define
a deadband applicable to your process.
See
pH PID Settings screen, on page111
for more information.
The deadband is set to 0.
pH is not coming
to equilibrium
even if the pumps
are running.
Fill the acid/base supply vessel.
Acid/base supply is empty.
Prime the pumps.
The pumps are not primed.
Free the feed line.
Feed line before or after the pump is
kinked.
Free the feed line.
Feed line before or after the pump is
clamped.
Conduct a study to verify the PID param-
eters. The following factors have been
identified as important:
PID parameters are not applicable for
the system.
•
Quantity of media
•
The pump type
•
Concentration of acid / base
•
Mapping strategy
•
Buffering capability of media
•
Mixing of the mixer vessel contents
(weight and viscosity dependent).
270
Xcellerex XDUO 2500 Mixer Operating Instructions 29146667 AH
9 Troubleshooting
9.5 pH equilibrium
