160
pH Low Alarm
This error message indicates the pH reading is below the user-programmed minimum allowable
value.
Possible
Causes
Corrective
Actions
The programmed value is too close to
Go to the pH input page and make sure that the
pH set point.
the Low Alarm Limit is set for at least 0.5 pH
units below the set point minus the dead band.
Chemical supply empty.
Replenish chemical supply.
Faulty pH electrode.
Clean and calibrate the electrode as described
in Section 7.3 above. If the calibration fails,
see troubleshooting for pH Calibration Failure
above.
Control direction set incorrectly.
For acid feed the control direction should be
“force lower” for caustic feed, “force higher”.
Go to the Relay Output Page and verify the
correct
setting.
Control device set at too high a flow rate.
Reduce the flow rate of the control device.
Metering pump is siphoning.
Install or repair the anti-siphon valve.
Faulty control device.
Repair or replace the control device.
Blown fuse.
Replace the fuse (F2 or F3).
Faulty control device wiring.
Correct the control device wiring.
Faulty pH output relay.
Replace the relay interface board.
The pH dead band is set too high.
Go to the pH Output Page and change the dead
band to be as low as possible to prevent the
pH relay from chattering. If the pH reading
fluctuates by +/- 0.02 pH units, then a dead
band of 0.05 is sufficient.
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