Walchem WebMaster ONE Instruction Manual page 163

pH High Alarm
This error message indicates the pH reading exceeds the user-programmed maximum allowable
value.
Possible Causes
The programmed value is too close to
pH set point.
Chemical supply empty.
Faulty pH electrode.
Control direction set incorrectly.
Control device set at too high a flow rate.
Metering pump is siphoning.
Faulty control device.
Blown fuse.
Faulty control device wiring.
Faulty pH output relay.
The pH dead band is set too high.
Corrective Actions
Go to the pH Input Page and make sure that the
the High Alarm Limit is set at least 0.5 pH
units above the set point.
Replenish chemical supply.
Clean and calibrate the electrode as described
in Section 7.3 above. If the calibration fails,
see troubleshooting for pH Calibration Failure
above.
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.
Reduce the flow rate of the control device.
Install or repair the anti-siphon valve.
Repair or replace the control device.
Replace the fuse (F2 or F3).
Correct the control device wiring.
Replace the relay interface board.
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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