Walchem WebMaster ONE Instruction Manual page 160

Disinfection Sensor Calibration Failure
This error message occurs after calibrating the chlorine or chlorine dioxide electrode. The
controller will display a calibration failure if the offset calculated in the Zero Calibration is outside
of the range –20 to 40 mV or the slope calculated in the One Point Process Calibration is outside
of the range -10 to -100 mV per ppm.
Possible Causes
Insufficient conditioning
Insufficient sample flow
Dirty electrode.
Air bubbles on membrane
Faulty membrane.
High Pressure
No electrolyte fill solution in membrane cap
Faulty analysis equipment or reagents
Sensor cable disconnected.
Faulty core interface circuit board
(if Sensor 1).
Faulty sensor option circuit board
(if Sensors 2-4).
Corrective Actions
Wait for the appropriate amount of time before
attempting a calibration.
Increase flow rate to between 30 and 100 liters
per hour
Clean electrode and recalibrate as described in
Section 7.6 above.
Dislodge bubbles. Adjust flow rate higher if
necessary.
Replace membrane
Reduce pressure to below 1 atmosphere and
refill cap with electrolyte
Fill membrane cap with electrolyte. Replace
membrane cap if it will not hold solution.
Consult test equipment instructions
Reconnect cable. Make sure that the +/- 5
VDC and the IN-, IN+ wires are firmly
attached.
Go to the Sensor Input Page and perform a self
test. If this passes, then the problem is with the
sensor or its wiring. If it fails, then disconnect
the sensor from the circuit board and try the
self test again. If it still fails, replace the circuit
board.
Troubleshoot as above. Replace the sensor
option board if self test fails.
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