17
Calibration Failure
For WebMaster
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
(mV/ppm) calculated in the One Point Process Calibration is outside of the
range of the nominal mV per 0.1 to 2.0 ppm.
For WDIS:
The acceptable range for the slope (mV/ppm) is the nominal mV per 0.5 to
2.0 ppm. The range of mV for a Zero Calibration is –100 mV to 100 mV.
For W100 or W600 or 900:
The calibration will fail if the adjustment to the gain is outside of 0.2 to
10.0, or if the calculated offset is outside of -40 to 40 mV.
To calculate the nominal slope for your sensor, divide the high end of the
nominal range by -2000. For example, for a 0-20 ppm sensor, the nominal
slope is -2000/20 = -100 mV/ppm.
Possible Causes
Corrective Actions
Insufficient conditioning
Wait for the appropriate amount of time
before attempting a calibration.
Insufficient sample flow
Increase flow rate to between 30 and 100
liters per hour
Air bubbles on membrane
Dislodge bubbles. Adjust flow rate higher
if necessary.
Dirty membrane
Clean membrane
Faulty membrane
Replace membrane cap.
High Pressure
Reduce pressure to below 1 atmosphere and
refill cap with electrolyte
No electrolyte fill solution in
membrane cap
Fill membrane cap with electrolyte.
Replace membrane cap if it will not hold
solution.
Faulty sensor
Replace sensor
Faulty analysis equipment or
reagents
Consult test equipment instructions
Sample contaminated with
interfering molecule (refer to
Sensitivity specification in
section 6.0)
Remove source of contamination
Faulty wiring
Check wiring
Faulty controller sensor input
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.
