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Diagnostics and Messages
January 2009 UDA2182 Universal Dual Analyzer Product Manual 193
12.3 Calibration Diagnostics
pH/ORP/DO
All of the possible errors are detected during a probe calibration and will abort the
calibration process with the message “FAIL” appearing briefly, followed by a return to
the online pH/ORP/DO display. At that point, the specific error will be displayed as
described. In addition, any of following errors may occur during probe calibration and
abort the calibration process.
Table 12-2 Probe Calibration Diagnostics
Status Message Definition
BUFFER SPAN TOO LOW
The span between pH buffer 1 and pH buffer 2 is less than 2 pH. Use a set of
buffers that are at least 2 pH apart. As a warning status, will clear when an
appropriate buffer 2 value is selected. As an error message, will abort
calibration and preserve original slope value.
OFFSET UNDERRANGE
Resulting pH offset (standardization) value is less than –2 pH after pH slope
calibration. Calibration is aborted and original pH offset and slope values are
preserved.
OFFSET OVERRANGE
Resulting pH offset (standardization) value is greater than 2 pH after pH slope
calibration. Calibration is aborted and original pH offset and slope values are
preserved.
SLOPE UNDERRANGE
Resulting pH slope is less than 80%. Calibration is aborted and original slope
value is preserved.
SLOPE OVERRANGE
Resulting pH slope is greater than 105%. Calibration is aborted and original
slope value is preserved.
CAL FACTOR UNDERRANGE
Resulting DO calibration factor is less than 0.001268. DO calibration is
aborted and original calibration factor is preserved.
CAL FACTOR OVERRANGE
Resulting DO calibration factor is greater than 0.040580. DO calibration is
aborted and original calibration factor is preserved.
PROBE CURRENT TOO LOW
DO probe current is less than 5 µA. DO bias scan is aborted and original bias
voltage is preserved.
PROBE CURRENT TOO HIGH
DO probe current exceeds the greater of 133% of the probe current at last
successful calibration or 160 µA. During DO bias scan, scan is aborted and
original bias voltage is preserved.
READINGS UNSTABLE
DO air PV or temperature readings too unstable for successful air calibration.
Calibration is aborted and original calibration factor is preserved.
SOLUTION UNSTABLE
pH solution PV or temperature readings too unstable for successful auto
buffer calibration. Calibration is aborted and original pH offset (for buffer 1) or
slope value (for buffer 2) is preserved.
SOLUTION TEMP TOO LOW
pH solution temperature readings less than minimum of 0 degrees C. Auto
buffer calibration is aborted and original pH offset (for buffer 1) or slope value
(for buffer 2) is preserved
SOLUTION TEMP TOO HIGH
pH solution temperature readings greater than maximum of 100 degrees C.
Auto buffer calibration is aborted and original pH offset (for buffer 1) or slope
value (for buffer 2) is preserved