< 12. Troubleshooting >
12-9
IM 11M12D01-01E
6) If the sensor assembly has deteriorated gradually, check the condition of the sensor assembly
following the procedure below.
a. Use the ▼ key to check Cell resistance. It should be 200 Ω or less if the cell (sensor) is new. On
the other hand, if the cell (sensor) is approaching the end of its service life, it will be 3 to 10 kΩ.
b. Use the ▼ key to check Cell robustness. It should say “life > 1 year” if the cell (sensor) is in good
condition.
F12-10E.ai
Ch1
Span gas ratio: 0 .1 %
Zero gas ratio: 1 0 1 . 3 %
Response time: 0 s
Cell robustness: life> 1 year
Cell resistance: 1 1
Ω
Next cal date: 0 0 0 0 2 0 0 0
Figure 12.10 Detailed Data Display (Cell Robustness)
3) Alarm 3: Span calibration coefficient alarm
In automatic or semi-automatic calibration, this alarm is generated when the span correction ratio is
out of the range of 0 ± 18% (refer to Subsection 9.1.3, “Compensation”). The following are suspected
as the cause:
(1) The oxygen concentration of the span gas does not agree with the value of the span gas set
“Calibration setup.”
(2) The flow of the span gas is out of the specified flow value (600 ± 60 ml/min).
(3) The sensor assembly is damaged and the cell voltage is abnormal.
<Locating cause of failure, and countermeasures>
(1) Confirm the following and carry out calibration again: If the items are not within their proper
states, correct them.
a. If the display “Span gas conc.” is selected in “Calibration setup,” the set point should agree
with the concentration of span gas actually used.
b. The calibration gas tubing should be constructed so that the span gas does not leak.
(2) If no alarm is generated as a result of carrying out recalibration, it is suspected that improper
calibration conditions were the cause of the alarm in the preceding calibration. In this case, no
specific restoration is necessary.
(3) If an alarm is generated again as a result of carrying out recalibration, deterioration of or damage
to the cell (sensor) is suspected as the cause of the alarm. Replacement of the cell with a new
one is necessary. However, before replacement, carry out the procedure described in step (3)
of <Locating cause of failure, and counter measures> in Subsection 12.2.3, 2) “Alarm 2: Zero
calibration coefficient alarm.”
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