Yokogawa Single Channel Oxygen Analyzer System ZR22/ZR402 - Manual (Page 192)

IM 11M12A01-03E 12-8
b. Display “Calibration time history” by pressing the
᭢ key (Figure 12.6). Since
the ten previous span-correction factor and zero-correction factor values can be
checked in this display, changes in deterioration of the sensor can be seen.
Cell voltage: 0 . 6 mV
Thermo voltage: 4 2 . 1 mV
C.J.resistance: 1 1 8 1 . 4 ⍀
Cell resistance: - 4 ⍀
Soft.rev.: 0 . 2 4
Tag:
F12.5E.EPS
Hold
Calibration data:
1: 2 0 0 0 / 07 / 07 1 4 : 57
Span gas ratio: - 2 . 9 %
Zero gas ratio: 7 0 . 3 %
2: 2 0 0 0 / 07 / 07 1 4 : 5 4
Span gas ratio: - 2 . 9 %
Zero gas ratio: 8 9 . 7 %
Tag:
Hold
Figure 12.5 Detailed Data Display Figure 12.6 Calibration History
(5) If deterioration of the sensor assembly has occurred abruptly, it may show that the
check valve, which prevents moisture in the furnace from getting into the calibration
gas tubing, has failed. If the gas in the furnace gets into the calibration gas tubing, it
condenses and remains in the gas tubing as condensate. The sensor assembly is
considered to be broken for the reason that the condensate is blown into the sensor
assembly by the calibration gas during calibration and so the cell cools quickly.
(6) If the sensor assembly has been gradually deteriorating, check the sensor assembly
status in the following procedure:
a. Display “Cell resistance” by pressing the
᭢ key. A new cell will show a cell
resistance value of 200
⍀ or less. On the other hand, a cell (sensor) that is
approaching the end of its service life will show a resistance value of 3 to 10
k
⍀.
b. Display “Cell robustness” by pressing the
᭢ key. A good cell (sensor) will
show “Life > 1 year” (Figure 12.7).
Span gas ratio: - 2 . 9 %
Zero gas ratio: 7 0 . 3 %
Response time: 0 s
Cell robustness: life< 1 month
Cell temperature: 1 0 6 7
Њ C
C.J.temperature: 4 7
Њ
C
Tag:
Hold
F12.7E.EPS
Figure 12.7
12.2.2.3 Alarm 7: Span-point Calibration Coefficient Alarm
In automatic or semiautomatic calibration, this alarm is generated when the span
correction factor is out of the range of 0
Ϯ 18% (refer to Section 9.1.3, “Compensa-
tion”). 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
Ϯ 60 mL/min).
(3) The sensor assembly is damaged and the cell voltage is abnormal.