Yokogawa Multi Channel Oxygen Analyzer System ZR22/AV550G - Manual (Page 165)

IM 11M12D01-01E 10-3
10. Other Functions
10.1.7 Cell Response Time
The cell’s response time is obtained in the procedure shown in Figure 10.3. If only
either a zero-point or span calibration has been carried out, the response time will not be
measured just as it will not be measured in manual calibration.
mA
90%
100%
The response time is obtained after the corrected calibration curve has been found. The response time
is calculated as the time interval between the ten percent and 90 percent output points.
10% of analog
output span
Five minutes maximum
Response time
Start calibration
Time
Calibration
complete
F10.3E.EPS
Figure 10.3 Typical response time characteristic
10.1.8 Robustness of a Cell
The robustness of a cell is an index for predicting the remaining life of a sensor and is
expressed as one of four time periods during which the cell may still be used:
(1) more than a year
(2) more than six months
(3) more than three months
(4) less than one month
The above four time periods are tentative and only used for preventive maintenance, not
for warranty of the performance.
This cell’s robustness can be found by a total evaluation of data involving the response
time, the cell’s internal resistance, and calibration factor. However, if a zero or span
calibration was not made, the response time cannot be measured. In such a case, the
response time is not used as a factor in evaluating the cell's robustness..
10.1.9 Cell’s Internal Resistance
A new cell (sensor) has an internal resistance of 200
⍀ maximum. As the cell degrades,
so will the cell’s internal resistance increase. The degradation of the cell cannot be
evaluated just by changes in cell’s internal resistance, however. Those changes in the
cell’s internal resistance are just a guide to the extent the cell is degrading. The updated
values obtained during the calibration are displayed.