YOKOGAWA ZR22S, Руководство пользователя

Страница: 146 / 206

<10. Other Functions>
10-2
IM 11M13A01-02E
10.1.2 Thermocouple Voltage
The cell temperature is measured with a Type K (chromel-alumel) thermocouple.
The thermocouple cold junction is located in the detector terminal box. The cell temperature and
the thermocouple voltage (including the voltage corresponding to the cold junction temperature)
are displayed.
10.1.3 Cold Junction Resistance (C.J. Voltage)
The ZR22 Detector measures the cold junction temperature using an RTD (Pt 1000).
(The earlier model of ZO21D uses transistors to measure the cold junction temperature.)
If detector “ZR22” is selected in the Basic setup display, the RTD resistance values will be
displayed. If the ZO21D is selected, the transistor voltage will be displayed.
10.1.4 Cell’s Internal Resistance
A new cell (sensor) indicates its internal resistance of 200 Ω 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.
10.1.5 Software Revision
The revision (number) of the software installed is displayed.
10.1.6 Span gas and Zero gas Correction Ratios
These are used to check for degradation of the sensor (cell). If the correction ratio is beyond the
limits as shown in Figure 10.2, the sensor should no longer be used.
These ratios can be found by calculating the data as shown below.
21.0 p1 0.51
81.92
ez
e1
es
0
C
A B
Zero gas correction ratio = (B/A) x 100 (%) Correctable range: 100 ± 30%
Span gas correction ratio = (C/A) x 100 (%) Correctable range: 0 ± 18%
Cell
electromotive
force, mV
Calibration curve
before correction
Previous
zero gas data
Corrected calibration curve
(theoretical calibration curve)
Zero origin
Span origin
(Span gas concentration)
Oxygen concentration (vol%O
2
)
F10-2E.ai
Figure 10.2 Span gas and Zero gas Correction Ratios