YOKOGAWA ZR22G User Manual page 156

From the above equations (1) and (2), we obtain:
E = -K log y/a = -Klog [(100 – x) 30.21] /21
= - K log (1 –0.01 x) .................. Equation (3)
where, K = Constant
Using the above equation (3), we can calculate the water vapor in vol % from the electromotive
force.
Sample gas
Electrode
Figure 9.2 Schematic Diagram of Measurement Principle
(B) For the "mixing ratio" measurement
Assuming that the mixing ratio is rkg/kg, then "r" can be calculated from the value of H
as follows:
r = 0.622 3 x/(100 – x) ............... Equation (4)
From the above equations (1), (2) and (4), we obtain:
E = -K log y/a = -K log 50.622 3 21/(0.622 + r)/216
= -K log 0.622/(0.622 + r) ... ...... Equation (5)
where, K = Constant
With Equation (5), we can obtain the mixing ratio rkg/kg from the electromotive force.
120
100
80
60
40
20
0
0.1
Figure 9.3
Zirconia element
Comparison
water vapor
+
H O
2
concentration
indicator
-
1
Oxygen concentration PX (%O
Oxygen concentration vs. cell output
<9. Calibration>
Water vapor Air
100% 100%
x%
H O
2
79%
100%
N
2
21%
y%
O
2
Sample gas composition
F9-1E.ai
10
)
2
IM 11M12G01-02EN
9-3
O vol %
2
100
F9-2E.ai
1sh Edition : Mar. 25, 2021-00