Yokogawa PH72 Personal pH/ORP Meter - Manual (Page 71)

IM 12B03D02-01E 9-4
9. Technical Information
9.3 Temperature Compensation
In equation 9.3, 2.3026RT/F represents the emf per pH unit and varies depending on
temperature.
Table 9.1 EMF per pH (values of 2.3026RT/F)
0
5
10
15
20
25
30
Temperature
(
؇
C)
54.20
55.19
56.18
57.18
58.17
59.16
60.15
2.3026RT/F
(mV)
Temperature
(
؇
C)
2.3026RT/F
(mV)
Temperature
(
؇
C)
2.3026RT/F
(mV)
35
40
45
50
55
60
65 61.14
62.14
63.13
64.12
65.11
66.11
67.10 70
75
80
85
90
95
100
68.09
69.08
70.07
71.07
72.06
73.05
74.04
T0901.EPS
Table 9.1 presents the relationship between the temperature and the emf per pH unit, and
the relationship between the pH and the emf at each temperature is shown in Figure 9.4.
Measurement without temperature compensation will result in measured pH values
including errors as shown in Table 9.2.
The PH72 meter automatically modifies the calibration line according to the temperature
measured by the temperature element incorporated in an electrode (except needle type
and test tube size pH sensors).
0
؇
C
20
؇
C
60
؇
C
80
؇
C
-500
0
+500
pH7
pH2
mV
4 6
8
10 12 pH14
F0904.EPS
Figure 9.4 pH vs EMF at Each Temperature