Thermo Scientific Orion 310, Instruction Manual

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PerpHecT ® Orion 310, 320, 330 Instruction Manual
16
Table 1 pH Error due to 1 ° C Temperature Change (in pH units)
A. What Is digital LogR?
PerpHecT pH meters allow for direct temperature measurement and
temperature compensation from your pH electrode. With simultaneous
measurement of pH and temperature, the patented Orion digital LogR
technology makes it possible using most standard glass pH electrodes.
The system is based on using the electrical resistance of the glass sensing
bulb as the temperature probe. The name comes from the fact that the
logarithm of the resistance of the bulb varies almost linearly with the
reciprocal of the absolute temperature (See
Figure 5 ). Almost all common
pH glasses show a similar decrease in resistance with increasing
temperature, and can be used with other types of meters. However,
only the exact shape of the curve for Orion PerpHecT electrodes
is in the meter’s memory.
To maximize system performance and accuracy, use PerpHecT ROSS and
PerpHecT pH electrodes.
Introduction to Patented digital LogR pH Measurement for Orion 310
10
20
30
40
50
60
70
80
90 0.004
0.003
0.003
0.003
0.003
0.003
0.003
0.003
0.003 0.011
0.010
0.010
0.010
0.009
0.009
0.009
0.008
0.008 0.007
0.007
0.007
0.006
0.006
0.006
0.006
0.006
0.006 0.014
0.014
0.014
0.013
0.012
0.012
0.012
0.011
0.011 0.018
0.017
0.017
0.016
0.015
0.015
0.015
0.014
0.014
pH 12
or pH 2 pH 11
or pH 3 pH 10
or pH 4 pH 9
or pH 5 pH 8
or pH 6
TEMP. ( ° C)
2.7
-1 0 1 2 3 4 5 6 7
2.6
2.8
2.9
3
3.1
3.2
3.3
3.4
3.5
3.6
3.7
3.8
T
emperature (1000/Degrees K
elvin)
Figure 5
Log of Resistance
Cal Point Values
Calculated Values