45
Appendix 2: Calculating Temperature Coefficients
To determine the temperature coefficient of your sample solution use
this formula:
TC =
100 x CT2 - CT1
CT1(T2 - 25) - CT2(T1 - 25)
TC = Temperature coefficient
CT1 =Conductivity at Temp. 1
CT2 = Conductivity at Temp. 2
T1 = Temp. 1
T2 = Temp. 2
25 = 25°C
NOTE: A controlled temperature water bath is ideal for this procedure.
1.
Immerse the probe into a sample of your solution and adjust the temperature
coefficient to 0% (that is, no compensation) by performing the following:
A. From conductivity measurement mode, press the SET key.
B. Press the
▲
key until the lower display reads P8.0.
C. Press the ENTER key twice. The lower display reads tCO and the upper
display shows the temperature coefficient value.
D. Press the
▼
key until the upper display shows 0.0.
E. Press ENTER key to confirm the value.
F. Press CAL/MEAS key twice to return to measurement mode.
2.
Wait for 5 minutes. Note T1 and CT1 (conductivity at T1).
3.
Condition the sample solution and probe to a temperature (T2) that is about
5°C to 10°C different from T1, and note the conductivity reading CT2.
NOTE: Record your results for future reference. Ideally T1 and T2 should bracket
your measurement temperature, and should not differ by more than 5°C.
4.
Calculate the temperature coefficient of your solution according to the for-
mula shown above.
5.
Enter the temperature coefficient you calculated into the meter.
A. From conductivity measurement mode, press the SET key.
B. Press the
▲
key until the lower display reads P8.0.
C. Press the ENTER key twice. The lower display reads tCO and the upper
display shows the temperature coefficient value (should be 0, per step 1-D
above).
D. Press the
▲
key until the upper display shows your calculated
temperature coefficient.
E. Press ENTER key to confirm the value.
F. Press CAL/MEAS key twice to return to measurement mode.
The calculated temperature coefficient will now be applied to all the meter
readings.
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