247 CONDUCTIVITY AND TEMPERATURE PROBES
7
7. MAINTENANCE
Routine maintenance includes thoroughly
cleaning the orifice of the 247 probe with the
black nylon brush provided and a little soapy
water. Rinse thoroughly.
8. ANALYSIS OF ERRORS
8.1 EC MEASUREMENT ERROR
1. Bridge Measurement Error: < 1.0%
2. Calibration Error:
bridge measurement: < 0.5%
calibration solution: < 1.0%
3. Ionization Error of KCl and Na+ Solutions
After Correction:
< 2.0%, 0.45 to 7.0 mS cm
-1
< 8.0%, 0.005 to 0.45 mS cm
-1
Correction of Ionization Errors. Figures 8.1-1 and
8.1-2 show the amount of correction applied by the
example program to compensate for ionization
effects on the measurements. Also shown is an
ideal correction. Factors were derived by
measuring the standard solutions described in
Section 2.2 with values of 0.0234, 0.07, 0.4471,
07, 1.413, 2.070, 3.920, and 7.0 mS cm
-1
.
FIGURE 8.1-1. Plot of Ideal and Actual Correction between 0 and 0.44 mS cm
-1
FIGURE 8.1-2. Plot of Ideal and Actual Correction between 0.44 and 7.0 mS cm
-1
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