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User‘s manual for CX-401 multifunction meter
v6.0x
11. NOTICES ABOUT THE TEMPERATURE COMPENSATION AND
INTERPRETATION OF THE pH MEASUREMENT RESULTS
CX-401 meter has a possibility of manual and automatic temperature
compensation, what enables eliminating errors which result from affecting the
electrode characteristics by the temperature changes. The pH meter is a mV
meter which displays voltage counted to pH unit. In a constant temperature
there is a constant mV value per one pH unit. In 20
0
C it is 58,168 mV. The
value of mV per one pH unit changes together with the temperature, what
is taken into consideration in the formula for “k coefficient” of the pH
electrode:
k = 0.198423 T
Calculating this change into measurement result is called temperature
compensation. It is connected with a change of the electrode efficiency
and not with a change of the pH value of the measured solution caused
by the temperature change.
Changes of the pH values with the temperature in the majority of solutions
are rather slight, however in e.g. pure water they tend to be significant.
Comparing values of solutions that tend to be affected by the temperature
change should be done in the same temperature. Sometimes the results of
measurements in the same solution in stable temperature are different.
These are possible reasons of such situations:
- differences occur because of poor quality of the electrode;
- the result is treated as stabilised too soon (medium quality electrode needs
about 40 seconds to full stabilisation);
- the measured solution is not homogeneous and lack of magnetic stirrer
does not allow for obtaining similar results;
-
during measurements in sewage some chemical reactions, which change
the result, may occur.
The final measurement error is dependent mainly on the electrode’s quality,
the temperature measurement error, the quality of the buffers applied for
calibration and accuracy while performing procedures connected with
calibration as well as measurements. The meter may cause minor
differences.
Содержание CX-401
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Страница 3: ...USER S MANUAL WATERPROOF MULTIFUNCTION METER CX 401 Before use please read the instructions carefully...
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Страница 7: ...1 I INTRODUCTION...
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Страница 25: ...19 II pH MEASUREMENT...
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Страница 45: ...39 III CONDUCTIVITY AND SALINITY MEASUREMENT...
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Страница 71: ...65 IV OXYGEN CONCENTRATION MEASUREMENT...
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Страница 87: ...81 V ATMOSPHERIC PRESSURE MEASUREMENT...
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