Hanna Instruments EC 214 - Manual (Page 8)

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PROBE MAINTENANCE
After every series of measurements,
rinse the probe with tap water.
If a more thorough cleaning is re-
quired, remove the sleeve and clean
the probe with a cloth or a non-
abrasive detergent.
After cleaning the probe, always
re-calibrate the instrument.
The 4-ring platinum probe body is
made of glass. For this reason great
care while handling the probe must
be taken.
• Immerse the probe into a solution sample and adjust the
“TEMPERATURE COEFFICIENT” knob to 0% (no compensation).
• Condition sample and probe at 25°C, and note the conductivity
reading C
25
.
• Condition sample and probe to a temperature t°C (approximately
5°C to 10°C different from 25°C), and note the conductivity
reading C
t
.
• The temperature coefficient ( β)of the solution is then calculated
using the following formula:
β = 100 x (C
t
- C
25
) / [(t - 25) x C
25
]
The above procedure is suitable for determining the temperature
coefficient in the laboratory where the temperature of the solution can
be determined and controlled.
If this is not possible, e.g. during on-site measurements, the following
procedure should be used:
• Immerse the probe into the test solution and turn the “TEMPERA-
TURE COEFFICIENT” knob to 0% (no compensation).
• Allow the conductivity reading to stabilize (the reading should not
change by more than ±0.2 mS within 1 minute) and record the
value, C.
• Repeat the procedure with a different solution temperature,
changed by more than 10°C. Wait for the reading to stabilize.
• Adjust the “TEMPERATURE COEFFICIENT” knob until the display
reads the previously recorded “C” value.
• The value indicated by the knob is the temperature coefficient of
the solution.
DETERMINATION OF THE TEMPERATURE
COEFFICIENT OF A SOLUTION (EC 215)