Hanna Instruments ec 214 用户手册

PROBE MAINTENANCE

Rinse the probe with tap water after
every series of measurements. If a
more thorough cleaning is required,
remove the sleeve and clean the
probe with a cloth or a nonabrasive
detergent.
After cleaning the probe, re-calibrate
the instrument.
The four ring platinum probe body
is in glass. For this reason great
care while handling the probe must
be taken.

• Immerse the probe into a sample of the solution and adjust the

“TEMPERATURE COEFFICIENT” knob to 0% (i.e. no compensa-
tion).

• Condition the sample and probe at 25 C and note the conductivity

reading C25.

• Condition the sample and probe to a temperature t C which is

approximately 5 C to 10 C different from 25 C and note the
conductivity reading Ct.

• The temperature coefficient ß of the solution is calculated with

the formula:

(Ct - C25)

ß = 100 x ---------------------------

(t - 25) x C25

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 the temperature of the solution changed

by more than 10 C. Wait for the conductivity reading to stabilize.

• Adjust the “TEMPERATURE COEFFICIENT” knob until the display

reads the value C as recorded earlier.

• The value indicated by the knob is the temperature coefficient of

the solution.

DETERMINATION OF THE TEMPERATURE

COEFFICIENT OF A SOLUTION

(EC 215 & EC 215R)