Hanna Instruments HI 8633 - Manual (Page 15)

15
Highly acidic, alkaline samples or solutions with high salt content
might have a different coefficient than the customary 2% per degree °C.
In order to calculate this coefficient follow the procedure below:
• Immerse the probe of
HI 8733 in the sample and adjust the
TEMPERATURE COEFFICIENT knob to 0% (i.e. no compensation).
• Condition the sample and probe to 25°C and note the conductivity
reading, C
25
.
• Condition the sample and probe to a different temperature t°C
(approximately 10°C different from 25°C) and note the conductivity
reading C
t
.
• The temperature coefficient
β
of the solution is calculated as given
by the following formula:
(C
t
- C
25
)
β
= 100 x
(t - 25) x C
25
The above procedure is suitable for determining the temperature
coefficient in a laboratory or where the temperature of the solution
can be controlled.
If this is not possible (e.g. on-site measurements), the following
procedure can be used providing the sample temperature varies by at
least 5°C or preferably 10°C:
• Immerse the probe of
HI 8733 in the test solution and turn the
TEMPERATURE COEFFICIENT knob to 0% (no compensation).
• Check the conductivity reading and record the value. Make sure
the reading is stable, i.e. no greater variations than ±0.2 mS/cm
within a minute.
• Repeat the procedure when the temperature of the test solution
has changed by at least 5°C. Wait for the conductivity reading to
stabilize.
• Adjust the TEMPERATURE COEFFICIENT knob until the display
shows the same value as recorded earlier.
• The value indicated by the knob is the temperature coefficient of
the solution.
DETERMINING THE TEMPERATURE
COEFFICIENT OF A SOLUTION (HI 8733)