NAVI D-25 Instruction Manual page 199

7 Reference
7.3 Ion measurement
● Standard solution
● Temperature of standard solution and liquid to be
measured
188
Finding the ION concentration of the solution being
measured requires prior calibration of the ION meter
using a prepared standard solution with a known ION
concentration.
The number of times the meter is to be calibrated
depends on the accuracy desired. Calibration is usually
performed once a day, prior to making measurements.
Calibrating the meter when the standard solution has
been mixed using a stirrer or other utensil will improve
the electrode
stability.
・ Basically, at least two standard solutions of different
concentrations should be used to calibrate this meter.
If the approximate ION concentration of the liquid to
be measured is known, standard solutions having
lower and higher concentrations than that liquid
should be used for calibration. In such cases, the
standard solution with the lower ION concentration
should have 1/10 the concentration of the standard
solution with the higher concentration.
・ If the approximate ION concentration of the liquid to
be measured is unknown, choose low and high-
concentration standard solutions with a larger
differential than the 1/10 used in the above example.
However, be sure not to exceed the limits of the ION
electrode detection capabilities or linearity.
The meter is equipped with a built-in temperature
compensation function. Nevertheless, the temperature
of the standard solution during calibration and the
temperature of the liquid being measured while it is
being measured should be kept as close as possible, to
ensure accurate measurement.
This is because the output of the ION electrode and the
reference electrode changes according to changes in
temperature. The greater the difference in temperature
between the standard solution and the liquid being
responsiveness and measurement
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