LAQUAtwin series (Na
+
) Operation
2
CODE: GZ0000460286
Basic Operation
Calibration
Calibration is required before measurement.
Use standard solution within the measurement
range in the specifications. See also the tip of
“How to select standard solution” below.
Tip
Calibration values are saved even if the meter
is switched OFF.
Calibration value is rewritten if calibration is
repeated using the same standard solution.
Tip
How to select standard solution:
The following table show an example of the rela-
tionship between the concentrations of targeted
samples and standard solution used for calibra-
tion.
For accurate measurement, calibrate using 2
points of standard solution with a tenfold or more
concentration difference encompassing the tar-
get concentration.
When the concentration to be measured is very
high or very low, accuracy may be poorer.
Measurement
Power ON
1. Press and hold the ON/
OFF switch.
The power is switched ON,
and the meter model
number is displayed on the
LCD.
Power OFF
1. Press and hold the ON/OFF switch.
The power is switched OFF.
Calibration points
The number of calibration points is up to 2.
Multi-point calibration
1. Set the concentrations of standard solution
for calibration referring to "
1st calibra-
tion point setting" (page 5) and "
2nd cal-
ibration point setting" (page 5).
The 1st point is set to 150 ppm and the 2nd
point is set to 2000 ppm by the default.
2. Open the light shield cover and place some
drops of the standard solution on the flat
sensor taking care to cover the entire flat
sensor.
Rinsing the sensor with the standard solution
beforehand will provide a more accurate
calibration as it will reduce sample crossover
contamination.
3. Close the light shield cover and press the
CAL switch.
The meter enters the CAL mode and blinks the
display of the set 1st-point concentration.
Pressing the MEAS switch switches the
displayed value between the set
concentrations.
4. With the set concentration of the 1st point
displayed, press the CAL switch.
and
blink, and the calibration value is
displayed.
After the calibration is complete,
and
stop blinking and the measured value is
displayed.
The calibration value at 25
C is displayed for 1
s and the display returns to the measurement
mode automatically.
5. Open the light shield cover and remove the
standard solution. Then remove moisture
on the sensor by gently dabbing with a soft
tissue.
This completes the 1st point calibration.
6. To perform 2nd point calibration, repeat
steps 2. to 5.
Calibration error
If
blinks and Er4 (error dis-
play) appears, the calibration
has failed.
Perform electrode conditioning.
Check that the correct standard solution is used,
and repeat calibration after cleaning the sensor.
If the calibration repeatedly fails when using the
correct standard solution(s), the sensor may
have deteriorated. Replace the sensor with new
one.
Light shield cover
[unit: ppm]
Targeted sample
concentration
Standard solution
Low
High
2000
2000
9000
150
150
2000
15
15*
150
*How to prepare 15 ppm standard solution:
Mix one part 150 ppm standard solution to 9 parts
purified water (1:9 volume ratio).
Sample setting
1. Open the light shield cover and put some
drops of sample on the flat sensor to cover
the entire flat sensor.
2. Close the light shield cover.
Measurement mode
The auto stable (AS) mode and the auto hold
(AH) mode can be selected. Refer to "
Mea-
surement mode change" (page 5) for the opera-
tion to set the measurement mode.
Auto stable (AS) mode
This is the default setting.
appears when
the measured value meets the stability criteria.
If the value changes,
disappears.
1. Confirm that the meter is in the measure-
ment mode, and place a sample on the sen-
sor.
When the read value meets
the stability criteria,
appears and the reading is
locked.
2. Document the displayed value when
appears.
If the read value does not meet the stability
criteria,
disappears and the reading
changes with time.
Auto hold (AH) mode
appears when the measured value meets
the stability criteria. The reading then locks
and will not change until the MEAS switch is
pressed for the next measurement.
1. Confirm that the meter is in the measure-
ment mode, and place a sample on the sen-
sor.
2. Press the MEAS switch.
The auto hold function is
activated.
blinks until the
measured value has
stabilized.
When the measured value is stable,
stops
blinking and the displayed value is locked with
and
displayed simultaneously.
3. Document the displayed value.
4. Press the MEAS switch.
The auto hold function is deactivated and
disappears.
Be sure to perform this step before starting the
next measurement. Or, you may mistake the
displayed hold value for the next measured
value.
