6
Digital Conductivity Meter
44
6.4 Calibration
Important Information on Meter Calibration:
Your meter has five measuring ranges. You have an
option of calibrating your meter in a single point
calibration for all the five ranges or for better
accuracy; you can calibrate one point in each of the
measuring ranges (up to five points). This selection
of single point calibration and multi point calibration
can be set in the SETUP menu Program P9.2.
When you perform a single point recalibration, the
old calibration will be replaced by the new one even
if the new calibration is done in a different range
from the old calibration. For example, if you have
previously calibrated at 1413µS in 0 to 2000µS
range, and you re-calibrate at 12.88 mS in 0 to
20.00 mS range, the new calibration will override
the previous calibration in 0 to 2000µS range.
In the case of multi point calibration, when you
perform a multipoint recalibration, old calibrations
are replaced only on a range basis. For example, if
you previously calibrated at 1413µS in 0 to 2000µS
range and you re-calibrate at 1500µS (also in 0 to
2000µS range), the meter will replace only the old
calibration data (1413µS) in that range.
The meter will retain all calibration data in other
ranges. To completely recalibrate your meter, or
when you use a replacement electrode, it is best
to clear all calibration data.
6.4.1 Preparing the Meter for Calibration
Before starting calibration, make sure you are in
the correct measurement mode. For best results,
select a standard value close to the sample value
you are measuring.
6.4.2 Temperature Calibration
Your electrode features a built-in temperature
sensor which is factory calibrated. Calibrate your
sensor only if you suspect temperature errors may
have occurred over a long period of time or if you
have a replacement electrode.
1
Connect the electrode.
2
Switch the meter on. ATC will appear at
the bottom right-hand corner of the LCD.
3
Press CAL/MEAS. The CAL indicator appears.
4
Press MODE to enter temperature calibration mode.
5
Dip the electrode into a solution of known
temperature (i.e. a temperature bath). Allow time
for the built-in temperature sensor to stabilise.
6
Scroll with
MI/
or
MR/
to set the correct
temperature value (i.e. the temperature
of the temperature bath).
7
Press
HOLD/ENTER
to confirm. The meter will be
calibrated and return to the measurement mode.
NOTE:
To exit without confirming the
temperature calibration value, press CAL/MEAS.
NOTE:
If the ATC does not light up, see SETUP
menu Program P1.3 to switch it on.
NOTE:
Since temperature affects the accuracy of
conductivity/TDS, it is recommended to carry out
a conductivity/TDS calibration after a temperature
calibration is done.
6.4.3 Automatic or Manual, Single
or Multi point Calibration (P9.0)
Choose automatic conductivity calibration or manual
conductivity/TDS calibration. In the automatic
calibration mode, the meter automatically detects
and verifies the appropriate known calibration
standards solutions before accepting these particular
calibration standards as one of its calibration
values in a specific measurement range.
The known calibration standards used for
automatic calibration are:
At 25.0°C: 841µS, 14131µS, 12.88mS, 111.8mS
At 20.0°C: 761µS, 12781µS, 11.67mS, 102.1mS
In the manual calibration, non-standard
calibration values can be used. You can manually
input the appropriate values as your desired
calibration standards in each specific range.
6.4.4 Selection of Automatic
or Manual Calibration (P9.1)
Automatic calibration is applicable in conductivity
measurement mode only, manual calibration is
applicable in both conductivity and TDS mode.
Only from the conductivity measurement mode;
1
Press
SETUP
.
2
Press
MI/
or
MR/
until you
view parameter P9.0 (ASC).
3
Press
HOLD/ENTER
. The upper
display will show “ACA”.
