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Aquaprobe
®
AP-7000 Instruction Manual
10401-00894 Rev M
14.8. Calibrating EC
EC calibration is always carried out at a single point. There is a choice of two pre-set
calibration standards or you can enter any calibration standard value between 100µS/cm
and 99,999µS/cm manually.
The pre-set standards are: Aquaread
®
RapidCal (EC value 2570µS/cm) and Aquaread
®
SC-35 (35ppt sodium chloride solution), which is specifically for use when measuring EC
and salinity in sea water.
The calibration solution value you use to calibrate EC should always be chosen to be as
near to the readings you expect to see in the field as possible. If you are not sure what
values to expect, RapidCal is a good choice as this will give reasonably accurate readings
across a wide range of EC values.
SC-35 calibration solution is available from Aquaread
®
dealers or can be easily
manufactured by adding 33.03 grams of laboratory grade sodium chloride (99.9% pure) to
1 litre of deionised water. RapidCal is available from all Aquaread
®
dealers.
The Probe's central wiper forms an integral, working part of the Probe’s EC
measurement system, and MUST be fitted during calibration and measurement for
correct operation.
If you try to calibrate the Probe without the wiper fitted, you will
get erroneous results.
For best results, calibrate as close to 25ºC as possible. The probe will compensate for
temperature variation in the Calibration Standard during calibration.
1.
Pour 400mL of calibration solution into one of the calibration cups provided.
Remove the storage cap from the pH electrode if fitted, wash the Probe in
distilled water, then gently lower the Probe into the calibration cup.
2.
Ensure the liquid level is at least two thirds of the way up the
calibration cup.
Low liquid level will result in erroneous EC calibration
.
Refer to the photograph in section 10
3.
Activate the probe cleaning feature in order to remove any air bubbles that
may be clinging to the electrodes. Wait until thetemperature and EC
measurements are completely stable.
4.
Ensure the temperature of the solution is between 5ºC and 40ºC (41ºF -
104ºF).
5.
Press the
MENU
key then select
Calibration.
The following screen will be
displayed.
Calibration
RapidCal
DO 100%
Full Cal
6.
Select
Full Cal.
The screen will change to:
Calibration
pH/REDOX(ORP)
DO/EC
Aux Electrodes
© 2017 Aquaread
®
Ltd.
www.aquaread.com
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