Aquaprobe
®
AP-700, AP-800 & AP-2000 Instruction Manual
10401-00870 Rev R
7.
Select ZERO. The screen will change to:
PLEASE WAIT
Stabilising
000%
The Meter will wait until the readings are stable, then it will send the calibration command
to the Probe, where the calibration takes place. During calibration, the Calibrating screen is
displayed and the progress counter counts up. If the calibration is successful, the counter
will reach 100% and the following screen will be displayed.
Output:1318mV
Calibrating
100%
Press [OK]
The Calibration Report on the top line displays the voltage output from the Turbidity
Receiver Electrode in millivolts (mV). This value is stored in the Probe's memory and can
be recalled at any time. See section
10.7 Calibration Data Storage and Retrieval
. Press
OK then ESC repeatedly to return to normal reading mode.
16.4.8.
Verifying the Zero Calibration
An accurate zero point calibration is essential to the correct operation of the turbidity
electrode. The zero point calibration can sometimes be erroneous due to small air bubbles
or microscopic suspended solids in the calibration solution. For this reason, it is important
to verify the zero point calibration before proceeding to calibrate the other points.
After calibrating the zero point, remove the Probe from the calibration bottle then reinsert,
agitate and allow the reading to settle. Check the turbidity reading is /- 1NTU of
zero. If not, re-calibrate the zero point.
16.4.9.
Calibrating the Turbidity 20 NTU & 1000 NTU Points
When calibrating the 20 NTU and 1000 NTU points,
the Zero point must be calibrated
first within the same calibration session (i.e. without turning the Aquameter
®
off)
.
Remove the Probe from the zero calibration bottle, rinse thoroughly in fresh water (if using
RapidCal solution), shake off any excess and dry the outer sleeve with a soft cloth.
Gently invert,
do not shake
,
a bottle of
20 NTU or 1000 NTU Stabilised Formazin
Turbidity Standard
solution (available from most lab supply companies) several times to
thoroughly mix.
Formazin Turbidity Standard is hazardous to your health. Be sure to handle with care
and to read and comply with all health and safety advice.
Three-quarters fill a calibration bottle with the solution and drop the Probe in all the way.
Again, agitate and swirl the Probe and bottle several times in order to remove any air
bubbles that may be clinging to the Turbidity electrode.
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®
Ltd.
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