Aquaprobe
®
AP-700, AP-800 & AP-2000 Instruction Manual
10401-00870 Rev R
13.5.2.
Calibrating the Second Point
The pH electrode can now be calibrated at either pH 4.01 or pH 10.00.
If you intend to
calibrate at both pH 4.01 and pH 10.00, both points must be calibrated in the same
session, i.e. without turning the power off.
If the power is removed after calibrating just one additional point (pH 4.01 for example), the
probe will automatically calculate and save a calibration value for the uncalibrated third
point in order to maintain the electrode's linearity.
To calibrate the second point, fill a calibration bottle with fresh pH 4.01 or pH 10.00 solution
and drop the Probe in all the way. Follow the procedure detailed above, but at step 6,
select either pH4.01 or pH10.0, dependent upon the solution you are using. Wait while the
Meter stabilises and calibrates. When the ‘Calibrating 100%’ screen is displayed, the
calibration report will display the slope for the pH electrode in millivolts (mV) per pH unit. If
this slope goes below 45mV/pH at 25
°
C, the pH electrode should be serviced. Press
OK
then press the
ESC
key repeatedly to get back to the main display.
Remove the Probe from the calibration bottle, rinse thoroughly in fresh water, shake off any
excess and dry the outer sleeve with a soft cloth.
13.5.3.
Calibrating the Third Point
Without switching the Aquameter
®
off or disconnecting the Probe, fill a calibration bottle
with fresh pH 4.01 or pH 10.00 solution and drop the Probe in all the way. Follow the
procedure detailed above, but at step 6, select either pH4.01 or pH10.0 dependent upon
the solution you are using. Wait while the Meter stabilises and calibrates. When the
‘Calibrating 100%’ screen is displayed, the calibration report will display the slope for the
pH electrode in millivolts (mV) per pH unit. If this slope goes below 45mV/pH at 25
°
C, the
pH electrode should be serviced. Press
OK
then press the
ESC
key repeatedly to get back
to the main display.
Remove the Probe from the calibration bottle, rinse thoroughly in fresh water, shake off any
excess and dry the outer sleeve with a soft cloth. Dampen the sponge in the storage cap
with storage solution and fit it to the pH/ORP electrode. pH calibration is now complete.
13.6. Errors During Calibration
If a problem occurs during calibration, an error message will be displayed. Refer to
Calibration Error Messages
in section 10 for error message handling.
13.7. pH Electrode Efficiency
If the pH electrode becomes worn or clogged, its efficiency and response time can be
reduced. The efficiency of the pH electrode is constantly monitored and in the event of the
efficiency dropping below 85%, ‘ERROR 01’ will be flashed on the bottom line of the
display. If this occurs, or if the pH reading response becomes slow, recondition the
electrode as described below.
13.8. Servicing the pH Electrode
1.
Remove the pH or combined pH/ORP electrode from the Probe body
(see
Electrode Removal and Replacement
).
2.
Rinse with methyl alcohol.
3.
Replace the electrode.
4.
Re-calibrate.
© 2017 Aquaread
®
Ltd.
www.aquaread.com
Page 38 of 141
