17
4.3 pH Calibration
1.
Plug the pH sensor into the
Probe 1
,
Probe 2
or
Probe 3
socket and the temperature sensor
into the
Temp.
socket. Switch the meter on.
2.
Select pH Mode and the desired pH resolution (see section 4.1).
3.
Ensure that temperature has already been calibrated, or manually set (see sections 7.1 and 7.4).
NOTE: If the decimal point in the temperature reading is shown by a “
∗∗
”, then the
temperature readout is not calibrated.
4.
Remove the wetting cap from the pH sensor. Rinse the pH and Temperature sensors in distilled
water and blot them dry.
5.
Ensure that the primary and secondary buffers to be used have been correctly selected for
automatic buffer recognition. See section 4.2.
6.
Place both electrodes into a small sample of primary buffer (pH6.88 or 7.00), so that the bulb
and reference junction are both covered, as per the diagram below.
DO NOT
place the electrodes directly into the buffer bottle.
7.
Select pH Calibration for Channel 1, 2 or 3.
(e.g.
→
→
F1:Calibrate
F1:Calibrate
→
→
F1:Channel 1
F1:Channel 1
→
→
F1:pH
F1:pH
).
The display should now look something like this…
6*85pH Buffer=
6*85pH Buffer=6
6.86 25.0
.86 25.0
O
O
c
c
Press ENTER to Calibrate, or Edit Buffer.
Press ENTER to Calibrate, or Edit Buffer.
The current pH reading is shown on the left. Note the “
∗∗
”, indicating that pH is currently not
calibrated. Wait for this reading to stabilise before attempting to calibrate the
900-I3
.
The buffer that the
900-I3
has attempted to recognise is also displayed with the correct value at
the current temperature.
Press
to calibrate to the displayed buffer.
Otherwise, enter an alternative buffer using the Numeric Keypad, and then press
.
If a 1 point calibration has been performed, the “
∗∗
” will not be removed until a full 2 point
calibration has been performed.