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6. pH Calibration
6.1 Calibration Procedure
1.
Plug the pH sensor into the
pH
socket. Temperature measurements are made
via the Conductivity sensor, so this needs to be connected to the
Conductivity/Salinity
socket for Automatic Temperature Compensation.
2.
Switch the meter on.
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.
5.
Rinse the pH and Conductivity sensors in distilled water and blot them dry.
6.
Ensure that you are using the primary buffer for which the
WP-81T
has been
set (see section 15).
Place both electrodes into a small sample of pH6.88 (or pH7.00) buffer, so
that the bulb and reference junction are both covered.
DO NOT
place the electrodes directly into the buffer bottle.
7.
Select pH Calibration.
→
F1:Cal.
→
F2:pH
8.
When the reading has stabilised, press the
key to calibrate. If a 1 point
calibration has been performed, the
∗
will not be removed until a full 2 point
calibration has been performed.
9.
Rinse the pH and Conductivity electrodes in distilled water and blot them dry.
10.
Place both sensors into a small sample of pH4.00 or pH9.23 Buffer, so that
the bulb and reference junction are both covered.
DO NOT
place the
electrodes directly into the buffer bottle.
NOTE:
pH9.23 buffer is highly unstable. Avoid using this buffer if
possible. Discard immediately after use
.
11.
Select pH Calibration
→
F1:Cal.
→
F2:pH
12.
When the reading has stabilised, press the
key to calibrate. The
∗
will now
be replaced by a decimal point, if calibration was successful.
13.
The
WP-81T
is calibrated for pH and is ready for taking pH measurements.
Discard the used samples of buffer.