pH/mV Temperature Meter
430-020
89907X0088 Issue 2
5 Calibration and Measurement
Before performing a measurement the instrument must be calibrated. It is
recommended that the instrument is calibrated daily to achieve consistent
and accurate results. Model 430-020 has a 2 point calibration process. The
first calibration point MUST be buffer pH 7.00. The second calibration point
depends on the acidity of the solution which is to be measured. For samples
with a pH around 5 the second calibration point should be 4.01 pH buffer.
For samples with a pH around 8 the second calibration point should be
10.01pH buffer. Always rinse the pH and temperature probes in de-ionised
water before placing in each buffer solution. If the ATC probe is connected
the instrument automatically compensates for the resulting change in
electrode response due to temperature during the calibration process.
Press the ON/OFF key to switch the instrument on. If the temperature probe
is not connected ‘MANUAL’ will be displayed above the temperature value. If
manual temperature adjustment is being used, the temperature of the
solution must be measured using a thermometer so that the temperature can
be manually adjusted.
Place the pH electrode and temperature probe into 7.00 pH buffer solution
and allow the reading to stabilise. Stir, then press and hold down the CAL
key for 3 seconds. Auto-Cal will flash up on the display and then the current
reading will be displayed. Once the reading has stabilised press the CAL
key, rinse the electrode and temperature probe in deionised/distilled water
and place them into 4.01 pH or 10.01 pH solution and allow the reading to
stabilise, again stir the solution to remove any air bubbles. To finish press
the CAL key, ‘Calibrated Ok’ will flash up and the display will show the
solution value of the buffer.
To abort the calibration point at any time press the ON/OFF key and the
meter will revert back to any previous calibration values.
During the calibration process the instrument will automatically detect the
buffer solution. However if you know the exact pH value for the buffer at a
given temperature (temperature coefficient) you can change the offset BS
(buffer solution 7.00pH) and slope BS (buffer solution 4.01 or 10.01) by
using the Up or Down arrow keys. Refer to your calibration
solutions/capsules temperature coefficients before any alterations are
carried out.
