VWR 662-2283, Operating Manual

Page: 19 / 33

PH20 Maintenance | 7
B-H86.0.11.DB201-1.0 19 / 33
7.3 Calibration and adjustment
7.3.1 pH calibration
Description
In order to obtain reliable measurements, the device and electrode must be aligned
with each other. In pH measurement, this is referred to as a calibration. In order to
conduct a pH measurement, proceed as follows.
For automatic calibration, open the
Calibration
menu. See Automatic pH calibration
[
}
p. 20] .
Prerequisite – The product is switched on.
Instruction
1. Carefully remove the protective cap from the electrode.
2. Rinse off the electrode with distilled or deionised water.
Outcome of an action Now, the product can be calibrated.
7.3.1.1 Explanation
The following steps describe how to calibrate the product.
To achieve a precise measurement, observe the following points.
NOTE
If possible, the calibration range should overlap the measuring range. To achieve this,
it is recommended to use buffer solutions for measurements as follows:
– below pH 7 uses pH 7.0 and pH 4.0 buffer
– above pH 7 uses pH 7.0 and pH 10.0 buffer
NOTE
Calibrations are only possible in a temperature range from 0 °C to 60 °C! We recom-
mend performing calibration at temperatures between 10 °C and 40 °C.
NOTE
Calibration should be conducted at the same temperature used for the measurement
in the medium. To equalize the temperatures of the buffer solutions and electrode,
they should be stored together for a while in a place that is protected against draught.
NOTE
Measure the temperature of the buffer solution with a thermometer. The exact value of
the buffer solution is temperature dependent and can be determined based on the
tables provided.
NOTE
Always use fresh buffer solutions!