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12. Cleaning and maintenance
a) General information
• To ensure the measuring device’s accuracy over a longer period of time, it should be calibrated once a year.
• The instrument is absolutely maintenance-free except for occasional cleaning and battery and electrode replace-
ment.
• Regularly check the device for technical safety, for example, for damage to the casing or deformation, etc.
b) Cleaning the casing
Always observe the following safety information before cleaning the device:
• Do not use abrasive detergents, petrol, alcohol or other similar chemicals to clean the device. These may corrode
the surface of the measuring instrument. In addition, the vapours emitted by these substances are explosive and
harmful to your health. Do not use sharp-edged tools, screwdrivers or metal brushes to clean the device.
• To clean the device and the display, use a clean, lint-free, antistatic and slightly damp cleaning cloth. Allow the
device to dry completely before using it again.
c) Cleaning the probe
• The electrode must be cleaned after each measurement.
• For normal cleaning, rinse the probe with distilled water.
• A pepsin-cleaning fluid is required for measurements in protein-containing liquids (e.g. milk). Leave the electrode in
the pepsin-cleaning fluid for about 5 minutes and then rinse thoroughly with distilled water.
• Dab the electrode dry and put the moisture container on the electrode.
• Check the liquid level (potassium chloride, KCL) in the moisture container. It is required that the electrode does not
dry out during prolonged storage.
d) Regeneration of the pH glass electrode
pH electrodes are wearing parts. A dried glass electrode has a negative effect on service life. Dried electrodes may be
recovered to render the open-pore glass layer permeable again.
Dip the dried electrode in plenty of soaking solution (3 mol KCl solution) for min. 24 hours and then try re-calibrate.
If this is not successful, extend the time again by 24 hours. Then, a measurement should be possible; if not, the
electrode must be replaced.
