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7 The pH combination electrode
pH combination electrodes are "consumables" – parts that are subjected to
chemical and mechanical wear, and must therefore be replaced when the
required parameters can no longer be upheld, even after meticulous cleaning.
When using them, it must be taken into account that some substances in
aqueous solutions (e.g hydrofluoric acid (HF)) can attack glass. Chemicals may
also react with the KCl electrolyte in the combination electrode and/or lead to
the diaphragm becoming clogged
Problem cases
7.1
pH combination electrodes for various application areas
Application area
Drinking water monitoring, aquaria, fish-farming,
sea and lake water, etc.
General aqueous media, beverage industry, factory
laboratories, chemistry, etc.
In the food industry, for insertion measurement in
sausages, meat, cheese, fruit and other semi-solid
foods, for soil measurement, small liquid samples, etc.
26
- with solutions containing proteins, such as those used for medical or
biological measurement, KCL can cause denaturation of the protein.
- colloidal varnishes.
- solutions containing an enhanced concentration of silver ions.
- low-ion solution (very pure/high-purity water)
- solutions containing solvents.
If measurements are to be carried out in these or similar solutions, then we
recommend that the pH determination is made as briefly as possible, to avoid
unnecessary demands on the combination electrode.
After the measurement, the combination electrode must be cleaned and
stored either in a KCl reservoir or with a wettening cap.
Substances that are deposited on the measuring membrane or diaphragm will
affect the measurement, and must be regularly removed. This can be
achieved, for instance, through an automatic cleaning system.
.
pH combination electrode:
Version / Type / Sales No. (TN)
JUMO ecoLine pH, 2 m fixed connecting
cable and BNC connector
Type 201005/65-18-45-2000-76-120/837
TN 20/00417300
JUMO labLine pH, KCl-filled, 1 m fixed
cable connection and BNC connector
Type 201030/76-10-07-40-1000-76-120/
000
TN 20/00300196
JUMO labLine pH insertion electrode,
plastic type, solid gel electrolyte, 1 m fixed
cable connection with BNC connector
Type 201030/62-15-11-40-1000-76-120/
052
TN 20/00448527
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