5 | Bases for measurement
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B-H86.0.12.DB2-1.0
– GE 120 BNC is an insertion electrode and is preferably used for measurements in
cheese, fruit and meat. For measurements in products containing proteins, the
electrode must be cleaned with a special cleaner. For this purpose, we recom-
mend the GRL 100 pepsin cleaning solution.
– GE 125 BNC is a waterproof, universally applicable, durable and low-maintenance
gel electrode with ceramic diaphragm. It can be immersed above the shaft for an
extended time.
– GE 151 BNC is a glass electrode and is preferably used in galvanic applications
for paints and lacquers.
– GE 173 BNC is an alkaline-resistant glass electrode with ground diaphragm and
gel electrolyte for chemical and waste water applications.
5.1.6 Service life
The service life of electrodes is normally at least 8 to 10 months. When cared for prop-
erly, this can usually increase to more than 2 years. The actual life will vary depending
on the particular application.
5.1.7 Care and maintenance
NOTE
The GAK 1400 working and calibration set includes all necessary products for calibra-
tion, care and maintenance of the electrode. Normal cleaning takes place with the
GRL 100 pepsin cleaning solution into which the electrode is immersed for 5 minutes
before being rinsed off with clean water.
NOTE
Crystallisation of the 3 mol/l KCL solution is unavoidable. Crystallised potassium chlor-
ide on the protective cap and shaft can easily be removed with a fingernail or cloth
and is therefore not a defect or grounds for complaint.
Dirty electrodes must be cleaned. The suitable cleaning agents for the pH glass mem-
brane are listed in the table below.
Impurities
Cleaners
General residue
Mild detergent
Inorganic coatings
Commercially available liquid glass clean-
ers
Metal compounds
1 mol/l HCl solution or GRL 100 pepsin
cleaning solution
Oil and grease
Special cleaner or solvent
Biological coatings with protein
1% pepsin enzyme in 0.1 molar GRL 100
HCl solution
Resin lignins
Acetone
Extremely resistant residues
Hydrogen peroxide or sodium hypochlor-
ide
The material of the pH probe must always be protected. Plastic shafts must not be
cleaned in solvents, etc. If in doubt, contact the manufacturer to inquire about suitable
cleaners for the existing electrode. This is also important in the case of aggressive
substances or other substances that are not primarily water-based!
