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Idiomas disponibles
pH/Redox
Electrodes
(Combination
Electrodes)
Operating
Instructions
B 20.2900.0
2010-03-09/00073374
1 Notes
If you encounter difficulties during startup,
please do not interfere with the electrode in
any way that is impermissible. By doing so,
you could endanger your rights under the
instrument warranty. Please contact your
supplier.
!
Each electrode is a quality product and is
individually tested and packaged.
!
Storage should be in a dry room at -5 to +30°C.
Because pH and redox electrodes have limited
suitability for storage, we do not recommend
storing them for longer than 6 months.
!
All electrodes are provided with a rinsing cap or
container for transport and storage to prevent the
sensor elements from drying out.
!
The electrode should be kept in a 3mol/l solution
of KCl.
!
If the electrode has been stored dry for an
extended time, however, it must be conditioned
before being used for measurements. For this
purpose the electrode is immersed in a 3mol/l
solution of KCl for about 24 hours.
!
The pH-sensitive membrane glass must be
handled carefully (no skin contact, protect against
damage, etc.)!
!
Make certain that electrical connections and
cables are kept clean and dry.
If you send the electrode back,
we need a brief description of the fault:
Electrode cannot be calibrated
Display is not stable
Other fault:
Electrodes must not be allowed to dry out
during use or storage!
Do not keep the electrode in distilled water!
3mol / l KCl
2 Sensor installation
!
Electrodes must be installed vertically. The
maximum angle to the vertical is 80°.
80°
10°
!
The internal buffer must cover the inside surface
of the membrane glass. Air bubbles in the
membrane chamber must be removed by light
shaking of the electrode in the vertical.
3 Calibration and measuring
Always follow the instructions in the manual
for the transmitter you are using as well!
!
When a new pH electrode is placed in operation
with a measurement amplifier, a calibration must
be performed.
!
Typically a two-point calibration is required for pH
electrodes. Two standard buffer solutions are
required (for example pH 7.0 and 4.0). Usually the
buffer solutions are selected to bracket the later
measurement range.
Rinse off the electrode with water between
measurements!
First step
Connect the pH/redox electrode with the transmitter
and immerse it in a buffer or test solution (for example
pH 7.0 or 468 mV).
!
With manual temperature entry, adjust the
temperature of the buffer solution on the
measuring instrument.
!
Wait until the display value for the pH/redox (and
temperature) has stabilized. Then adjust the pH/
redox value of the first buffer/test solution on the
transmitter.
Rinse off the pH electrode with deionized water and
carefully dry it with a soft cloth.
For redox electrodes the calibration is now
complete!
Second step
!
Immerse the pH electrode in a second buffer
solution (for example pH 4.0 or 10.0) and wait
until the display value has stabilized. Then enter
the pH value of the second buffer solution.
!
The measuring instrument determines the zero
point and slope of the sensor.
!
Rinse off the electrode with deionized water and
carefully dry it with a soft cloth.
!
The calibration is complete.
80°
4 Cleaning
The membrane glass must never be
10°
exposed to aggressive or abrasive cleaning
agents (scouring milk, etc.)!
Cleaning the membrane glass must not
result in any scratches!
!
Impurities that have accumulated on the surface
of the membrane glass and diaphragm must be
removed!
!
The electrode must be adequately washed off
after every cleaning!
!
If careful dabbing with a soft moist cleaning tissue
proves unsuccessful, various chemical cleaning
methods can be used depending on the type of
impurity:
Type of
accumulation
Lime and
metal hydroxide
coatings
Greases and oils
Protein
Accumulation
containing sulfides
Inorganic
coatings
5 Maintenance
!
Under normal conditions (e.g. clean medium,
stable, non-extreme pH values) cleaning is
recommended every 14 days with monthly
calibration.
!
Electrodes are naturally consumed by loss of salt
from the reference system, etc. A drift in
measured values after some time is therefore
normal measuring behavior.
!
If the measured values drift, the electrode must
be cleaned and calibrated!
!
Cleaning and calibrating cycles can be adjusted
depending on the application and process
parameters.
6 Service life
and warranty
H O
2
!
All pH and redox electrodes are wear parts.
Their
depends on care and conditions of usage!
Depending on the application, the time until an
electrode must be replaced could vary from a few
days to several years. Because of this, it is not
possible to offer a credible guaranty for a
minimum service life.
!
If the glass is broken, claims under the warranty
are normally not honored.
!
If you believe there may be a defect in material or
manufacturing, please contact your supplier.
Cleaning agent
Diluted hydrochloric acid
(1-3%)
Organic solutions (for example
ethanol) or a solution
containing a surfactant
(dishwashing detergent, etc.)
Pepsin in diluted hydrochloric
acid
Cleaning mixture consisting of
hydrochloric acid and thiourea
Hydrochloric acid (0.1 mol/l) or
caustic soda (0.1 mol/l)
operational
capability
("service
H O
2
life")
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