8 Maintenance
8.1 Meter maintenance
Never unscrew the two halves of the housing!
The meters do not require any maintenance other than an occasional wipe with a damp cloth. The housing is
made of acrylonitrile butadiene styrene/polycarbonate (ABS/PC). This material is sensitive to some organic
solvents, such as toluene, xylene and methyl ethyl ketone (MEK).
Any spillage should be wiped off immediately.
8.2 Electrode maintenance
Make sure the pH electrode is always kept filled with the appropriate filling solution.
For maximum accuracy, any filling solution that may have "crept" and encrusted the outside of the electrode
should be removed with deionized water.
Always store the electrode according to the manufacturer's instructions and do not allow it to dry out.
If the electrode slope falls rapidly, or if the response becomes sluggish, the following procedures may help. Try
one of the following, depending on your sample.
Problem
Fat or oil build-up
pH sensor membrane has dried out
Protein build-up in the diaphragm of a pH sensor
Silver sulfide contamination of pH sensor
Note
Cleaning and filling solutions should be handled with the same care as that given to toxic or corrosive
substances.
8.3 Disposal
In conformance with the European Directive 2012/19/EU on Waste Electrical and Electronic
Equipment (WEEE) this device may not be disposed of in domestic waste. This also applies
to countries outside the EU, per their specific requirements.
Please dispose of this product in accordance with local regulations at the collecting point
specified for electrical and electronic equipment. If you have any questions, please contact
the responsible authority or the distributor from which you purchased this device. Should this
device be passed on to other parties, the content of this regulation must also be related.
8.4 Error messages
Message
pH/mV/ion/temperature/conductivity/TDS/
salinity/resistivity exceeds max. limit
pH/mV/ion/temperature/conductivity/TDS/
salinity/ resistivity below min. limit
Memory is full
SevenGo Duo pro™
Action
Degrease the membrane with cotton wool soaked in
either acetone or a soap solution.
Soak the tip of the electrode overnight in 0.1M HCl
Remove deposits by soaking the electrode in an HCl/
pepsin solution.
Remove deposits by soaking electrode in a thiourea
solution.
Run a new calibration after treatment.
Description and Resolution
Measurement limits are activated in the menu settings and
measured value is outside these limits.
Check the sample.
Check sample temperature.
Make sure that the pH electrode wetting cap has been
removed and that the electrode is properly connected and
placed in the sample solution.
Max. 500 measurement data can be stored in the memory.
Delete all or partial data in the memory, otherwise you will
not be able to store new measurement data.
Maintenance 27