10. Maintenance
Generally speaking, under normal operation, the controller produced by our
company need no maintenance expect regular cleaning and calibration of the electrode
to ensure accurate and stable measurement and system operation.
The cleaning cycle for the electrode depends on the pollution degree of the
measurement sample. Generally speaking, it is recommended to make weekly cleaning.
The following chart gives introductions of different cleaning methods according to
different type of contaminations to provide the operators with reference for cleaning
and maintenance.
Type of Contaminations
Cleaning methods
Measuring solutions containing proteins.
（
Contamination of the junction
）
The electrode should be soaked in Pepsin
/
HCl
for several hours. METTLER-TOLEDO 9891
Electrode Cleaner is recommended.
Measuring solution containing sulfides.
（
The
junction becomes black
）
The junction should be soaked in Thiourea/HCl
solution until being bleached.
METTLER-TOLEDO 9892 Electrode Cleaner
is recommended.
Contamination by grease or organic
substance
Short rinsing of the electrode with acetone and
ethanol.
Acid and alkaline soluble contaminations
Rinsing the electrode with 0.1mol/l NaOH or
0.1mol/l HCl for a few minutes.
Apply clean water to flash the electrode after above cleaning steps and immerse theelectrode
in 3M KCl solution for 15 minutes at least, and then calibrate the electrode.
The electrode should only be rinsed and never rubbed or otherwise mechanicallycleaned,
since this would lead to electrostatic charges. This could cause an increase in the response
time.
In cleaning the platinum electrode, the platinum ring of the electrode can be rubbed
gently with a wet soft piece of cloth.
※
The frequency of electrode cleaning depends on the type and degree of contamination.
However it is recommended that the electrode be cleaned once a week.
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