5 Maintenance
CleanFit P CPA 471
20
Hauser
Selecting cleaning agents
The selection of cleaning agent depends on the type of fouling. The most frequent
fouling and the associated cleaning agents are listed in the table below:
!
Note!
Do not use solvents containing halogen for cleaning. This could destroy
the plastic components on the assembly.
!
Note!
Only clean redox electrodes mechanically. Chemical cleaning applies a potential to the
electrode that takes several hours to decay. This potential causes measuring errors.
5.2
Calibration
Careful and regular calibrations are indispensable to ensure reliable and precise
measurement. Calibration cycles depend on the application and the required
measurement accuracy.
In practice, calibration cycles must be determined on a case by case basis. At the start,
we recommend frequent calibration, e.g. one a week, in order to familiarise yourself with
the running characteristics.
When carrying out the calibration, always refer to the calibration instructions of the
associated measuring transmitter (see Operating Instructions of the measuring
transmitter).
Calibration with electrode removed
!
Note!
•
The calibration times depend on the process conditions and the measuring medium.
•
If the assembly has a balanced, high-impedance connection, set up an electrical
connection between the potential matching connection (PM) and the buffer solution.
•
Do not allow electrodes to stand in distilled water.
•
Do not allow electrodes to stand dry.
Type of contamination
Cleaning agent
Greases and oils
Substances containing tensides (alkaline) or water-
soluble organic solvents (e.g. alcohol)
Calciferous deposits, metal hydroxide deposits,
heavy biological deposits
3% HCl
or with Chemoclean:
HCl (10%) in injector thinned to approx. 3%
Sulphide deposits
Mixture of hydrochloric acid (3%) and
thiocarbamide (commercially available)
Protein deposits
Mixture of hydrochloric acid (01 molar) and
pepsin (commercially available)
Fibres, suspended substances
Water under pressure, poss. with surface-active
agents
Light biological deposits
Water under pressure
