4
Maintenance
Electrode soiling may impair measurement to
such an extent that the electrode ceases to
function, e.g. due to:
• coatings on the pH-sensitive glass
membrane
→
poor response time and low
sensitivity or slope.
• soiling or blockage of the membrane
→
poor response time and unstable
measured values.
To ensure reliable measurement clean the
electrodes regularly. The frequency and
intensity of cleaning depend on the medium
to be measured.
4.1
Cleaning
Clean the electrodes:
• before every calibration
• regularly during operation,
if necessary.
Cleaning can be carried out manually or with
an automatic cleaning system such as
Chemoclean or Sonoclean.
Caution:
•
Do not use abrasive cleaning
agents on the electrodes. This
could lead to irreparable
malfunctions of the measuring
surfaces.
•
After cleaning, thoroughly rinse
the whole system with water
(if possible, distilled or de-
ionised). Any residue of cleaning
agents may severely impair
measurement.
•
The measuring system must be
re-calibrated after each cleaning.
Manual cleaning
All parts coming in contact with the medium,
such as electrodes or flow assembly, must be
cleaned regularly. When an outlet or sampling
pipe is installed, rinse the drain on the base of
the flow assembly.
• Light soiling can be removed
with suitable cleaning agents.
• More severe soiling can be removed by
brushing carefully with a soft brush and a
suitable cleaning agent.
• Stubborn dirt may be dissolved by soaking
the appropriate parts in the cleaning fluid.
Automatic cleaning
Cyclic automatic cleaning in an installed
condition may be carried out by the
Chemoclean automatic spray cleaning
system. The complete system includes the
CYR 10 injector box and the CYR 20
programmer (see Chapter 5, Accessories).
Various diluted chemicals or pressurised
water may be used as cleaning agents
depending on the type of soiling.
Use the Sonoclean automatic ultrasonic
cleaning system (see Chapter 5, Accessories)
for automatic cleaning without cleaning
agents.
Selection of cleaning agents
The cleaning agent chosen is dependent on
the type of soiling. The most frequent type of
soiling and the appropriate cleaning agents
are listed in the following table:
Type of soiling
Cleaning agent
Grease, lubricants, oils
Detergents or
water-soluble organic
solvents (e.g. alcohol)
Lime deposits or metal
hydroxides
3% HCl
Sulphate deposits from
precipitation reactions
Mixture of 3% HCI with
a 1% Titripex (EDTA)
Protein deposits (food
industry)
Mixture of 3% HCI with
saturated Pepsin
xa240e04.chp
FlowFit P CPA 240
4 Maintenance
Hauser
11
