IM 12D08N05-01E
7-1
<7. MAINTENANCE>
7. MAINTENANCE
SPARE PARTS
See Customer Maintenance Parts List.
7.1 Periodic maintenance
The converter requires very little periodic maintenance, except to make sure the front
window is kept clean in order to permit a clear view of the display and allow proper
operation of the touchscreen. If the window becomes soiled, clean it using a soft damp
cloth or soft tissue. To deal with more stubborn stains, a neutral detergent may be used.
When you must open the front cover and/or glands, make sure that the seals are clean
and correctly fitted when the unit is re-assembled in order to maintain the housing’s
weatherproof integrity against water and water vapor. The pH measurement uses high
impedance sensors and may otherwise be prone to problems caused by exposure of the
circuitry to condensation.
NOTE
Never use harsh chemicals or solvents. In the event that the window does become heavily
stained or scratched, refer to the parts list for replacement part numbers.
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Battery
The SC450G converter contains a logbook feature that uses a clock to provide the timings.
The instrument contains a lithium cell (battery) to support the clock function when the
power is switched off. The cell has an expected working life of 10 years. Should this cell
need to be replaced, contact your nearest Yokogawa service center.
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Fuse
There is a circuit board mounted fuse protecting the instrument. If you suspect that this
needs to be replaced, contact your nearest Yokogawa service center.
7.2 Periodic maintenance of the sensor
NOTE
Maintenance advice listed here is intentionally general in nature. Sensor maintenance is
highly application specific.
In general conductivity measurements do not need much periodic maintenance. If the
SC450G indicates an error in the measurement or in the calibration, some action may be
needed (ref. chapter 8 troubleshooting).
When a 2-electrode sensor has become fouled an insulating layer may be formed on the
surface of the electrodes and consequently, an apparent increase in cell constant may
occur, giving a measuring error.
This error is:
2 x Rv/Rcel x 100 %
where: Rv = the resistance of the fouling layer
Rcel = the cell resistance
