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5.5
SCHEDULED SERVICING
The following procedures are guides to the maintenance requirements of the monitor.
The procedure chosen depends on the particular installation and sample conditions.
5.5.1
WEEKLY
If the monitor is continuously running at high concentrations, greater than 100ppb, a
weekly Single Point Calibration is recommended. See Section 3.7.1 Single Point
Calibration.
5.5.2
MONTHLY
o
Replace the bottle of reagent buffer solution. The level of solution should not be
allowed to fall below about three-quarters full. On high ambient temperature
installations and for low sodium concentrations, the solution may require
replacement more frequently.
o
Check the level of reference electrode filling solution bottle; replace as required.
o
The following procedures should be carried out:
When the sodium concentration is above 1ppb, carry out a Two Point Calibration - see
Section 3.7.2; note the slope value.
Sodium Measuring Electrode Etching/Regeneration Instructions:
When the sodium concentration is below 1ppb, apply the following regen/etch
procedure before carrying out a Two Point Calibration:
Note
. When used for prolonged periods at low concentrations, leeching of
sodium ions from the electrode surface accelerates the aging process of the
electrode which is shown by poor response time, low slope value and a
limitation to respond to low levels. Calibration may then be in error because
of slow response and poor reproducibility. The regen procedure minimizes
problems from these sources.
Also: Etching is not for new probes- this should be done as part of the
monthly maintenance procedure.
o
Remove the sodium electrode from the flowcell; it is not necessary to detach the
electrode lead.
