OVA7000 Routine Service Manual V1.5
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3.4
Working Electrode Maintenance
The electro-active surface of the working electrode will not remain perfect for an indefinite period. Periodically
the electrode surface will need to be renewed.
A deterioration of the surface will usually manifest itself as a low standard peak or lack of reproducibility,
particularly on repeat analyses of a standard sample whose characteristics are known.
3.4.1
Polishing procedure
Working electrode polishing procedure.
1.
Click the
Stop
button to stop the OVA7000.
2.
Drain the cell by clicking the drain pump in the Run screen with the Manual tab selected.
3.
Press
Main Menu
to return to the Main screen, which puts the instrument into standby mode.
4.
Remove the electrode with the electrode tool supplied.
5.
Rinse the electrode surface with deionised water to remove any particulates present, then wipe the
surface of the electrode with a clean tissue.
6.
Open the polishing kit supplied and put 2 or 3 drops of the polishing fluid onto the polishing pad.
7.
Place the electrode onto the polishing pad and gently polish the surface by moving the electrode in a
circular motion for approximately 30 seconds.
8.
Rinse the electrode surface with deionised water.
Warning: Do not allow fingers to touch the surface of the electrode at any time. Grease will severely
reduce the sensitivity of the electrode.
9.
Replace the electrode in the cell but do not connect alligator clip. Add a couple of mL of rinse or
electrolyte solution to the cell.
10.
Restore the OVA7000 to operational mode as described in section 2.3, Initiating OVA7000 Operation
on page 9. Reconnect the working electrode alligator clip before commencing operation.
3.5
Filter Maintenance
Filter maintenance may be divided into three components per stream, each of which may be required at different
intervals.
The filter pump’s tubing lifespan is very much dependent on the OVA7000’s application. Where the filter
pump is required to run continuously it is recommended the tubing is replaced every 2 weeks. In
applications where the pump is non-continuous then the following formula can be used as a guide:
Tubing life (weeks) = 2 x 24 ÷ hours running per day
The other application dependent factor is the corrosive or abrasive properties of the raw sample fluid. If this
is an issue, then the tubing will need to be replaced regularly, irrespective of how often the pump runs. For
very corrosive sample streams this should be weekly.
The filter assembly should be cleaned as required. This may vary from weekly to monthly depending on the
level of solids in the sample.
Non-pump sample stream tubing need generally only be replaced every 3 to 6 months. This may
occasionally be more frequently required if visible deterioration of tubing occurs.
Before performing any filter related maintenance, stop the OVA7000 as per section 2.4, Stopping OVA7000
Operation on page 9.
