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20.2 Replatinising Conductivity Electrodes
There are several ways to replatinise Conductivity electrodes.
1.
The simplest way is to return the electrode to the TPS factory. We can fully
clean the electrode, replatinise it and test all aspects of its performance.
2.
An automatic replatiniser is available from TPS, along with replatinising
solution. This will plate the electrodes for the right amount of time at the
correct current. Ordering details are as follows:
Automatic Conductivity Electrode Replatiniser
Part No 122160
20mL Platinising Solution (suitable for approx 30 uses)
Part No 122300
1.
Conductivity electrodes can be manually replatinised, according to the
following procedure:
1) Soak the electrode in a solution of 1 part Concentrated HCl and 10 parts
distilled water for approximately 5 minutes.
2) Rinse the electrode well in distilled water.
3) Immerse the electrode in platinising solution at least to the vent hole in the
white plastic cover. Platinising solution is available from TPS (part no
122300). Alternatively, platinising solution can be prepared by dissolving
1g of Hydrogen Chloroplatinate (H
2
PtCl
16
) in 30mL of distilled water, and
including about 0.01g of Lead Acetate ((CH
3
COO)
2
Pb) and a drop or two
of concentrated HCl.
4) Apply a direct current of 10mA between pins 1 and 5 of the electrode plug,
as per the diagram below. Reverse the polarity every 30 seconds. After
approximately 8 minutes (4 minutes per electrode wire), they should have
an even “soot” like appearance. Avoid excess current and this will cause
incorrect platinising.
5) After platinising, rinse the electrode well in distilled water.
6) If you have any doubts about any of these steps, then you should consider
returning the electrode to the factory. The cost of replatinising is quite
low, and you will be guaranteed of the best possible result.
Pin 1
Pin 5
Electrode Connector