18.2
Replatinising Conductivity Sensors
There are several ways to replatinise Conductivity sensors.
1. The simplest way is to return the sensor to the TPS factory. We can
fully clean the sensor, 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 sensors for the right amount of time at the
correct current. Ordering details are as follows…
Automatic Conductivity Sensor Replatiniser
Part No 122160
20mL Platinising Solution (suitable for approx 30 uses) Part
No
122300
3. Conductivity sensors can be manually replatinised, according to the
following procedure…
1) Soak the sensor in a solution of 1 part Concentrated HCl and 10
parts distilled water for approximately 5 minutes.
2) Rinse the sensor well in distilled water.
3) Immerse the sensor 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 sensor
plug, as per the diagram below. Reverse the polarity every 30
seconds. After approximately 8 minutes (4 minutes per sensor wire),
they should have an even “soot” like appearance. Avoid excess
current and this will cause incorrect platinising.
5) After platinising, rinse the sensor well in distilled water.
6) If you have any doubts about any of these steps, then you should
consider returning the sensor to the factory. The cost of replatinising
is quite low, and you will be guaranteed of the best possible result.
Sensor Connector
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