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19.4 Replatinising Conductivity Sensors
The
smart
CHEM
-C
is fitted with an automatic sensor platinising function to restore Conductivity
sensors to correct performance. To replatinise Conductivity sensors…
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. Plug the Conductivity sensor into the
Platiniser
socket.
4. Immerse the sensor in platinising solution, so that both of the platinum plates are well covered.
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.
5. Select Platiniser mode (
→
→
F3:Mode
→
→
F5:Re-Plat.
). The Platiniser screen is
now displayed…
Platiniser
Cell in Plat. socket
k=1 Detected
Press Enter to Start
6. Press
to start platinising the sensor. The
smart
CHEM
-C
confirms how long it will
platinise the sensor for, and count down how much time is remaining. The following example
is for a k=1 sensor…
Platinising for
3:00 minutes
2:59 minutes left
Press menu to quit
Press
to quit platinising at any time. Remove the sensor and rinse well in distilled water.
If the sensor has not been fully platinised, start the process again from step 1.
7. When the platinising cycle is complete, the following screen is displayed and the
smart
CHEM
-C
will beep…
Platinising complete
Un-Plug & Rinse Cell
Press Menu to Exit
Press
and remove the sensor from the platinising solution. Rinse well in distilled water.
8. The sensor is now replatinised, with its surface restored to “as new” condition. The sensor must
be recalibrated before use, as its span will have changed.