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20. Appendices
20.1 Care, Cleaning and Maintenance of Conductivity Electrodes
20.1.1
Care of Conductivity electrodes
The conductivity section of the electrode supplied with your
WP-81T
consists of
two platinum wires that are plated with a layer of “platinum-black”. This is quite
a soft layer and is required for stable, accurate measurements. In time, the
platinum-black layer may wear off in some applications, at which time the
electrode will require replatinising (see section 20.2). You can help to maintain the
platinum-black layer by following these simple rules:
1.
NEVER
touch or rub the electrode wires with your fingers, cloth etc.
2.
Avoid using the electrode in solutions that contain a high concentration of
suspended solids, such as sand or soil, which can abrade the electrode wires.
Filter these types of solutions first, if possible.
3.
Avoid concentrated acids. If you must measure acids, remove the electrode
immediately after taking the measurement and rinse well with distilled water.
Conductivity electrodes can be stored dry. Ensure that the electrode is stored in a
covered container, to avoid dust and dirt build-up.
20.1.2
Cleaning of Conductivity of Electrodes.
Platinised platinum Conductivity electrodes can only be cleaned by rinsing in a
suitable solvent.
DO NOT wipe the electrode wires
, as this will remove the
platinum-black layer.
1.
Rinsing in distilled water will remove most build-ups of material on the
electrode wires.
2.
Films of oils or fats on the electrode wires can usually be removed by rinsing
the electrode in methylated spirits.
3.
Stubborn contamination can be removed by soaking the electrode in a solution
of 1 part Concentrated HCl and 10 parts distilled water. The electrode should
not be soaked for more than approximately 5 minutes, otherwise the platinum-
black layer may start to dissolve.
4.
If all of these methods fail, then the last resort is to physically scrub the
electrode wires, which will remove the contaminant and the layer of platinum-
black. Use only a cloth or nylon scouring pad. DO NOT USE STEEL WOOL.
The electrode will then need to be cleaned in HCl, as per step 3 and
replatinised, as per section 20.2.