Gold Cathode:
For correct sensor operation, the gold cathode must be textured properly. It can become tarnished or plated with
silver after extended use. Never use chemicals or abrasives not recommended or supplied by YSI.
First dry the sensor tip completely with lens cleaning tissue. Wet 400 grit wet/dry sand paper with a small amount
of clean water and place it face up in the palm of your hand. Next, with your free hand, hold the sensor in a
vertical position, tip down. Place the sensor tip directly down on the sanding disk and twist it in a circular motion
to sand the gold cathode. The goal is to sand off any build-up and to lightly scratch the cathode to provide a
larger surface area for the electrolyte solution under the membrane. Usually, 3 to 4 twists of the sanding disk are
sufficient to remove deposits and for the gold to appear to have a matte finish. Rinse thoroughly and wipe the
gold cathode with a wet paper towel before putting on a new membrane cap.
Note: Be sure to: (1) Only use fine 400 grit wet/dry sand paper and (2) Sand as mentioned in the above
procedures. Not adhering to either of these instructions can damage the electrodes. If this procedure is
unsuccessful, as indicated by improper DO sensor performance, contact your local YSI Representative or a YSI
Authorized Service Center.
Galvanic Sensors – Model # 605202
The Galvanic dissolved oxygen sensor is continuously reducing oxygen even when the Pro Plus is turned off.
This factor allows the sensor to be used with no warm-up time as soon as the instrument is powered on.
However, because the sensor is “on” all the time, some solid from the oxidation of the zinc anode will form in the
electrolyte within 1-2 weeks of activation. The Galvanic electrolyte solution will appear milky white after use but
this will not affect the accuracy of the sensor unless there is excessive build up which may result in jumpy
readings. Otherwise, the color change is acceptable and normal as long as DO readings remain stable. The rate
of solid formation is dependent on the type of membrane installed. The formation of solids typically form more
rapidly with the 5912 (black 1 mil Teflon), less rapid with 5913 (yellow 1.25 mil PE), and least rapid with 5914
(blue 2 mil PE).
When changing the membrane, rinse the anode and cathode with distilled or deionized water and wipe with a
clean paper towel. If white deposits are evident on the anode after rinsing and wiping, remove the deposits by
sanding the anode with 400 grit wet/dry sand paper following the “Mechanical Cleaning” instructions under the
Polarographic Silver Anode maintenance section. If there are deposits on the cathode, sand the cathode with
400 grit wet/dry sand paper following the maintenance instructions listed for the Polarographic Gold Cathode.
Note: Do not perform the Polarographic chemical cleaning on a Galvanic sensor.
If this procedure is unsuccessful, as indicated by improper sensor performance, contact your local YSI
Representative or a YSI Authorized Service Center.
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