Ysi 5422 Electrode Maintenance; Ysi 5420 And 5421 Sensor Maintenance - YSI MultiDO 5400 User Manual

Before reinstalling the sensor cap, make sure that the cavity is completely dry
before proceeding with the installation. If water is found, dry the cavity with
lens cleaning tissue. Finally, clean the clear window on the end of the probe with
lens cleaning tissue.

YSI 5422 Electrode Maintenance

The gold cathode and silver anode require cleaning about once or twice per year.
Perform the following cleaning procedures if, after a DO membrane change, the DO
readings are erratic and/or a good calibration can not be performed.
Silver Anode Cleaning
After extended use, a thick layer of AgCl builds up on the silver anode reducing the
sensitivity of the sensor. The anode must be cleaned about once or twice per year
(depending on use) to remove this layer and restore proper performance.
The cleaning can be chemical and/or mechanical:
Chemical Cleaning: Remove the membrane cap and soak the electrodes in a 14%
ammonium hydroxide solution for 2 to 3 minutes, followed by a thorough rinsing
with clean water. The anode should then be thoroughly wiped with a wet, lint free
cloth to remove the residual layer from the anode.
Mechanical Cleaning: Sand off the dark layer from the silver anode with 400 grit
wet/dry sandpaper. Wrap the sandpaper around the anode and twist the sensor.
Rinse the anode with clean water after sanding, followed by wiping thoroughly with
a wet lint free cloth.
Note - After cleaning, install a new membrane cap with fresh electrolyte and then
perform a calibration. Refer to the instruction sheet included with the Membrane
kit for instruction on how to replace a membrane.
Turn the instrument on and allow the system to stabilize for at least 30 minutes. If, af-
ter several hours, you are still unable to calibrate, contact YSI Customer Service.
Gold Cathode Cleaning
For correct sensor operation, the gold cathode must be textured properly. It can
become tarnished or plated with silver after extended use. The gold cathode can
be cleaned by using 400 grit wet/dry sand paper. This should be done about once
or twice per year.
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Using the sand paper provided in the YSI 5238 Probe Reconditioning Kit, wet sand
the gold with a twisting motion about 3 times or until all silver deposits are removed
and the gold appears to have a matte finish. Rinse the cathode with clean water after
sanding, followed by wiping thoroughly with a wet, lint free cloth. If the cathode
remains tarnished, contact YSI Customer Service.
Note - After cleaning, install a new membrane cap with fresh electrolyte and then
perform a calibration. Refer to the instruction sheet included with the Membrane
kit for instruction on how to replace a membrane.

YSI 5420 and 5421 Sensor Maintenance

Perform the following to periodically clean the 5420 and 5421 electrodes.
1. Unscrew the lower body from the upper body.
Figure 6.1
2. Safely dispose of the electrolyte that is a special molarity, reagent grade
Sodium Chloride solution (salt water).
3. Using the Membrane Tool, unscrew the Membrane Lock in the lower
body.
Maintenance
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