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To clean and resurface the sensor, follow the instructions below.
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 that have not been recommended
or supplied by YSI.
First dry the sensor tip completely with lens cleaning tissue. Wet
a sanding disc and place it face up in the palm of you hand. Next,
with your free hand, hold the sensor in a vertical position, tip down.
Place the sensor tip directly down on the sanding disc 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 O
2
solution under the membrane. Usually, 3 to 4 twists of
the sanding disc 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. If the cathode remains tarnished, contact YSI Technical Support or
the Authorized dealer where you purchased the instrument.
Silver Anode
After extended use, a thick layer of Silver Chloride (AgCl) builds up on
the silver anode reducing the sensitivity of the sensor. The anode must
be cleaned to remove this layer and restore proper performance. The
cleaning can be chemical and/or mechanical:
Chemical cleaning
: Remove the membrane cap and rinse the sensor
with deionized or distilled water. Soak the sensing section of the
sensor in a 14% ammonium hydroxide solution for 2 to 3 minutes or
in a 3% ammonia solution overnight for 8-12 hours (most household
ammonia cleaners are typically around 3%). Rinse heavily in cool tap
water followed by a thorough rinsing with distilled or deionized water.
The anode should then be thoroughly wiped with a wet paper towel to
remove the residual layer from the anode. You can smell the tip of the
sensor to help ensure all the ammonia has been rinsed off. Trapping
residual ammonia under the new membrane cap can quickly tarnish
the electrode and/or give false readings.
Chemical cleaning should be performed as infrequently as
possible. First attempt a membrane change and recalibrate. If
a new membrane does not resolve the problem, then proceed
with cleaning.
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