YSI Incorporated
YSI 550 DO Handheld Instrument
9
7.
It is also possible for the silver anode, which is the entire silver body of the probe, to become
contaminated, which will prevent successful calibration. To clean the anode, follow the Anode
cleaning instructions in the following section. Next, rinse the sensor tip and Electrolyte
reservoir with deionized water, add new Electrolyte solution, and install a new membrane and
O-ring. Turn the instrument on and allow the system to stabilize for at least 30 minutes. If,
after several hours, you are still unable to calibrate, return the YSI 550 DO Instrument to a YSI
authorized service center for service, See Section 7, Warranty and Repair for more
information.
8.
To keep the electrolyte from drying out, store the probe in the calibration/storage chamber with
the wet sponge.
3.6 PROBE MAINTENANCE
ELECTRODE CLEANING
It is always a good practice to keep the probe in good operating condition.
SILVER ANODE
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 to remove this layer and restore proper performance. The
cleaning can be chemical or mechanical:
•
Chemical cleaning: Remove the membrane cap and soak the entire anode section in a
14% ammonium hydroxide solution for 2 to 3 minutes, 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.
•
Mechanical cleaning: Sand off the dark layer from the silver anode with 400 grit wet/dry
sandpaper. Wrap the wet sandpaper around the anode and twist the probe. Rinse the anode
with clean water after sanding, followed by wiping thoroughly with a wet paper towel.
GOLD CATHODE
For correct probe 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 the adhesive backed
sanding disc and tool provided in the YSI 5238 Probe Reconditioning Kit.
Using the sanding 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. If the cathode remains tarnished, return the probe for service. Wipe the gold
cathode thoroughly with a wet paper towel before putting on a new membrane cap.
Summary of Contents for 550 DO
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