YSI 5200A - Manual (Page 91)

YSI 5200A
180 YSI 5200A
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For correct sensor operation, the gold cathode must always be bright. If it -
is tarnished (which can result from contact with certain gases) or plated
with silver (which can result from extended use with a loose or wrinkled
membrane), the gold surface must be restored. To restore the cathode,
refer to Gold Cathode Cleaning on the next page.
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,
after 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.
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.
pH and Combination pH/ORP Sensor Cleaning
Cleaning is required whenever deposits or contaminants appear on the glass and/
or platinum surfaces of these sensors or when the response of the sensor becomes
slow.
Remove the sensor from the cable assembly. 1.
Initially, simply use clean water and a soft clean cloth, lens cleaning tis- 2.
sue, or cotton swab to gently remove all foreign material from the glass
bulb (YSI 5564 and YSI 5565) and platinum button (YSI 5565). Then, use
a moistened cotton swab to carefully remove any material that may be
blocking the reference electrode junction of the sensor.
CAUTION: When using a cotton swab with the YSI 5564 or YSI 5565, be careful
NOT to wedge the swab tip between the guard and the glass sensor. If necessary,
remove cotton from the swab tip, so that the cotton can reach all parts of the sensor
tip without stress.
Note - If good pH and/or ORP response is not restored by the above procedure,
perform the following additional procedure:
Soak the sensor for 10-15 minutes in clean water containing a few drops 1.
of commercial dish washing liquid.
GENTLY clean the glass bulb and platinum button by rubbing with a cot- 2.
ton swab soaked in the cleaning solution.
Rinse the sensor in clean water, wipe with a cotton swab saturated with 3.
clean water, and then re-rinse with clean water.
Note - If good pH and/or ORP response is still not restored by the above procedure,
perform the following additional procedure:
Soak the sensor for 30-60 minutes in one molar (1 M) hydrochloric acid 1.
(HCl). This reagent can be purchased from most chemical supply compa-
nies. Be sure to follow the safety instructions included with the acid.
GENTLY clean the glass bulb and platinum button by rubbing with a cot- 2.
ton swab soaked in the acid.
Rinse the sensor in clean water, wipe with a cotton swab saturated with 3.
clean water, and then re-rinse with clean water. To be certain that all traces
of the acid are removed from the sensor crevices, soak the sensor in clean
tap water for about an hour with occasional stirring.
Maintenance Maintenance