Orbisphere 3600 series - Ammonia Cleaning; Nitric Acid Cleaning; Polish Sensor Face

30 3600 Analyzer for O
2
Measurement—Operator’s Manual
3600O2.OM.E9903
1.5.5.1 Ammonia Cleaning
Fill the sensor electrolyte reservoir with a solution of 25% by weight ammonium
hydroxide (NH
4
OH) in water and leave for 10 minutes. Then rinse with water for
at least one minute.
Inspect the sensor head. The counter electrode (anode) should be a uniform,
silver-white color. If it is clean, rinse the electrolyte reservoir with water for a full
minute. However, if the sensor head is still discolored, repeat the above procedure.
If three consecutive cleanings do not produce the desired result, you should use
the nitric acid cleaning procedure described below.
1.5.5.2 Nitric Acid Cleaning
Rinse out the sensor head with water and proceed as follows.
Place concentrated (up to
approximately 70% by weight,
but no stronger) nitric acid
(HNO
3
) in the sensor
electrolyte reservoir, just
enough to cover the anode
only, not the cathode.
Leave the acid in place for no
longer than 5 seconds. Then
empty out the acid and rinse
thoroughly with water.
WARNING: Nitric acid is dangerous! Should your skin be exposed to nitric
acid, wash immediately and thoroughly with water.
If the anode is still not completely clean, alternate between nitric acid and
ammonium hydroxide cleanings.
1.5.6 Polish Sensor Face
After cleaning, screw on the membrane
support, “finger tight”, using its
mounting tool. (Note: The support has
one smooth side with a groove, and one
side that is raised in the center, as
shown. Make sure the smooth side with
a groove faces out when installed.)
Because there is a danger of over
tightening the plastic threads, the sensor
has a safety feature that causes the
membrane support to “skip” its threads
harmlessly if over tightened. Should this occur, re-tighten with less force.
Place the polishing cloth
in its dish on a flat
surface and shake a little
polishing powder onto
the cloth, adding
enough clean water to
make a loose, watery
mixture.
Holding the sensor
vertically, and using a
Using nitric acid to clean sensor electrode
Note:
Always use protective gloves and goggles!
Tightening membrane support (note
proper orientation, grooved side “up”)
Mixing polishing powder and
water on polishing cloth
Polishing sensor with
circular motion