Xylem WTW DurOx 325 User manual

OPERATING MANUAL
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DurOx 325
DISSOLVED OXYGEN SENSOR
OPERATING MANUAL

DurOx 325
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Copyright © 2020 Xylem Analytics Germany GmbH
Printed in Germany.

DurOx 325 Contents
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Contents
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1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2 Safety instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3 Commissioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4 Measuring / Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4.1 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4.2 Measuring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4.3 Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5 Maintenance, cleaning, replacement . . . . . . . . . . . . . . . . . 8
5.1 General maintenance notes . . . . . . . . . . . . . . . . . . . . . . . 8
5.2 Outside cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
5.3 Changing the electrolyte and membrane cap . . . . . . . . . . 9
5.4 Cleaning the electrodes . . . . . . . . . . . . . . . . . . . . . . . . . 11
5.5 Checking the sensor for freedom from zero-current . . . . 13
5.6 Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
6 What to do if ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
7 Technical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
8 Wear parts and accessories . . . . . . . . . . . . . . . . . . . . . . . 17

Contents DurOx 325
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DurOx 325 Overview
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1 Overview
Structure
Recommended
fields of
application
On site measurements in rivers, lakes and wastewater
1Connection head
2Shaft housing
3Temperature sensor and auxiliary electrode
4Ventilation area
5Lead counter electrode (anode)
6Insulator
7Gold working electrode (cathode)
8WP-D membrane cap (filled with electrolyte solution)
9Protective hood
7
6
5
3
1
2
4
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Safety instructions DurOx 325
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2 Safety instructions
This operating manual contains special instructions that must be followed
during the operation of the D.O. sensor.
Always keep this operating manual in the vicinity of the sensor.
Special user
qualifications
The membrane cap of the D.O. sensor is filled with a small amount of an
alkaline electrolyte solution. All maintenance work that requires dealing with
the electrolyte solution must only be carried out by persons who know how to
safely deal with chemicals.
General safety
instructions
The individual chapters of this operating manual use safety labels like the one
below to indicate danger:
CAUTION
indicates instructions that must be followed precisely in order to avoid
slight injuries or damage to the instrument or the environment.
3 Commissioning
Scope of delivery D.O. sensor DurOx 325, filled with electrolyte solution and ready to
operate
Calibration and storage vessel, OxiCal®-D
1 exchange membrane cap, WP-D
Electrolyte solution, ELY/G
Cleaning solution, RL/G
Polishing strip, SF 300
Operating manual
Note
The membrane cap that is mounted on the sensor for delivery serves mainly
as a transport protection. Depending on the duration of the transport and
storage period, it may have a shortened operational lifetime. If the measuring
system cannot be calibrated (error message of the instrument), please
proceed according to section REPLACING THE ELECTROLYTE SOLUTION AND
MEMBRANE CAP.
Preparing the
sensor for
measurement
Connect the sensor to the measuring instrument. The sensor is immediately
ready to measure. It is not necessary to polarize the sensor.

DurOx 325 Measuring / Operation
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4 Measuring / Operation
4.1 Calibration
Note
For calibration, please refer to the operating manual of the measuring
instrument.
4.2 Measuring
Note the required minimum depth of immersion and minimum approach flow
(see chapter 7 TECHNICAL DATA).
The minimum flow can be provided in different ways, e. g.:
The flow of the water to be measured is sufficient (aeration tank, water
pipe, stream)
Slowly pull the sensor through the water by hand (lake, container), or
Use a flow aid, e.g. stirrer.
4.3 Storage
Always store the sensor in the calibration and storage vessel at a
temperature in the range 0 ... +50 °C (32 ... 122 °F). Make sure that the
sponge in the calibration and storage vessel is always moist.
Calibration and
storage vessel,
OxiCal®-D
Moisten the sponge:
Pull out the insert (1).
Take out the sponge (2), wet it, then slightly squeeze it out.
Put in the sponge and install the insert in the calibration and storage
vessel again.
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Maintenance, cleaning, replacement DurOx 325
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5 Maintenance, cleaning, replacement
5.1 General maintenance notes
For your safety Note the following safety instructions when handling electrolyte and cleaning
solutions:
CAUTION
The ELY/G electrolyte solution and RL-G cleaning solution irritate the
eyes and skin. Note the following points when dealing with these
solutions:
During working activities, always wear suitable protective gloves
and protective goggles/face shield.
If it comes into contact with the skin, rinse thoroughly with water and
immediately change contaminated clothing.
If it comes into contact with the eyes, rinse thoroughly with water
and consult a doctor.
Note the safety datasheets.
CAUTION
Before all maintenance activities, disconnect the sensor from the
instrument.
Note
Information on how to order wear parts and maintenance equipment can be
found in chapter 8 WEAR PARTS AND ACCESSORIES.
5.2 Outside cleaning
Cleaning agents
After cleaning, thoroughly rinse with deionized water and recalibrate if
necessary.
Contamination Cleaning procedure
Lime sediments Immerse in acetic acid for 1 minute (volume
share = 10 %)
Fat/oil Clean with warm water that contains
washing-up liquid

DurOx 325 Maintenance, cleaning, replacement
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5.3 Changing the electrolyte and membrane cap
CAUTION
Before starting to work with the sensor, please note the GENERAL
MAINTENANCE INSTRUCTIONS on page 8.
General
information
WTW delivers the sensor ready to operate (see section 3). The electrolyte
solution and membrane cap must only be replaced if:
a calibration error occurs and the membrane is heavily contaminated
the membrane is damaged
the electrolyte solution is exhausted.
Changing the electrolyte and membrane cap
Unscrew the membrane cap.
Caution: Electrolyte solution!
For disposal of the membrane
head and electrolyte solution,
see section 5.6.
Rinse the sensor head with
deionized water.
Carefully rub and dry the
counter electrode with a lint-
free paper towel.
Immerse the sensor head
including the counter
electrode in RL/G cleaning
solution.
Allow to react for 1 to 3
minutes.
Thoroughly rinse the sensor
head with deionized water.
Water the counter electrode in
deionized water for at least
10 minutes.
RL/G
H O
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Maintenance, cleaning, replacement DurOx 325
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Carefully shake off the drops
of water.
Fill a new membrane cap with
ELY/G electrolyte solution.
Remove any air bubbles by
carefully tapping the
membrane head. Additionally,
you can prevent air bubbles
by throwing the first filling
away and refilling the
membrane cap.
Thoroughly rinse the sensor
head with electrolyte solution.
Hold the sensor inclined and
screw on the membrane head
fingertight using a paper
towel. Excess electrolyte
solution is forced out of the
ventilation area.
Check the filling:
Inspect the face surface. No
air bubbles may be present
within the dashed circle. Air
bubbles outside this area do
not interfere.
Note
For measurements under high pressure the filling must be
completely free of air bubbles.
Readiness to measure After approx. 30 to 50 minutes, the sensor is ready for operation.
Subsequently calibrate the sensor.
Note
If you want to measure very low oxygen concentrations (< 0.5 %
saturation), we recommend to let the sensor rest overnight and
then calibrate it.
ELY/G
ELY/G
Ventilation area
points upwards
3 mm