CellOx 325
Operating manual
Dissolved oxygen sensor
17
CellOx 325
18
Copyright © Weilheim 2002, WTW GmbH & Co. KG
Reprinting - even as excerpt s - is o nly allowed wit h the ex pli cit writt en a uthorization of WTW GmbH & Co. KG, Weilheim.
Printed in Germany.
CellOx 325 Contents
CellOx 325 - Contents
1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2 Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3 Commissioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
4 Measuring / Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.1 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.2 Measuring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.3 Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
5 Maintenance, cleaning, replacement . . . . . . . . . . . . . . . .23
5.1 General maintenance instructions . . . . . . . . . . . . . . . . . . 23
5.2 Exterior cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
5.3 Changing the electrolyte and membrane head . . . . . . . . 24
5.4 Cleaning the electrodes . . . . . . . . . . . . . . . . . . . . . . . . . 26
5.5 Checking the sensor for freedom from zero-current . . . . 28
5.6 Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
6 What to do if... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
7 Technical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
8 Wear parts and accessories . . . . . . . . . . . . . . . . . . . . . . . 32
19
Overview CellOx 325
1 Overview
Construction
213
456 87
1 WP 90 membrane cap (filled with electrolyte solution)
2 Shaft
3 Connection head
Recommended
fields of
application
4 Gold working electrode (cathode)
5 Insulator
6 Lead counter electrode (anode)
7 Ventilation area
8 Temperature sensor and auxiliary electrode
l On site measurements in rivers, lakes and wastewater
l Applications in water laboratories
l BOD measurements
20
CellOx 325 Safety
2Safety
This operating manual contains special instructions that must be followed
during the operation of the Dissolved Oxygen (D.O.) sensor.
Always keep this operating manual in the vicinity of the sensor.
Special user
qualifications
General safety
instructions
The membrane cap of the D. O. sensor is filled with a small amount of an
alkaline electrolyte solution. All ma intenance work th at requir es deali ng with
the electrolyte solution must only be carried out by persons who are familiar
with the safe handling of chemicals.
The individual chapters of thi s operating manual use safety labels like t he one
below to indicate danger:
Caution
indicates instructions tha t must be f ollowed pr ecisely in order t o avoid
slight injuries or damage to the instrument or the environment.
3 Commissioning
Scope of delivery l D. O. sensor CellOx 325, filled with electrolyte solution and operable
l 3 exchange membrane caps WP 90
l Calibration and storage vessel, OxiCal
l Operating manual
Note
The membrane cap that is mounted on t he sensor for del ivery ser ves 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 on the instrument), please proceed according to section R
BRANE CAP.
EPLACING THE ELECTROLYTE SOLUTION AND MEM-
®
-SL
Getting the sensor
ready for
measuring
Connect the sensor to th e measur ing i nstr ument. The sen sor is immediatel y
ready to measure. It is not necessary to polarize the sensor.
21
Measuring / Operation CellOx 325
4 Measuring / Operation
4.1 Calibration
Note
For calibration, please ref er to the ope rat ing manual of the meas uri ng inst rument.
4.2 Measuring
Please note the required minimum im mersion dept h and mini mum flow (s ee
chapter 7 T
The minimum flow can be provided in different ways, e. g.:
l The flow velocity of the water to be measur ed is sufficient (aerati on tank,
water pipe, stream)
l Slowly pull the sensor through the water by hand (lake, container), or
ECHNICAL DATA).
Calibration vessel,
®
OxiCal
-SL
l Use a flow aid, e. g. a magnetic stirrer with stirring devic e (see chapter 8
EAR PARTS AND ACCESSORIES)
W
4.3 Storage
Always store the sensor in the calibration vessel at a temperature of 0 to
+50 °C. Make sure that the sponge in the calibration vessel is always moist.
12
Moisten the sponge:
l Remove the cap (1).
l Take out the sponge (2), wet it, then slightly squeeze it out.
l Reinsert the sponge and close the calibration vessel with the cap.
22
CellOx 325 Maintenance, cleaning, replacement
5 Maintenance, cleaning, replacement
5.1 General maintenance instructions
For your safety When dealing with the ELY/G electrolyte solution, observe the following
safety instructions:
Caution
The ELY/G electrolyte solution irritates eyes and skin. When dealing
with the ELY/G electrolyte solution, observe the following points:
l During working activities, always wear suitable protective gloves
and protective goggles/face shield.
l If it comes into contact with the ski n, rinse thoroughly with water and
immediately change contaminated clothing.
l If it comes into contact with the eyes, rinse thoroughly with water
and consult a doctor.
l Follow the safety datasheet.
Caution
Before all maintenance activities, disconnect the sensor from the
instrument.
Cleaning agents
Note
Information on how to order wear parts and mainten ance accessories can be
found in chapter 8 W
EAR PARTS AND ACCESSORIES.
5.2 Exterior cleaning
Contamination Cleaning procedures
Lime sediments Immerse in acetic acid for 1 minute ( vol ume
share = 20 %)
Fat/oil Clean with warm water that contains wash-
ing-up liquid
After cleaning, thoroughly rinse with deionized water and recalibrate if
necessary.
23
Maintenance, cleaning, replacement CellOx 325
5.3 Changing the electrolyte and membrane head
Caution
Before starting to work with the sensor, please note the GENERAL
MAINTENANCE INSTRUCTIONS on page 23.
General
information
WTW delivers the sensor ready to operate (see section 3). The electrolyte
solution and the membrane head must only be replaced if:
l a calibration error occurs and the membrane is heavily contaminated
l the membrane is damaged
l the electrolyte solution is exhausted
l in case of a leak message by the measuring instrument.
Changing the electrolyte solution and the membrane head
Unscrew the membrane
head.
Caution:
Electrolyte solution!
Rinse the sensor head with
deionized water.
For disposal of the membrane
head and electrolyte solution,
see section 5.6.
Carefully rub and dry the
counter electrode with a lintfree paper towel.
RL/G H O
Immerse the sensor head including the counter electrode
in RL/G cleaning solution.
Allow to react for 1 to 3 minutes.
24
Thoroughly rinse the sensor
head with deionized water.
2
Water the counter electrode in
deionized water for at least
10 minutes.
CellOx 325 Maintenance, cleaning, replacement
ELY/G
Carefully shake off the drops
of water.
ELY/G
Thoroughly rinse the sensor
head with electrolyte solution.
Fill a new membrane cap with
ELY/G electrolyte solution.
Hold the sensor inclined and
screw on the membrane head
fingertight using a paper towel. Excess electrolyte solut ion
is forced out of the ventilation
area.
Remove any air bubbles by
carefully tapping the membrane head. Additionally, you
can prevent air bubbles by
throwing the first f ill away and
refilling the membrane head.
4mm
Check the filling:
Inspect the face surface. No
air bubbles may be present
within the dashed circle
(approx. the black area). 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.
25
Maintenance, cleaning, replacement CellOx 325
5.4 Cleaning the electrodes
Caution
Before starting to work with the sensor, please note the GENERAL
MAINTENANCE INSTRUCTIONS on page 23.
General
information
Cleaning the electrodes
Unscrew the membrane
head.
Caution:
For disposal of the membrane
head and electrolyte solution,
see section 5.6.
Electrolyte solution!
Cleaning is only required in cases of slopes that are too small or too large
(sensor cannot be calibrated) that cannot be res olved by changi ng the membrane head and electrolyte solution.
Rinse the sensor head with
deionized water.
SF 300
Using the rough side of the
wet SF 300 polishing strip,
polish off any contamination
from the gold working electrode using light pressure.
Caution:
ventional sandpaper or glassfiber brushes.
Do not use any con-
Rinse the sensor head with
deionized water.
26
Wipe the counter electrode
with a lint-free paper towel
and carefully remove any
loose white deposits.
RL/G
Immerse the sensor head including the counter electrode
in RL/G cleaning solution.
Allow to react for 1 to 3 minutes.
CellOx 325 Maintenance, cleaning, replacement
H O
2
Thoroughly rinse the sensor
head with deionized water.
ELY/G
Fill a new membrane cap with
ELY/G electrolyte solution.
Water the counter electrode in
deionized water for at least
10 minutes.
Remove any air bubbles by
carefully ta pp ing the membrane head. Additionally, you
can prevent air bubbles by
throwing the first fill away and
refilling the membrane head.
Carefully shake off the drops
of water.
ELY/G
Rinse the sensor head with
electrolyte solution.
Hold the sensor inclined and
screw on the membrane head
fingertight using a paper towel. Excess electrolyte soluti on
is forced out of the vent il ation
area.
4mm
Check the filling:
Inspect the face surface. No
air bubbles may be present
within the dashed circle
(approx. the black area). Air
bubbles outside this area do
not interfere.
27
Maintenance, cleaning, replacement CellOx 325
Note
For measurements under high pressure the fill mus t 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 concentrati ons (< 0.5 % saturation),
we recommend to let the sensor rest overnight and then cali b rate it.
5.5 Checking the sensor for freedom from zero-current
The sensor is zero-current free. Checking the sensor for freedom from zerocurrent is only necessary i n the case of malfunct ions that cannot be remedied
by exchanging the electrolyte solution and membrane head or by cleaning
the electrodes.
There are two possibiliti es to check the senso r for freedom fr om zero-current:
l Measurement in a nitrogen atmosphere (recommended method)
l Measurement in a sodium sulfite soluti on according to DIN EN 25814/
ISO 5814.
Caution
If you check the sensor according to DIN EN 25814/ISO 5814, do not
leave the sensor in the sodium sulfite soluti on for more than 2 minutes.
Danger of sensor poisoning!
Test criterion The sensor is OK if the measuring instrument displays < 1 % DO saturation
after 2 minutes.
28
CellOx 325 What to do if...
5.6 Disposal
Caution
The ELY/G electrolyte solution irritates eyes and skin. When dealing
with the ELY/G electrolyte solution, observe the following points:
l During working activities, always wear suitable protective gloves
and protective goggles/face shield.
l If it comes into contact with the ski n, rinse thoroughly with water and
immediately change contaminated clothing.
l If it comes into contact with the eyes, rinse thoroughly with water
and consult a doctor.
l Follow the safety datasheet.
Sensor and
membrane head
Electrolyte
solution
For disposal, unscrew the membrane head and rinse the sensor and
membrane head with water. We recommend disposing of the sensor without
the membrane head as electronic refuse. The membrane head may be
disposed of with the household refuse.
Disposal according to the safety data sheet.
6 What to do if...
Error symptom Cause Remedy
The sensor is in the air
and the display shows
0.0 mg/l or 0 % O
The sensor cannot be
calibrated
2
– No connection between
measuring instrument and sensor
– Cable defective
– No electrolyte in the membrane
head
– Contaminated membrane head
– Electrolyte depleted
– Check connection between
measuring instrument and sensor
– Replace and refill the membrane
head (see section 5.3)
– Replace and refill the membrane
head (see section 5.3).
Subsequently, wait for 30 to
50 min and recalibrate.
The sensor still cannot
be calibrated after
changing the electrolyte
and membrane head
Leak display appears – Membrane head not screwed on
Incorrect temperature
display
Mechanical damage to
the sensor
– Contaminated electrodes or
sensor toxification
tight enough
– Hole in the membrane
– Temperature sensor defective – Return the sensor
– Clean the electrodes (see
section 5.4)
– Screw membrane head tighter
– Replace and refill the membrane
head (see section 5.3)
– Return the sensor
29
Technical data CellOx 325
7 Technical data
General features Measuring principle Membrane covered galvanic sensor
Temperature compensation IMT compensation
(calculated by the measuring instrument)
Dimensions
(in mm)
Weight 170 g (with 1.5 m cable)
Materials Working electrode Gold
Counter electrode Lead
– Shaft
– Connection head
– Screwed cable gland
– Membrane head
Membrane FEP, 13
Sensor head Epoxy, PEEK
Thermistor housing VA steel 1.4571
Seals FPM (Viton)
Connection cable Lengths 1.5 ... 20 m
Diameter 6 mm
Smallest allowed
bend radius
Plug type Socket, 8 pins
Pressure
resistance
Sensor IP 68 (6 bar)
Sensor cable IP 68 (2 bar)
POM
µm
Permanent bend: 80 mm
Single time or short time bend: 50 mm
30
Plug IP 67 (when plugged in)
The CellOx 325 meets the requirements according to article 3(3) of the
97/23/EC directive ("Pressure equipment directive").
CellOx 325 Technical data
Measurement
conditions
Characteristic data
on delivery
Measuring ranges at 20 °C 0 ... 50 mg/l O
2
0 ... 600 % O2 saturation
0 ... 1250 mbar O
partial pressure
2
Temperature range 0 ... 50 °C
Max. allowed overpressure 6·10
5
Pa (6 bar)
Depth of immersion min. 6 cm
max. 20 m (depending on the cable length)
Operating position any
Approach flow > 3 cm/s at 10 % measurement accuracy
10 cm/s at 5 % measurement accuracy
18 cm/s at 1 % measurement accuracy
Zero signal < 0.1 % of the saturation value
Response time at 20 °Ct
Oxygen own consumption
(90 % of the final value display) < 10 s
90
(95 % of the final value display) < 16 s
t
95
(99 % of the final value display) < 60 s
t
99
0.008
µg·h
-1
(mg/l)
-1
at 20 °C
Drift approx. 3 % per month in the operating con-
dition
Pin assignment
Working life min. 6 months with one electrolyte fill
31
Wear parts and accessories CellOx 325
8 Wear parts and accessories
Wear parts and
maintenance
accessories
Accessories Description Model Order no.
Description Model Order no.
Set of exchange membrane caps (3 pieces) WP 90/3 202 725
Electrolyte solution ELY/G 205 217
Cleaning solution for lead counter electrode RL/G 205 204
Polishing film SF 300 203 680
Accessory kit, comprising:
– 3 exchange membrane caps WP 90
– Polishing film SF 300
– Electrolyte solution ELY/G
– Cleaning solution RL/G
Calibration and storage vessel OxiCal
Magnetic stirrer Oxi-Stirrer 300 203 810
Stirring accessory - provides a constant,
defined flow of the sensor, in conjunction
with the Oxi-Stirrer 300
Funnel set - for BOD measurements in
Winkler bottles
ZBK 325 202 706
®
-SL 205 362
RZ 300 203 824
TS 19 205 710
Karlsruhe bottle - suitable for BOD
measurements
Fixing ring, recommended for measurements in Karlsruhe bottles
Flow-through accessory - for pressure- free
oxygen measurement with flow-through
quantities from 25 to 65 ml/min.
Shaft extension SVL 325 903 832
Plastic armoring A 325/K 903 830
Battery stirrer for dept h measurements - only
in conjunction with the A 325/K plastic
armoring
Note
For further accessories, refer to the WTW catalog or the Internet.
KF 12 205 700
FR 19 205 712
D 201 203 730
BR 325 203 826
32
Loading...