Endress+Hauser Oxymax H COS21D User manual

BA402C/07/en/02.06
71006960
Operating Instructions
Oxymax H COS21D
Dissolved oxygen sensor

Endress+Hauser
Brief overview
Here is how to use these Operating Instructions to commission your sensor quickly and safely:
Safety instructions
→ä4
→ä5
General safety instructions
Explanation of the warning symbols
You can find special instructions at the appropriate position in the chapter in question. The
positions are indicated with the icons Warning #, Caution "and Note !.
Æ
Installation
→ä7
→ä9
Here you can find installation conditions such as sensor dimensions and the angle of installation.
Installation examples can be found here.
Æ
Wiring
→ä11 Refer to theses pages for sensor wiring.
Æ
Sensor design and measuring principle
→ä14
→ä14
→ä15
Here you can read about the sensor design.
The measuring principle is explained on this page.
Here you can find the possible calibration methods.
Æ
Commissioning
→ä18 The sensor must be polarized before calibration. Please, read on the given page how to do it.
Æ
Maintenance
→ä19
→ä24
It is absolutely essential to carry out maintenance tasks on a regular basis.
Here you can find an overview of the spare parts which can be delivered as well as an overview
of the system.
Æ
Trouble-shooting
→ä23 If faults occur during operation, use the checklist to locate the cause.
Æ
Æ
Index
→ä28 You can find important terms and keywords on the individual sections here. Use the keyword
index to find the information you need quickly and efficiently.

Oxymax H COS21D
Endress+Hauser 3
Table of contents
1 Safety instructions . . . . . . . . . . . . . . . . 4
1.1 Designated use . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2 Installation, commissioning and operation . . . . . . . . 4
1.3 Operational safety . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.4 Return . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.5 Notes on safety icons and symbols . . . . . . . . . . . . . . 5
1.6 Cross reference symbols . . . . . . . . . . . . . . . . . . . . . 5
2 Identification . . . . . . . . . . . . . . . . . . . . 6
2.1 Product structure . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2 Scope of delivery . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3 Certificates and approvals . . . . . . . . . . . . . . . . . . . . 6
3 Installation . . . . . . . . . . . . . . . . . . . . . . 7
3.1 Incoming acceptance, transport, storage . . . . . . . . . . 7
3.2 Installation conditions . . . . . . . . . . . . . . . . . . . . . . . 7
3.3 Installation instructions . . . . . . . . . . . . . . . . . . . . . . 8
3.4 Installation examples . . . . . . . . . . . . . . . . . . . . . . . . 9
3.5 Post-installation check . . . . . . . . . . . . . . . . . . . . . . 10
4 Wiring . . . . . . . . . . . . . . . . . . . . . . . . 11
4.1 Sensor version for Ex applications . . . . . . . . . . . . . 11
4.2 Direct connection to Liquiline M . . . . . . . . . . . . . . 12
4.3 Connection via junction box . . . . . . . . . . . . . . . . . 13
4.4 Post-connection check . . . . . . . . . . . . . . . . . . . . . . 13
5 Function . . . . . . . . . . . . . . . . . . . . . . . 14
5.1 Sensor design . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.2 Measuring principle . . . . . . . . . . . . . . . . . . . . . . . . 14
5.3 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
6 Commissioning. . . . . . . . . . . . . . . . . . 18
6.1 Function check . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
6.2 Polarization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
6.3 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
7 Maintenance. . . . . . . . . . . . . . . . . . . . 19
7.1 Cleaning the sensor . . . . . . . . . . . . . . . . . . . . . . . . 19
7.2 Regenerating the sensor . . . . . . . . . . . . . . . . . . . . . 20
8 Accessories. . . . . . . . . . . . . . . . . . . . . 22
8.1 Connection accessories . . . . . . . . . . . . . . . . . . . . . 22
8.2 Installation accessories . . . . . . . . . . . . . . . . . . . . . . 22
8.3 Measurement, controlling and sensor cleaning . . . . 22
9 Trouble-shooting . . . . . . . . . . . . . . . . 23
9.1 Trouble-shooting instructions . . . . . . . . . . . . . . . . 23
9.2 Spare parts and consumable material . . . . . . . . . . . 24
9.3 Return . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
9.4 Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
10 Technical data . . . . . . . . . . . . . . . . . . . 25
10.1 Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
10.2 Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
10.3 Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
10.4 Performance characteristics . . . . . . . . . . . . . . . . . . 26
10.5 Mechanical construction . . . . . . . . . . . . . . . . . . . . 27
Index . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Safety instructions Oxymax H COS21D
4Endress+Hauser
1 Safety instructions
1.1 Designated use
The sensor is suitable for continuous measurement of dissolved oxygen in water.
The sensor version determines what the sensor is especially suitable for:
• COS21D-A (measuring range 0.05 to 20 mg/l)
– Measuring, monitoring and regulating the oxygen content in fermenters
– Monitoring the oxygen contents in biotechnological systems
• COS21D-B (trace measurement with high CO2partial pressure, measuring range 0.001 to
20 mg/l, preferred operational range 0.001 to 2 mg/l)
– Monitoring inerting units in the food industry
– Monitoring the residual oxygen contents in carbonated media in the beverage industry
• COS21D-C (trace measurement, measuring range 0.001 to 20 mg/l, preferred operational range
0.001 to 2 mg/l)
– Trace measurement in industrial applications such as inerting
– Monitoring residual oxygen contents in boiler feedwater
– Monitoring, measuring and regulating the oxygen contents in chemical processes
The COS21D sensor must be connected to the digital input of the Liquiline transmitter using the
CYK10 measuring cable for non-contact, digital data transfer.
Any other use than the one described here compromises the safety of persons and the entire
measuring system and is, therefore, not permitted.
The manufacturer is not liable for damage caused by improper or non-designated use.
1.2 Installation, commissioning and operation
Please note the following items:
• Installation, commissioning, operation and maintenance of the measuring system must only be
carried out by trained technical personnel.
The technical personnel must be authorized for the specified activities by the system operator.
• Electrical connection must only be carried out by a certified electrician.
• Technical personnel must have read and understood these Operating Instructions and must
adhere to them.
• Before commissioning the entire measuring point, check all the connections for
correctness. Ensure that electrical cables and hose connections are not damaged.
• Do not operate damaged products and secure them against unintentional
commissioning. Mark the damaged product as being defective.
• Measuring point faults may only be rectified by authorized and specially trained
personnel.
• If faults can not be rectified, the products must be taken out of service and secured against
unintentional commissioning.
• Repairs not described in these Operating Instructions may only be carried out at the
manufacturer’s or by the service organisation.
1.3 Operational safety
The sensor has been designed and tested according to the state of the art and left the factory in
perfect functioning order.
Relevant regulations and European standards have been met.
As the user, you are responsible for complying with the following safety conditions:
• Installation instructions
• Local prevailing standards and regulations.

Oxymax H COS21D Safety instructions
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1.4 Return
If the sensor has to be repaired, please return it cleaned to the sales centre responsible.
Please use the original packaging, if possible.
Please enclose the completed "Declaration of Hazardous Material and De-Contamination" (copy the
second last page of these Operating Instructions) with the packaging and the transportation
documents.
No repair without completed declaration!
1.5 Notes on safety icons and symbols
1.6 Cross reference symbols
#Warning!
This symbol alerts you to hazards. They can cause serious damage to the instrument or to persons
if ignored.
"Caution!
This symbol alerts you to possible faults which could arise from incorrect operation. They could
cause damage to the instrument if ignored.
!Note!
This symbol indicates important items of information.
È ä 1 This symbol indicates a cross reference to a defined page (e.g. p. 1).
È å 2 This symbol indicates a cross reference to a defined figure (e.g. fig. 2).

Identification Oxymax H COS21D
6Endress+Hauser
2 Identification
2.1 Product structure
2.2 Scope of delivery
The following items are included in the delivery:
• Oxygen sensor with transport protection cap for membrane protection
• Electrolyte, 1 bottle, 50 ml (1.7 fl.oz.)
• Pipette for filling with electrolyte
• Operating Instructions, English
If you have any questions, please contact your supplier or your sales center responsible.
2.3 Certificates and approvals
Version COS21D-A*2
ATEX II 1G EEX ia IIC T3/T4/T6
Application, operational range
A Standard 0.05 to 20 mg/l
B Trace, beverages (CO2compatible) 0,001 to 2 mg/l
C Trace, power plants 0.001 to 2 mg/l
Shaft length
1120mm
Approvals
1None
2 ATEX/FM (ATEX II 1G EEX ia IIC T3/T4/T6, COS21D-A* only)
Certificates
1None
2 EN10204 3.1
Options
1None
COS21D- Complete order code

Oxymax H COS21D Installation
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3 Installation
3.1 Incoming acceptance, transport, storage
• Make sure the packaging is undamaged!
Inform the supplier about damage to the packaging. Keep the damaged packaging until the matter
has been settled.
• Make sure the contents are undamaged!
Inform the supplier about damage to the delivery contents. Keep the damaged products until the
matter has been settled.
• Check that the scope of delivery is complete and agrees with your order and the shipping
documents.
• The packaging material used to store or to transport the product must provide shock protection
and humidity protection. The original packaging offers the best protection. Also, keep to the
approved ambient conditions (see "Technical data").
• If you have any questions, please contact your supplier or your sales center responsible.
3.2 Installation conditions
3.2.1 Angle of installation
The sensor must be installed with an angle of inclination of at least 10 ° to the horizontal in an
assembly, support or a suitable process connection. Other angles are not permissible. Do not install
the sensor overhead.
!Note!
Make sure you comply with the instructions for installing sensors. You will find them in the
Operating Instructions for the assembly used.
3.2.2 Mounting location
• Select the installation location so that there is easy access for later calibration.
• Make sure that upright posts and assemblies are secured safely and vibration-free.
• For immersed operation in an activated sludge basin, select an installation location which
produces a typical oxygen concentration.
a0005584-en
Fig. 1: Permitted angle of installation
10° 10° Not permissible!
Not permissible!
Permissible angle of installation

Installation Oxymax H COS21D
8Endress+Hauser
3.3 Installation instructions
3.3.1 Measuring system
A complete measuring system comprises:
• The digital oxygen sensor Oxymax H COS21D
• A transmitter, e.g. Liquiline M CM42
• An appropriate measuring cable, e.g. CYK10
• Optional: an assembly, e.g. fixed installation assembly CPA442, flow assembly CPA240 or
retractable assembly CPA475
3.3.2 Installing a measuring point
For a complete installation of a measuring point, proceed as follows:
1. Install a retractable or a flow assembly (if used) into the process.
2. Connect the water supply to the rinse connections (if you use an assembly with cleaning
function).
3. Install and connect the oxygen sensor.
"Caution!
•Do not install the sensor suspended from the cable.
• Screw the sensor into the assembly so that the cable is not twisted.
• Avoid exerting excessive tensile force on the cable (e.g. from jerky pulling).
• Select the installation location so that there is easy access for later calibration.
#Warning!
When using metallic assemblies and installation equipment, comply with national grounding
regulations.
a0001398
Fig. 2: Example of a measuring system
1 Liquiline M CM42
2 Measuring cable CYK10
3 Digital oxygen sensor Oxymax H COS21D
4 Fixed installation assembly CPA442
1
2
3
4

Oxymax H COS21D Installation
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3.4 Installation examples
3.4.1 Fixed installation
The CPA442 fixed installation assembly allows a sensor to be easily adapted to almost any process
connections from Ingold nozzles to Varivent or Triclamp connections.
This type of installation is very suitable for tanks and larger pipes. The sensor achieves a defined
immersion depth in the medium in an easy manner →å2.
3.4.2 Flow assembly
The CPA240 flow assembly offers up to three installation slots for sensors with a shaft diameter of
12 mm (0.47"), a shaft length of 120 mm (4.7") and a process connection Pg 13.5.
It is very suitable for use in pipes or at hose connections.
During trace measurement in particular, ensure the assembly is completely vented to avoid
measuring errors.
a0005720
Fig. 3: CPA240 flow assembly with protective hood
a0005721
Fig. 4: Bypass installation
1 Main line
2Mediumremoval
3, 6 Manually actuated or solenoid valves
4 Sampling
5 Flow assembly with installed sensor
7 Medium return

Installation Oxymax H COS21D
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3.4.3 Retractable assembly
The assembly is designed for installation on tanks and pipes. Suitable nozzles must be available for
this.
Install the assembly at places with constant flow. The minimum pipe diameter is DN 80.
a0005722-en
Fig. 5: Suitable and unsuitable installation positions with a retractable assembly
1 Ascending pipe, best position
2 Horizontal pipe, sensor top down, impermissible due to air cushion or foam bubble forming
3 Horizontal pipe, installation with permissible installation angle (acc. to sensor version)
4 Overhead installation, impermissible due to missing electrolyte contact of the sensor electrodes
5 Down pipe, impermissible
!Note!
Do not install the assembly at places where air cushions or foam bubbles can form.
Measuring errors can occur, if:
• the sensor is not immersed into the medium
• suspended particles are settled on the sensor membrane
• the sensor is installed overhead.
3.5 Post-installation check
• Sensor and cable undamaged?
• Cap undamaged?
• Compliance with permissible sensor installation position?
• Is the sensor installed in an assembly and is not suspended from the cable?
• Avoid moisture by rain by fitting the protective cap to the immersion assembly?

Oxymax H COS21D Wiring
Endress+Hauser 11
4 Wiring
#Warning!
• The electrical connection must only be carried out by a certified electrician.
• Technical personnel must have read and understood the instructions in this manual and must
adhere to them.
• Ensure that there is no voltage at the power cable before beginning the connection work.
4.1 Sensor version for Ex applications
4.1.1 Quick wiring guide
"Caution!
• Oxygen sensors for use in Ex areas have a special, conductive O-ring. The metallic sensor shaft is
electrically connected to the conductive mounting location (e.g. a metallic assembly) by means of
the O-ring.
• You must take appropriate measures to connect the assembly or the mounting location to the
operational ground in accordance with Ex guidelines.
• Ex versions of digital sensors with Memosens technology are marked with an orange-red ring on
the plug-in head.
a0003366
Fig. 6: Connection in the Ex area

Wiring Oxymax H COS21D
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4.1.2 Temperature classes
!Note!
If the ambient temperatures indicated are observed, no temperatures which are impermissible for
the temperature class in question will occur at the sensor.
4.2 Direct connection to Liquiline M
Temperature class
T3 T4 T6
Ambient temperature Ta–10 ... +135 °C –10 ... +110 °C –10 ... +60 °C
Reference temperature Tref +25 °C
a0001087
Fig. 7: View in device
a0001078
Fig. 8: Wiring diagram

Oxymax H COS21D Wiring
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4.3 Connection via junction box
To extend the sensor connection beyond the length of the fixed cable, the connection has to take
place using a junction box RM (--> Accessories). The extension to the transmitter is established by
means of the CYK81 special measuring cable (→å9).
a0005724
Fig. 9: Wiring diagram with junction box RM
1Sensor
2 Junction box
3 Extension cable
4Transmitter
4.4 Post-connection check
YE YE
BN
GN GN
YE
WH
187
188
197
198
12
3
4
GN
BN
WH
BN
WH
Instrument status and specifications Remarks
Are the sensor, assembly, junction box or cable damaged? Visual inspection
Electrical connection Remarks
Does the supply voltage of the transmitter match the specifications on the
nameplate?
Are the installed cables strain-relieved and not twisted ?
Is the cable type route completely isolated ? Power cable/weak current cable
Are the power supply and signal cable correctly connected to the
transmitter ?
Use the connection diagram of the
transmitter.
Are all the screws terminals properly tightened ? Tighten
Are all the cable entries installed, tightened and sealed ? For cable entries lateral: cable loops
downwards for water to be able to drip off.
Are all the cable entries installed downwards or lateral ?

Function Oxymax H COS21D
14 Endress+Hauser
5Function
5.1 Sensor design
5.2 Measuring principle
5.2.1 Polarization
When the sensor is connected to the transmitter, a fixed external voltage is applied between the
cathode and anode. The resulting polarization current is indicated on the display of the transmitter.
The current starts high but then drops over time. The sensor can only be calibrated when the display
is stable.
Reference value for practically complete polarization of a sensor that was in storage for an extended
period beforehand:
• COS21D-A/C: 2 hours
• COS21D-B: 12 hours
After this time, measurements close to the determination limit make sense.
The polarization time needed is shorter for sensors which were in operation shortly beforehand.
5.2.2 Membrane cap
The oxygen dissolved in the medium is conveyed to the membrane by the incoming flow. The
membrane is only permeable for dissolved gases. Other substances dissolved in the liquid phase e.g.
ionic substances, will not penetrate through the membrane. Therefore, medium conductivity has
no impact on the measuring signal.
a0005631
Fig. 10: Design
1 Threaded connection Pg 13.5
2Anode
3 Membrane cap
4 Protective cap
5 Memosens plug-in head
6 Cathode
7Membrane
a0005619
Fig. 11: Dimensions
1
2
3
4
5
6
7

Oxymax H COS21D Function
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The sensor is supplied with a standard membrane cap which can be used for all common
applications.
The membrane cap is pretensioned at the factory and can be installed directly.
There are also special membrane cap kits as an option (--> Accessories):
• FDA-Kit: membrane materials are in conformity with FDA
• SIP/CIP-Kit: membrane material is specially designed for the high demands of frequent SIP/CIP
processes
!Note!
The electrolytes in the membrane caps are specific to the sensor versions and must not be mixed
together!
5.2.3 Amperometric principle
The oxygen molecules diffused through the membrane are reduced to hydroxide ions (OH-) at the
cathode. Silver is oxidized to silver ions (Ag+) at the anode (this forms a silver halogenide layer).
A current flows due to the electron donation at the cathode and the electron acceptance at the
anode. Under constant conditions, this flow is proportional to the oxygen content of the medium.
This current is converted in the transmitter and indicated on the display as an oxygen concentration
in mg/l, as a saturation index in % SAT or as an oxygen partial pressure in hPa.
5.2.4 Memosens technology
The sensor is connected to the cable connection (CYK10) without contact. The power and data are
transferred inductively
Once connected to the transmitter, the data saved in the sensor are read digitally. You can call up
these data using the corresponding DIAG menu.
Data that digital sensors save include the following:
• Manufacturer data
– Serial number
–Ordercode
– Date of manufacture
• Calibration data
– Calibration date
– Calibration values
– Number of calibrations
– Serial number of the transmitter used to perform the last calibration
• Operational data
– Date of commissioning
– Hours of operation under extreme conditions
– Number of sterilizations
– Data for sensor monitoring.
5.3 Calibration
Calibration is a means of adapting the transmitter to the characteristic values of the sensor.
Normally, sensor calibration is seldom necessary. It is necessary after:
• First commissioning
• Replacing a membrane or electrolyte
• Cleaning the cathode
• Long breaks in operation without power supply
Within the framework of system monitoring and supervision, for example, the calibration can also
be cyclically monitored (at typical time intervals, depending on operating experience) or renewed.

Function Oxymax H COS21D
16 Endress+Hauser
5.3.1 Types of calibration
You can carry out single-point or two-point calibration for the sensor.
In most applications, single-point calibration suffices in the presence of oxygen (=calibration of
measured value at air).
The additional calibration of the zero point (two-point calibration) improves the precision of the
measurement results in the trace range. Calibrate the zero point with nitrogen or with water free
from oxygen, for example. In doing so, make sure the measured value has settled correctly to avoid
incorrect measurements in the trace range at a later stage.
Types of calibration:
• Slope:
– Air (saturated with water vapor, e.g. near the water surface)
– Air-saturated water
– Variable air (entering the current relative humidity and the current air pressure)
– Data entry
• Zero point:
– Zero point calibration (nitrogen or water free from oxygen)
– Data entry
• Reference:
– Zero point
– Slope
!Note!
The following section only describes the calibration in air (saturated with water vapor) as the easiest
method of calibration and therefore the recommended method.
However, this type of calibration is only possible if the air temperature is ≥–5 °C (23 °F).
5.3.2 Calibration in air
1. Remove the sensor from the medium.
2. Clean the outside of the sensor with a damp cloth. Then dry the sensor membrane e.g. by using
a tissue.
3. If the sensor is removed from a closed pressure system with a process pressure greater than
atmospheric pressure:
– Open the membrane cap to equilibrate the pressure and clean the cap if necessary.
– Replace the electrolyte filling and close the membrane cap again.
– Wait for the polarization time to end.
4. Then wait while the sensor adjusts to the temperature of the ambient air. This takes about 20
minutes. Check that the sensor is not in direct sunlight during this time.
5. If the measured value display on the transmitter is stable, carry out the calibration in
accordance with the Operating Instructions of the transmitter.
6. Place the sensor in the medium again.
!Note!
Make sure you comply with the instructions for calibration in the Operating Instructions of the
transmitter.
5.3.3 Calculation example for the calibration value
As a check, you can calculate the expected calibration value (transmitter display) as shown in the
following example (salinity is 0).
1. Determine:
– The ambient temperature for the sensor (air temperature for "air" calibration method,water
temperature for "air-saturated water" calibration type)
– the altitude above sea level
– the current air pressure L(=rel. air pressure to sea level) at the time of calibration. (If
undeterminable, use 1013 hPa (407 inH2O) for an approximate calculation.)

Oxymax H COS21D Function
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2. Define:
–thesaturationvalueSacc. to the first table
– the factor Kacc. to the second table
3. Calculate the calibration value C:
C = S .K .L
Example
• Air calibration at 18°C (64 °F), altitude 500 m (1650 ft) above sea level, air pressure 1009 hPa
(405 inH2O) =1.009 bar
• S = 9.45 mg/l, K = 0.943, L = 1.009
Calibration value C = 9.17 mg/l.
!Note!
You do not need factor K from the table if your device returns the absolute air pressure Labs
(location-dependent air pressure) as the measured value.
Thus, the formula for calculation is: C = S .Labs.
° C / °F S
[mg/l=ppm]
° C / °F S
[mg/l=ppm]
° C / °F S
[mg/l=ppm]
° C / °F S
[mg/l=ppm]
0 / 32 14.64 11 / 52 10.99 21 / 70 8.90 31 / 88 7.42
1 / 34 14.23 12 / 54 10.75 22 / 72 8.73 32 / 90 7.30
2 / 36 13.83 13 / 55 10.51 23 / 73 8.57 33 / 91 7.18
3 / 37 13.45 14 / 57 10.28 24 / 75 8.41 34 / 93 7.06
4 / 39 13.09 15 / 59 10.06 25 / 77 8.25 35 / 95 6.94
5 / 41 12.75 16 / 61 9.85 26 / 79 8.11 36 / 97 6.83
6 / 43 12.42 17 / 63 9.64 27 / 81 7.96 37 / 99 6.72
7 / 45 12.11 18 / 64 9.45 28 / 82 7.82 38 / 100 6.61
8 / 46 11.81 19 / 66 9.26 29 / 84 7.69 39 / 102 6.51
9 / 48 11.53 20 / 68 9.08 30 / 86 7.55 40 / 104 6.41
10 / 50 11.25
Altitude
[m / ft]
KAltitude
[m / ft]
KAltitude
[m / ft]
KAltitude
[m / ft]
K
0 1.000 550 / 1800 0.938 1050 / 3450 0.885 1550 / 5090 0.834
50 / 160 0.994 600 / 1980 0.932 1100 / 3610 0.879 1600 / 5250 0.830
100 / 330 0.988 650 / 2130 0.927 1150 / 3770 0.874 1650 / 5410 0.825
150 / 490 0.982 700 / 2300 0.922 1200 / 3940 0.869 1700 / 5580 0.820
200 / 660 0.977 750 / 2460 0.916 1250 / 4100 0.864 1750 / 5740 0.815
250 / 820 0.971 800 / 2620 0.911 1300 / 4270 0.859 1800 / 5910 0.810
300 / 980 0.966 850 / 2790 0.905 1350 / 4430 0.854 1850 / 6070 0.805
350 / 1150 0.960 900 / 2950 0.900 1400 / 4600 0.849 1900 / 6230 0.801
400 / 1320 0.954 950 / 3120 0.895 1450 / 4760 0.844 1950 / 6400 0.796
450 / 1480 0.949 1000 / 3300 0.890 1500 / 4920 0.839 2000 / 6560 0.792
500 / 1650 0.943

Commissioning Oxymax H COS21D
18 Endress+Hauser
6 Commissioning
6.1 Function check
Before first commissioning, check if:
• the sensor is correctly installed
• the electrical connection is correct.
If using an assembly with automatic cleaning, check the correct water connection at the assembly
rinse connection.
#Warning!
Danger of medium leaking off
Before applying compressed air to an assembly with cleaning facility, make sure the connections are
correctly fitted. Otherwise, the assembly may not be insert into the process.
6.2 Polarization
The sensor was tested in the factory for perfect functionality and is supplied ready for operation.
To prepare for calibration, proceed as follows:
1. Remove the sensor protective cap.
2. Place the externally dry sensor in atmospheric air. The air should be saturated with water
vapour. Therefore, install the sensor as close to the water surface as possible. When calibrating
the sensor membrane, make sure the membrane remains dry. Therefore, avoid any direct
contact with the water surface.
3. Connect the sensor to the transmitter and switch on the transmitter.
4. Switch-on the transmitter.
If you connect the sensor to the transmitter, polarization is automatically performed after
switching on the transmitter.
5. Wait for the polarization time to end.
"Caution!
• When you remove the sensor from the medium, protect the sensor from strong sunlight.
• Make sure you comply with the instructions for commissioning and calibration in the Operating
Instructions of the transmitter.
6.3 Calibration
Calibrate the sensor (air calibration) immediately after the polarization time has elapsed.
The calibration intervals depend heavily on:
• The application and
• The installation position of the sensor.
The following methods help you determine how long the calibration intervals should be:
1. Check the sensor one month after its being put into operation by taking it out of the fluid,
drying it and then measuring the oxygen saturation index at air after 10 minutes.
Decide using the results:
a. If the measured value is not at 100 ± 2 %SAT, you have to calibrate the sensor.
b. Otherwise, double the length of time to the next inspection.
2. Proceed as per Point 1 after two, four and/or eight months. In this way, you can determine
the optimum calibration interval for your sensor.
!Note!
Be sure to calibrate the sensor at least once a year.

Oxymax H COS21D Maintenance
Endress+Hauser 19
7 Maintenance
Maintenance work must carried out at regular intervals. To ensure that it is carried out, we
recommend you enter the maintenance dates into an operations logbook or in an
operations calendar in advance.
The maintenance cycle primarily depends on the system, the installation conditions and the
medium in which measurement is taking place.
The following activities must be carried out:
• Cleaning the sensor
(In particular when the membrane is soiled)
• Check the measuring function:
1. Remove the sensor from the medium.
2. Clean and dry the membrane.
3. After about 10 minutes, measure the oxygen saturation index in air (without recalibration).
4. The measured value should be near to 100% SAT
• If necessary, replace a defective membrane or one which cannot be cleaned any more.
• Recalibration.
(if desired or required)
7.1 Cleaning the sensor
The measurement can be corrupted by sensor fouling or malfunction, e.g.:
• Coatings on the sensor membrane
--> cause longer response times and a reduced slope under certain circumstances.
• Soiling or poisoning of the electrolyte
--> causes longer response times and false measurement.
To ensure reliable measurement, the sensor must be cleaned at regular intervals. The frequency and
intensity of the cleaning operation depend on the measuring medium.
Clean the sensor:
• before every calibration
• at regular intervals during operation as necessary
• before returning it for repairs.
Depending on the type of soiling, proceed as follows:
"Caution!
After cleaning, rinse the sensor with copious amounts of clean water.
Type of soiling Cleaning
Salt deposits Immerse the sensor in drinking water or in 1-5% hydrochloric acid
for a few minutes. Afterwards, rinse it with copious amounts of water.
Dirt particles on the sensor body
(not cap!)
Clean the sensor body mechanically with water and a suitable brush.
Dirt particles on the membrane cap or the
membrane
Clean with water and a soft sponge.

Maintenance Oxymax H COS21D
20 Endress+Hauser
7.2 Regenerating the sensor
Parts of the sensor will suffer wear and tear during operation.
Suitable action can restore normal operating functionality. This action includes:
#Warning!
Before beginning regeneration, switch off the power supply at the transmitter.
7.2.1 Replacing the sealing ring
Replacing the sealing ring is only necessary when it is visibly damaged. For replacement, use only
original sealing rings.
7.2.2 Replacing the electrolyte
The electrolyte is slowly used up during measuring. The cause of this is electrochemical substance
reactions. No substance reactions occur in the de-energized state and the electrolyte is not used up.
The electrolyte life is shortened by diffused, dissolved gases such as H2S, NH3or high concentrations
of CO2.
The theoretical service life of an electrolyte filling for use in air-saturated drinking water at 20 °C
(68 °F) is as follows:
• COS21D-A: 100 weeks
• COS21D-B/C: 20 weeks
#Warning!
Risk of acid burns!
The electrolyte is very caustic. You must follow the appropriate occupational safety regulations.
Always wear protective gloves and goggles with handling electrolytes.
To replace the electrolyte, proceed as follows:
1. Remove the membrane cap.
2. Replace the electrolyte and, if necessary, the membrane cap.
3. Place the membrane cap back on the sensor and screw the cap closed to the stop.
4. Reset the electrolyte replacement counter (Liquiline calibration menu, "Electrolyte
replacement").
7.2.3 Replacing the membrane cap
Removing the old membrane cap
1. Remove the sensor from the medium.
2. Clean the outside of the sensor.
3. Unscrew the membrane cap.
4. If necessary, clean the cathode or replace the sealing ring if it is damaged.
5. Rinse the electrode holder with drinking water.
Installing the new membrane cap
1. Make sure that there are no dirt particles on the sealing surface.
Action Cause
Cleaning the cathode soiled or plated cathode
Replacing the sealing ring visual damage to the sealing ring
Replacing the electrolyte unstable or implausible measuring signal or electrolyte soiling
Replacing the membrane cap uncleanable membrane, damaged membrane (hole or overstretch)