Endress+Hauser Oxymax W COS51D User manual

BA413C/07/en/10.08
71083533
Operating Instructions
Oxymax W COS51D
Digital sensor for dissolved oxygen

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
→ä10
Here you can find installation conditions such as sensor dimensions and the angle of installation.
Installation examples can be found here.
Æ
Wiring
→ä13 Refer to theses pages for sensor wiring.
Æ
Sensor design and measuring principle
→ä15
→ä16
→ä17
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
Maintenance
→ä21
→ä27
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
→ä26 If faults occur during operation, use the checklist to locate the cause.
Æ
Æ
Index
→ä32 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 W COS51D
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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 Sensor version for applications in hazardous locations
5
1.5 Return . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.6 Notes on safety icons and symbols . . . . . . . . . . . . . . 5
1.7 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 . . . . . . . . . . . . . . . . . . . . . . . 10
3.5 Post-installation check . . . . . . . . . . . . . . . . . . . . . . 12
4 Wiring . . . . . . . . . . . . . . . . . . . . . . . . 13
4.1 Quick wiring guide . . . . . . . . . . . . . . . . . . . . . . . . 13
4.2 Temperature ranges . . . . . . . . . . . . . . . . . . . . . . . . 13
4.3 Direct connection to the transmitter . . . . . . . . . . . 14
4.4 Connection via junction box . . . . . . . . . . . . . . . . . 14
4.5 Post-connection check . . . . . . . . . . . . . . . . . . . . . . 14
5 Device description . . . . . . . . . . . . . . . 15
5.1 Sensor design . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
5.2 Measuring principle . . . . . . . . . . . . . . . . . . . . . . . . 16
5.3 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
6 Commissioning. . . . . . . . . . . . . . . . . . 20
6.1 Function check . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
6.2 Polarization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
6.3 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
7 Maintenance. . . . . . . . . . . . . . . . . . . . 21
7.1 Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
7.2 Replacing wear and tear materials . . . . . . . . . . . . . 22
8 Accessories. . . . . . . . . . . . . . . . . . . . . 24
8.1 Connection accessories . . . . . . . . . . . . . . . . . . . . . 24
8.2 Installation accessories . . . . . . . . . . . . . . . . . . . . . . 24
8.3 Measurement, controlling and sensor cleaning . . . . 25
9 Trouble-shooting . . . . . . . . . . . . . . . . 26
9.1 Trouble-shooting instructions . . . . . . . . . . . . . . . . 26
9.2 Sensor checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
9.3 Spare parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
9.4 Return . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
9.5 Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
10 Technical data . . . . . . . . . . . . . . . . . . . 29
10.1 Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
10.2 Performance characteristics . . . . . . . . . . . . . . . . . . 29
10.3 Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
10.4 Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
10.5 Mechanical construction . . . . . . . . . . . . . . . . . . . . 30
11 EC Declaration of Conformity . . . . . . . 31
Index . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Safety instructions Oxymax W COS51D
4Endress+Hauser
1 Safety instructions
1.1 Designated use
The oxygen sensor is suitable for continuous measurement of dissolved oxygen in water.
Typical applications are:
• Measuring, monitoring and regulating the oxygen content in activated sludge basins.
• Monitoring the oxygen content in the sewage treatment plant outlet.
• Monitoring, measuring and regulating the oxygen content in public waters and fish farming
water.
• Monitoring of oxygen enrichment in drinking water.
Any other use than the one described here compromises the safety of persons and the entire
measuring system and is 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.
Trained 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. 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 organization.
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 W COS51D Safety instructions
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1.4 Sensor version for applications in hazardous locations
• The certified oxygen sensor Oxymax W COS51D-G**0 may only be connected via the measuring
cable CYK10-G**1 to approved intrinsically safe digital sensor circuits of the transmitter Liquiline
M CM42-*G*. The electrical connection instruction must be followed.
• The measuring cable CYK10-G and its coupling must be protected from electrostatic charging, if
installed through zone 0.
• The sensor may not be operated under process conditions where electrostatic charging is likely to
occur. The designated use in media with a conductivity of at least 10 nS/cm can be assumed as
electrostatic uncritical.
• Ex versions of digital sensors with Memosens technology are indicated by an orange-red ring on
the plug-in head.
• The maximum permissible cable length is 100 m (330 ft).
1.5 Return
If the device requires repair, please send it cleaned to the sales centre responsible. Please use the
original packaging, if possible.
Please enclose the completed "Declaration of contamination" (copy the second last page of these
Operating Instructions) with the packaging and the transportation documents.
No repair without completed "Declaration of contamination"!
1.6 Notes on safety icons and symbols
1.7 Cross reference symbols
#Warning!
This symbol alerts you to hazards that 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 W COS51D
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
• Accessories set with the following contents:
– 2 replacement cartridges (replacement membrane caps)
– 10 plastic ampoules containing electrolyte
– 1 sealing kit with 3 O-rings
– 6 abrasive sheets
• Operating Instructions (on CD only)
• Brief Operating Instructions (paper version)
If you have any questions, please contact your supplier or your local sales center.
2.3 Certificates and approvals
2.3.1 ATEX II 1G Ex ia IIC T6
The inductive sensor-cable-plug-in system Memosens consisting of:
• oxygen sensor Oxymax W COS51D-G**0 and
• measuring cable CYK10-G**1
is suitable for the use in explosion-hazardous locations acc. to the type-examination certificate BVS
04 ATEX E 121 X . The corresponding EC declaration of conformity is part of this document.
2.3.2 FM/CSA
Version COS51D-O****
IS Class 1 Division 1 ABCD T4/T6
Class 1 Zone 0 AEx ia IIC T4/T6
Approval
A Non-hazardous area
GATEX
OFM/CSA
Head type
S NPT 3/4", G1, Memosens connector
Cable length
8 Standard version, without cable
Membrane cap
0Normal,t
90 approx. 3 min.
1Fast,t
90 approx. 0.5 min.
Accessories
0 No accessories
COS51D- Complete order code

Oxymax W COS51D Installation
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3 Installation
3.1 Incoming acceptance, transport, storage
• Make sure the packaging is undamaged!
Inform the supplier about any 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 contents. Keep the damaged products until the matter
has been settled.
• Check that the order is complete and agrees with your 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 local sales center.
3.2 Installation conditions
3.2.1 Dimensions
a0006742
Fig. 1: Dimensions

Installation Oxymax W COS51D
8Endress+Hauser
3.2.2 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.
3.2.3 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.
3.3 Installation instructions
3.3.1 Measuring system
A complete measuring system comprises at least:
• the digital oxygen sensor Oxymax W COS51D
• a transmitter, e.g. Liquiline M CM42
• a special measuring cable, CYK10
• an assembly, e.g. immersion assembly CYA611 or retractable assembly COA451
Optional (see accessories):
• Universal suspension assembly support CYH101 for immersion operation
• Junction box RM (with cable extension)
• Automatic cleaning system Chemoclean with spray head
a0006741-en
Fig. 2: Permissible angle of installation
10° 10° Not permissible!
Not permissible!
Permissible angle of installation

Oxymax W COS51D Installation
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3.3.2 Installing a measuring point
!Note!
For immersed operation, install the individual modules away from the basin on a solid base. Only
carry out the final installation at the intended installation location.
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.
4. Install an immersion or an suspension assembly (if used) into the process.
"Caution!
• For immersed operation, the sensor must be installed in an immersion assembly (e.g. CYA611).
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.
a0006735
Fig. 3: Measuring system (example)
1 Digital oxygen sensor Oxymax W COS51D
2 Retractable assembly COA451
3 Liquiline M CM42
4 Measuring cable CYK10

Installation Oxymax W COS51D
10 Endress+Hauser
3.4 Installation examples
3.4.1 Immersion operation
Upright post and chain assembly
For large basins, where sufficient installation distance is required from the basin edge (aeration
basin, especially), it is advisable to use the upright post and chain assembly (→å4, →å5).
The free swinging of the immersed assembly practically rules out vibrations from the upright post.
According to this effect, the sensor life time can be extended.
Upright post and fixed immersion assembly
The preferable type of installation for strong or turbulent flow (> 0.5 m/s) in the basin or open
channels is to secure the device to an upright post and a securely mounted immersion tube
(→å6). If the flow is very strong, a second transverse pipe can be installed with its own pipe
support.
a0004103-en
Fig. 4: Universal suspension assembly holder with
immersible pendulum assembly
1 Weather protection cover
2 Upright post, square pipe SS AISI 304
3 Transverse pipe SS AISI 304
4Starhandle
5 Second fixing possibility for transverse pipe
6 Immersion assembly CYA 611
a0004104-en
Fig. 5: Immersion assembly CYA 611
1 Protection cap
2 Worm drive hose clip
3 Pipe clips (detailed drawing in right half)
4 PVC pipe
5 Threaded coupling

Oxymax W COS51D Installation
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a0004105-en
Fig. 6: Universal suspension assembly holder CYH101 with immersion assembly CYY105
1Starhandle
2 Pipe holder
3 Fixing bracket
4 Immersion assembly (= immersion tube)
Basin rim mounting with immersion assembly
For fixing to the sides of the basin or channel, we recommend the use of an basin rim mounting of
the immersion assembly (→å7, →å8).
If there is strong turbulence or flow, a second basin rim mounting must be used for the immersion
assembly.
Floating body
To aid installation in strongly fluctuating water levels, e.g. in rivers or lakes, there is a floating body
COA 110-50 available (→å9).
a0004106
Fig. 7: Horizontal basin rim mounting
1 Protection cover for cable entry
2 Assembly holder
3 Immersion assembly SS 1.4301 (AISI 304)
a0004107
Fig. 8: Vertical basin rim mounting
4 Basin rim mounting
5Starhandle
1
2
3
4
5
1
2
3
5
4

Installation Oxymax W COS51D
12 Endress+Hauser
3.4.2 Flow assembly
The COA250-A flow assembly (→å10) with automatic self-venting is suitable for use in
pipelines or hose connections. The inlet is at the bottom of the assembly, the outlet at the top
(connection thread G¾). It can be installed in a pipe by using two 90° pipe brackets to allow inflow
to the assembly (→å11, Pos. 6).
3.5 Post-installation check
• Sensor and cable 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 putting the protective cap on the assembly?
a0004108-en
Fig. 9: Floating body
1
2
3
4
5
6
7
Cable route with strain relief and rain protection
Mounting ring for ropes and chains with locking
screw
Lugs Ø15, 3 x 120 ° for anchoring
Saltwater-resistant plastic float
Pipe 40x1, stainless steel 1.4571 (AISI 316Ti)
Shock absorber and weight
Oxygen sensor
a0004113-en
Fig. 10: Flow assembly COA250-A
1 Screw-in part for sensor
2Screwring
3 Meter body
4 Connection thread G¾
5 Dummy plug (connection for spray head CUR3)
a0004114
Fig. 11: Bypass installation with manually
actuated valves or solenoid valves
1 Main line
2 Medium return
3 Oxygen sensor
4, 7 Manually actuated or solenoid valves
5 Flow assembly COA250-A
6 90 ° pipe bracket
8Mediumremoval
1
2
3
4
5
6
7
G1
800/31.50
500/19.69 220/8.66
Ø200/7.87
mm/inch
1
23
4
6
7
8
5

Oxymax W COS51D Wiring
Endress+Hauser 13
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 Quick wiring guide
4.2 Temperature ranges
!Note!
If the ambient temperatures indicated are observed, no temperatures which are impermissible for
the temperature class in question will occur at the sensor.
a0010056
Fig. 12: Connection in hazardous locations
II 2G
II 1G II 3G
EX
EX
4...20 mA
COS21D COS51D
Zone 1
Zone 0 Zone 2
CYK10
Ex ia
Temperature class
T6
Ambient temperature Ta–5 ... +50 °C

Wiring Oxymax W COS51D
14 Endress+Hauser
4.3 Direct connection to the transmitter
The sensor is electrically connected to the transmitter by means of the special measuring cable
CYK10.
4.4 Connection via junction box
To extend the sensor 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.
The maximum permissible cable length is 100 m (328 ft).
4.5 Post-connection check
a0003350
Fig. 13: Special measuring cable CYK10
a0005724
Fig. 14: Wiring diagram with junction box RM
1Sensor
2 Junction box
3 Extension cable
4Transmitter
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.
Long enough length of cable core stripped and correct in terminal? Check seating (pull slightly)
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 ?
YE YE
BN
GN GN
YE
WH
187
188
197
198
12
3
4
GN
BN
WH
BN
WH
GY GY

Oxymax W COS51D Device description
Endress+Hauser 15
5 Device description
5.1 Sensor design
The sensor consists of the following function units:
•Sensorshaft
•Protectionbasket
!Note!
• Alternatively to the protection basket, you can use a spray head COR 3 (optional, see
"Accessories") for use in immersed operation with cleaning function.
• The membrane cap screwed onto the sensor head is filled with electrolyte. The screw connection
seals it from the medium.
• The membrane which is in contact with the medium is pretensioned in the factory.
a0006935
Fig. 15: Sensor design
1 Memosens Plug-in head
2 Threaded connection NPT ¾"
3 Threaded connection G1
4 Sensor shaft
5 Protection basket
6Goldcathode
7Membrane
8 Electrolyte
9Anode
a0004149
Fig. 16: Sensor head, cutaway drawing
7Membrane
8 Electrolyte
9Anode
10 Reference electrode
11 Threaded connection for protection basket
12 Sealing ring
13 Threaded connection for membrane cap
14 Membrane cap
a0004150
Fig. 17: Sensor head, top view
6 Cathode
1
3
4
5
6
7
8
9
2
10
11
12
13
14
7
8
9
10
6

Device description Oxymax W COS51D
16 Endress+Hauser
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.
5.2.2 Membrane
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.
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 Potentiostatic three-electrode-system
The high-impedance, current-free reference electrode plays an important role.
The formation of a silver bromide or silver chloride coating on the anode uses up the bromide or
chloride ions dissolved in the electrolyte
In the case of conventional membrane-covered sensors working with the two-electrode system, this
causes an increase in signal drift.
This is not the case with the three-electrode system:
The change in bromide or chloride concentration is registered by the reference electrode and an
internal control circuit holds the working electrode potential constant. The advantages of this
principle are significantly increased accuracy of the signal and considerably extended calibration
intervals.
5.2.5 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
– Data for sensor monitoring.

Oxymax W COS51D Device description
Endress+Hauser 17
5.3 Calibration
Calibration is a means of adapting the transmitter to the characteristic values of the sensor.
As normally no zero calibration is required for the sensor, a single-point calibration is carried out in
the presence of oxygen.
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.
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 (minimum 99.995%)
or with water free from oxygen, for example. In doing so, make sure the measured value has settled
correctly (20 to 30 minutes) 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 absolute air pressure)
– Data entry
• Zero point:
– Zero point calibration (nitrogen or water free from oxygen)
– Data entry
• Reference:
– Grab sample calibration
– Offset
– Slope
5.3.2 Calibration intervals
The calibration intervals depend heavily on:
• The application and
• The installation position of the sensor.
You can determine the intervals with the following method:
1. Check the sensor one month after its being put into operation:
– Remove the sensor from the medium.
– Clean the outside of the sensor with a damp cloth.
– Then dry the sensor membrane e.g. by using a tissue.
– Measure the oxygen saturation index at air after 10 minutes.
Decide using the results:
a. If the measured value is not at 102 ±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.

Device description Oxymax W COS51D
18 Endress+Hauser
5.3.3 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. 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.
4. If the measured value display on the transmitter is stable, carry out the calibration in
accordance with the Operating Instructions of the transmitter.
5. Place the sensor in the medium again.
!Note!
Make sure you comply with the instructions for calibration in the Operating Instructions of the
transmitter.
5.3.4 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.)
2. Define:
–thesaturationvalueSacc. to the first table
– the factor Kacc. to the second table
° 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

Oxymax W COS51D Device description
Endress+Hauser 19
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.
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
Altitude
[m / ft]
KAltitude
[m / ft]
KAltitude
[m / ft]
KAltitude
[m / ft]
K

Commissioning Oxymax W COS51D
20 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 connection of the cleaning agent
(e.g. water or air).
#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 inserted 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 (calibration type "Air") immediately after it’s polarization.