Endress+Hauser Viomax CAS51D Operating Instructions Manual

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Operating Instructions

Viomax CAS51D

Photometric sensor for SAC or nitrate measurement

BA00459C/07/EN/14.17
71350074

AUTHORIZED DISTRIBUTOR:
InstrumentsAndControl.com
Houston, Texas USA
[e-mail]
281-609-7170

Table of contents Viomax CAS51D

2 Endress+Hauser

Table of contents

1 Document information .............. 3

1.1 Warnings ............................ 3

1.2 Symbols used .......................... 3

1.3 Symbols on the device ................... 3

2 Basic safety instructions ............ 4

2.1 Requirements for personnel ............... 4

2.2 Designated use ........................ 4

2.3 Occupational safety ..................... 4

2.4 Operational safety ...................... 5

2.5 Product safety ......................... 5

3 Device description .................. 6

3.1 Sensor design ......................... 6

3.2 Dimensions ........................... 6

3.3 Operating principle ..................... 8

4 Incoming acceptance and product

identification ..................... 11

4.1 Incoming acceptance ................... 11

4.2 Product identification ................... 11

4.3 Scope of delivery ...................... 12

4.4 Certificates and approvals ............... 12

5 Installation ....................... 13

5.1 Installation conditions .................. 13

5.2 Mounting the sensor ................... 14

5.3 Immersion operation ................... 15

5.4 Flow operation ....................... 17

5.5 Mounting the cleaning unit .............. 22

5.6 Post-installation check .................. 23

6 Electrical connection .............. 24

6.1 Connecting to the transmitter ............ 24

6.2 Ensuring the degree of protection .......... 25

6.3 Post-connection check .................. 25

7 Operation ......................... 26

7.1 Calibration .......................... 26

7.2 Cyclic cleaning ........................ 30

8 Diagnostics and troubleshooting ... 30

9 Maintenance ...................... 31

9.1 Maintenance intervals .................. 31

9.2 Cleaning the sensor .................... 31

9.3 Maintenance of optical filters and strobe

lamp ............................... 31

10 Repairs ........................... 32

10.1 Return .............................. 32

10.2 Disposal ............................ 32

11 Accessories ....................... 33

11.1 Assemblies .......................... 33

11.2 Holder .............................. 33

11.3 Compressed air cleaning ................ 33

11.4 Standard solutions ..................... 34

12 Technical data .................... 35

Index .................................. 38

Viomax CAS51D Document information

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1 Document information

1.1 Warnings

Structure of information Meaning

L

DANGER

Causes (/consequences)

Consequences of non-compliance
(if applicable)

‣

Corrective action

This symbol alerts you to a dangerous situation.
Failure to avoid the dangerous situation will result in a fatal or serious
injury.

L

WARNING

Causes (/consequences)

Consequences of non-compliance
(if applicable)

‣

Corrective action

This symbol alerts you to a dangerous situation.
Failure to avoid the dangerous situation can result in a fatal or serious
injury.

L

CAUTION

Causes (/consequences)

Consequences of non-compliance
(if applicable)

‣

Corrective action

This symbol alerts you to a dangerous situation.
Failure to avoid this situation can result in minor or more serious injuries.

NOTICE

Cause/situation

Consequences of non-compliance
(if applicable)

‣

Action/note

This symbol alerts you to situations which may result in damage to
property.

1.2 Symbols used

Symbol Meaning

Additional information, tips

Permitted or recommended

Not permitted or not recommended

Reference to device documentation

Reference to page

Reference to graphic

 Result of a step

1.3 Symbols on the device

Symbol Meaning

Reference to device documentation

Basic safety instructions Viomax CAS51D

4 Endress+Hauser

2 Basic safety instructions

2.1 Requirements for personnel

• Installation, commissioning, operation and maintenance of the measuring system may
be carried out only by specially trained technical personnel.

• The technical personnel must be authorized by the plant operator to carry out the
specified activities.

• The electrical connection may be performed only by an electrical technician.

• The technical personnel must have read and understood these Operating Instructions
and must follow the instructions contained therein.

• Measuring point faults may be repaired only by authorized and specially trained
personnel.

Repairs not described in the Operating Instructions provided may only be carried out
directly by the manufacturer or by the service organization.

2.2 Designated use

CAS51D is a photometric sensor for SAC or nitrate measurement in liquid media.

The sensor is particularly suited for use in the following applications:

• Monitoring and regulating water treatment plants

• Monitoring surface waters

SAC measurement

• Organic load in WWTP inlet

• Organic load WWTP outlet

• Discharger monitoring

• Organic load in drinking water

Nitrate measurement

• Nitrate measurement in naturally bodies of water

• Monitoring nitrate content in WWTP outlet

• Monitoring nitrate content in aeration basins

• Monitoring and optimizing denitrification phases

Use of the device for any purpose other than that described, poses a threat to the safety of
people and of the entire measuring system and is therefore not permitted.

The manufacturer is not liable for damage caused by improper or non-designated use.

2.3 Occupational safety

L

CAUTION

UV light

UV light can damage the eyes

‣

Never look into the cuvette gap while the sensor is in operation.

As the user, you are responsible for complying with the following safety conditions:

• Installation guidelines

• Local standards and regulations

Electromagnetic compatibility

• The product has been tested for electromagnetic compatibility in accordance with the
applicable European standards for industrial applications.

• The electromagnetic compatibility indicated applies only to a product that has been
connected in accordance with these Operating Instructions.

Viomax CAS51D Basic safety instructions

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2.4 Operational safety

1. Before commissioning the complete measuring point, verify that all connections are
correct. Ensure that electrical cables and hose connections are undamaged.

2. Do not operate damaged products, and protect them against unintentional operation.
Label the damaged product as defective.

3. If faults cannot be rectified,
products must be taken out of service and protected against unintentional operation.

2.5 Product safety

The product is designed to meet state-of-the-art safety requirements, has been tested, and
left the factory in a condition in which it is safe to operate. The relevant regulations and
European standards have been observed.

Device description Viomax CAS51D

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3 Device description

3.1 Sensor design

The sensor is designed as a 40 mm sensor that can be operated directly and completely in
the process without the need for further sampling (in situ). One version of the sensor
measures the amount of nitrate in the medium while another version measures the SAC
value of the medium.

The sensor comprises the following assemblies:

• Power supply

• High-voltage generation for the strobe lamp,

• Photometer cuvette
central component in which the measuring light interacts with the medium.

• Detectors,
detect the measuring signals, digitize them and process them to form a measured value.

• Controller,
responsible for controlling internal sensor processes and transmitting data.

All data - including the calibration data - are stored in the sensor. The sensor can be
precalibrated and used at a measuring point, calibrated externally, or used for several
measuring points with different calibrations.

3.2 Dimensions

50

(1.97)

40 (1.57)

388 (15.28)

78 (3.07)

NPT “¾

G1

2 (0.08)

8 (0.31)

12 (0.47)

20 (0.79)

14.5 (0.57)

A0013193

 1 Sensor with 2 mm gap width, dimensions in

mm (inch)

NPT “¾

G1

78 (3.07)

394 (15.51)

8 (0.31)

40 (1.57)

14 (0.55)

20 (0.79)

12 (0.47)

14.5 (0.57)

A0013208

 2 Sensor with 8 mm gap width, dimensions in

mm (inch)

Viomax CAS51D Device description

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20 (0.79)

12 (0.47)

14.5 (0.57)

40 (1.57)

NPT “¾

G1

69 (2.72)

40 (1.57)

46 (1.81)

426 (16.77)

A0031311

 3 Sensor with 40 mm gap width, dimensions in

mm (inch)

Device description Viomax CAS51D

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3.3 Operating principle

3.3.1 Measuring principle

The light from a pulsed, high-stability strobe lamp (item 3) passes through the
measurement section

1)

(item 2). A beam splitter (item 6) directs the light beam to the
two receivers (items 1 and 5). A filter upstream from the receivers only lets through light
in the measuring wavelength or reference wavelength.

1

2

3

4

56

A0013213

 4 Measuring principle of nitrate sensor

1 Measuring receiver with filter
2 Cuvette gap
3 Strobe lamp
4 Lens
5 Reference receiver with filter
6 Beam splitter

Within the measurement section, the medium in the cuvette (water, dissolved substances
and particles) absorbs light across the entire spectrum. In the measuring wavelength
range, the measured component

2)

takes an additional part of its energy from the light.

The ratio of the light signal of the measuring wavelength to the light signal of the
reference wavelength is used to calculate the measured value.

• If only water and turbidity are present, both signals are attenuated to the same degree

and the ratio remains constant.

• If the medium contains the measured component, the signal of the measuring

wavelength is attenuated more and the ratio changes.

This change in the ratio can be converted to determine the nitrate concentration or the
SAC value. This dependency is non-linear.

Conclusion:

• Long measurement sections are required for low concentrations of the measured

component.
For clear water measurements, this is achieved with the 8 mm cuvette for nitrate
measurement and the 40 mm cuvette for SAC measurement.

• For high turbidity values, longer measurement sections result in the total absorption of

light - the measured values are no longer valid.
For media with high turbidity values (activated sludge applications), the nitrate sensor
with the 2 mm cuvette returns good, reliable measured values.
The SAC sensor with the 2 mm cuvette is ideal for measuring the organic load in the
inlet of municipal wastewater treatment plants.

1) Measurement section = open path through cuvette

2) Nitrate or substances that contribute to the spectral absorption coefficient (SAC)

Viomax CAS51D Device description

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3.3.2 Nitrate measurement

The sensor is designed for measuring nitrate. As nitrite is also measured, it could also be
regarded as an NOx sensor.

Nitrate ions absorb UV light in the range of approx. 190 to 230 nm. Nitrite ions have a
similar absorption rate in the same range.

The sensor measures the light intensity of the 214 nm wavelength (measuring channel).
At this wavelength, nitrate and nitrite ions absorb light in proportion to their
concentration, while the light intensity in the reference channel remains virtually
unchanged at 254 nm.

Interference factors, such as turbidity, fouling or organic hydrocarbons, are factored out
mathematically.

The signal ratio between the reference wavelength and measurement wavelength
constitutes the measurement result. This ratio is converted to the concentration of nitrate
using the calibration curve programmed into the sensor.

3.3.3 Cross-interference when measuring nitrate

The following have a direct impact on the measuring range:

• Total solids (TS) and turbidity

• Sludge properties

• Nitrite

Trends:

• A higher proportion of TS or greater turbidity reduces the upper end of the measuring
range, resulting in a smaller measuring range.

• High COD

3)

levels reduce the upper end of the measuring range, resulting in a smaller

measuring range.

• Nitrite is measured as nitrate, thus resulting in a higher measured value.

The following can be deduced from the interdependencies cited above:

• Sludge floc causes scattering in the medium, resulting in the attenuation of both the
measuring and reference signal to varying degrees. This in turn can bring about a
change in the nitrate value due to turbidity.

• High concentrations of oxidizable substances

4)

in the medium may result in an increase

in the measured value.

• Nitrite absorbs light in a similar wavelength range to nitrate and is measured along with
nitrate. The dependency is constant: 1.0 mg/l nitrite is displayed as 0.8 mg/l nitrate.

• An adjustment to the customer process is always worthwhile.

3.3.4 SAC measurement

Many organic substances absorb light in the range of 254 nm. In the SAC sensor,
absorption on the measuring wavelength (254 nm) is compared with the largely
unaffected reference measurement at 550 nm.

KHP (potassium hydrogen phthalate C8H5KO4) is the established organic reference in SAC
measurement operations. That is why the sensor is calibrated in the factory using KHP.

The SAC value can be regarded as a trend indicator of the organic load in a medium. For
this purpose, it is converted to COD, TOC, BOD and DOC

5)

using predefined, adjustable
factors:
c (TOC) = 0.4705 * c (KHP)
c (COD) = 1.176 * c (KHP)
c (BOD) = 1.176 * c (KHP)
c (DOC) = 0.4705 * c (KHP)

3) COD = Chemical Oxygen Demand

4) Specified as COD. Corresponds to the quantity of oxygen that would be required to oxidize the substances if oxygen were the oxidizing agent.

5) Chemical Oxygen Demand (COD), Total Organic Carbon (TOC), Biochemical Oxygen Demand (BOD), Dissolved Organic Carbon (DOC)

Device description Viomax CAS51D

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The ratio to SAC (based on KHP) is calculated as follows:
1/m = 1.487 mg/l COD = 1.487 mg/l BOD = 0.595 mg/l TOC = 0.595 mg/l DOC

Many components that absorb light at 254 nm deviate significantly from KHP in terms of
their absorption behavior. For this reason, an adjustment to the customer process is
worthwhile.

3.3.5 Cross-interference when measuring SAC

The following have a direct impact on the measuring range:

• COD

• Color

Trends:

• Oxidizable substances, absorbing at 550 nm, distort the measurement result. In
instances of this nature, a comparison or calibration is necessary.

• Coloration that absorbs in the green spectral range increases the measured value.

• Oxidizable substances with different spectral properties to KHP (potassium hydrogen
phthalate) distort the measurement result. In instances of this nature, a comparison or
adjustment is necessary.

Viomax CAS51D Incoming acceptance and product identification

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4 Incoming acceptance and product

identification

4.1 Incoming acceptance

1. Verify that the packaging is undamaged.
 Notify your supplier of any damage to the packaging.

Keep the damaged packaging until the matter has been settled.

2. Verify that the contents are undamaged.
 Notify your supplier of any damage to the delivery contents.

Keep the damaged products until the matter has been settled.

3. Check the delivery for completeness.
 Check it against the delivery papers and your order.

4. Pack the product for storage and transportation in such a way that it is protected
against impact and moisture.

 The original packaging offers the best protection.

The permitted ambient conditions must be observed (see "Technical data").

If you have any questions, please contact your supplier or your local sales center.

4.2 Product identification

4.2.1 Nameplate

The nameplate provides you with the following information on your device:

• Manufacturer identification

• Extended order code

• Serial number

• Safety information and warnings

‣

Compare the data on the nameplate with your order.

4.2.2 Product identification

Product page

www.endress.com/cas51d

Interpreting the order code

The order code and serial number of your product can be found in the following locations:

• On the nameplate

• In the delivery papers

Obtaining information on the product

1. Go to the product page for your product on the Internet.

2. At the bottom of the page, click the link Online Tools and then select Access device
specific information.

 An additional window opens.

3. Enter the order code from the nameplate into the search field and then select Show
details.

 You will receive information on each feature (selected option) of the order code.

Incoming acceptance and product identification Viomax CAS51D

12 Endress+Hauser

Manufacturer's address

Endress+Hauser Conducta GmbH+Co. KG
Dieselstraße 24
D-70839 Gerlingen

4.3 Scope of delivery

The delivery comprises:

• Sensor in the version ordered

• Operating Instructions

4.4 Certificates and approvals

4.4.1 

The product meets the requirements of the harmonized European standards. As such, it
complies with the legal specifications of the EU directives. The manufacturer confirms
successful testing of the product by affixing to it the  mark.

4.4.2 EAC version

The product has been certified according to guidelines TP TC 004/2011 and TP TC
020/2011 which apply in the European Economic Area (EEA). The EAC conformity mark
is affixed to the product.

Viomax CAS51D Installation

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5 Installation

5.1 Installation conditions

5.1.1 Mounting location

‣

Choose a mounting location that can be easily accessed at a later stage.

‣

Ensure that upright posts and fittings are fully secured and vibration-free.

‣

Select an installation location that produces a typical nitrate concentration / a typical
SAC value for the application in question.

‣

Do not install the sensor above aeration discs. Oxygen bubbles may accumulate at the
cuvette gap and distort the measured value.

5.1.2 Orientation

A0013268

 5 Sensor orientation, arrow =

direction of flow

‣

Align the sensor so that the cuvette gap is rinsed by
means of the flow.

Flexdip CYA112 wastewater assembly and Flexdip CYH112 bracket

A0013267

 6 Horizontal, fixed installation

The installation angle is 90°.

‣

Align the sensor in such a way that the
cuvette gap is rinsed by means of the
flow.

A0013270

 7 Suspended vertically from a chain

The installation angle is 0°. Tried and tested
arrangement when operating in ventilated
zones.

‣

Ensure that the sensor is adequately
cleaned. There must be no buildup on the
optical windows.

Installation Viomax CAS51D

14 Endress+Hauser

Flow assembly CAS51D 2-40 mm for small sample volumes

1

2

3

4

5

A0013266

 8 Horizontally, in flow assembly, arrow points in the direction of flow

1 Sensor
2 Flow assembly
3 Medium outlet
4 Medium inflow
5 Window, required for aligning the sensor

Flowfit CYA251 flow assembly

1 2

3

4

5

6

A0032901

 9 Horizontally, in flow assembly CYA251, arrow points in the direction of flow

1 Sensor
2 Medium outlet
3 Cap
4 Flow assembly
5 Medium inflow
6 Rinse connection

5.2 Mounting the sensor

5.2.1 Installation instructions

To ensure correct measurement, the windows in the cuvette must be free from any
sedimentation. The best way to ensure this is through the use of a cleaning unit
(accessory) operated by compressed air.

‣

For horizontal orientations:
Mount the sensor in such a way that the cuvette gap is located at the side.

Viomax CAS51D Installation

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5.3 Immersion operation

5.3.1 Fixed installation with wastewater assembly

1

2

3

4

A0013347

 10 Installation secured on railing

1 Wastewater assembly Flexdip CYA112
2 Flexdip CYH112 holder
3 Rail
4 Viomax CAS51D

1

2

3

4

5

A0013215

 11 Installation with upright post

1 Protective cover
2 Liquiline CM44x multi-channel transmitter
3 Wastewater assembly Flexdip CYA112
4 Viomax CAS51D
5 Flexdip CYH112 holder

This type of installation is particularly suitable for strong or turbulent medium flow
(>0.5 m/s (1.6 ft/s)) in basins or channels. A cleaning unit (accessory) operated by
compressed air significantly extends the maintenance intervals for the sensor.

Installation Viomax CAS51D

16 Endress+Hauser

5.3.2 Installation with chain retainer

2

3

A0013348

 12 Chain retainer on railing

1 Wastewater assembly Flexdip CYA112
2 Flexdip CYH112 holder
3 Rail
4 Viomax CAS51D

2

3

4

A0013351

 13 Chain retainer on upright post

1 Protective cover
2 Liquiline CM44x multi-channel transmitter
3 Wastewater assembly Flexdip CYA112
4 Viomax CAS51D
5 Flexdip CYH112 holder

The chain retainer is particularly suitable for applications that require a sufficient distance
between the mounting location and the edge of the aeration basin. As the assembly is
freely suspended, any vibration of the upright post is practically ruled out.

The swinging movement of the chain retainer enhances the self-cleaning effect of the
optics. A cleaning unit (accessory) operated by compressed air significantly extends the
maintenance intervals for the sensor.

Viomax CAS51D Installation

Endress+Hauser 17

5.4 Flow operation

5.4.1 Flow assembly for clear water and small sample volumes

2

3

4

A0013352

 14 Sensor with flow assembly

1 Transmitter
2 Viomax CAS51D
3 Flow assembly
4 Sensor holder

Secure holder

Ø 6.5 (0.26)

86

(3.39)

30 (1.18)

100 (3.94)

70 (2.76)

**

70 (2.76)

60 (2.36)

A0013290

 15 Dimensions in mm (inch)

** Variable length

1. For the necessary installation dimensions, refer to the drawing. Mount the sensor in
a horizontal position (as shown in the drawing).

Drill the holes for the mounting clamps into a wall or panel.

2. Secure the mounting clamps. The required fastening fixtures (screws, wall plugs) are
not included in the scope of delivery of the kit and must be provided by the customer.

Installation Viomax CAS51D

18 Endress+Hauser

3.

Release the hexagonal nuts on the mounting clamps and remove the top part of the
clamp.

4.

M5

Position the sensor in the mounting clamps and screw on the top parts, tightening by
hand (it should still be possible to move the sensor).

Mount the flow assembly

A0033056

 16 Sensor installed in flow assembly

1.

Release the threaded rings on the flow assembly and remove both O-rings.

2. Check if the silicone grease provided with the kit is permitted for use in your
application. If not, use a grease that is suitable for your application

Lubricate the O-rings.

3.

First slide a threaded ring (thread in the direction of the assembly) onto the sensor,
followed by an O-ring .

Viomax CAS51D Installation

Endress+Hauser 19

4.

Now slide the assembly onto the sensor, followed by the second O-ring and the
second threaded ring.

5.

Open the cap on the viewing window.

6.

Position the assembly on the sensor in such a way that the cuvette gap is visible in
the center of the window.

7.

Tighten both threaded rings. Ensure that the assembly cannot change position.

8.

The cuvette gap must still be visible in the center of the viewing window:
Close the viewing window again with the cap.
 To guard against loss:

Secure the viewing window to one of the hose connections (no diagram) using
the transparent cord.

Installation Viomax CAS51D

20 Endress+Hauser

Connection diagram

1

3

56

2

7

2

2 4

A0013361

1 Main pipe 5 Flow assembly
2 Manually actuated or solenoid valves 6 Medium inflow
3 Medium outlet 7 Medium removal
4 Medium return

‣

Connect the medium inflow and outlet to the assembly's hose connections as shown in
the diagram.

 This fills the assembly from below and ensures that the assembly is self-venting.

There must be a minimum flow rate of 100 ml/h (0.026 gal/h). Increased response times
must be taken into account.

As an alternative to bypass operation, you can also direct the sample flow from a filter unit
with an open outlet through the assembly:

2

A0013434

 17 Flow assembly with open outlet

1 Pump
2 Open outlet
3 Filter unit

Viomax CAS51D Installation

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5.4.2 Flow assembly Flowfit CYA251

3

4

6

5

2

A0032917

 18 Measuring system with CYA251

1 Transmitter
2 Flow assembly
3 Medium outlet
4 Cap
5 Medium inflow
6 Viomax CAS51D

1

3

56

2

7

2

2 4

A0032920

 19 Connection diagram
1 Main pipe 5 Medium inflow
2 Manually actuated or solenoid valves 6 Flow assembly
3 Medium outlet 7 Medium removal
4 Medium return

Mount the sensor in the assembly in accordance with its Operating Instructions
(BA00495C).

There must be a minimum flow rate of 100 ml/h (0.026 gal/h). Increased response
times must be taken into account.

Installation Viomax CAS51D

22 Endress+Hauser

As an alternative to bypass operation, you can also direct the sample flow from a filter unit
with an open outlet through the assembly:

2

A0032921

 20 Flow assembly with open outlet

1 Pump
2 Open outlet
3 Filter unit

5.5 Mounting the cleaning unit

Sensors with gap width of 2 mm or 8 mm

Mount the compressed air cleaning unit prior to installing the sensor in the measuring
point, or remove the sensor from the medium. Clean the sensor if necessary.

1.

Screw the elbow plug from the accessory kit into the mounting hole behind the
sensor gap, and tighten by hand as far as it will go.

2.

Connect the compressed air supply provided by the customer. The hose piece with
hose coupling provided with the sensor can be used if desired.

Viomax CAS51D Installation

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SAC sensors with a gap width of 40 mm

Mount the compressed air cleaning unit prior to installing the sensor in the measuring
point, or remove the sensor from the medium. Clean the sensor if necessary.

1.

Screw the air diffuser from the accessory kit into the mounting holes behind the
sensor gap, and tighten by hand as far as it will go.

2.

Connect the compressed air supply provided by the customer. The hose piece with
hose coupling provided with the sensor can be used if desired.

5.6 Post-installation check

Put the sensor into operation only if you can answer "yes" to the following questions:

• Are the sensor and cable undamaged?

• Is the orientation correct?

• Is the sensor installed in an assembly and not freely suspended from the cable?

Electrical connection Viomax CAS51D

24 Endress+Hauser

6 Electrical connection

L

WARNING

Device is live

Incorrect connection may result in injury or death

‣

The electrical connection may be performed only by an electrical technician.

‣

The electrical technician must have read and understood these Operating Instructions
and must follow the instructions contained therein.

‣

Prior to commencing connection work, ensure that no voltage is present on any cable.

6.1 Connecting to the transmitter

6.1.1 Applying the cable shield to the grounding rail of the
transmitter

L

WARNING

Sensor not grounded

If maintenance work (lamp replacement) is not performed correctly, moisture or dirt may
penetrate the housing and cause an electric shock to anyone who touches it.

‣

To guarantee safety in your workplace, always connect the sensor's cable shield to the
grounding rail of the transmitter or control cabinet.

If possible, only use terminated genuine cables. The sensor cables must be shielded.

Cable sample (does not necessarily correspond to the genuine cable supplied)

1

2

3

 21 Terminated cable

1 Outer shield (exposed)
2 Cable cores with ferrules
3 Cable sheath (insulation)

4

 22 Inserting the cable

4 Grounding clip

 23 Tighten screw (2 Nm)

The cable shield is grounded using
the grounding clamp.

1)

1) Please note the instructions in the "Guaranteeing the degree of protection" section.

1. Release a suitable cable gland on the underside of the housing and remove the
dummy plug from the entry.

2. Making sure the gland is facing the right direction, thread the gland onto the cable
end and pull the cable through the entry and into the housing.

3. Route the cable in the housing in such a way that the exposed cable shield fits into
one of the cable clamps and the cable cores can be easily routed as far as the
connection plug on the electronics module.

4. Screw on the cable clamp and clamp the cable in place. Then tighten the screw of the
cable clamp.

5. Connect the cable cores as per the wiring diagram.

Viomax CAS51D Electrical connection

Endress+Hauser 25

6. Lastly, tighten the cable gland from the outside.

6.1.2 Connecting the sensor

You have the following connection options:

• via M12 connector (version: fixed cable, M12 connector)

• via sensor cable to the plug-in terminals of a sensor input on the transmitter (version:
fixed cable, end sleeves)

85 86

85

2DS

1

2

86

97 88 8798

97 88 8798

Sensor 1

Sensor 2

PK

GY

GN
YE

Sensor

85 86

85

1

2

86

97 88 8798

Sensor 1

PK

GY

GN
YE

BN
WH

Sensor

A0033092

 24 Sensor connection to sensor input (left) or via M12 connector (right)

The maximum cable length is 100 m (328 ft).

6.2 Ensuring the degree of protection

Only the mechanical and electrical connections which are described in these instructions
and which are necessary for the required, designated use, may be carried out on the device
delivered.

‣

Exercise care when carrying out the work.

Otherwise, the individual types of protection (Ingress Protection (IP), electrical safety, EMC
interference immunity) agreed for this product can no longer be guaranteed due, for
example, to covers being left off or cable (ends) which are loose or insufficiently secured.

6.3 Post-connection check

‣

Put the sensor into operation only if you can answer yes to all of the following
questions.

Device condition and specifications Notes

Is the outside of the sensor, assembly and cable undamaged? Visual inspection

Electrical connection Notes

Has cable shield been applied to grounding rail of transmitter? Cable shield is absolutely

essential

Are the installed cables strain-relieved and not twisted?

Operation Viomax CAS51D

26 Endress+Hauser

Device condition and specifications Notes

Is a sufficient length of the cable cores stripped, and is it positioned in the
terminal correctly?

Check the fit (by pulling
gently)

Are all the screws terminals properly tightened? Tighten

7 Operation

‣

Verify that a representative measured value is displayed on the transmitter.

‣

For solids that have a tendency to form deposits, ensure that the medium is mixed
sufficiently.

7.1 Calibration

Calibration is performed in the process by comparing the values to an external standard
method, by calibrating with standard solutions or by using a combination of both (addition
of standard).

7.1.1 Factory calibration

Nitrate sensor

The sensor is precalibrated on leaving the factory.
As such, it can be used in a wide range of clear water measurements without the need for
additional calibration.

SAC sensor

The sensor is precalibrated on leaving the factory (calibrated with KHP).
Calibration to the customer process is nevertheless advantageous in the majority of cases.
Reason: Organic compounds other than KHP react differently in the spectrum.

The factory calibration is based on a three-point calibration of. The factory calibration
cannot be deleted and can be retrieved at any time. All other calibrations - performed as
customer calibrations – are referenced to this factory calibration.

7.1.2 Types of calibration

In addition to the uneditable factory calibration, the sensor stores six other data records.
Each calibration data record can have up to five calibration points.

• Single-point calibration
This causes a change in the slope. This type of calibration is used if the measured value
only changes to a limited extent.

• Two-point calibration
This causes a change in the slope and zero point. This type of calibration is used if the
measured value changes to a large extent.

• Multipoint calibration
Calibration at three or more points always causes the measuring curve to be recalculated
(including zero point and slope).

• Temperature adjustment by entering a reference value

If you use one or two medium concentration values for calibration, the factory data record
is recalculated using these measuring points (non-linear function) and saved as the new
data record. The original factory calibration is not lost.

Viomax CAS51D Operation

Endress+Hauser 27

If you use three or more concentration values for calibration, a completely new calibration
function is calculated that no longer takes the original factory calibration data record into
account.

Give your calibration data records meaningful and useful names. For example, the
name could contain the name of the application on which your data record was
originally based. This makes it easier for you to distinguish between different data
records.

7.1.3 Stability criterion

During the calibration process, the measured values are checked to ensure that they
remain constant.

You use the stability criterion to define maximum deviations during a calibration. Only a
measured value within the specified deviation is accepted.

The stability criterion includes:

• The maximum permitted deviation in temperature measurement

• The maximum permitted deviation in measured value as a %

• the minimum time frame in which these values must be maintained

If the measured value or temperature deviate more than is permitted in the specified time
frame, this calibration point becomes invalid and a warning is issued.

The stability criteria are used to monitor the quality of the individual calibration points in
the course of the calibration process. The aim is to achieve the best possible calibration
quality in the shortest possible time frame while taking external conditions into account.

• For high-precision calibrations in the laboratory, the maximum deviation permitted in
the measured value can be kept as small as possible and the time frame selected can be
as long as possible..

• For calibrations in the field in adverse weather and environmental conditions, the
maximum deviation permitted in the measured value can be kept suitably large and the
time frame selected can be kept suitably short.

Operating Instructions Memosens inputs BA01245C

7.1.4 Determining the reference values in the laboratory

Nitrate sensor

1. Take a representative sample of the medium.
 Outlet water is very suitable for obtaining a representative sample. In this case,

you do not have to carry out the subsequent step concerning value stabilization.

2. Take suitable measures to ensure that the process of nitrate reduction in the sample
does not progress any further, such as immediate filtration (0.45 µm) of the sample
as per DIN 38402.

3. Determine the concentration of nitrate in the sample using the laboratory method
(for example, by colorimetric means using a cuvette test ‐ the standard method as per
DIN 38405 Part 9).

SAC sensor

1. Take a representative sample of the medium.
 Outlet water is very suitable for obtaining a representative sample. In this case,

you do not have to carry out the subsequent step concerning value stabilization.

2. Take suitable measures to ensure that the process of biological and chemical
reduction in the sample does not progress any further.

3. Determine the measured values of your sample array using the laboratory method
(for example, by colorimetric means using a cuvette test).

Operation Viomax CAS51D

28 Endress+Hauser

7.1.5 Nitrate sensor

Processes with nitrate values > 0.1 mg/l

1. Take a sample and determine the nitrate concentration in the laboratory.

2. Calibrate and adjust the sensor with the laboratory value.

Processes with very different nitrate values

1. At time A, take a sample with a high concentration, and measure and calibrate the
sample.

2. At time B - which can be a few days after time A - take a sample with a low
concentration, and measure and calibrate the second value.

Calibration with the addition of standard

If the sludge parameters tend to be constant, you can perform the calibration with a
sample with a low concentration of nitrate and then add standard to the sample.

1. Take a larger sample (bucket) and analyze some of it by colorimetric means.

2. Calibrate the value of the calorimetric measurement in the sensor.

3. Add standard to the sample and determine its laboratory value.

4. Calibrate the laboratory value of the sample with added standard in the sensor.

Avoid incorrect measurements.

‣

Drinking water may contain higher concentrations of nitrate and is not suitable as a
blank value. Use fully deionized water as a blank value.

‣

During calibration, make sure the sample is homogeneous.

‣

When calibrating, start with a low concentration and increase the concentrations
gradually to prevent nitrate carryover.

‣

Clean and dry the sensor after a calibration. Ensure that there is no medium residue in
the cuvette gap. In this way, you avoid mixing the different samples and changing the
nitrate concentrations.

7.1.6 SAC sensor

General calibration steps

1. Take a sample.

2. Determine the SAC value of the sample in the laboratory.

3. Calibrate and adjust the sensor using the laboratory value.

In the SAC sensor version, the calculated variables COD, TOC, BOD and DOC can also be
output if desired, in addition to the actual measured variable. These variables are based on
the following ratios:

1 mg/l KHP = ~1.176 mg/l COD
1 mg/l KHP = ~0.4705 mg/l TOC
1 mg/l KHP = ~1.176 mg/l BOD
1 mg/l KHP = ~0.4705 mg/l DOC

Use other conversion factors

Sometimes the conversion factors for COD, TOC, BOD or DOC are predetermined by control
bodies. In such instances, these factors can be adjusted as follows:

1. Copy the factory data record to a free data record of your choice in the SAC basic
setting.

A copy is necessary because the factory data record cannot be modified. If you already have
another data record, you can change its factors directly.

Viomax CAS51D Operation

Endress+Hauser 29

2. Activate the new data record. (in the Setupmenu)

3. Set the desired factor. (in the CALmenu)

4. Set your device to the desired measured variable. (in the Setupmenu)

Operating Instructions Memosens inputs BA01245C.

The SAC sensor can be calibrated for the measured variables SAC, COD, TOC, BOD and
DOC.

If the sensor has been calibrated for the measured variable SAC, the conversion factors for
COD, TOC, BOD or DOC can be adjusted at a later stage. If calibrated for TOC, COD, BOD or
DOC, only the factor for the measured variable in use can be changed subsequently.

Avoid incorrect measurements.

‣

Drinking water contains many organic elements. The use of fully ionized water as a
blank is also recommended here.

‣

During calibration, make sure the medium is homogeneous.

‣

Avoid any carryover of organic elements during calibration.

Processes with widely varying SAC values

Record calibration points for different operating statuses. Example of a WWTP inlet:

• After a rainy spell

• In "normal conditions"

• After a dry spell

1. Save the points in a data record of your choice and add the associated laboratory
results.

2. Activate the calibration once you have set a sufficient number of points.

While this type of calibration can be more time-consuming, it allows the precise
adjustment of the measurement technology to the operating conditions of the plant.

7.1.7 Calibrating and adjusting the sensor

To calibrate the sensor, use the same medium sample or sample array that you used to
determine the laboratory measured values. The sample array can also be pure standard
solutions.

1. Select a data record.

2. Put the sensor into the medium.

3. During calibration, make sure the medium is as homogeneous as possible.

4. Start the calibration for the measuring point.

5. If you wish to calibrate just one point:
End the calibration by accepting the calibration data.
 Otherwise continue with the next step.

6. Add parent solution to the sample for the 2nd measuring point and determine the
measured value. The reference value is calculated from the laboratory measured
value plus the added concentration.

7. Repeat the previous step as often as needed until you have the desired number of
calibration points (max. 5).

To avoid incorrect calibration from carryover:

• Always go from a low concentration to a high concentration.

• Clean and dry the sensor after each measurement.

• Make sure to remove medium residue in the sensor gap and in the connection opening
for the compressed air (e.g. by rinsing with the next calibration solution).

Diagnostics and troubleshooting Viomax CAS51D

30 Endress+Hauser

7.2 Cyclic cleaning

Compressed air is most suitable for automatic cyclic cleaning. There is a connection for
compressed air on every sensor. The cleaning unit, which is supplied with the device or can
be retrofitted, operates effectively at a rate of 20 l/min (5.4 US gal/min).

Type of soiling Cleaning interval Cleaning duration

Severe fouling with rapid buildup 5 min 10 s

Low risk of soiling 10 min 10 s

8 Diagnostics and troubleshooting

When troubleshooting, the entire measuring point must be taken into account:

• Transmitter

• Electrical connections and cables

• Assembly

• Sensor

The possible causes of error in the following table relate primarily to the sensor.

Problem Testing Solution

No display, no sensor
reaction

• Power supplied to transmitter?

• Sensor connected correctly?

• Medium flow present?

• Buildup on optical windows?

1. Connect mains voltage

2. Connect sensor correctly

3. Ensure medium is flowing

4. Clean sensor

Display value too high
or too low

• Buildup on optical windows?

• Gas bubbles present?

• Sensor calibrated?

1. Cleaning

2. Eliminate gas bubbles

3. Calibration

4. Check data record and modify if necessary

5. Examine in workshop with test unit

Display value
fluctuating greatly

Gas bubbles present? 1. Eliminate gas bubbles

2. Check mounting location and select a
different mounting location if necessary.

Please observe the troubleshooting instructions provided in the Operating Instructions
of the transmitter. Check the transmitter if necessary.

Viomax CAS51D Maintenance

Endress+Hauser 31

9 Maintenance

You must perform maintenance tasks at regular intervals.

We recommend setting the maintenance times in advance in an operations journal or log.

The maintenance cycle primarily depends on the following:

• The system

• The installation conditions

• The medium in which measurement takes place

L

CAUTION

Risk of injury from acids or medium, damage to clothing and equipment

‣

Switch off the cleaning unit before removing the sensor from the medium.

‣

Wear protective goggles and safety gloves.

‣

Clean away splashes on clothes and other objects.

9.1 Maintenance intervals

The sensor requires very little maintenance, particularly if a cleaning unit is connected.
Nevertheless, maintenance must be performed at regular intervals. Schedule maintenance
times in advance in an operations journal or log.

Monthly: Visual check, clean sensor if necessary.

Cleaning intervals depend on the medium.

Every two years: Replace optical filters (manufacturer service team)

Every four years: Replace strobe lamp (manufacturer service team)

9.2 Cleaning the sensor

Sensor fouling can affect the measurement results and even cause a malfunction.

The sensor must be cleaned regularly to ensure reliable measurement results. The
frequency and intensity of the cleaning process depend on the medium.

Clean the sensor:

• As specified in the maintenance schedule

• Before every calibration

• before returning it for repairs.

Type of soiling Cleaning measure

Lime deposits

‣

Immerse the sensor in 1 to 5% hydrochloric acid (for several minutes).

Dirt particles on the optics

‣

Clean the optics with a cleaning cloth.

Buildup on the optics

‣

Wet a cotton bud with 1 to 5% hydrochloric acid and use it to clean the optics.

After cleaning:

‣

Rinse the sensor thoroughly with water.

9.3 Maintenance of optical filters and strobe lamp

This work must be performed only by the manufacturer service team. Contact your Sales
Center.→  32

Replacing the optical filter and strobe lamp also entails recalibrating and readjusting
the sensor in the factory.

Repairs Viomax CAS51D

32 Endress+Hauser

10 Repairs

10.1 Return

The product must be returned if repairs or a factory calibration are required, or if the
wrong product was ordered or delivered. As an ISO-certified company and also due to legal
regulations, Endress+Hauser is obliged to follow certain procedures when handling any
returned products that have been in contact with medium.

To ensure swift, safe and professional device returns, please read the return procedures
and conditions at www.endress.com/support/return-material.

10.2 Disposal

The device contains electronic components and must therefore be disposed of in
accordance with regulations on the disposal of electronic waste.

Observe the local regulations.

Viomax CAS51D Accessories

Endress+Hauser 33

11 Accessories

11.1 Assemblies

FlexdipCYA112

• Immersion assembly for water and wastewater

• Modular assembly system for sensors in open basins, channels and tanks

• Material: PVC or stainless steel

• Product Configurator on the product page: www.endress.com/cya112

Technical Information TI00432C

Flowfit CYA251

• Connection: See product structure

• Material: PVC-U

• Product Configurator on the product page: www.endress.com/cya251

Technical Information TI00495C

Flow assembly for CAS51D

• For small flow volumes

• Connection: hose, OD 6 mm

• Material: PVC-U

• Two brackets for CAS51D

• Order number: 71110000

11.2 Holder

Flexdip CYH112

• Modular holder system for sensors and assemblies in open basins, channels and tanks

• For Flexdip CYA112 water and wastewater assemblies

• Can be affixed anywhere: on the ground, on the capstone, on the wall or directly onto
railings.

• Stainless steel version

• Product Configurator on the product page: www.endress.com/cyh112

Technical Information TI00430C

11.3 Compressed air cleaning

Compressed air cleaning for CAS51D

• Connection: 6 or 8 mm (metric) or 6.35 mm (¼")

• Order numbers for sensor with 2 mm gap or 8 mm gap:
– 6 mm (with 300 mm hose and 8 mm adapter)

Order No.: 71110787

– 6.35 mm (¼")

Order No.: 71110788

• Order numbers for sensor with 40 mm gap:
– 6 mm (with 300 mm hose and 8 mm adapter)

Order No.: 71126757

– 6.35 mm (¼")

Order No.: 71126758

Accessories Viomax CAS51D

34 Endress+Hauser

1

2

4

A

B

A0013263

 25 Compressed air cleaning for CAS51D

A Cleaning for sensors with 2 mm and 8 mm gap
B Cleaning for sensors with 40 mm gap
1 Adapter, 8 mm
2 300 mm hose (Ø = 6 mm)
3 Coupling, 6 mm or 6.35 mm (¼") for 2 mm and 8 mm gap
4 Coupling, 6 mm or 6.35 mm (¼") for 40 mm gap

Compressor

• For compressed air cleaning

• 230 V AC order no. 71072583

• 115 V AC order no. 71194623

11.4 Standard solutions

Nitrate standard solutions, 1 liter

• 5 mg/l NO3-N, order number: CAY342-V10C05AAE

• 10 mg/l NO3-N, order number: CAY342-V10C10AAE

• 15 mg/l NO3-N, order number: CAY342-V10C15AAE

• 20 mg/l NO3-N, order number: CAY342-V20C10AAE

• 30 mg/l NO3-N, order number: CAY342-V20C30AAE

• 40 mg/l NO3-N, order number: CAY342-V20C40AAE

• 50 mg/l NO3-N, order number: CAY342-V20C50AAE

KHP standard solution

CAY451‐V10C01AAE, 1000 ml parent solution 5 000 mg/l TOC

Viomax CAS51D Technical data

Endress+Hauser 35

12 Technical data

12.1 Input

Measured values Nitrate

NO3-N [mg/l], NO3 [mg/l]

SAC

SAC [1/m], COD [mg/l], TOC [mg/l], BOD [mg/l], DOC [mg/l], transmission [%]

Measuring ranges

CAS51D-**A2 (2 mm gap width) 0.1 to 50 mg/l NO3-N

0.4 to 200 mg/l NO

3

Clear water and sludge activation

CAS51D-**A1 (8 mm gap width) 0.01 to 20 mg/l NO3-N

0.04 to 80 mg/l NO

3

Clear water (for a COD (KHP) concentration of up to 125 mg/l
and up to 50 FNU turbidity based on the mineral component of
kaolin)

CAS51D-**C1 (40 mm gap width) SAC 0.1 to 50 1/m

COD/BOD 0.15 to 75 mg/l

1)

TOC/DOC 0.06 to 30 mg/l

1)

Clear water, small measuring range, drinking water

CAS51D-**C2 (8 mm gap width) SAC 0.5 to 250 1/m

COD/BOD 0.75 to 370 mg/l

1)

TOC/DOC 0.3 to 150 mg/l

1)

Clear water, average measuring range, drinking water, WWTP
outlet, monitoring of water bodies

CAS51D-**C3 (2 mm gap width) SAC 1.5 to 700 1/m

COD/BOD 2.5 to 1000 mg/l

1)

TOC/DOC 0.9 to 410 mg/l

1)

Organic load in inlet, discharger monitoring, industrial processes

1) equivalent KHP

The possible measuring range depends to a large extent on the medium
characteristics.

Empirical values for typical COD measuring ranges

Inlet of municipal WWTP 0 to 4000 mg/l COD

Inlet from dairy-processing industry 0 to 10 000 mg/l COD

Inlet from chemical industry 0 to 10 000 mg/l COD

Technical data Viomax CAS51D

36 Endress+Hauser

12.2 Performance characteristics

Reference operating
conditions

20°C (68 °F), 1013 hPa (15 psi)

Measured error

6)

Nitrate For 0.1 to 50 mg/l NO3-N (2 mm cuvette gap):

2 % of full-scale value above 10 mg/l
±0.2 mg/l below 10 mg/l

For 0.01 to 20 mg/l NO3-N (8 mm cuvette gap):
2 % of full-scale value above 2 mg/l

±0.04 mg/l below 2 mg/l

SAC 2 % of full-scale value when measuring with potassium

hydrogen phthalate (KHP) as the standard

Repeatability

6)

Nitrate

At least ±0.2 mg/l NO3-N

SAC

0.5 % of end of measuring range (for homogeneous media)

Detection limits Nitrate

• CAS51D-AAA1

0.003 mg/l NO3-N

• CAS51D-AAA2

0.013 mg/l NO3-N

SAC

In relation to the standard potassium hydrogen phthalate (KHP):

• CAS51D-AAC1

0.045 mg/l COD

• CAS51D-AAC2

0.3 mg/l COD

• CAS51D-AAC3

1.5 mg/l COD

Detection limits Nitrate

• CAS51D-AAA1

0.01 mg/l NO3-N

• CAS51D-AAA2

0.043 mg/l NO3-N

SAC

In relation to the standard potassium hydrogen phthalate (KHP):

• CAS51D-AAC1

0.15 mg/l COD

• CAS51D-AAC2

1.0 mg/l COD

• CAS51D-AAC3

5.0 mg/l COD

Long-term drift Nitrate

Better than 0.1 mg/l NO3-N over one week

6) The measured error includes all of the sensor's and transmitter's uncertainties (measuring chain). It does not include any uncertainties resulting
from the reference material or from any necessary adjustment.

Viomax CAS51D Technical data

Endress+Hauser 37

SAC

Better than 0.2 % of end of measuring range over one week

12.3 Environment

Ambient temperature
range

-20 to +60 °C (-4 to 140 °F)

Storage temperature -20 to +70 °C (0 to 160 °F)

Degree of protection IP 68 (1 m (3.3 ft) water column over 60 days, 1 mol/l KCl)

12.4 Process

Process temperature 5 to 50 °C (41 to 122 °F)

Process pressure (absolute) 0.5 to 10 bar (7 to 145 psi) absolute

Minimum flow No minimum flow required.

12.5 Mechanical construction

Dimensions →  6

Weight Approx. 1.6 kg (3.53 lbs) (without cable)

Materials Sensor Stainless steel 1.4404 (AISI 316 L)

Optical windows Quartz glass
O-rings EPDM

Process connections G1 and NPT ¾''

Index Viomax CAS51D

38 Endress+Hauser

Index

A

Accessories ................................ 33

Ambient temperature range ................... 37

Approvals ................................. 12

C

Cable shield ............................... 24

Calibration

Factory calibration ........................ 26

Certificates ................................ 12

Check

Connection ..............................25

Installation ............................. 23

Cleaning ............................... 30, 31

Cleaning unit .............................. 22

Cross-interference

Nitrate ..................................9

SAC ................................... 10

Cyclic cleaning ..............................30

D

Degree of protection ......................... 37

Designated use .............................. 4

Detection limits .............................36

Device description ............................ 6

Diagnosis ................................. 30

Dimensions .................................6

Disposal .................................. 32

E

Electrical connection ......................... 24

Ensuring the degree of protection ............... 25

F

Factory calibration ...........................26

Flow operation ............................. 17

I

Immersion operation ......................... 15

Incoming acceptance ......................... 11

Input .....................................35

Installation ................................ 13

Installation instructions .......................14

Interpreting the order code .................... 11

L

Long-term drift ............................. 36

M

Maintenance ...............................31

Maintenance intervals ........................31

Manufacturer's address ....................... 12

Materials ................................. 37

Maximum measured error ..................... 36

Measured values ............................ 35

Measuring principle ...........................8

Measuring ranges ........................... 35

Mechanical construction ...................... 37

Minimum flow ............................. 37

Mounting location ...........................13

N

Nameplate ................................ 11

Nitrate .................................... 9

O

Operating principle ........................... 8

Operation ................................. 26

Optical filters .............................. 31

Orientation ................................ 13

P

Performance characteristics ....................36

Post-connection check ........................25

Post-installation check ....................... 23

Process connections ..........................37

Process pressure (absolute) .................... 37

Process temperature ......................... 37

Product identification ........................ 11

Product page ...............................11

R

Reference operating conditions ................. 36

Repairs ................................... 32

Repeatability ...............................36

Return ................................... 32

S

SAC ...................................... 9

Safety instructions ............................4

Scope of delivery ............................ 12

Sensor ................................... 14

Cleaning ............................... 31

Connecting ..............................25

Design .................................. 6

Dimensions .............................. 6

Stability criterion ............................27

Storage temperature ......................... 37

Strobe lamp ............................... 31

Symbols ................................... 3

T

Technical data ..............................35

Troubleshooting ............................ 30

U

Use .......................................4

W

Warnings .................................. 3

Weight ................................... 37

Wiring ................................... 24

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