Endress+Hauser Viomax CAS51D User manual

Products Solutions Services
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
Endress+Hauser 3
1 Document information
1.1 Warnings
Structure of information Meaning
LDANGER
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.
LWARNING
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.
LCAUTION
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
LCAUTION
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
Endress+Hauser 5
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
6 Endress+Hauser
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
8 Endress+Hauser
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.
123
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
Endress+Hauser 11
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
123
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
Endress+Hauser 15
5.3 Immersion operation
5.3.1 Fixed installation with wastewater assembly
12
3
4
A0013347
 10 Installation secured on railing
1 Wastewater assembly Flexdip CYA112
2 Flexdip CYH112 holder
3 Rail
4 Viomax CAS51D
12
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
12
3
4
A0013348
 12 Chain retainer on railing
1 Wastewater assembly Flexdip CYA112
2 Flexdip CYH112 holder
3 Rail
4 Viomax CAS51D
12
3
4
5
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
12
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
13
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
1
3
A0013434
 17 Flow assembly with open outlet
1 Pump
2 Open outlet
3 Filter unit