Vega VEGASON 62 User manual

Operating Instructions
Ultrasonic sensor for continuous level
measurement
VEGASON 62
Four-wire 4 … 20 mA/HART
Document ID: 28779

2
Contents
VEGASON 62 • Four-wire 4 … 20 mA/HART
28779-EN-231026
Contents
1 About this document ............................................................................................................... 4
1.1 Function ........................................................................................................................... 4
1.2 Target group ..................................................................................................................... 4
1.3 Symbols used................................................................................................................... 4
2 For your safety ......................................................................................................................... 5
2.1 Authorised personnel ....................................................................................................... 5
2.2 Appropriate use................................................................................................................ 5
2.3 Warning about incorrect use............................................................................................. 5
2.4 General safety instructions............................................................................................... 5
2.5 Conformity........................................................................................................................ 5
2.6 FulllmentofNAMURrecommendations ......................................................................... 6
2.7 InstallationandoperationintheUSAandCanada ........................................................... 6
2.8 Environmental instructions ............................................................................................... 6
3 Product description................................................................................................................. 7
3.1 Conguration.................................................................................................................... 7
3.2 Principle of operation........................................................................................................ 8
3.3 Packaging, transport and storage..................................................................................... 8
3.4 Accessories...................................................................................................................... 9
4 Mounting................................................................................................................................. 11
4.1 General instructions ....................................................................................................... 11
4.2 Housing features ............................................................................................................ 12
4.3 Mountinginstructions ..................................................................................................... 15
5 Connecting to power supply................................................................................................. 22
5.1 Preparing the connection ............................................................................................... 22
5.2 Connection procedure.................................................................................................... 23
5.3 Wiring plan, double chamber housing ............................................................................ 24
5.4 Switch-on phase............................................................................................................. 25
6 Set up with the display and adjustment module PLICSCOM ............................................ 27
6.1 Insert display and adjustment module............................................................................ 27
6.2 Adjustment system......................................................................................................... 28
6.3 Setup steps .................................................................................................................... 28
6.4 Menuschematic............................................................................................................. 41
6.5 Saving the parameterisation data................................................................................... 43
7 Setup with PACTware............................................................................................................. 45
7.1 Connect the PC via VEGACONNECT ............................................................................ 45
7.2 Parameter adjustment .................................................................................................... 46
7.3 Save parameter adjustment data.................................................................................... 47
8 Set up with other systems .................................................................................................... 48
8.1 DD adjustment programs ............................................................................................... 48
9 Maintenanceandfaultrectication...................................................................................... 49
9.1 Maintenance .................................................................................................................. 49
9.2 Rectify faults................................................................................................................... 49
9.3 Exchanging the electronics module................................................................................ 50
9.4 Software update ............................................................................................................. 51
9.5 How to proceed if a repair is necessary.......................................................................... 51

3
Contents
VEGASON 62 • Four-wire 4 … 20 mA/HART
28779-EN-231026
10 Dismount................................................................................................................................. 52
10.1 Dismounting steps.......................................................................................................... 52
10.2 Disposal ......................................................................................................................... 52
11 Supplement ............................................................................................................................ 53
11.1 Technical data ................................................................................................................ 53
11.2 Dimensions .................................................................................................................... 56
11.3 Industrial property rights................................................................................................. 58
11.4 Trademark ...................................................................................................................... 58
Safety instructions for Ex areas:
TakenoteoftheExspecicsafetyinstructionsforExapplications.
These instructions are attached as documents to each instrument
with Ex approval and are part of the operating instructions.
Editing status: 2023-10-24

4
1 About this document
VEGASON 62 • Four-wire 4 … 20 mA/HART
28779-EN-231026
1 About this document
1.1 Function
This instruction provides all the information you need for mounting,
connection and setup as well as important instructions for mainte-
nance,faultrectication,safetyandtheexchangeofparts.Please
read this information before putting the instrument into operation and
keep this manual accessible in the immediate vicinity of the device.
1.2 Target group
This operating instructions manual is directed to trained personnel.
Thecontentsofthismanualmustbemadeavailabletothequalied
personnel and implemented.
1.3 Symbols used
Document ID
This symbol on the front page of this instruction refers to the Docu-
ment ID. By entering the Document ID on www.vega.com you will
reach the document download.
Information, note, tip: This symbol indicates helpful additional infor-
mation and tips for successful work.
Note: This symbol indicates notes to prevent failures, malfunctions,
damage to devices or plants.
Caution: Non-observance of the information marked with this symbol
may result in personal injury.
Warning: Non-observance of the information marked with this symbol
may result in serious or fatal personal injury.
Danger: Non-observance of the information marked with this symbol
results in serious or fatal personal injury.
Ex applications
This symbol indicates special instructions for Ex applications.
• List
The dot set in front indicates a list with no implied sequence.
1 Sequence of actions
Numbers set in front indicate successive steps in a procedure.
Disposal
This symbol indicates special instructions for disposal.

5
2 For your safety
VEGASON 62 • Four-wire 4 … 20 mA/HART
28779-EN-231026
2 For your safety
2.1 Authorised personnel
All operations described in this documentation must be carried out
only by trained and authorized personnel.
During work on and with the device, the required personal protective
equipment must always be worn.
2.2 Appropriate use
VEGASON 62 is a sensor for continuous level measurement.
Youcannddetailedinformationabouttheareaofapplicationin
chapter "Product description".
Operational reliability is ensured only if the instrument is properly
usedaccordingtothespecicationsintheoperatinginstructions
manual as well as possible supplementary instructions.
2.3 Warning about incorrect use
Inappropriate or incorrect use of this product can give rise to applica-
tion-specichazards,e.g.vesseloverllthroughincorrectmounting
or adjustment. Damage to property and persons or environmental
contamination can result. Also, the protective characteristics of the
instrument can be impaired.
2.4 General safety instructions
This is a state-of-the-art instrument complying with all prevailing
regulations and directives.The instrument must only be operated in
atechnicallyawlessandreliablecondition.Theoperatingcompany
is responsible for the trouble-free operation of the instrument.When
measuring aggressive or corrosive media that can cause a danger-
ous situation if the instrument malfunctions, the operating company
has to implement suitable measures to make sure the instrument is
functioning properly.
The safety instructions in this operating instructions manual, the
national installation standards as well as the valid safety regulations
and accident prevention rules must be observed.
For safety and warranty reasons, any invasive work on the device
beyond that described in the operating instructions manual may be
carried out only by personnel authorised by us. Arbitrary conversions
ormodicationsareexplicitlyforbidden.Forsafetyreasons,onlythe
accessoryspeciedbyusmustbeused.
To avoid any danger, the safety approval markings and safety tips on
the device must also be observed.
2.5 Conformity
The device complies with the legal requirements of the applicable
country-specicdirectivesortechnicalregulations.Weconrmcon-
formity with the corresponding labelling.

6
2 For your safety
VEGASON 62 • Four-wire 4 … 20 mA/HART
28779-EN-231026
The corresponding conformity declarations can be found on our
homepage.
Electromagnetic compatibility
The instruments are designed for use in an industrial environment.
Nevertheless, electromagnetic interference from electrical conductors
and radiated emissions must be taken into account, as is usual with a
class A instrument according to EN 61326-1. If the instrument is used
inadierentenvironment,itselectromagneticcompatibilitywithother
devices must be ensured by suitable measures.
2.6 FulllmentofNAMURrecommendations
NAMURistheautomationtechnologyuserassociationintheprocess
industryinGermany.ThepublishedNAMURrecommendationsare
acceptedasthestandardineldinstrumentation.
ThedevicefullstherequirementsofthefollowingNAMURrecom-
mendations:
• NE 21: 2012 – Electromagnetic compatibility of equipment
• NE 43 – Signal level for fault information from measuring transduc-
ers
• NE53–Compatibilityofelddevicesanddisplay/adjustment
components
For further information see www.namur.de.
2.7 InstallationandoperationintheUSAand
Canada
ThisinformationisonlyvalidforUSAandCanada.Hencethefollow-
ing text is only available in the English language.
InstallationsintheUSshallcomplywiththerelevantrequirementsof
theNationalElectricalCode(NEC-NFPA70)(USA).
Installations in Canada shall comply with the relevant requirements of
the Canadian Electrical Code (CEC Part I) (Canada).
2.8 Environmental instructions
Protection of the environment is one of our most important duties.
That is why we have introduced an environment management system
with the goal of continuously improving company environmental pro-
tection.Theenvironmentmanagementsystemiscertiedaccording
to DIN EN ISO 14001.
Pleasehelpusfullthisobligationbyobservingtheenvironmental
instructions in this manual:
• Chapter "Packaging, transport and storage"
• Chapter "Disposal"

7
3 Product description
VEGASON 62 • Four-wire 4 … 20 mA/HART
28779-EN-231026
3 Product description
3.1 Conguration
The scope of delivery encompasses:
• Ultrasonicsensor
The further scope of delivery encompasses:
• Documentation
– Quick setup guide VEGASON 62
– Instructions for optional instrument features
– Ex-specic"Safety instructions" (with Ex versions)
– Ifnecessary,furthercerticates
Information:
Optional instrument features are also described in this operating
instructions manual.The respective scope of delivery results from the
orderspecication.
The VEGASON 62 consists of the components:
• Processttingwithtransducer
• Housing with electronics
• Housing cover, optionally available with display and adjustment
modulePLICSCOM
Thecomponentsareavailableindierentversions.
1
2
3
Fig. 1: VEGASON 62, Aluminium double chamber housing
1 Housing cover with integrated PLICSCOM (optional)
2 Housing with electronics, optionally available with plug connector
3 Processttingwithtransducer
Thetypelabelcontainsthemostimportantdataforidenticationand
use of the instrument:
• Instrument type
• Information about approvals
Scope of delivery
Constituent parts
Type label

8
3 Product description
VEGASON 62 • Four-wire 4 … 20 mA/HART
28779-EN-231026
• Congurationinformation
• Technical data
• Serial number of the instrument
• QRcodefordeviceidentication
• Numerical code for Bluetooth access (optional)
• Manufacturerinformation
Tondorderdata,documentsorsoftwarerelatedtoyourdevice,you
have the following options:
• Moveto"www.vega.com"andenterinthesearcheldtheserial
number of your instrument.
• Scan the QR code on the type label.
• Open the VEGA Tools app and enter the serial number under
"Documentation".
3.2 Principle of operation
VEGASON 62 is an ultrasonic sensor for continuous level measure-
ment. It is suitable for liquids and solids in virtually all industries,
particularly in the water and waste water industry.
The transducer of the ultrasonic sensor transmits short ultrasonic
pulsestothemeasuredproduct.Thesepulsesarereectedby
medium surface and received back by the transducer as echoes.
The running time of the ultrasonic pulses from emission to reception
is proportional to the distance and hence the level. The determined
level is converted into an appropriate output signal and outputted as
measured value.
Four-wire electronics with separate power supply.
Thesupplyvoltagerangecandierdependingontheinstrument
version.
Thedataforpowersupplyarespeciedinchapter"Technical data".
Measuredvaluetransmissioniscarriedoutviathe4…20mA/HART
output separate from power supply.
The backlight of the display and adjustment module is powered by
the sensor.The prerequisite for this is a supply voltage at a certain
level.Theexactvoltagespecicationsarestatedinchapter"Technical
data".
3.3 Packaging, transport and storage
Your instrument was protected by packaging during transport. Its
capacity to handle normal loads during transport is assured by a test
based on ISO 4180.
The packaging of standard instruments consists of environment-
friendly, recyclable cardboard. For special versions, PE foam or PE
foil is also used. Dispose of the packaging material via specialised
recycling companies.
Documents and software
Application area
Functional principle
Voltage supply
Packaging

9
3 Product description
VEGASON 62 • Four-wire 4 … 20 mA/HART
28779-EN-231026
Transport must be carried out in due consideration of the notes on the
transport packaging. Nonobservance of these instructions can cause
damage to the device.
The delivery must be checked for completeness and possible transit
damage immediately at receipt. Ascertained transit damage or con-
cealed defects must be appropriately dealt with.
Uptothetimeofinstallation,thepackagesmustbeleftclosedand
stored according to the orientation and storage markings on the
outside.
Unlessotherwiseindicated,thepackagesmustbestoredonlyunder
the following conditions:
• Not in the open
• Dry and dust free
• Not exposed to corrosive media
• Protected against solar radiation
• Avoiding mechanical shock and vibration
• Storage and transport temperature see chapter "Supplement -
Technical data - Ambient conditions"
• Relative moisture 20 … 85 %
With instrument weights of more than 18 kg (39.68 lbs) suitable and
approved equipment must be used for lifting and carrying.
3.4 Accessories
The instructions for the listed accessories can be found in the down-
load area on our homepage.
The display and adjustment module is used for measured value indi-
cation, adjustment and diagnosis.
The integrated Bluetooth module (optional) enables wireless adjust-
ment via standard adjustment devices.
The interface adapter VEGACONNECT enables the connection of
communication-capableinstrumentstotheUSBinterfaceofaPC.
The VEGADIS 81 is an external display and adjustment unit for VEGA
plics®sensors.
VEGADIS 82 is suitable for measured value indication and adjustment
of sensors with HART protocol. It is looped into the 4 … 20 mA/HART
signal cable.
ThePLICSMOBILET81isanexternalGSM/GPRS/UMTSradiounit
for transmission of measured values and for remote parameter adjust-
ment of HART sensors.
The protective cover protects the sensor housing against soiling and
intense heat from solar radiation.
Transport
Transport inspection
Storage
Storage and transport
temperature
Lifting and carrying
Display and adjustment
module
VEGACONNECT
VEGADIS 81
VEGADIS 82
PLICSMOBILE T81
Protective cover

10
3 Product description
VEGASON 62 • Four-wire 4 … 20 mA/HART
28779-EN-231026
Screwedangesareavailableindierentversionsaccordingtothe
followingstandards:DIN2501,EN1092-1,BS10,ASMEB16.5,
JIS B 2210-1984, GOST 12821-80.
Flanges

11
4Mounting
VEGASON 62 • Four-wire 4 … 20 mA/HART
28779-EN-231026
4 Mounting
4.1 General instructions
Note:
For safety reasons, the instrument must only be operated within the
permissibleprocessconditions.Youcannddetailedinformationon
the process conditions in chapter "Technical data" of the operating
instructions or on the type label.
Hence make sure before mounting that all parts of the instrument ex-
posed to the process are suitable for the existing process conditions.
These are mainly:
• Active measuring component
• Processtting
• Process seal
Process conditions in particular are:
• Process pressure
• Process temperature
• Chemical properties of the medium
• Abrasionandmechanicalinuences
The instrument is suitable for standard and extended ambient condi-
tionsacc.toDIN/EN/IEC/ANSI/ISA/UL/CSA61010-1.Itcanbeused
indoors as well as outdoors.
Select an installation position you can easily reach for mounting and
connectingaswellaslaterretrottingofadisplayandadjustment
module.The housing can be rotated by 330° without the use of any
tools.You can also install the display and adjustment module in four
dierentpositions(eachdisplacedby90°).
Usetherecommendedcables(seechapter"Connecting to power
supply") and tighten the cable gland.
You can give your instrument additional protection against moisture
penetration by leading the connection cable downward in front of the
cablegland.Rainandcondensationwatercanthusdraino.This
applies mainly to outdoor mounting as well as installation in areas
where high humidity is expected (e.g. through cleaning processes) or
on cooled or heated vessels.
To maintain the housing protection, make sure that the housing lid is
closed during operation and locked, if necessary.
Process conditions
Suitability for the ambient
conditions
Installation position
Moisture

12
4Mounting
VEGASON 62 • Four-wire 4 … 20 mA/HART
28779-EN-231026
Fig. 2: Measures against moisture ingress
Metric threads
In the case of instrument housings with metric thread, the cable
glands are screwed in at the factory. They are sealed with plastic
plugs as transport protection.
You have to remove these plugs before electrical connection.
NPT thread
In the case of instrument housings with self-sealing NPT threads, it is
not possible to have the cable entries screwed in at the factory. The
free openings for the cable glands are therefore covered with red dust
protection caps as transport protection.
Prior to setup you have to replace these protective caps with ap-
proved cable glands or close the openings with suitable blind plugs.
GaugepressureinthevesseldoesnotinuenceVEGASON62.Low
pressure or vacuum does, however, damp the ultrasonic pulses.This
inuencesthemeasuringresult,particularlyifthelevelisverylow.
Withpressuresunder-0.2bar(-20kPa)youshoulduseadierent
measuring principle, e.g. radar or guided radar (TDR).
4.2 Housing features
Thelterelementinthehousingisusedforventilationofthehousing.
Foreectiveventilation,thelterelementmustalwaysbefreeof
deposits.Therefore,mountthedevicesothatthelterelementis
protected against deposits.
Note:
Do not use a high-pressure cleaner to clean housings in standard
typesofprotection.Thelterelementcouldbedamagedandmois-
ture could penetrate the housing.
Cable entries - NPT
thread
Cable glands
Pressure/Vacuum
Filter element

13
4Mounting
VEGASON 62 • Four-wire 4 … 20 mA/HART
28779-EN-231026
2 3 4
1
1
11
1
6
5
Fig.3:Positionofthelterelementdependingonhousing
1 Filter element
2 Plastic single chamber
3 Aluminium single chamber, stainless steel single chamber (precision cast-
ing)
4 Stainless steel single chamber (electropolished)
5 Plastic double chamber
6 Aluminium - double chamber
Information:
For devices in protection class IP66/IP68 (1 bar), ventilation is pro-
videdbyacapillaryinthexedcable.Inthesedevices,ablindplugis
installedinthehousinginsteadofthelterelement.
The housing of VEGASON 62 can be rotated completely by 360°. This
enables optimal reading of the display and easy cable entry.1)
For housings made of plastic or electropolished stainless steel, this is
done without tools.
For housings made of aluminium or stainless steel (precision cast-
ing), a locking screw must be loosened for turning, see the following
illustration:
Housing orientation
1) No limitation by a rotation stop

14
4Mounting
VEGASON 62 • Four-wire 4 … 20 mA/HART
28779-EN-231026
1
2 3
1
Fig. 4: Position of the locking screw depending on housing
1 Locking screw
2 Aluminium, stainless steel single chamber housing (precision casting)
3 Aluminium - double chamber
Proceed as follows:
1. Loosen locking screw (hexagon size 2.5)
2. Turn housing into requested position
3. Re-tighten the locking screw (torque see chapter "Technical
data").
With the aluminium and stainless steel housing (precision casting),
the housing cover can be secured with a screw.This protects the
device against unauthorised opening of the cover.
32
11
Fig. 5: Position of the safety screw depending on housing
1 Safety screw
2 Aluminium, stainless steel single chamber housing (precision casting)
3 Aluminium - double chamber
Proceed as follows to secure the cover:
1. Screw the housing cover on tightly by hand
2. Unscrewthelockingscrewfromthecoveruptothestopusinga
size 4 hexagonal spanner
3. Check if the cover can no longer be turned
The housing cover is unlocked in the opposite way.
Note:
The locking screw has two holes drilled through the head.Thus it can
also be sealed.
Cover catch

15
4Mounting
VEGASON 62 • Four-wire 4 … 20 mA/HART
28779-EN-231026
4.3 Mounting instructions
Screw VEGASON 62 into the mounting socket with an appropriate
spannerappliedtothehexagonoftheprocesstting.Max.torquesee
chapter "Technical data".
Warning:
The housing must not be used to screw the instrument in! Applying
tightening force can damage internal parts of the housing.
When mounting the sensor, keep a distance of at least 200 mm
(7.874 in) to the vessel wall. If the sensor is installed in the center of
dished or round vessel tops, multiple echoes can arise.These can,
however, be suppressed by an appropriate adjustment (see chapter
"Setup").
1
2
> 200 mm
Fig. 6: Mounting on round vessel tops
1 Reference plane
2 Vessel center or symmetry axis
If this distance cannot be maintained, a false signal suppression
should be carried out during setup. This applies particularly if buildup
on the vessel wall is expected. In such cases, we recommend repeat-
ing the false signal suppression at a later date with existing buildup.
In vessels with conical bottom it can be advantageous to mount the
device in the centre of the vessel, as measurement is then possible
down to the bottom.
Screwing in
Installation position

16
4Mounting
VEGASON 62 • Four-wire 4 … 20 mA/HART
28779-EN-231026
Fig. 7: Vessel with conical bottom
Socket pieces should be dimensioned so that the lower end of the
transducer protrudes at least 10 mm (0.394 in) out of the nozzle.
ca. 10 mm
Fig. 8: Recommended socket mounting
Ifthereectivepropertiesofthemediumaregood,youcanmount
VEGASON 62 on sockets which are higher than the length of the
transducer.Youwillndrecommendedvaluesforsocketheightsinthe
following illustration. The socket end should be smooth and burr-free,
if possible also rounded. Carry out a false signal suppression.
Nozzle

17
4Mounting
VEGASON 62 • Four-wire 4 … 20 mA/HART
28779-EN-231026
d
d
h
100 mm/4"
150 mm/6"
200 mm/8"
300 mm/12"
400 mm/16"
500 mm/20"
h
Fig. 9: Deviating socket dimensions
In liquids, direct the device as perpendicular as possible to the me-
dium surface to achieve optimum measurement results.
Fig. 10: Alignment in liquids
To reduce the blocking distance to the medium, you can also mount
VEGASON62withabeamdeector.Bydoingthis,itispossibleto
llthevesselnearlytomaximum.Suchanarrangementissuitable
primarilyforopenvesselssuchase.g.overowbasins.
~200
~400x400
45°
Fig.11:Beamdeector
The ultrasonic sensor should be installed at a location where no
installations cross the ultrasonic beam.
Vessel installations such as for example, ladders, limit switches, heat-
ing spirals, struts etc. can cause false echoes that interfere with the
usefulecho.Makesurewhenplanningyourmeasuringsitethatthe
ultrasonic signals have a "clear view" to the measured product.
In case of existing vessel installations, a false signal suppression
should be carried out during setup.
Sensor orientation
Vessel installations

18
4Mounting
VEGASON 62 • Four-wire 4 … 20 mA/HART
28779-EN-231026
If large vessel installations such as struts or supports cause false
echoes, these can be attenuated through supplementary measures.
Small,inclinedsheetmetalorplasticbaesabovetheinstallations
scatter the ultrasonic signals and avoid direct false echoes.
α
α
α
α
α
α
Fig.12:Coverat,large-areaproleswithdeectors
If there are agitators in the vessel, a false signal suppression should
be carried out with the agitators in motion. This ensures that the
interferingreectionsfromtheagitatorsaresavedwiththebladesin
dierentpositions.
Fig. 13: Agitators
Donotmounttheinstrumentsinorabovethellingstream.Makesure
thatyoudetectthemediumsurface,nottheinowingproduct.
Agitators
Inowingmedium

19
4Mounting
VEGASON 62 • Four-wire 4 … 20 mA/HART
28779-EN-231026
Fig.14:Inowingliquid
Throughtheactionoflling,stirringandotherprocessesinthevessel,
dense foams which considerably damp the emitted signals may form
on the medium surface.
If foams are causing measurement errors, the device should be used
in a standpipe or, alternatively, the more suitable guided radar sen-
sors (TDR) should be used.
Guidedwaveradarisunaectedbyfoamgenerationandisparticu-
larly suitable for such applications.
If there are strong air currents in the vessel, e.g. due to strong winds
in outdoor installations or air turbulence, e.g. by cyclone extraction
youshouldmountVEGASON62inastandpipeoruseadierent
measuring principle, e.g. radar or guided radar (TDR).
Byusingastandpipe(surgeorbypasstube),theinuenceofvessel
installations, foam generation and turbulence is excluded.
Standpipes must extend all the way down to the requested min. level,
as measurement is only possible within the tube.
Foam
Air turbulences
Standpipe measurement

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4Mounting
VEGASON 62 • Four-wire 4 … 20 mA/HART
28779-EN-231026
max.
min.
1
Fig. 15: Standpipe in the tank
1 Vent hole: ø 5 … 10 mm (0.197 … 0.394 in)
VEGASON 62 can be used from tube diameters of 50 mm (1.969 in).
Avoid large gaps and thick welding joints when connecting the tubes.
Generally carry out a false signal suppression.
Measurementinastandpipeisnotrecommendedforextremely
adhesive products.
Theshortexamplesgiveyouintroductoryinformationonow
measurement.Detailedplanninginformationisavailablefromume
manufacturers and in special literature.
3 ... 4 hmax
≥ 50 mm
90°
23
1
hmaxdmin
≥ 2 mm x hmax
90°
42 3
Fig. 16: Flow measurement with rectangular overfall: dmin. = blocking distance of
the sensor (see chapter "Technical data"); hmax.=max.llingoftherectangular
spillway
1 Overfallorice(sideview)
2 Upstream water
3 Tailwater
4 Overfallorice(viewfromtailwater)
In general, the following points must be observed:
• Install the sensor on the headwater side
Flow measurement with
rectangular overfall