Operating Instructions
VEGAPULS 56K
Contents
Safety information ........................................................................ 3
Note Ex area ................................................................................ 3
1 Product description .................................................................. 4
1.1 Function ................................................................................. 4
1.2 Application features ............................................................. 6
1.3 Adjustment ............................................................................ 7
1.4 Antennas ............................................................................... 9
2 Types and versions ................................................................. 10
2.1 Type survey ........................................................................ 10
3 Mounting and installation ..................................................... 11
3.1 General installation instructions ........................................ 11
3.2 Measurement of liquids ..................................................... 12
3.3 Measurement in standpipe (surge or bypass tube) ...... 14
3.4 False echoes ...................................................................... 20
3.5 Common installation mistakes ........................................... 22
Contents
4 Electrical connection .............................................................. 24
4.1 Connection and connection cable .................................... 24
4.2 Connecting the sensor ...................................................... 24
4.3 Connecting the external indicating instrument VEGADIS 50 26
4.4 Configuration of measuring systems ............................... 27
5 Set-up ........................................................................................ 34
5.1 Adjustment media .............................................................. 34
5.2 Adjustment with PC ............................................................ 34
5.3 Adjustment with adjustment module MINICOM ............... 36
5.4 Adjustment with HART® handheld ................................... 42
6 Diagnosis .................................................................................. 44
6.1 Simulation ............................................................................ 44
6.2 Error codes ........................................................................ 44
7 Technical data .......................................................................... 45
2 VEGAPULS 56K
22915-EN-041227
Contents
7.1 Data ..................................................................................... 45
7.2 Dimensions ......................................................................... 52
7.3 Approvals ........................................................................... 55
Supplement ..................................................................................... 56
Safety Manual ................................................................................. 56
1 General ............................................................................... 56
1.1 Validity ................................................................................. 56
1.2 Area of application............................................................... 56
1.3 Relevant standards ............................................................. 56
1.4 Determination of safety-related characteristics.................. 57
2 Planning .............................................................................. 58
2.1 Low demand mode ..... .......................................................... 58
2.2 High demand or continuous mode ....................................... 58
2.3 General ................................................................................ 58
3 Set-up ................................................................................. 59
3.1 Mounting and installation..................................................... 59
3.2 Adjustment instructions and parameter adjustment ........... 59
3.3 Configuration of the processing unit ................................... 59
4 Reaction during operation and in case of failure ............. 60
5 Recurring function test ....................................................... 60
6 Safety-related characteristics ........................................... 61
SIL declaration of conformity .................................................... 62
CE declaration of conformity ..................................................... 63
Safety information
Please read this manual carefully, and also take
note of country-specific installation standards
(e.g. the VDE regulations in Germany) as well
as all prevailing safety regulations and accident prevention rules.
For safety and warranty reasons, any internal
Note Ex area
Please note the attached safety instructions
containing important information on installation
and operation in Ex areas.
These safety instructions are part of the operating instructions manual and come with the Ex
approved instruments.
work on the instruments, apart from that involved in normal installation and electrical connection, must be carried out only by VEGA
personnel.
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VEGAPULS 56K 3
1 Product description
Level measurement in high temperature processes or of products with high temperatures
was formerly very difficult or even impossible. And if the measurement had to be made
under high pressure, as well, there was practically no measuring system available. Not to
mention a non-contacting system with high
measurement accuracy.
In distillation and stripper columns, levels
(e.g. of sump, plate and head products)
were usually measured indirectly up to now
via pressure transmitters or differential pressure measurements. The installation required
for such pressure measuring systems (pressure lines, pressure transmitters…) is considerable and expensive, often amounting to
several times the value of the sensor itself.
Due to the lack of suitable alternatives, instrumentation departments have not only had to
live with this but also accept high maintenance costs (cleaning of measuring pipes,
errors by condensation, buildup on the diaphragm) as well as inadequate accuracy
(temperature errors, density fluctuations,
installation faults…).
The requirements of the petrochemical industry on a non-contact level sensor are the
following:
• independent of temperature and pressure
• process temperature up to 350°C
• process pressure up to 64 bar
• high resistance wetted parts, materials for
universal use
• accuracy 0.1 %
• rugged metal housing
• Ex-approved (available in EEx d and EEx
ia)
• loop-powered as well as digitally connectable
This state of affairs defines the development
goals for a high-temperature radar level
measuring system, the VEGAPULS 56 series.
The new series represents an innovation in
high temperature radar sensors for level
measurement, in temperatures up to 350°C
and pressures up to 64 bar.
Product description
The sensors would not have been possible
without the new developments in materials
science and production technology. A specially developed ceramic is used as coupling
material. It has high frequency characteristics
similar to those of plastic materials, which are
normally used. But it demonstrates incredibly
high chemical and thermal resistance.
The sensor is connected to the process only
via high-grade, expensive materials. This
refers not so much to the flange of high-alloy
stainless steel (1.4571 or better), as to the
specially developed ceramic (Al2O3) and its
connecting elements. The ceramic rod receives from the high frequency module (from
the intelligent Fuzzy-Logic processing electronics) the radar signals and its coneshaped end operates as emitter and
receiver. The seal between stainless steel
flange and ceramic rod is an expensively
produced tantalum seal ring.
1.1 Function
Radio detecting and ranging: Radar.
VEGAPULS radar sensors are used for noncontact and continuous distance measurement. The measured distance corresponds
to a filling height and is outputted as level.
Measuring principle:
emission – reflection – reception
Extremely small 5.8 GHz radar signals are
emitted from the antenna of the radar sensor
as short pulses. The radar pulses reflected
by the sensor environment and the product
are received by the antenna as radar echoes. The running period of the radar pulses
from emission to reception is proportional to
the distance and hence to the level.
22915-EN-041227
4 VEGAPULS 56K
Product description
Meas. distance
emission - reflection - reception
The radar pulses are emitted by the antenna
system as pulse packets with a pulse duration of 1 ns and pulse intervals of 278 ns; this
corresponds to a pulse package frequency
of 3.6 MHz. In the pulse intervals, the antenna
system operates as a receiver. Signal running periods of less than one billionth of a
second must be processed and the echo
image evaluated in a fraction of a second.
1 ns
Hence, it is possible for the VEGAPULS 56
radar sensors to process the slow-motion
pictures of the sensor environment precisely
and in detail in cycles of 0.5 to 1 second
without using time-consuming frequency
analysis (e.g. FMCW, required by other radar
techniques).
Nearly all products can be measured
Radar signals display physical properties
similar to those of visible light. According to
the quantum theory, they propagate through
empty space. Hence, they are not dependent on a conductive medium (air), and they
spread out like light at the speed of light.
Radar signals react to two basic electrical
properties:
- the electrical conductivity of a substance
- the dielectric constant of a substance.
All products which are electrically conductive
reflect radar signals very well. Even slightly
conductive products provide a sufficiently
strong reflection for a reliable measurement.
All products with a dielectric constant ε
greater than 2.0 reflect radar pulses sufficiently (note: air has a dielectric constant εr of
1).
r
278 ns
Pulse sequence
%
VEGAPULS can achieve this through a special time transformation procedure which
spreads out the more than 3.6 million echo
images per second in a slow-motion picture,
then freezes and processes them.
50
40
30
20
10
5 %
5
0
2
0
25 %
4 6 8 12 14 16 18
10
40 %
20
ε
r
Reflected radar power dependent on the dielectric
t
t
constant of the measured product
Time transformation
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VEGAPULS 56K 5
Product description
Signal reflectivity grows stronger with increasing conductivity or increasing dielectric
constant of the product. Hence, nearly all
substances can be measured.
With standard flanges from DN 50 up to DN
250, ANSI 2“ up to ANSI 10“ the sensor antenna systems are adapted to the various
products and process environments. The
high-quality materials withstand extreme
chemical and physical conditions. The sensors deliver stable, reproducible analogue or
digital level signals with reliability and precision, and have a long useful life.
Continuous and accurate
Unaffected by temperature, pressure and
atmosphere content, VEGAPULS radar sensors measure quickly and accurately the
levels of widely varying products.
%
0,03
0,02
0,01
0
100 500 1000 1300 ˚C
0
0,018 %
Temperature influence: Temperature error absolutely
zero (e.g. at 500°C 0.018 %)
%
10
5
0
10
0
0,8 %
20 30 40 60
50
0,023 %
3 %
70 80 90 110 120 130 140
100
bar
1.2 Application features
Applications
• level measurement of liquids and solids
• measurement also in vacuum
• all slightly conductive materials and all
substances with a dielectric constant > 2.0
can be measured
• measuring range 0 … 20 m
Two-wire technology
• power supply and output signal on one
two-wire cable
• 4 … 20 mA output signal or digital output
signal
Rugged and abrasionproof
• non-contact
• high-resistance materials
Exact and reliable
• accuracy 1 mm
• unaffected by noise, vapours, dusts, gas
compositions and inert gas stratification
• unaffected by varying density and temperature of the medium
• measurement in pressures up to 64 bar
and product temperatures up to 350°C
Communicative
• individual connection, with 15 sensors on
one two-wire cable (digital output signal)
• integrated measured value display
• optional display module separate from
sensor
• connection to all BUS systems: Interbus S,
Modbus, Siemens 3964R, Profibus DP,
Profibus FMS, ASCII
• adjustment from the PLC level
Ex approvals
• CENELEC, FM, CSA, ABS, LRS, GL, LR,
ATEX, PTB
Pressure influence: Error with pressure increase very
low (e.g. at 50 bar 0.8 %)
VEGAPULS 56 sensors now make radar level
measurement possible in plants where it was
hitherto unthinkable.
6 VEGAPULS 56K
22915-EN-041227
Product description
1.3 Adjustment
Every measurement set-up is unique. For
that reason, every radar sensor needs some
basic information on the application and the
environment, e.g. which level means "empty“
and which level "full“. Beside this "empty and
full adjustment“, many other settings and
adjustments are possible with VEGAPULS
radar sensors.
The adjustment and parameter setting of
radar sensors is carried out with
- the PC
- the detachable adjustment module MINICOM
- the HART® handheld
Adjustment with the PC
The set-up and adjustment of the radar sensors is generally done on the PC with the
adjustment software PACT
gram leads quickly through the adjustment
and parameter setting by means of pictures,
graphics and process visualisations.
The PC can be connected at any measuring
site in the system or directly to the signal
cable. It is connected by means of the twowire PC interface converter VEGACONNECT 3
to the sensor or the signal cable.
ware
TM.
The pro-
The adjustment and parameter data can be
saved with the adjustment software on the
PC and can be protected by passwords. On
request, the adjustments can be quickly
transferred to other sensors.
2
2
PLC
Adjustment with the PC on the 4 … 20 mA signal and
supply cable to the PLC or directly on the sensor
+-
2
4 ... 20 mA
2
Adjustment with the PC on the 4 … 20 mA signal and
supply cable to the PLC or directly on the sensor
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VEGAPULS 56K 7
2
2
4 ... 20 mA
Product description
Adjustment with the adjustment module
MINICOM
With the small (3.2 cm x 6.7 cm) 6-key adjustment module with display, the adjustment
can be carried out in clear text dialogue. The
adjustment module can be plugged into the
radar sensor or into the optional, external
indicating instrument.
Tank 1
m (d)
12.345
Detachable adjustment module MINICOM
ESC
+
Tank 1
-
m (d)
12.345
OK
2
4 ... 20 mA
ESC
+
-
OK
Adjustment with the HART® handheld
VEGAPULS series 50 sensors with
4 … 20 mA output signal can also be adjusted with the HART® handheld. A special
DDD (Data Device Description) is not necessary - the sensors can be adjusted with the
HART® standard menus of the handheld.
To make adjustments, simply connect the
HART Communicator
HART® handheld
HART® handheld to the 4 … 20 mA output
signal cable or insert the two communication
cables of the HART® handheld into the adjustment jacks on the sensor.
ESC
+
Tank 1
-
m (d)
12.345
OK
4
Adjustment with detachable adjustment module on the
radar sensor or on the external indicating instrument
VEGADIS 50
HART® handheld on the 4 … 20 mA signal cable
Unauthorised sensor adjustments can be
prevented by removing the adjustment module.
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22915-EN-041227
Product description
1.4 Antennas
The antenna is the eye of the radar sensor.
The shape of the antenna, however, doesn’t
give a casual observer the slightest clue on
how carefully the antenna geometry must be
adapted to the physical properties of electromagnetic waves. The geometrical form determines focal properties and sensitivity - the
same way it determines the sensitivity of a
unidirectional microphone.
Various antenna configurations are available
for different applications and process conditions. Beside the focussing properties, each
is characterised by special chemical and
physical features.
Horn antennas
Horn antennas focus the radar signals very
well. Manufactured of
1.4571 (StSt) or Hastelloy
C22 they are very rugged
and physically as well as
chemically resistant.
Horn antennas are used for
measurement in closed or
open vessels.
Pipe antenna
Pipe antennas on surge or bypass tubes form a complete
antenna system in conjunction
with a measuring pipe (which
can also be bent). Pipe antennas
are best suited for products with
extreme turbulence or products
with low dielectric constant.
The antenna can be configured
with or without horn. Antennas
with horn are characterized by
very high antenna gain - reliable
measurement results are
achieved even in case of products with very bad reflection
properties.
The measuring pipe constitutes
a conductor for radar signals.
The running period of the radar
DN 50
signals changes in the pipe and
depends on the pipe diameter.
The pipe inner diameter must be
programmed into the electronics
so that the running period can
be compensated.
DN 150
DN 80
DN 250
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VEGAPULS 56K 9
2 Types and versions
VEGAPULS 56 are a newly developed generation of very compact high temperature
radar sensors. For the first time it is now
possible to carry out a non-contact level
measurement under high temperatures and
pressures. They bring the benefits of radar
level measurement to applications where
previously, due to extreme process conditions, the special special advantages of radar had to be forgone.
VEGAPULS 56 radar sensors are perfectly
adapted to two-wire technology. They transmit the supply voltage and the output signal
via one two-wire cable. An analogue
4 … 20 mA output signal is available as output or measuring signal.
VEGAPULS 56
DN 150
VEGAPULS 56
DN 50 pipe antenna
VEGAPULS 56
DN 80 pipe antenna
Types and versions
2.1 Type survey
General features
• level measurement on processes and
products under high temperatures and
high pressures
• measuring range 0 … 20 m
• Ex-approved in Zone 1 and Zone 10 (IEC)
or Zone 0 and Zone 20 (ATEX) classification mark EEx ia IIC T6 or
EEx d ia IIC T6
• integrated measured value display
• external measured value display which can
be mounted up to 25 m away in Ex-area
Survey of features
Signal output
– 4 … 20 mA active (four-wire sensor)
– 4 … 20 mA passive (two-wire sensor)
Power supply
– two-wire technology (power supply and
signal output via one two-wire cable)
– four-wire technology (power supply sepa-
rated from the signal cable)
Process fitting
– DN 50; ANSI 2“
– DN 80; ANSI 3“
– DN 100; ANSI 4“
– DN 150; ANSI 6“
– DN 200; ANSI 8“
– DN 250; ANSI 10“
Adjustment
–PC
– adjustment module in the sensor
– adjustment module in the external indicat-
ing instrument
– HART® handheld
Antennas
– horn antenna with stainless steel horn and
ceramic tip
– standpipe antenna with ceramic tip
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;;
;;
;;
;;
;;
;;
;;
;;
;;
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;;
Mounting and installation
3 Mounting and installation
3.1 General installation instructions
Measuring range
The reference plane for the measuring range
of the sensors is the lower edge of the flange.
The measuring range is 0 … 20 m. With
measurements in surge or bypass tubes
(pipe antenna) the max. measuring distance
decreases (see „Technical data - Measuring
range“).
Keep in mind that in measuring environments
where the medium can reach the sensor
flange, buildup may form on the antenna and
later cause measurement errors.
Reference plane
min. meas.
distance
full
min. meas.
distance
full
empty
Measuring
range
min.
min. meas.
distance
empty
max. meas. distance 20 m
Measuring range (operating range) and max. measuring distance
Note: Use of the sensors for applications with solids is limited.
False echoes
If flat obstructions in the range of the radar
Flat obstructions and struts cause strong
false echoes. They reflect the radar signal
with high energy density.
Interfering surfaces with rounded profiles
scatter the radar signals into the surrounding
space more diffusely and thus generate false
echoes with a lower energy density. Hence,
those reflections are less critical than those
from a flat surface.
Profiles with smooth interfering surfaces cause large
false signals
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VEGAPULS 56K 11
signals cannot be avoided, we recommend
diverting the interfering signals with a deflector. The deflector prevents the interfering
signals from being directly received by the
radar sensor. The signals are then so lowenergy and diffuse that they can be filtered
out by the sensor.
Round profiles diffuse radar signals
Cover smooth interfering surfaces with deflectors
Mounting and installation
Emission cone and false echoes
The radar signals are focused by the antenna system. The signals leave the antenna
in a conical path similar to the beam pattern
of a spotlight. This emission cone depends
on the antenna used.
Any object in this beam cone will reflect the
radar signals. Within the first few meters of
the beam cone, tubes, struts or other installations can interfere with the measurement. At a
distance of 6 m, the false echo of a strut has
an amplitude nine times greater than at a
distance of 18 m.
At greater distances, the energy of the radar
signal distributes itself over a larger area,
thus causing weaker echoes from obstructing surfaces. The interfering signals are
therefore less critical than those at close
range.
If possible, orient the sensor axis perpendicularly to the product surface and avoid
vessel installations (e.g. pipes and struts)
within the 100% emission cone. If possible,
provide a "clear view“ to the product inside
the emission cone and avoid vessel installations in the first third of the emission cone.
Optimum measuring conditions exist when
the emission cone reaches the measured
product perpendicularly and when the emission cone is free from obstructions.
Heat insulation
In case of process temperature of more than
200°C an insulation on the rear of the flange is
necessary to keep radiated heat away from
the sensor electronics.
The best would be to incorporate the sensor
insulation into the vessel insulation and insulate up to approx. the first pipe segment.
40°C
60°C
350°C
Heat insulation
100°C 240°C
Vessel insulation
max. 350°C
12 VEGAPULS 56K
22915-EN-041227
Mounting and installation
3.2 Measurement of liquids
Sensor on DIN socket piece
Radar sensors are usually mounted on short
DIN socket pieces. The lower side of the
instrument flange is the reference plane for
the measuring range. The antenna must
always protrude out of the flange pipe.
> 10 mm
Mounting on round vessel tops
Reference plane
Mounting on short DIN socket piece
If the DIN socket piece is longer, please
make sure that the horn antenna protrudes at
least 10 mm out of the socket.
> 10 mm
Mounting on longer DIN socket pieces
On dished vessel tops, please do not mount
the instrument in the centre or close to the
vessel wall, but approx.½ vessel radius from
the centre or from the vessel wall.
Dished tank tops can act as paraboloidal
reflectors. If the radar sensor is placed in the
focal point of the parabolic tank top, the radar
sensor receives amplified false echoes. The
radar sensor should be mounted outside the
focal point. Parabolically amplified echoes are
thereby avoided.
Reference plane
1
/2 vessel radius
When mounting on dished or rounded vessel
tops, the antenna must also protrude at least
10 mm (long socket side).
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VEGAPULS 56K 13
Mounting on round vessel tops
Mounting and installation
Sensor directly on the vessel top
If the stability of the vessel will allow it (sensor
weight), flat mounting directly on the vessel
top is a good and cost-effective solution. The
top side of the vessel is the reference plane.
Reference plane
Mounting directly on flat vessel top
3.3 Measurement in standpipe
(surge or bypass tube)
General instructions
Measurement in a standpipe is preferred in
vessels which contain many installations, e.g.
heating tubes, heat exchangers or fast-running agitators. Measurement is then possible
when the product surface is very turbulent,
and vessel installations can cause no false
echoes.
Due to the concentration of the radar signals
within the measuring tube, even products
with small dielectric constants (εr= 1.6 up to
3) can be reliably measured in surge or by-
pass tubes. Note the following instructions.
Surge pipes which are open at the bottom
must extend over the full measuring range
(i.e. down to 0% level), as measurement is
only possible within the tube.
It is advantageous to mount a deflector at the
tube end. This enables the minimum level of
the product to be reliably detected. This is
particularly important for products with a
dielectric figure < 5.
Marking
hole in the
intermediate flange
Surge pipe in the socket
piece
max.
min.
Surge pipe welded to
the tank
Vent hole
Deflector
Pipe antenna system in the tank
Make sure the required upper vent hole in
the surge pipe is aligned with the marking
hole in the intermediate flange (polarisation
direction of the radar signals).
As an alternative to a surge pipe in the vessel, a pipe antenna system outside the vessel in a bypass tube is also possible.
Please note that when measuring in a surge
or bypass tube, the max. measuring range is
reduced by 5 … 20 % (e.g. DN 50: 16 m
instead of 20 m and DN 100 only 19 m instead of 20 m).
Align the sensor such that the type label lies
on one axis with the tube holes or the tube
connection openings. The polarisation of the
radar signals enables a considerably stabler
measurement with this alignment.
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14 VEGAPULS 56K
;;;
;;;
;
;
;
;
;
Mounting and installation
Marking hole
100 %
;
;
;
;
;
0 %
Tube flange system as bypass tube
Adhesive products
When measuring adhesive products, the the
surge pipe must have a larger diameter. For
non-adhesive products, a 50 mm measuring
tube is a good and cost-effective solution. In
slightly adhesive products, use preferably a
surge pipe with a nominal width of 100 mm or
150 mm so that buildup cannot cause measurement errors. The measurement of extremely adhesive products in a standpipe is
not possible at all.
DN 50
DN 80
ø 50
ø 80
100 %
75 %
DN 100
ø 100
DN 150
ø 150
0 %
Extended bypass tube on a vessel with turbulent
product movements
Pipe antenna with DN 50, DN 80, DN 100 and DN 150
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VEGAPULS 56K 15
Mounting and installation
Standpipe measurement of inhomogeneous products
If you want to measure inhomogeneous or
stratified products in a surge pipe, it must
have holes, elongated holes or slots. These
openings ensure that the liquid is mixed and
corresponds to the liquid in the vessel.
Polarisation direction
Due to radar signal polarisation, the holes or
slots must be positioned in two rows offset
by 180°. The radar sensor must then be
mounted so that the type label of the sensor
is aligned with the rows of holes.
Marking hole
Row of holes in one axis with the marking hole
homogeneous
liquids
slightly inhomogeneous
liquids
Surge pipe with ball valve
If a ball valve is mounted in the surge pipe,
maintenance and servicing can be carried
out without opening the vessel (e.g. if it contains liquid gas or toxic products).
A prerequisite for trouble-free operation is a
ball valve throat that corresponds to the pipe
diameter. The valve must not have rough
edges or constructions in its channel.
inhomogeneous
liquids
Openings in a surge pipe for mixing of inhomogeneous products
very inhomogeneous liquids
The more inhomogeneous the measured
product, the closer the openings should be
spaced.
16 VEGAPULS 56K
Make sure that standpipe ventilation is provided.
22915-EN-041227
Mounting and installation
Ball valve
DN 50
Standpipe ventilation
ø50
Deflector
Correct
Pipe antenna: The surge pipe open to the bottom
must have a ventilation or compensation hole on top
Incorrect
Wrong polarisation direction
When measuring in a surge pipe, especially
when there are holes for mixing, it is important that the radar sensor is aligned with the
rows of holes. The rows of holes of the surge
pipe (displaced by 180°) must be in one
plane with the polarisation direction of the
radar signals. The polarisation direction is the
same plane as the marking hole.
Lockable measuring pipe on a pipe antenna system
Installation errors in standpipe
Missing ventilation hole
Marking
hole
Pipe antenna systems must be provided with
a vent hole at the upper end of the surge
pipe. A missing hole causes wrong measurements.
The polarisation direction is in the same plane as the
marking hole. The sensor must be aligned with the
marking hole to the rows of holes or the openings.
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VEGAPULS 56K 17
;
Guidelines for standpipe construction
Flange DN 50
100 %
Rz ≤ 30
Connecting
sleeve
150…500
Welding neck flange
2,9…6
Welding of the connecting sleeves
5…15
0,0...0,4
Mounting and installation
Radar sensors for measurement on surge or
bypass tubes are used in the flange sizes
DN 50, DN 80, DN 100 and DN 150.
On the left you see the constructional features of a measuring pipe (surge or bypass
tube) as exemplified by a radar sensor with a
DN 50 flange.
The radar sensor with DN 50 flange forms a
functioning measuring system only in conjunction with a measuring pipe.
The measuring pipe must be smooth inside
(average roughness Rz ≤ 30). Use stainless
steel tubing (drawn or welded lengthwise) for
construction of the measuring pipe. Extend
the measuring pipe to the required length
with weld-on flanges or with connecting
sleeves. Make sure that no shoulders or
projections are created during welding. Before welding, join pipe and flange with their
inner surfaces flush and exactly fitting.
Avoid welding through the pipe wall. The pipe
must remain smooth inside. Roughness or
welding beads on the inner surfaces must be
carefully removed and burnished, as they
cause false echoes and encourage product
buildup.
Welding neck
flanges
Deburr the
holes
Deflector
0 %
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
~45˚
Welding of the welding
neck flange
2,9
1,5…2
0,0…0,4
ø 51,2
Vessel bottom
Meas. pipe fastening
Min. product level
to be measured
(0 %)
18 VEGAPULS 56K
22915-EN-041227
Mounting and installation
On the left, you see the constructional features of a measuring pipe as exemplified by
a radar sensor with a DN 100 flange.
Radar sensors with flanges of DN 80,
DN 100 and DN 150 are equipped with a
horn antenna. Instead of the welding neck
flange also a smooth welding flange can be
used on the sensor side of these sensors.
In agitated products, fasten the measuring
pipe to the vessel bottom. Provide additional
fastenings for longer measuring pipes.
Flange DN 100
100 %
Deburr the
holes
Connecting
sleeve
Welding neck
flanges
Rz ≤ 30
Deflector
0 %
2
150…500
ø 96
ø 100,8
~45˚
Smooth welding
neck flange
Welding of the smooth
welding neck flanges
5…15
0,0…0,4
3,6
Welding of the welding
neck flange
3,6
1,5…2
0,0…0,4
Meas. pipe
fastening
Min. product
level to be
measured
(0 %)
With the deflector on the measuring pipe end,
the radar signals are reflected away from the
vessel bottom. This assures that, in nearly
empty vessel and products with low dielectric constants, the medium is detected, not
the vessel bottom. Products with low dielectric constant are penetrated by the signals
and, when the product level is low, allow the
vessel bottom to deliver stronger echoes
than the product surface.
Due to the deflector, the useful signal, and
thus the measurement value, can be clearly
detected in a nearly empty vessel and the
0 % level can be reliably detected.
Vessel bottom
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Mounting and installation
3.4 False echoes
The radar sensor must be installed at a location where no installations or inflowing material
cross the radar pulses. The following examples and instructions show the most frequent
measuring problems and how to avoid them.
Vessel protrusions
Vessel forms with flat protrusions can make
measurement very difficult due to their strong
false echoes. Baffles mounted above these
flat protrusions scatter the false echoes and
guarantee a reliable measurement.
Correct Incorrect
Shield
Vessel protrusions (ledge)
Intake pipes, i.e. for the mixing of materials with a flat surface directed towards the sensor - should be covered with an angled baffle
that scatters false echoes.
Vessel installations
Vessel installations, such as e.g. ladders,
often cause false echoes. Make sure when
planning your measuring location that the
radar signals have free access to the measured product.
Correct Incorrect
Ladder
Vessel installations
Ladder
Struts
Struts, like other vessel installations, can
cause strong false echoes that are superimposed on the useful echoes. Small baffles
effectively prevent a direct reception of false
echoes. These false echoes are scattered
and diffused in the surrounding space and
are then filtered out as "echo noise“ by the
measuring electronics.
Correct Incorrect
Correct Incorrect
Shields
Shield
Vessel protrusions (intake pipe)
20 VEGAPULS 56K
Struts
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Mounting and installation
Strong product movements
Strong turbulence in the vessel, e.g. caused
by powerful agitators or strong chemical
reactions, can seriously interfere with the
measurement. A surge or bypass tube (see
illustration) of sufficient size always enables
reliable and problem-free measurement even
if strong turbulence occurs in the vessel,
provided there is no product buildup in the
tube.
Correct Incorrect
100 %
75 %
0 %
Strong product movements
Products with a tendency to light buildup can
be detected by using a measuring tube with
100 mm nominal width or larger. In such a
measuring tube, light buildup does not cause
any problems.
Correct Incorrect
Buildup
Inflowing material
Do not mount the instrument in or above the
filling stream. Ensure that you detect the
product surface and not the inflowing material.
Correct
Incorrect
Buildup
If the sensor is mounted too close to the
vessel wall, product buildup and other de-
Inflowing liquid
posits on the vessel wall cause false echoes.
Position the sensor at a sufficient distance
from the vessel wall. Please also note chapter
"4.1 General installation instructions“.
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VEGAPULS 56K 21
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