VEGA PULS43 User Manual

Operating Instructions

VEGAPULS 43

4 … 20 mA; HART® compact sensor

Contents

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
2	Types and versions ...................................................................		9
	2.1	Type survey ..........................................................................	9
	2.2	Antenna ...............................................................................	10
3	Mounting and installation .....................................................		11
	3.1	General installation instructions ........................................	11
	3.2	Measurement of liquids .....................................................	14
	3.3	Measurement in standpipe (surge or bypass tube) ......	15
	3.4	False echoes ......................................................................	21
	3.5	Common installation mistakes ...........................................	22
4	Electrical connection ..............................................................		25
	4.1	Connection and connection cable ....................................	25
	4.2	Connection of the sensor ..................................................	27
	4.3	Connection of the external indicating instrument
		VEGADIS 50 .......................................................................	31
	4.4	Configuration of measuring systems ...............................	32
5	Set-up ........................................................................................		40
	5.1	Adjustment media ..............................................................	40
	5.2	Adjustment with PC ............................................................	40
	5.3	Adjustment with adjustment module MINICOM ...............	42
	5.4	Adjustment with HART® handheld ...................................	48
6	Diagnostics ...............................................................................		50
	6.1	Simulation ............................................................................	50
	5.2	Error codes ........................................................................	50
2			VEGAPULS 43 – 4 … 20 mA

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Contents

7 Technical data ..........................................................................		51
7.1	Technical data .....................................................................	51
7.2	Approvals ...........................................................................	56
7.3	Dimensions .........................................................................	57

Supplement .....................................................................................			59
Safety Manual		.................................................................................	59
1	General ...............................................................................		59
	1.1	Validity .................................................................................	59
	1.2	Area of application ...............................................................	59
	1.3	Relevant standards .............................................................	59
	1.4	Determination of safety-related characteristics ..................	60
2	Planning ..............................................................................		61
	2.1	Low demand mode ...............................................................	61
	2.2	High demand or continuous mode .......................................	61
	2.3	General ................................................................................	61
3	Set-up	.................................................................................	62
	3.1	Mounting and installation .....................................................	62
	3.2	Adjustment instructions and parameter adjustment ...........	62
	3.3	Configuration of the processing unit ...................................	62
4	Reaction during operation and in case of failure .............		63
5	Recurring function test .......................................................		63
6	Safety-related characteristics ...........................................		64
SIL declaration of conformity ....................................................			65
CE conformity declaration .........................................................			66

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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 work on the instruments, apart from that involved in normal installation and electrical connection, must be carried out only by qualified VEGA personnel.

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.

VEGAPULS 43 – 4 … 20 mA

3

Product description

1 Product description

Sensors used in the food and pharmaceutical industries must meet very high demands: they must have long-term stability, they must be accurate, robust, easy to set up, chemically resistant and flawlessly hygienic. Many level sensors meet those demands only halfway. Radar sensors, which are otherwise widely used, are not usually found in hygienic and sterile applications because their antennas are difficult to clean. The newly developed VEGAPULS 43 radar sensor was designed especially for areas of application in hygienic and sterile production. Radar sensors are ideal because they operate without touching the medium, are free of wear and ageing, and perform well regardless of pressure (-1 … +40 bar) or temperature

(-40°C … +150°C). The new antenna design of VEGAPULS 43, having no recesses or gaps, presents a smooth surface (like a smooth vessel wall) to CIP and SIP processes. It allows all the methods of modern, environment-friendly system hygiene and has, of course EHEDG, FDA and 3A approvals. The sensor faces the medium only with a small, extremely dense TFM-PTFE surface through which it transmits very small

(0.15 mW) radar pulses. A very fast, intelligent electronics creates from the resulting echoes a precise image of the surroundings and calculates from the pulse running time the level in the vessel every 0.1 s. This value is then outputted as a 4 … 20 mA signal. Compared with the PTFE commonly used in hygienic applications, the improved TFMPTFE has a far denser polymer structure and a noticeably higher surface quality (Ra < 0.8). As a result, proven radar technology is now available for sterile production processes. The spectrum of applications for the new radar sensor is broad and varied: serum production, face cream, fruit juice, etc.

Due to their small housing dimensions and process fittings, the compact sensors are unobstrusive and, above all, cost-effective monitors of your product levels. With their integrated display, they enable highprecision level measurements and can be used for applications in which the advantages of non-contact measurement could never before be realized.

VEGAPULS radar sensors are perfectly adapted to two-wire technology. The supply voltage and the output signal are transmitted via one two-wire cable. The instruments produce an analogue 4 … 20 mA signal as output, i.e. measurement signal.

1.1 Function

Radio detecting and ranging: Radar. VEGAPULS radar sensors are used for noncontact, continuous distance measurement. The measured distance corresponds to a filling height and is outputted as level.

Measuring principle:

emission – reflection – reception

Extremely small 26 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.

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4	VEGAPULS 43 – 4 … 20 mA

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	Product description
		Hence, it is possible for the radar sensors to
		process the slow-motion pictures of the sen-
		sor environment precisely and in detail in
		cycles of 0.5 to 1 second without using time-
		consuming frequency analysis (e.g. FMCW,
	Meas.	required by other radar techniques).
	distance
		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 depend-
		ent on a conductive medium (air), and they
	emission - reflection - reception	spread out like light at the speed of light.
		Radar signals react to two basic electrical
	The radar pulses are emitted by the antenna	properties:
		-	the electrical conductivity of a substance
	system as pulse packages with a pulse
		-	the dielectric constant of a substance.
	duration of 1 ns and pulse intervals of
	278 ns; this corresponds to a pulse package	All products which are electrically conductive
	frequency of 3.6 MHz. In the pulse intervals,
		reflect radar signals very well. Even slightly
	the antenna system operates as a receiver.
		conductive products provide a sufficiently
	Signal running periods of less than one bil-
		strong reflection for a reliable measurement.
	lionth of a second must be processed and
	the echo image evaluated in a fraction of a	All products with a dielectric constant εr
	second.
		greater than 2.0 reflect radar pulses suffi-
		ciently (note: air has a dielectric constant εr of
	1 ns	1). Signal reflectivity grows stronger with
		increasing conductivity or increasing dielec-
		tric constant of the product. Hence, nearly all
	278 ns	substances can be measured.

Pulse sequence										%
										50												40 %
VEGAPULS radar sensors can achieve this
										40
through a special time transformation proce-										30							25 %
dure which spreads out the more than 3.6										20
million echo images per second into a quasi										10			5 %
slow-motion picture, then freezes and proc-										5
										0
esses them.												0					10					20 εr
												2		4	6	8		12	14	16	18
										Reflected radar power dependent on the dielectric
										constant of the measured product
			t				t
Time transformation
VEGAPULS 43 – 4 … 20 mA																						5

				Product description
	With standard flanges of DN 50 to DN 150,		1.2 Application features
	ANSI 2“ to ANSI 6“ or G 1½ A and 1½“ NPT,
	the sensor antenna systems can be adapted		Applications
	to various products and measuring environ-
			•	level measurement of any liquid
	ments.
			• measurement also in vacuum
	The high-quality materials can also withstand		•	all slightly conductive materials and all
				substances with a dielectric constant > 2.0
	extreme chemical and physical conditions.
			• measuring range 0 … 10 m (DN 50).
	The sensors deliver stable, reproducible
				measuring range 0 … 20 m (DN 80, DN
	analogue or digital level signals with reliability
				100, DN 150).
	and precision.
			Two-wire technology
	Continuous and reliable		• power supply and output signal on one
				two-wire cable (Loop powered)
	Unaffected by temperature, pressure and		• 4 … 20 mA output signal or HART® output
				signal.
	atmosphere content, VEGAPULS radar sen-
	sors are used for quick and reliable continu-		Rugged and abrasionproof
	ous level measurement of widely varying		•	non-contact
	products.		•	high-resistance materials

%					Exact and reliable
0,03			0,023 %		• accuracy 0.05 %.
0,02					• resolution 1 mm
		0,018 %
0,01					• unaffected by noise, vapours, dusts, gas
0					compositions and inert gas stratification
0	100	500	1000	1300 ˚C	• unaffected by varying density and tem-
Temperature influence: Temperature error absolutely					perature of the medium
zero (e.g. at 500°C 0.018 %)					• measurement in pressures up to 16 bar
					and product temperatures up to 150°C.

%
10
5										2,8 %				3,89 %
					1,44 %
	0,29 %
0
	10	20	30	40		60	70	80	90		110	120	130	140 bar
0					50					100

Pressure influence: Error with pressure increase very low (e.g. at 50 bar 1.44 %)

Communicative

•integrated measured value display

•optional display module separate from sensor

•adjustment with detachable adjustment module, pluggable in the sensor or in the external display

•adjustment with HART® handheld

•adjustment with the PC.

Approvals

• CENELEC, ATEX, PTB, FM, CSA, ABS, LRS, GL, LR, FCC.

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6	VEGAPULS 43 – 4 … 20 mA

Product description

	1.3 Adjustment	The PC can be connected at any measuring
		site in the system or directly to the signal
	Every measurement set-up is unique. For	cable. It is connected by means of the two-
		wire PC interface converter VEGACONNECT 3
	that reason, every radar sensor needs some
		to the sensor or the signal cable. The adjust-
	basic information on the application and the
		ment and parameter data can be saved with
	environment, e.g. which level means "empty“
		the adjustment software on the PC and can
	and which level "full“. Beside this "empty and
		be protected by passwords. On request, the
	full adjustment“, many other settings and
		adjustments can be quickly transferred to
	adjustments are possible with VEGAPULS
		other sensors.
	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 PACTwareTM. The program leads quickly through the adjustment and parameter setting by means of pictures, graphics and process visualisations.

2

2 PLC

Adjustment with the PC on the 4 … 20 mA signal and supply cable or directly on the sensor (figure: a twowire sensor)

2

4 ...20 mA

2

Adjustment with the PC on the analogue 4 … 20 mA signal and supply cable or directly on the sensor (four-wire sensor)

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VEGAPULS 43 – 4 … 20 mA

7

Product description

Adjustment with the adjustment module MINICOM

The small (3.2 cm x 6.7 cm) 6-key adjustment module with display allows the adjustment to be carried out in clear text dialogue. The adjustment module can be plugged into the radar sensor or into the optional, external indicating instrument.

Adjustment with the HART® handheld

Series 40 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.

Tank 1 - + ESC

m (d)

12.345 OK

Detachable adjustment module MINICOM

Unauthorised sensor adjustments can be prevented by removing the adjustment module.

HART Communicator

HART® handheld

To make adjustments, simply connect the 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.

Tank 1	-	+	ESC
m (d)
12.345			OK

			2	4 ...20 mA
2
		4 ... 20 mA	2
Tank 1	- +	ESC
m (d)
12.345		OK

4

HART® handheld on the 4 … 20 mA signal cable

Adjustment with detachable adjustment module. The adjustment module can be plugged into the radar sensor or into the external indicating instrument VEGADIS 50.

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8	VEGAPULS 43 – 4 … 20 mA

Types and versions

2 Types and versions

2.1 Type survey

VEGAPULS 43 sensors are manufactured with three process connections:

-flange connections (block flanges) in DN 50, 80, 100, 150, ANSI 2“, 3“, 4“, 6“

-TRI-Clamp 2“

-hygienic fitting DN 50.

Survey of features

General features

•Application preferably for liquids in storage tanks and process vessels with increased accuracy requirements.

•Measuring range 0 … 10 m or 0 … 20 m.

•Ex approved in Zone 1 (IEC) or Zone 1 (ATEX) classification mark EEx ia [ia] IIC T6.

•Integrated measured value display.

Survey

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Signal outputs

-active (4 … 20 mA)

-passive (4 … 20 mA, loop powered)

Process fitting, optionally available with

-DN 50; ANSI 2“

-DN 80; ANSI 3“

-DN 100; ANSI 4“

-DN 150; ANSI 6“

-TRI-Clamp (50, 80)

-hygienic fitting (50, 80)

Adjustment

-PC

-adjustment module in the sensor

-adjustment module with external indicating instrument

-HART® handheld

Measuring range
-	DN 50, ANSI 2“	0 … 10 m
-	DN 80, ANSI 3“	0 … 20 m
-	DN 100, ANSI 4“	0 … 20 m
-	DN 150, ANSI 6“	0 … 20 m
-	TRI-Clamp 50, 80	0 … 10 m
- hygienic fitting 50, 80		0 … 10 m
VEGAPULS 43 – 4 … 20 mA		9

Types and versions

2.2 Antenna

Hygienic design

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 hygienic VEGAPULS 43 radar sensors are equipped with an antenna that can be cleaned as easily as a smooth vessel wall. The previously used horn and rod antennas are gone. Only a small coneshaped bulge protrudes into the process vessel. The small cone acts like a lens that focuses the radar signals into a high-fre- quency beam. The relative dielectric constant of the small 140° PTFE cone represents the calculation index of the lens. The visible part of the antenna (small cone), however, does not give a clue as to how precisely the geometrical form of the antenna has to be adapted to the physical properties of electromagnetic waves. The shape governs the focusing of the waves and hence the sensitivity, just as shape governs the sensitivity of a unidirectional microphone. The production of such an electromagnetic lens requires much empirical knowledge in the areas of high-frequency physics and materials science.

Beside the aforementioned geometry necessary for antennas used in the food and pharmaceutical industry, the choice of materials for the newly developed VEGAPULS 43 sensors is critical for cleaning and sterilisation. Fully automatic cleaning (CIP) and sterilisation (SIP) of entire production facilities (without disrupting production or having to dismantle and disassemble parts of the equipment) is, in practice, not an easy task. Dirt and contaminants get trapped mechanically in pores, fissures, scratches and recesses, and even remain on smooth walls due to electrostatic attraction.

PTFE is commonly found in hygienic applications. The small plastic cone of the sterile, pharmaceutical VEGAPULS 43 radar sensor, which is at the same time antenna and process seal, consists of a TFM-PTFE material. This is a fluorothermoplastic which has additional distinct advantages compared to PTFE, such as e.g., reduced load deformation, denser polymer structure as well as smoother surface (Ra < 0.8 µm). The other known advantages of PTFE, such as, e.g., higher temperature resistance (< 200°C), high chemical resistance as well as resistance to brittleness and ageing are still present or have even been enhanced. Perfluorelastomers and fluorthermoplasts are resistant to virtually all chemical media, such as e.g., amines, ketones, esters, acids (sulphuric acid, phosphoric acid, hydrochloric acid, nitric acid), alkalis (caustic soda), oxidants, fuels and oils. Beside their use in the chemical industry, these materials are being applied more and more in sterilisation and pharmaceutical technologies. The only limits to these materials are in applications with fluorine under high pressure or with liquid alkali metals (sodium or potassium), where explosive reactions may occur.

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10	VEGAPULS 43 – 4 … 20 mA

Mounting and installation

3 Mounting and installation

3.1 General installation instructions

Measuring range

The reference plane for the measuring range of the sensor is the lower edge of the flange.

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.

Note: The series 40 sensors are suitable for measurement of solids only under certain conditions.

empty full	Reference plane
	max.
	max.
	Meas.range
	min.

Measuring range (operating range) and max. measuring distance Note: Use of the sensors for applications with solids is limited.

False echoes

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.

If flat obstructions in the range of the radar 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

Profiles with smooth interfering surfaces cause large false signals

Cover smooth, flat surfaces with deflectors

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VEGAPULS 43 – 4 … 20 mA

11

			Mounting and installation
Emission cone and false echoes		If possible, provide a "clear view“ to the
		product inside the emission cone and avoid
The radar signals are focused by the an-		vessel installations in the first third of the
tenna system. The signals leave the antenna		emission cone.
in a conical path similar to the beam pattern		Optimum measuring conditions exist when
of a spotlight. This emission cone depends
on the antenna used. Any object in this beam		the emission cone reaches the measured
cone will reflect the radar signals. Within the		product perpendicularly and when the emis-
first few meters of the beam cone, tubes,		sion cone is free from obstructions.
struts or other installations can interfere with
the measurement. At a distance of 6 m, the		Examples of vessel echoes
false echo of a strut has an amplitude nine
times greater than at a distance of 18 m.
		The following vessel images show a typical
At greater distances, the energy of the radar		echo pattern in a vessel. The example shows
signal distributes itself over a larger area,		a process vessel with a slow double-bladed
thus causing weaker echoes from obstruct-		stirrer. In the lower area, the vessel is
ing surfaces. The interfering signals are		equipped with heating spirals. A thin, angled
therefore less critical than those at close		inlet tube ends in the vessel centre between
range.		the stirrer blades.
If possible, orient the sensor axis perpen-
dicularly to the product surface and keep		Empty vessel
vessel installations (e.g. pipes and struts) out
of the emission cone.
The illustrations of the emission cones are
simplified and represent only the main beam
- a number of weaker beams also exist. Un-
der difficult measuring conditions, the an-
tenna location and alignment must be chosen
with the objective of reducing false echoes.
Only giving attention to the size of the useful
echo is not adequate when measuring condi-
tions are unfavourable.
In a difficult measuring environment, search-
ing for a mounting location with the lowest
possible false echo intensity will bring the
best results. In most cases, the useful echo
will then be present with sufficient strength.
With the adjustment software PACTwareTM on			When the vessel is empty, you see the ech-
the PC, you can have a look at the echo im-			oes of the vessel installations around the
age and optimise the mounting location.			emission cone. Beside the large bottom echo,
			you see a number of additional false echoes.
			The false echoes of the vessel installations
			are saved during a false echo recording. For
			this reason, the false echo recording must be
			carried out when the vessel is empty.

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12	VEGAPULS 43 – 4 … 20 mA

Mounting and installation

False echoes from the top down:		The product echo moves to the centre of the
-	first inlet tube fastening	meas. range. At the end of the meas. range,
-	upper stirrer blade	you now see an echo at a position where the
-	second inlet tube fastening	bottom echo previously was in the empty
-	angled inlet tube	vessel. This echo is a multiple echo of the
-	upper heating tubes	product echo and is located at twice the
-	lower stirrer blade	distance of the product echo.

-remaining heating tubes

-vessel bottom

Filled vessel

¼ filling

After filling, the bottom echo is replaced by the product echo.

½ filling

When the vessel is completely filled, you see additional multiple echoes at two, three or four times the distance of the product surface echo.

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VEGAPULS 43 – 4 … 20 mA

13

			Mounting and installation
	3.2 Measurement of liquids		The flange screws of VEGAPULS 43 must
			always be tightened with a torque of approx.
	Flange antenna		60 Nm so that the PTFE seal is tight.
	Horn antenna on DIN socket piece		Dished tank tops can act as paraboloidal
			reflectors. If the radar sensor is placed in the
	Radar sensors are usually mounted on short
			focal point of the parabolic tank top, the radar
	DIN socket pieces. The lower side of the
			sensor receives amplified false echoes. The
	instrument flange is the reference plane for
			radar sensor should be mounted outside the
	the measuring range. The socket piece
			focal point. Parabolically amplified echoes are
	should be as short as possible.
			thereby avoided.

max.	d	h max.
	50 mm/2"	100 mm
h	80 mm/3"	150 mm
	100 mm/4"	250 mm
	150 mm/6"	400 mm
	d

Deviating socket dimensions

Horn antenna 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.

Mounting on a block flange is especially advantageous. Due to its very shallow recess, it is an ideal solution also for hygienic and aseptic applications.

> 400 mm

Mounting on dished tank end

In vessels with dished or rounded tops, please do not mount the instrument in the centre or close to the vessel wall.

14

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Mounting and installation

	3.3 Measurement in standpipe	Make sure the required upper vent hole in
	(surge or bypass tube)	the surge pipe is aligned with the sensor
		type label.
	General instructions	As an alternative to a surge pipe in the ves-
	Measurement in a standpipe is preferred in	sel, a pipe antenna system outside the ves-
		sel in a bypass tube is also possible.
	vessels which contain many installations, e.g.
		The surge and bypass tubes must generally
	heating tubes, heat exchangers or fast-run-
		be made of metal. For plastic tubes, a
	ning stirrers. Measurement is then possible
		closed, conductive jacket is always required.
	when the product surface is very turbulent,
		When using a metal tube with plastic inner
	and vessel installations can cause no false
		coating, make sure that the thickness of the
	echoes.
		coating is minimal (approx. 2 … 4 mm).
	Due to the concentration of the radar signals	Align the sensor so that the type label lies on
	within the measuring tube, even products
		the same axis as the tube holes or the tube
	with small dielectric constants (εr= 1.6 up to
		connection openings. The polarisation of the
	3) can be reliably measured in surge or by-	radar signals enables a considerably stabler
	pass tubes.
		measurement with this alignment.

Surge pipe welded	Surge pipe in the
to the tank	socket piece
Type label
max	max
Vent hole
ø 5 … 10 mm
min	min
without deflector	with deflector

Pipe antenna system in the tank

Type label

> 300 mm

100 %

0 %

Tube flange system as bypass tube

When mounting a VEGAPULS 43 on a bypass tube (e.g. on a previous floating or displacer unit), the radar sensor should be placed approx. 300 mm or more from the max. level.

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. The tube inner diameter should be max. 100 mm or correspond to the size of the antenna horn.

VEGAPULS 43 – 4 … 20 mA

15

			Mounting and installation
	For products with small dielectric constants	Connections to the bypass tube
	(< 4), the bypass tube should have a length
	greater than would normally be required for	The connections to the bypass tubes must
	the lower tube connection. Products with
		be fashioned in such a way that only minimal
	small dielectric constants are partly pen-
		reflections are caused by the walls of the
	etrated by the radar signals, allowing the
		connecting tubes. This is especially important
	tube bottom to produce a stronger echo than
		for the breather connection in the upper part
	the product (when the bypass tube is nearly
		of the tube. Observe the following points:
	empty). By extending the tube downward,
		•	Use small openings for the connection.
	some liquid remains at the bottom even when
		•	The diameter of the connecting tubes
	the vessel is completely empty.
			should not exceed 1/3 of the bypass diam-
			eter.
		•	The tube connections must not protrude
	Type label		into the bypass tube.
		• Large welding beads in the tubes should
			be avoided.
	> 300 mm	•	Additional connections to the bypass tube
			must lie in the same plane as the upper
	100 %		and lower vessel connection (above each
			other or displaced by 180°).
	0 %
	300 ... 800 mm
	Tube flange system as bypass tube
	If enough liquid (300 … 800 mm) remains in
	the blind lower end of the tube, the portion of
	the signal that penetrates the liquid and re-	Optimum connection to the bypass tube
	flects from the tube bottom is sufficiently
	damped - the sensor can then easily distin-
	guish it from the echo of the liquid surface. In
	cases where there is not enough liquid at the
	bottom of the tube, a deflector situated there
	will carry out the same function. It deflects
	signals that reach the tube bottom into the
	standard connection opening.
		Welding beads too large

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16	VEGAPULS 43 – 4 … 20 mA

Mounting and installation

Tube connection protrudes

Additional connection in the bypass tube in one plane

Use of guide tubes

In case of very rough inner surfaces in existing bypass tubes (e.g. due to corrosion), large connecting tube openings, as well as bypass tubes with more than 100 mm inner diameter, the use of a guide tube inside the existing bypass tube is recommended. This reduces the noise level and increases measurement reliability considerably. The flange of the guide tube can be easily mounted as a sandwich flange between vessel and sensor flange.

Guide tube

Guide tube in existing surge or bypass tubes

To increase the min. distance, the guide tube can project out of the surge or bypass tube. This can be done by welding a flat welding flange on the outside of the extended guide tube. In both cases, an appropriate breather hole is necessary.

Extended guide tube

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VEGAPULS 43 – 4 … 20 mA

17

Seals on tube connections and tube extensions

Microwaves are very sensitive to gaps in flange connections. If connections are made without proper care, distinct false echoes as well as increased signal noise can result. Observe the following points:

•The applied seal should correspond to the tube inner diameter.

•If possible, conductive seals such as conductive PTFE or graphite should be used.

•There should be as few seal positions as possible in the guide tube.

Flange connections on bypass tubes

Adhesive products

With non-adhesive or slightly adhesive products, use a surge pipe with a nominal width of e.g. 50 mm. VEGAPULS 43 radar sensors with 26 GHz technology are for the most part insensitive to buildup in the measuring tube. Nevertheless, buildup should not block the measuring tube.

For products with somewhat heavier buildup, the use of a DN 80 to max. DN 100 standpipe or surge pipe can make measurement possible despite buildup. But with extremely adhesive products, measurement in a standpipe is not possible at all.

18

Mounting and installation

Standpipe measurement of inhomogeneous products

				...ø 5	15

homogeneous			slightly inhomogeneous
liquids			liquids
								ø 5...15

inhomogeneous liquids

Openings in a surge pipe for mixing 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.

The more inhomogeneous the measured product, the closer the openings should be spaced.

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.

Every wider slot causes a false echo. The slots should therefore not exceed a width of

10 mm in order to keep the signal noise level

to a minimum. Round slot ends are better 26626 than rectangular ones. - EN-041227

VEGAPULS 43 – 4 … 20 mA

Mounting and installation

Type label

		...ø 5	15

Row of holes in one axis with the type label

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).

Ball valve

> 300 mm

Vent hole

ø50

	Deflector
	Tube antenna system with ball valve cutoff in measur-
	ing tube
	A prerequisite for trouble-free operation is a
	ball valve throat that corresponds to the pipe
	diameter and provides a flush surface with
	the pipe inner wall. The valve must not have
041227-EN-26626	any rough edges or constrictions in its chan-

nel. The distance to the sensor flange should be at least 300 mm.

VEGAPULS 43 – 4 … 20 mA

Guidelines for standpipe construction

The radar sensors with a DN 50 flange only form a functioning measuring system in conjunction with a measuring tube.

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 adhesion.

If the vessel contains agitated products, fasten the measuring pipe to the vessel bottom. Provide additional fastenings for longer measuring pipes.

In products with lower dielectric values (< 4), a part of the radar signal penetrates the medium. If the vessel is nearly empty, echoes are generated by both the product and the vessel bottom. The echo from the vessel bottom can in some cases be stronger than the echo from the product surface. If a deflector is installed below the open end of the measuring tube, the radar signals are scattered and prevented from reaching the vessel bottom. This ensures that, in nearly empty vessels or with products of low dielectric value, the product delivers a more distinct echo than the vessel bottom.

Due to the deflector, the useful echo (and thus the measured value) remains clearly detectable in a nearly empty vessel, and the 0 % level can be reliably measured.

19

Mounting and installation

Flange
DN 100
Deburr the
holes
2	ø 95
	5…10

150…500

	Connecting	3,6
	sleeve
	Welding neck
	flanges
		3,6

Welding of the smooth welding flange

100 %

Welding of the connecting sleeves

0,0…0,4

Welding of the welding neck flanges

1,5…2

0,0…0,4

The standpipe or surge pipe can be equipped with a quadrant pipe at its end instead of a deflector. The quadrant pipe reflects the radar signals that penetrate the medium diffusely to the side and diminishes strong echoes from the tube end or the vessel bottom.

0 %

Quadrant pipe on the bypass tube end

0 %

Quadrant pipe on the standpipe end

	ø 100,8
Deflector		Meas. pipe fastening
0 %		Vessel
	~45û	bottom

041227-EN-26626

20	VEGAPULS 43 – 4 … 20 mA

26626-EN-041227

Mounting and installation

3.4 False echoes

Vessel installations

The radar sensor must be installed at a location where no installations or inflowing material cross the radar impulses. 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

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.

Correct

Incorrect

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

Ladder

Vessel installations

Struts

Struts, like other vessel installations, can cause strong false echoes that are superimposed on the useful echoes. Small baffles effectively prevent a direct false echo reception. 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

Shields

Struts

Vessel protrusions (intake pipe)

VEGAPULS 43 – 4 … 20 mA

21