DE102015122542A1 - Field device of process measuring technology - Google Patents

Abstract

A process measuring field device comprising a vibration-type sensor (15, 36) for determining a viscosity, a density and / or a size of a fluid medium contained in a container and / or a pipeline, wherein the sensor (15, 36) also has a Sensor arrangement (14, 31) with at least two sensor elements, in particular two electrodes (7, 25, 26), which sensor arrangement (14, 31) detects measured values for determining a resistance of the medium between the two sensor elements in a first operating mode and which in a second operating mode measured values for determining a reactance of the medium between the two sensor elements detected.

Description

The invention relates to a field device of process measuring technology with a vibration-type sensor according to the preamble of claim 1.

Field instruments of process measurement with a vibration sensor and especially Coriolis flowmeters have been known for many years. The basic structure of such a measuring device is, for example, in the EP 1 807 681 A1 In the context of the present invention, reference is made in full to the structure of a generic field device in the context of the present invention. This measuring technology and corresponding measuring devices have been extensively described by the applicant in numerous other patent applications.

Typically, Coriolis flowmeters have at least one or more vibratable tubes which can be vibrated by means of an exciter. These vibrations are transmitted over the pipe length and are varied by the type of flowable medium in the pipe and its flow rate. A sensor, or in particular two sensors spaced apart from one another, can receive the varied oscillations in the form of a measuring signal or a plurality of measuring signals at another point on the tube. An evaluation unit can then determine the flow and / or the density of the medium from the measurement signal (s)

Respective exciters and / or sensors are usually based on an electro-dynamic principle and are usually constructed in several parts and include a magnet-generating unit for generating a magnetic field and a coil penetrated by this magnetic field. This coil is usually made of wire and is wound on a bobbin, typically a cylindrical bobbin. This technology has proven itself in principle.

Field devices with sensors of the vibration type can also be designed as level gauges. For many years Endress and Hauser have distributed products under the name "Liquiphant". Typical of this type of level gauges is a diaphragm from which protrude two fork arms of a fork-shaped element with opposite flat surfaces in the direction of the medium. The membrane and thus also the bifurcated element is transmitted via ultrasonic transducers, e.g. a so-called bimorph driven to vibrate, these vibrations being damped depending on the density and / or viscosity of the medium between the fork arms. This vibration damping can be detected metrologically and can be used to determine the viscosity and / or the density of the medium.

Heterogeneous liquid media, in particular dispersions and / or suspensions, can be characterized by determining the density and by rheological measurements. For polar liquid media, in particular for aqueous or alcoholic systems, with proportions of ionic compounds, however, this characterization is not sufficient. It should be noted that the time stability of aqueous dispersions and suspensions is highly dependent on the ionic constituents. For a quality determination in these cases the measurement of the density and the rheological properties are insufficient.

The DE 10 2013 200 685 A discloses a Coriolis flowmeter with a device for measuring the electrical conductivity for checking a filling state of the tube. However, only the effective resistance is determined here. A consideration of the medium temperature is also not in this conductivity measurement and is not required.

The object of the present invention is therefore to provide a field device of process measurement technology which makes it possible in a compact manner to determine both the density or viscosity of a medium and the proportions of ionic compounds.

The invention achieves this object by providing a field device having the features of claim 1.

A field device according to the invention of process measuring technology comprises a vibration-type sensor for determining a viscosity, a density and / or a size of a fluid medium contained in a container and / or a pipeline, wherein the sensor additionally has a sensor arrangement with at least two sensor elements. These may be preferably, but not exclusively, two electrodes.

In a first operating mode, the sensor arrangement is set up to detect measured values for determining a resistance of the medium between the two sensor elements and to acquire measured values for determining a reactance of the medium between the two sensor elements in a second operating mode. The terms of the reactance and reactance refer in the context of the present invention to electrical resistances.

The impedance of a liquid medium can be determined from the effective resistance and the reactance. In this case, the effective resistance is dependent on the frequency and the ion concentration in the liquid medium. The ionic portions can be characterized integrally. The dielectric components of the medium, eg also colloids or sedimented solids, can be taken into account by the reactance.

Further advantageous embodiments of the invention are the subject of the dependent claims.

The field device may comprise a transmitter for determining the viscosity, the density and / or a quantity derivable therefrom, wherein the effective resistance and the reactance of the medium and / or an impedance of the medium comprising the active and the reactance by this transmitter from those in the first and in the second operating mode detected measured values is determined. Thus, for example, only one transducer is needed to determine both the density and the impedance of the medium, whereby a compact field device is feasible.

The transmitter, in particular a computing unit of the transmitter can be advantageously equipped such that a comparison of the determined active and reactive resistance and / or the impedance of the medium with at least one desired value, taking into account the medium temperature is feasible. The comparison of the active and reactive resistance is to be carried out with at least one reference value. The medium temperature can advantageously be determined by the field device itself or determined by one with an external sensor and fed to the field device. The setpoint may preferably be stored on a data memory which is part of the transmitter.

It is also advantageous if the transmitter can also be equipped to perform a comparison of a determined viscosity, density and / or the size of the medium derived therefrom with a predetermined desired value. Analogously, the arithmetic unit and the data memory can also be used for this purpose.

The field device can advantageously be designed as a Coriolis flow and / or Coriolis density meter and / or as a level gauge, in particular with a forked medium-contacting element. Thereby, a determination of further useful measurands, e.g. flow or level with one and the same compact meter. Corresponding flow and level measuring devices are well known to a person skilled in the art of process measurement technology.

In order to achieve a temperature measurement as close as possible to the location of the measurement of the active and reactive resistance, the sensor arrangement can advantageously have a temperature sensor for determining the temperature of the medium.

To protect the temperature sensor against mechanical and / or chemical influences, the sensor arrangement can have at least one electrode in which the temperature sensor is arranged. The electrode can preferably be used as a sensor element for measuring the effective resistance and / or the reactance.

The sensor can advantageously have a medium-contacting metallic wall. This can e.g. in the case of a Coriolis flowmeter, a fluid-carrying pipe section or, in the case of a level gauge, a rod-shaped housing which connects the sensor to the transmitter. In a particularly preferred embodiment, a channel may extend obliquely, in particular perpendicular to the longitudinal axis of the rod-shaped housing through this housing. The sensor arrangement can advantageously be arranged in the wall and be electrically insulated from this wall by an insulation. As a result, a signal transmission between the two sensor elements for determining the effective resistance and / or the reactance is prevented by the metallic wall or a measuring interference avoided.

The sensor arrangement may have at least two sensor elements for detecting the active resistance and the reactance, preferably two electrodes, which are advantageously operated in at least the second operating mode for determining the reactance with alternating current, while they are preferably operated in the first operating mode for determining the effective resistance with direct current. This approach advantageously allows a robust and low-interference measurement.

The transmitter of the field device is advantageously designed to modulate the frequency of the alternating current, wherein the sensor arrangement detects a reactance for each frequency. Since the reactance is frequency-dependent, a spectrum can be recorded by the frequency modulation, so that even difficult-to-detect constituents of a dispersion or suspension can be detected and quantified.

The transmitter can, as previously described, have a data memory. On this data storage can advantageously a record of resistances and / or reactances of at least one medium or more media be deposited advantageously at different temperatures.

The sensor arrangement can have only three sensor elements, in particular two electrodes and a temperature sensor, in an advantageous design-simple design, wherein the sensor arrangement determines the effective resistance of the medium between the two electrodes in a first operating mode and wherein the sensor arrangement in a second operating mode the reactance of the medium determined between the sensor elements. The operating modes are operated alternately, ie not at the same time, so that the sensor arrangement is operated in the first operating mode when the second operating mode does not take place and vice versa.

Alternatively, the sensor arrangement can have at least two first sensor elements, in particular two electrodes, for determining the effective resistance and at least two second sensor elements, in particular two further electrodes, for determining the reactance, the first and second operating states taking place simultaneously. This allows for time savings and short response times.

In the context of the present invention, the term "electrodes" does not only comprise rod-shaped electrodes, but may also include, for example, electrodes with plate-shaped sub-segments, preferably analogously to a plate capacitor.

It is furthermore advantageous if a data set for the effective resistance, the reactance, the impedance, the viscosity and / or the density of the medium for different binary mixtures is stored in the data memory of the transmitter at different concentrations of the two components.

For binary mixtures or binary mixtures, for example, individual of the aforementioned measured variables can be stored as concentration tables on the data memory. Each of the aforementioned measured quantities is able to provide information about the concentration present. By comparing the concentration values on the sensor elements to determine the density and the impedance, the respective determined concentration data can be compared or validated. In the event of a deviation from a setpoint, it can be concluded that there are deviations in the process or in the measuring system.

An example of this would be the concentration measurement in Clean in Place (CIP) processes. In the storage tanks for lye and acid, the concentrations must be determined. If the concentration is too low, it must be concentrated. The safe determination of concentration and the checking for impurities (for example, whether acid has penetrated into the leach tank) can be carried out by a level gauge in an aforementioned embodiment of the invention. This ensures a safe exclusion of the CIP medium from the production process, which is relevant for food safety, for example.

In a method according to the invention, the field device according to the invention can be used for the determination of dissolved and undissolved portions of a suspension or dispersion and operated accordingly in the abovementioned operating modes.

In particular, one or more phases of a multiphase mixture, which are detectable by the field device, belong to the undissolved components of a mixture. This includes, for example, oil droplets in water.

The determination of the two resistors or the impedance can additionally be used to monitor compliance with the operating parameters of a state defined according to the device specification. This may include, for example, the exceeding of a permissible medium temperature.

In addition, in a further embodiment, the sensor arrangement can have a pH sensor for determining the pH of the medium. Such applications are particularly necessary in the food industry and can be integrated in a compact manner in the field device, however, however, the implementation of a pH sensor increases the evaluation effort of the field device. Overall, an advantageous arrangement of the pH sensor and the temperature sensor in a sensor arrangement is recommended.

The invention will be explained in more detail with reference to several embodiments and with the aid of the accompanying figures. Show it:

1 a schematic partially sectioned perspective view of a field device according to the invention in the embodiment of a Coriolis flowmeter;

1a Part of an electrode for determining the electrical conductivity of a medium with integrated temperature sensor; and

2 schematic representation of a field device according to the invention in the embodiment of a level gauge.

The measuring principle of a Coriolis flowmeter is briefly discussed below with reference to a two-pipe Coriolis flowmeter. However, it is also known, for example, monotube or 4-pipe Coriolis flow meters, which are also included in the context of the present invention. In addition, Coriolis density meters are known which only determine the viscosity and / or the density of a medium, but not the flow. These devices can be manufactured on the basis of a MEMS chip, for example, and can be provided, for example, as a bypass to a pipeline.

The measuring principle is based on the controlled generation of Coriolis forces. These forces occur in a system whenever simultaneous translational (rectilinear) and rotational (rotating) movements overlap. The size of the Coriolis force depends on the moving mass, its velocity in the system and thus on the mass flow. Instead of a constant rotational speed, an oscillation occurs at the sensor.

In the case of the measuring sensor, two parallel measuring tubes through which the medium flows are oscillated in antiphase to form a kind of tuning fork. The Coriolis forces generated at the measuring tubes cause a phase shift of the tube oscillation. At zero flow, ie at standstill of the medium, both tubes oscillate in phase. At mass flow, the pipe vibration is delayed on the inlet side and accelerated on the outlet side. The larger the mass flow, the greater the phase difference of the two oscillating measuring tubes. By means of electrodynamic sensors, the tube vibration is tapped on the inlet and outlet side. The system balance is achieved by the mutual vibrations of the two measuring tubes. Basically, the measuring principle works independently of temperature, pressure, viscosity, conductivity and flow profile.

In addition to the mass flow, a density measurement of the medium is also possible. The measuring tube is excited at its resonance frequency. As soon as the mass and thus the density of the oscillating system, ie the measuring tube and the medium changes, the excitation frequency is readjusted. The resonance frequency is thus a function of the density of the medium. Because of this dependence, e.g. gain a density signal by means of a microprocessor.

The mass flow and the density can also be used to determine a volume flow.

For computational compensation of temperature effects, the temperature at the measuring tube can be detected. This signal corresponds to the process temperature and is also available as an output signal.

An inventive measuring device is exemplary in 1 as a Coriolis meter 1 shown. This in 1 shown measuring device is shown as a two-pipe variant. In this case, a medium through two mutually parallel tubes 2 passed, which in a sensor housing 5 are arranged. The sensor housing 5 has an elongated structure and has flanges for connection to a process line at two terminal positions. In addition, the meter preferably has a transmitter 4 or a transmitter, in which an evaluation unit is arranged.

From the above description of the measuring principle, it follows that a pipe through which a medium flows 2 first by a pathogen 3.II must be vibrated. And finally, the vibration frequency and / or vibration amplitude of a pipe 2 through sensors 3.I and 3.III detected.

In 1 are the causative agent 3.II and the sensors 3.I and 3.III identical design as a sensor / exciter unit and shown in a magnification.

The pipes 2 each have a bend, wherein the pathogen 3.II is arranged in the middle of the bend, relative to the longitudinal direction of the tubes, and a respective first sensor 3.I for detecting the vibrations of the tube 2 in a flow direction R before and a second sensor 3.III for detecting the vibrations of the tube 2 in a flow direction R behind the pathogen 3.II is arranged. This distance of both sensors 3.I and 3.III to the pathogen 3.II is preferably the same size. However, there are also known Coriolisessgeräte, which are designed as pipes without a corresponding bend.

The exciter and / or the receiver can operate, for example, according to the magnetic-inductive principle and a relative movement of the two tubes 2 to each other or the relative movement of a respective tube in the sensor housing 5 determine or set the measuring tubes in motion.

The Coriolis flowmeter can then by means of a flange 10 be connected to a process line, not shown.

How out 1 can be seen, the Coriolis flowmeter has a tubular inlet area 9 in which a flow division of the medium in the two tubes 2 he follows. Of the Inlet region may be made of metal and is in a flow direction R at the inlet ends of the tubes 2 arranged.

The entirety of the pipes 2 , the entry area 9 , the outlet area, as well as the sensors 3.I and 3.III as well as the pathogens 3.II form the transducer of the vibration type 15 of the Coriolis flowmeter.

In this inlet area 9 are two sensor elements in the form of two electrodes 7 arranged, with which a measurement can be made in terms of a resistance and a reactance of the medium, which is located between the two sensor elements. Alternatively, the arrangement of the electrodes can also be arranged in an outlet region.

In 1 are the electrodes 7 diametrically opposed to each other at the pipe circumference of the inlet region 9 arranged. However, it is also possible to position the electrodes next to one another with a small spacing, for example with electrode axes running parallel to one another.

The resistance of the medium can be known by the formula R = U / I where U is the voltage between the electrodes and I is the current between the electrodes.

The reactance can be determined by the formula Xc = 1 / 2π · f · C , where f is the frequency of an alternating current and C is the capacitance of the capacitor, ie the capacitance between the two electrodes. The electrodes are made of a conductive material, such as a metal or graphite. You can through an electrical insulation 11 , For example, a plastic sleeve, in the wall of the tubular inlet region 9 be introduced. Alternatively or additionally, at least the inlet region is provided at least in regions with an electrically insulating lining.

As an alternative to the variant with the two electrodes, only one electrode can be provided, which in conjunction with one between the flange 10 and the process line arranged ring electrode allows measurement of the active and the reactance of the medium

The at the electrodes 7 The determined impedance of the medium as the sum of the effective resistance and the reactance of the medium is transmitted by a measuring and evaluation unit. In addition, a temperature sensor for determining the temperature of the medium is arranged in the electrodes or outside the electrodes. The electrode 7 can be used as an electrode cup 7a be formed, as in the detailed representation 1a is shown. Arranged therein is the temperature sensor 12 ,

The entirety of the two electrodes 7 and the temperature sensor 12 form a sensor arrangement 14 ,

From the pathogens and sensors 3.I to 3.III go signal lines to a transmitter 6 from. This transmitter has a data memory, not shown, and a processing unit.

From the electrodes 7 In addition, one or more signal lines are used to determine the active and reactive resistance of the medium 8th to the transmitter 6 from.

From the temperature sensor 12 also goes a signal line 13 to the transmitter 6 from.

The 2 shows an exemplary level measuring device 21 for determining and / or monitoring a filling level in particular a container or at least individual components of such a level measuring device.

Level measuring devices for determining and / or monitoring a level in a pipeline or a container are known in various configurations. In particular, there are level measuring devices with a vibratable membrane, which is arranged in a rigid membrane edge. The membrane edge can also be part of a housing or be firmly connected to a housing of the level measuring device. Usually, such fill level measuring devices have a drive device which serves to vibrate the membrane with a drive end face of the drive device and / or serves to absorb a vibration of the membrane and to convert it into an electrical signal. In order to make this possible, such level measuring devices usually provide a fastening device for fastening the drive device to the membrane edge or rigidly connected to the membrane edge relative to the diaphragm edge on the housing.

In a manner known per se, the in 2 illustrated level measuring device 21 from a membrane 28 , which with their membrane edge 29 in a housing 30 is determinable. The membrane 28 is of the rigid membrane edge 29 surrounded, with the membrane 28 but remains capable of oscillating. In the front direction, the membrane 28 a vibrating body in the form of, for example, a fork 23 which serves as an antenna for transmitting vibrations of the membrane 28 serves in the front environment and at the same time as a receiver for vibrations from the front environment for transmission to the membrane 28 serves. In the back direction of the membrane 28 is a drive device 22 arranged, which against the membrane 28 is curious to mechanical vibrations of the drive device 22 on the membrane 28 or in the opposite direction.

In the drive device 22 it may be a so-called bimorph drive with one or more piezo bending transducer. Details of the drive, for example, the EP 2 031 359 A1 be taken over.

In this case, the entirety of the membrane 28 , the oscillating body, in particular the fork 23 and the drive device 22 a vibration type sensor 36 ,

As is known, with the above-described level measuring device 21 not only the level, but also the viscosity and / or the density of the medium are determined, which is in contact with the vibrating body.

The housing 22 is rod-shaped and extends at least up to a sensor arrangement 31 in the container, not shown, or the pipeline. This sensor arrangement 31 is located in one through the housing 22 extending tubular channel.

Within the channel are two sensor elements in the form of electrodes 25 and 26 , For example, as a metal or graphite, arranged to measure the resistance and the reactance of the medium, which is in the channel 24 located.

The wall of the canal 24 may preferably be made of metallic material or a plastic material. In the case of a metallic material, insulation is between the wall of the channel 24 and the respective electrode 25 or 26 intended.

In addition, in the channel 24 also a temperature sensor 27 be arranged to determine the medium temperature. Alternatively, in one of the electrode 25 or 26 the temperature sensor can be arranged. This can be done analogously to the in 1a illustrated embodiment variant.

From the drive device 22 and the sensor assembly 31 go each signal lines 32 - 34 to a transmitter 35 from. This transmitter 35 includes analog to the transmitter of 1 a data storage and a computing unit. In this case, a first signal line is used 32 the transmission of a measurement signal for determining the viscosity and is assigned to the drive unit. A second signal line 33 is used to transmit a measurement signal to determine the effective resistance and / or the reactance of the medium and is one or more of the electrodes 25 and or 26 assigned. A third signal line 34 is used to transmit a measurement signal to determine the temperature of the medium and is the temperature sensor 27 assigned.

The in 1 and 2 illustrated transmitter 26 or 35 also has further optional components, eg an input unit and / or an output unit, in particular in the form of a display.

The transmitter 26 and 35 may comprise a data set relating to the temperature and the viscosity and to the temperature and the impedance or the reactance and reactance of the medium or of several media. It can then undergo quality testing of the medium by comparing a setpoint for the viscosity of the medium and the electrical conductivity of the medium or a size in which the two aforementioned variables occur at a predetermined temperature.

The determined values or the setpoint value for the viscosity and / or density as well as for the impedance and / or the effective resistance and the reactance can then be adapted to each other by means of the current medium temperature and compared with each other. In the case of larger deviations, an issue can be issued with regard to a qualitative change of the medium.

The qualitative change relates in particular to dispersions and / or suspensions. In this case, a determination of dissolved and undissolved components or components in the dispersion and / or suspension can preferably take place.

The measurement of the effective resistance may be in a preferred range of 0.3 to 250 MHz. respectively.

The measurement of reactance may be in a preferred range of 0.2 to 80 GHz.

The present invention is not based on the in 1 and or 2 illustrated embodiments, but includes a variety of other variants.

The field device according to the invention requires little maintenance and only needs to be calibrated after operation of very long time intervals.

LIST OF REFERENCE NUMBERS

1

 Coriolismessgerät

2

 pipe

3.I

 sensor

3.II

 pathogen

3.III

sensor

5

 casing

6

 transmitters

7

 Electrodes for determining the electrical conductivity

7a

 sensor cup

8th

 signal line

9

 intake area

10

 flange

11

 insulation

12

 temperature sensor

13

 signal line

14

 sensor arrangement

15

 Vibration-type transducers

R

flow direction

21

 level meter

22

 driving means

23

 fork

24

 channel

25, 26

 electrode

27

 temperature sensor

28

 membrane

29

 membrane edge

30

 casing

31

 sensor arrangement

32

 signal line

33

 signal line

34

 signal line

35

 transmitters

36

 Vibration-type transducers

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1807681 A1 [0002]
• DE 102013200685 A [0007]
• EP 2031359 A1 [0065]

Claims (15)

Field instrument of process measurement technology comprising a vibration-type sensor ( 15 . 36 ) for determining a viscosity, a density and / or a derivable size thereof of a fluid medium located in a container and / or a pipeline, characterized in that the sensor ( 15 . 36 ) in addition a sensor arrangement ( 14 . 31 ) with at least two sensor elements, in particular two electrodes ( 7 . 25 . 26 ), which sensor arrangement ( 14 . 31 ) is arranged for acquiring measured values for determining a resistance of the medium between the two sensor elements in a first operating mode and which is set up for acquiring measured values for determining a reactance of the medium between the two sensor elements in a second operating mode. Field device of process measuring technology according to claim 1, characterized in that the field device comprises a measuring transducer ( 6 . 35 ), wherein the resistance and the reactance of the medium and / or an impedance of the medium comprising the effective resistance and the reactance through this transmitter (1) for determining the viscosity, the density and / or a derivable thereof 6 . 35 ) can be determined from the measured values acquired in the first and in the second operating mode. Field device according to claim 2, characterized in that the transmitter ( 6 . 35 ) is equipped to perform a comparison of the determined resistance and reactance and / or the impedance of the medium with at least one desired value taking into account the medium temperature. Field device according to one of the preceding claims, characterized in that the field device as Coriolis flow and / or Coriolis density meter ( 1 ) and / or as a level gauge ( 21 ), in particular with a forked medium-contacting element ( 23 ), is trained. Field device according to one of the preceding claims, characterized in that the sensor arrangement ( 14 . 31 ) a temperature sensor ( 12 . 27 ) for determining the temperature of the medium. Field device according to one of the preceding claims, characterized in that the sensor arrangement ( 14 ) at least one electrode ( 7a ), in which the temperature sensor ( 12 ) is arranged. Field device according to one of the preceding claims, characterized in that the sensor arrangement ( 14 . 31 ), or the at least two sensor elements for detecting the effective resistance and the reactance of the medium between the sensor elements, is operated in at least the second operating mode with alternating current and in the first operating mode with direct current. Field device according to claim 7, characterized in that the transmitter ( 6 . 35 ) is arranged to modulate the frequency of the alternating current, wherein the sensor arrangement ( 14 . 31 ) detects a reactance for each frequency. Field device according to one of the preceding claims, characterized in that the transmitter ( 6 . 35 ) has a data memory on which a record of effective resistances and / or impedance of at least one medium is deposited at different temperatures. Field device according to one of the preceding claims, characterized in that the sensor arrangement ( 14 . 31 ) only three sensor elements, in particular two electrodes ( 7 . 25 . 26 ) and a temperature sensor ( 12 . 27 ), wherein the sensor arrangement ( 14 . 31 ) in a first mode of operation the resistance of the medium between the two electrodes ( 7 . 25 . 26 ) and wherein the sensor arrangement ( 14 . 31 ) in a second mode of operation the reactance of the medium between the two electrodes ( 7 . 25 . 26 ), wherein the first and the second operating mode are respectively operated when the sensor arrangement is not in the respective other operating mode. Field device according to one of the preceding claims, characterized in that the sensor arrangement ( 14 . 31 ) has at least two first sensor elements, in particular two electrodes, for determining the effective resistance and at least two second sensor elements, in particular two further electrodes for determining the reactance, wherein the first and the second operating state occur simultaneously. Field device according to one of the preceding claims, characterized in that in the data memory of the transmitter ( 6 . 35 ) a record for the effective resistance, the reactance, the impedance, the viscosity and / or the density of the medium for various binary mixtures at different concentrations of the two components is deposited. Method for the determination of dissolved and undissolved portions of a suspension or dispersion by a field device according to one of the preceding claims. Use of a field device according to one of the preceding claims for the detection of multiphase mixtures, esp. Of two-phase mixtures. Use of a field device according to one of the preceding claims for monitoring compliance with the operating parameters of a state defined according to the device specification.

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