MAGNETIC FLOW METER

Abstract

A tubal measuring arrangement and a method for measuring the flow rate of fluid comprising ions, the measuring arrangement comprising at least one permanent magnet adapted to maintain a magnetic field substantially perpendicular to the flow of the fluid, at least one first detecting arrangement being positioned substantially perpendicular to the magnetic field and configured to conduct at least one first measurement, at least one first measuring circuit, at least one second detecting arrangement being positioned substantially along the direction of flow of the fluid, at least one second measuring circuit that is configured to conduct at least one second measurement at the second measuring arrangement, at least one evaluation unit and at least one control unit.

Claims

1-19. (canceled)

20. A tubal measuring arrangement for measuring the flow rate of fluid comprising ions, the measuring arrangement comprising at least one permanent magnet adapted to maintain a magnetic field substantially perpendicular to the flow of the fluid; at least one first detecting arrangement being positioned substantially perpendicular to the magnetic field and configured to conduct at least one first measurement; at least one first measuring circuit; at least one second detecting arrangement being positioned substantially along the direction of flow of the fluid; at least one second measuring circuit that is configured to conduct at least one second measurement at the second measuring arrangement; at least one evaluation unit; and at least one control unit.

21. The tubal measuring arrangement according to claim 20, wherein the first detecting arrangement comprises at least two first electrodes.

22. The tubal measuring arrangement according to claim 20, wherein the second detecting arrangement comprises at least two second electrodes.

23. The tubal measuring arrangement according to claim 20, wherein one of the second electrodes is identical with one of the first electrodes.

24. The tubal measuring arrangement according to claim 20, wherein the first measuring circuit is identical with the second measuring circuit.

25. The tubal measuring arrangement according to claim 20, wherein at least one resistor is connected in parallel to the first detecting arrangement.

26. The tubal measuring arrangement according to claim 20, wherein at least one switch is connected in parallel to the resistor and the first detecting arrangement adapted to close and release a short circuit to the first detecting arrangement.

27. The tubal measuring arrangement according to claim 20, wherein a first measurement of the first measuring arrangement and/or a second measurement of the second measuring arrangement is at least one of a voltage; and/or an electric current; and/or an electric charge or a charge transfer.

28. The tubal measuring arrangement according to claim 20, wherein the second measuring arrangement is angled against the magnetic field by at most 10°.

29. The tubal measuring arrangement according to claim 20, wherein the second measuring arrangement is angled against the magnetic field by less than 45°.

30. The tubal measuring arrangement according to claim 20, wherein the evaluation unit and/or the control unit comprises at least one timer module and/or is adapted to perform at least one control signal.

31. The tubal measuring arrangement according to claim 20, wherein the first measuring circuit and/or the second measuring circuit (600) comprise an analogue to digital converter.

32. The tubal measuring arrangement according to claim 20, wherein the at least one second detecting arrangement is adapted to be substantially parallel to the magnetic field and/or parallel to the flow of the fluid.

33. The tubal measuring arrangement according to claim 20, wherein the electrically conducting material is substantially inert to chemical reaction with the fluid, the material being preferably at least one of gold; platinum; titanium; stainless steel; polymer; ceramic; carbon nanotubes.

34. The tubal measuring arrangement according to claim 20, wherein the evaluation unit is adapted to compute at least the readouts of the first measuring unit and/or the readouts of the second measuring unit.

35. The tubal measuring arrangement according to claim 34, wherein the evaluation unit is further adapted to modify the signals provided by the first measuring circuit and/or by the second measuring circuit, preferably by at least one of a filter algorithm, a smoothening algorithm or a selection algorithm, the algorithm being at least one of a Kalman filter, a particle filter or a compressed sensing algorithm.

36. The tubal measuring arrangement according to claim 20, wherein the evaluation unit and at least the first measuring circuit and/or the second measuring circuit form one integrated circuit.

37. The tubal measuring arrangement according to claim 20, wherein the timer module is adapted to initiate at least one control signal to the switch that initiates the release and/or closure of a short circuit status within the first detecting arrangement.

38. The tubal measuring arrangement according to claim 20 wherein the timer module is adapted to carry out control signals with a period of less than 1 s and more than 1 ms.

39. The tubal measuring arrangement according to claim 20, wherein a sensor detecting a magnetic field is placed on and/or in the measuring arrangement detecting any changes to the magnetic field and transmitting its readout to the evaluation unit and/or to the control unit.

40. A method to measure the flow rate of a fluid comprising ions comprising the steps of providing a magnetic field by a permanent magnet substantially perpendicular to the flow of the fluid, the magnetic field; conducting at least one first measurement by providing at least one first measuring arrangement being positioned substantially perpendicular to the magnetic field; providing at least one first measuring circuit; providing at least one second detecting arrangement being positioned substantially along the direction of flow of the fluid; conducting at least one measurement by providing at least one second measuring circuit; conducting at least one evaluation by providing at least one evaluation unit; and providing at least one control unit.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0080] FIG. 1 depicts a view of a tubal measuring arrangement 1 in a schematic aspect of the mechanical arrangement.

[0081] FIG. 2 indicates an embodiment of the tubal measuring arrangement 1 in a schematic view of the electronical arrangement.

[0082] FIG. 3a-b show embodiments with a reduced set of electronic elements.

[0083] FIG. 4a-4c represent a variety of statuses of the tubal measuring arrangement 1 under specific conditions.

[0084] FIG. 5 depicts a schematic view of the tubal measuring arrangement 1 further indicating the relational positioning of the elements and further one embodiment of the electronic circuity.

[0085] FIG. 6 represents a spatial coordinate system.

[0086] FIG. 7 shows the relation of electrodes and induced tensions.

[0087] FIG. 8 indicates an effect of angular rearrangement of electrodes and the calculatory provisions

EMBODIMENTS

[0088] While the disclosure has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and non-restrictive; the disclosure is thus not limited to the disclosed embodiments. Variations to the disclosed embodiments can be understood and effected by those skilled in the art and practicing the claimed disclosure, from a study of the drawings, the disclosure, and the appended claims.

[0089] As used herein, including in the claims, singular forms of terms are to be construed as also including the plural form and vice versa, unless the context indicates otherwise. Thus, it should be noted that as used herein, the singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise.

[0090] The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to fulfill aspects of the present invention. The present technology is also understood to encompass the exact terms, features, numerical values or ranges etc., if in here a relative term, such as “about”, “substantially”, “ca.”, “generally”, “at least”, “at the most” or “approximately” is used in this specification, such a term should also be construed to also include the exact term. That is, e.g., “substantially straight” should be construed to also include “(exactly) straight”. In other words, “about 3” shall also comprise “3” or “substantially perpendicular” shall also comprise “perpendicular”. Any reference numerals in the claims should not be considered as limiting the scope.

[0091] In the claims, the terms “comprises/comprising”, “including”, “having”, and “contain” and their variations should be understood as meaning “including but not limited to”, and are not intended to exclude other components. Furthermore, although individually listed, a plurality of means, elements or method steps may be implemented. Additionally, although individual features may be included in different claims, these may possibly advantageously be combined, and the inclusion in different claims does not imply that a combination of features is not feasible and/or advantageous. In addition, singular references do not exclude a plurality.

[0092] Whenever steps were recited in the above or also in the appended claims, it should be noted that the order in which the steps are recited in this text may be the preferred order, but it may not be mandatory to carry out the steps in the recited order. That is, unless otherwise specified or unless clear to the skilled person, the order in which steps are recited may not be mandatory. That is, when the present document states, e.g., that a method comprises steps (A) and (B), this does not necessarily mean that step (A) precedes step (B), but it is also possible that step (A) is performed (at least partly) simultaneously with step (B) or that step (B) precedes step (A). Furthermore, when a step (X) is said to precede another step (Z), this does not imply that there is no step between steps (X) and (Z). That is, step (X) preceding step (Z) encompasses the situation that step (X) is performed directly before step (Z), but also the situation that (X) is performed before one or more steps (Y1), . . . , followed by step (Z). Corresponding considerations apply when terms like “after” or “before” are used.

[0093] It will be appreciated that variations to the foregoing embodiments of the invention can be made while still falling within the scope of the invention can be made while still falling within scope of the invention. Features disclosed in the specification, unless stated otherwise, can be replaced by alternative features serving the same, equivalent or similar purpose. Thus, unless stated otherwise, each feature disclosed represents one example of a generic series of equivalent or similar features.

[0094] Use of exemplary language, such as “for instance”, “such as”, “for example” and the like, is merely intended to better illustrate the invention and does not indicate a limitation on the scope of the invention unless so claimed. Any steps described in the specification may be performed in any order or simultaneously, unless the context clearly indicates otherwise.

[0095] All of the features and/or steps disclosed in the specification can be combined in any combination, except for combinations where at least some of the features and/or steps are mutually exclusive.

[0096] In particular, preferred features of the invention are applicable to all aspects of the invention and may be used in any combination.

[0097] The expressions “detection arrangement” and “detecting arrangement” are meant to have the same meaning and describe an identical element of the system.

[0098] Below, system embodiments will be discussed. These embodiments are abbreviated by the letter “S” followed by a number. When reference is herein made to a system embodiment, those embodiments are meant. [0099] S01: A tubal measuring arrangement (1) for measuring the flow rate (F) of fluid comprising ions, the measuring arrangement (1) comprising [0100] a. at least one permanent magnet (100) adapted to maintain a magnetic field (B) substantially perpendicular to the flow (F) of the fluid; [0101] b. at least one first detecting arrangement (200) being positioned substantially perpendicular to the magnetic field (B) and configured to conduct at least one first measurement; [0102] c. at least one first measuring circuit (500); [0103] d. at least one second detecting arrangement (400) being positioned substantially along the direction of flow (F) of the fluid; [0104] e. at least one second measuring circuit (600) that is configured to conduct at least one second measurement at the second measuring arrangement (400); [0105] f. at least one evaluation unit (700); and [0106] g. at least one control unit (800). [0107] S02: The measuring arrangement (1) according to the preceding embodiment, wherein the first detecting arrangement (200) comprises at least two electrodes (210). [0108] S03: The measuring arrangement (1) according to any of the preceding embodiments, wherein the second detecting arrangement (400) comprises at least two electrodes (410). [0109] S04: The measuring arrangement (1) according to any of the preceding embodiments, wherein one of the second electrodes (410) is identical with one of the first electrodes (210). [0110] S05: The measuring arrangement (1) according to any of the preceding embodiments, wherein the first measuring circuit (500) is identical with the second measuring circuit (600). [0111] S06: The measuring arrangement (1) according to any of the preceding embodiments, wherein at least one resistor (R) is connected in parallel to the first detecting circuit (200). [0112] S07: The measuring arrangement (1) according to any of the preceding embodiments, wherein at least one switch (300) is connected in parallel to the resistor (R) and the first detecting arrangement (200) adapted to close and release a short circuit to the first detecting arrangement (200). [0113] S08: The measuring arrangement (1) according to any of the preceding embodiments, wherein the first measurement and/or the second measurement is at least one of [0114] a) a voltage (U); and/or [0115] b) an electric current (I); and/or [0116] c) an electric charge (Q) or a charge transfer (Q). [0117] S09: The measuring arrangement (1) according to any of the preceding embodiments, wherein the second measuring arrangement (400) is angled against the magnetic field (B) by less than 90°, preferably at most 45°, more preferably at most 10°, most preferably around 0°. [0118] S10: The measuring arrangement (1) according to any of the preceding embodiments, wherein the evaluation unit (700) and/or the control unit (800) comprises at least one timer module and/or is adapted to perform at least one control signal. [0119] S11: The measuring arrangement (1) according to any of the preceding embodiments, wherein the first measuring circuit (500) and/or the second measuring circuit (600) comprise an analogue to digital converter. [0120] S12: The measuring arrangement (1) according to any of the preceding embodiments, wherein the at least one second detecting arrangement (400) is adapted to be substantially parallel to the magnetic field (B) and/or parallel to the flow (F) of the fluid. [0121] S13: The measuring arrangement (1) according to any of the preceding embodiments, wherein the resistor (R) is integral part of the first detecting arrangement (500). [0122] S14: The measuring arrangement (1) according to any of the preceding embodiments, wherein the fluid comprises water, preferably at least one of clean water, grey water or black water. [0123] S15: The measuring arrangement (1) according to any of the preceding embodiments, wherein at least the surface of the at least one first electrode(s) (210) and/or at least one second electrode (410) comprise(s) an electrically conducting material that is substantially inert to dissolution by the fluid. [0124] S16: The measuring arrangement (1) according to any of the preceding embodiments, wherein at least the surface of the at least one first electrode(s) (210) and/or at least one second electrode (410) comprise(s) an electrically conducting material that is substantially inert to chemical reaction with the fluid. [0125] S17: The measuring arrangement (1) according to embodiment S16, wherein the electrically conducting material is at least one of [0126] a. gold; [0127] b. platinum; [0128] c. titanium; [0129] d. stainless steel; [0130] e. polymer; [0131] f. ceramic; [0132] g. carbon nanotubes. [0133] S18: The measuring arrangement (1) according to any of the preceding embodiments, wherein the first control circuit (500) and/or the second control circuit is adapted to apply a second voltage to the first electrode(s) (210) and/or to the second electrode(s) (410) that is of opposite polarity to the polarity of the first voltage that is induced by the flow (F) of the fluid through the magnetic field (B) and/or an alternating voltage. [0134] S19: The measuring arrangement (1) according to embodiment S18, wherein the second voltage is applied in at least one surge that is significantly higher than the voltage(s) applied by the first voltage that is applied by the magnetic field (B). [0135] S20: The measuring arrangement (1) according to any of the preceding embodiments, wherein the fluid has a conductivity of at least 0,5 pS/cm. [0136] S21: The measuring arrangement (1) according to any of the preceding embodiments, wherein the evaluation unit (700) is adapted to compute at least the readouts of the first measuring unit (500) and/or the readouts of the second measuring unit (600). [0137] S22: The measuring arrangement (1) according to the preceding embodiment, wherein the evaluation unit (700) is further adapted to modify the signals provided by the first measuring circuit (500) and/or by the second measuring circuit (600), preferably by at least one of a filter algorithm, a smoothening algorithm or a selection algorithm. [0138] S23: The measuring arrangement (1) according to any of the embodiments S21 to S22, wherein the filter algorithm is at least one of a Kalman filter, a Particle filter and/or a compressed sensing algorithm. [0139] S24: The measuring arrangement (1) according to any of the embodiments S21 to S23, wherein the evaluation unit (700) displays its at least one result of the processed signals, stores and/or transmits its at least one result via a network and/or conveys its at least one result to the control unit (800). [0140] S25: The measuring arrangement (1) according to any of the embodiments S21 to S24, wherein the evaluation unit (700) is adapted to receive signals from a network, the signal being at least one of a control signal or an adjusting signal. [0141] S26: The measuring arrangement (1) according to any of the embodiments S21 to S25, wherein a sensor detecting a magnetic field is placed on and/or in the measuring arrangement (1) detecting any changes to the magnetic field (B) and transmitting its readout to the evaluation unit (700) and/or to the control unit (800). [0142] S27: The measuring arrangement (1) according to any of the preceding embodiments, wherein the evaluation unit (700) and at least the first measuring circuit (500) and/or the second measuring circuit (600) form one integrated circuit. [0143] S28: The measuring arrangement (1) according to any of the embodiments S21 to S27, wherein the evaluation unit (700) is adapted to integrate the detection of a change of the magnetic field (B) into its computations. [0144] S29: The measuring arrangement (1) according to any of the preceding embodiments, wherein the control unit (800) is adapted to receive data from at least one [0145] a) the evaluation unit (700); [0146] b) the sensor detecting a magnetic field; [0147] c) control panel. [0148] S30: The measuring arrangement (1) according to any of the preceding embodiments, wherein the control unit (800) is adapted to control at least one of [0149] a) a display unit; [0150] b) the switch (300); [0151] c) an external relay. [0152] S31: The measuring unit (1) according to any of the preceding embodiments, wherein the timer module (T) is adapted to initiate at least one control signal to the switch (300) that initiates the release and/or closure of a short circuit status within the first detecting arrangement (200). [0153] S32: The measuring unit (1) according to any of the preceding embodiments, wherein the timer module is adapted to carry out control signals with a period of less than 10 s, preferably less than 1 s, more preferably less than 10 ms, more preferably less than 1 ms and at least 1 μs, most preferably around 100 ns-100 μs. [0154] S32: The measuring arrangement (1) according to any of the preceding embodiments, wherein the evaluation unit (700), the control unit (800) and at least the first measuring circuit (500) and/or the second measuring circuit (600) form one integrated circuit. [0155] S33: The measuring arrangement (1) according to any of the preceding embodiments, wherein the measuring arrangement (1) is supplied with at least one grounding ring upstream and/or downstream of the tubal measuring arrangement (1) that houses at least the first and/or the second detection arrangement (200, 400) and/or is used to supply a defined potential to the any component. [0156] S34: The measuring arrangement (1) according to any of the preceding embodiments, wherein the evaluation unit (700) comprises at least one storage comprising tabular data.

[0157] Below, maintenance method embodiments will be discussed. The letter M followed by a number abbreviates the method embodiments. Whenever reference is herein made to method embodiments, these embodiments are meant. [0158] M01: A method to measure the flow rate (F) of a fluid comprising ions comprising the steps of [0159] a. providing a magnetic field (B) by a permanent magnet substantially perpendicular to the flow of the fluid (F), the magnetic field (B); [0160] b. conducting at least one first measurement by providing at least one first measuring arrangement (200) being positioned substantially perpendicular to the magnetic field (B); [0161] c. providing at least one first measuring circuit (500); [0162] d. providing at least one second detecting arrangement (400) being positioned substantially along the direction of flow (F) of the fluid; [0163] e. conducting at least one measurement by providing at least one second measuring circuit (600); [0164] f. conducting at least one evaluation by providing at least one evaluation unit (700); and [0165] g. providing at least one control unit (800). [0166] M02: A method to measure the flow rate (F) of a fluid comprising ions comprising the steps of [0167] a. providing a magnetic field (B) by a permanent magnet substantially perpendicular to the flow of the fluid (F), the magnetic field (B); [0168] b. conducting at least one first measurement by providing at least one first measuring arrangement (200) being positioned substantially perpendicular to the magnetic field (B); [0169] c. providing at least one first measuring circuit (500); [0170] d. conducting at least one evaluation by providing at least one evaluation unit (700) and [0171] e. conducting at least one control signal by providing at least one control unit (800).

DESCRIPTION OF THE FIGURES

[0172] FIG. 1 depicts a schematic view, how the mechanical elements of a tubal measuring arrangement 1 (also referred as tube) are located in relation to each other in one embodiment. The pipe 10 consists of a material that is substantially transparent for a magnetic field and does not conduct electricity. At least one magnet 100 is placed outside on or close to the surface of the pipe 10. The axis of the magnetic field B supplied by the at least one magnet 100 shall be pointing in an orthogonal orientation to the direction of the flow F of the fluid. Preferably, a second magnet is provided for, the orientation of the magnets so that they increase the magnetic field, thus the north pole of the one magnet being oriented to the south pole of the second magnet. If two magnets are supplied, they can advantageously be placed with their axes of the magnetic field B in line, however one magnet on either side of the measuring arrangement 1. It should be noted that while two magnets in line forming one resultant magnetic field B may be a preferred configuration, it is not mandatory to place the magnets in line; it should however be provided for the existence of a magnetic field B covering at least an area within the tube where a fluid flow F through.

[0173] Two electrodes 210 forming a pair of electrodes are placed inside the tube 1 and in contact with the fluid. The imaginary line between one pair of first electrodes 210 can also be referred to as axis E. More than one pair of electrodes can be supplied to form more than one axis. A first electrode 210 can be a strip of an electrically conducting material. Such a strip may be glued or otherwise secured to the inside of the tube. Each first electrode 210 and/or second electrode 410 is connected to the outside of the tube to establish a galvanic connection with external elements disclosed otherwise.

[0174] The shape of the first electrodes 210 and/or the second electrodes 410 is not restricted to be flat. The first electrodes 210 and/or the second electrodes 410 can show any shape that on the one hand constitute a good galvanic contact to the fluid; on the other hand, a minimum of turbulence to the fluid shall be affected.

[0175] Further, if a strip is selected to be a first electrode 210 and/or a second electrode 410, the orientation of the axis E is meant to be substantially orthogonal to the flow F of the fluid and also substantially orthogonal to the magnetic field B. The mutual relation of the three axes E, F and B is displayed in FIG. 6 for a better reference.

[0176] The second electrodes 410 are positioned in a substantially parallel line with the flow F of the fluid. As an alternative, or additionally, the second electrodes 410 may be positioned substantially parallel to the line of magnetic flow B. Variations in the relational angles are acceptable, as long as a least possible tension or current is induced by the motion of the ions (or electrons) that flow with the fluid in the flow F passing the magnetic field B.

[0177] It should be clear that the direction of the flow F is along the mechanical dimension of the tube 1. It is not significant whether the flow F directs into the one direction or into the opposite direction.

[0178] FIG. 2a depicts an embodiment showing the schematic electric relation of several components of the tubal measurement arrangement 1 (again, for brevity reasons referenced as tube 1). The first electrodes 210 are pairwise organized as the first detection arrangement 200. Several first detection arrangements 200 can be provided to reduce the influence of a disturbing signal, to surveil the integrity of other electrodes and/or the whole tube 1. The first detection arrangement 200 delivers the induced tension or current via galvanic connectors to a first measuring circuit 500. Such a first measuring circuit 500 may be an analogue to digital converter (ADC), a device that converts an analogue value that is delivered by the first detection arrangement 200 into a digital value. The functionality of such an ADC is assumed to be known by the person skilled in the art.

[0179] Periodically, an analogue value is digitized and delivered to an external device that handles the digital value. In this embodiment, the digital value delivered by the first measuring circuit 500 is transferred to an evaluation unit 700. Again, if more than one first measuring circuit 500 is supplied, more than one evaluation units can be assigned. Further, the first measuring circuits 500 can deliver their readouts to the evaluation unit in a time-sharing method, thus a switch is added between the first measuring circuit(s) 500 and the evaluation unit 700. The switch (not depicted) can select which first measuring circuit 500 delivers its readout to the evaluation unit 700.

[0180] The evaluation unit 700 carries out evaluations that are disclosed in more detail in the description portion of this application.

[0181] Further, the evaluation unit 700 delivers its results to a control unit 800. This control unit sends out the results received from the evaluation unit 700 to a display. Additionally, or alternatively, the control unit 800 may carry out further control functions, such can be the initiation of an alarm signal if, for instance, if irregular conditions are determined by the evaluation unit 700 on the basis of the measurements of the preceding components of the tube.

[0182] A timer (not depicted) may be provided to carry out various functions. The timer may initiate phases of measurement by the first measuring circuit 500 or may initiate whatever coordinating or timing signal as appropriate.

[0183] FIG. 2b depicts an embodiment showing the schematic electric relation of several components of the tubal measurement arrangement 1 (again, for brevity reasons referenced as tube 1). The second electrodes 410 are pairwise organized as the second detection arrangement 400. Several second detection arrangements 400 can be provided to reduce the influence of a disturbing signal, to surveil the integrity of other electrodes and/or the whole tube 1. The second detection arrangement 400 delivers the induced tension or current via galvanic connectors to a second measuring circuit 600. Such a second measuring circuit 600 may be an analogue to digital converter (ADC), a device that converts an analogue value that is delivered by the second detection arrangement 400 into a digital value. The functionality of such an ADC is assumed to be known by the person skilled in the art. Periodically, an analogue value is digitized and delivered to an external device that handles the digital value. In this embodiment, the digital value delivered by the second measuring circuit 600 is transferred to an evaluation unit 700. Again, if more than one second measuring circuit 600 is supplied, more than one evaluation units can be assigned. Further, the second measuring circuits 600 can deliver their readouts to the evaluation unit in a time-sharing method, thus a switch is added between the second measuring circuit(s) 600 and the evaluation unit 700. The switch (not depicted) can select which second measuring circuit 600 delivers its readout to the evaluation unit 700.

[0184] The evaluation unit 700 carries out evaluations that are disclosed in more detail in the description portion of this application.

[0185] Further, the evaluation unit 700 delivers its results to a control unit 800. This control unit sends out the results received from the evaluation unit 700 to a display. Additionally, or alternatively, the control unit 800 may carry out further control functions, such can be the initiation of an alarm signal if, for instance, if irregular conditions are determined by the evaluation unit 700 on the basis of the measurements of the preceding components of the tube.

[0186] FIG. 3a depicts an embodiment where resistance R makes it clear that in this embodiment not a current but a tension is measured at the first electrodes 210. A second electrode 410 works pairwise with one of the first electrodes 210 in a time-sharing method. A switch 300 selects whether the first electrodes are analyzed (first channel) or the second electrode 410 against the one first electrode 210 (second channel). The switch 300 may be driven by a timer module (not depicted) or have an internal logic to select the first or the second channel. The sharing of one electrode by two measuring channels is possible because the orientation of the first electrodes 210 is substantially perpendicular with the orientation of the second electrodes 410. Thus, placing one of the electrodes, in this embodiment a first electrode 210, can be placed in the origin of the spatial coordinate system (see FIG. 6) and thus take over also the function of one part of the second electrodes 410.

[0187] In a first state S1 of the switch 300 the two electrodes 210 are short circuited. In this state S1 at the entry of the first measuring circuit 500 the tension between the one second electrode 410 and one of the first electrodes 210 is measured. This is the tension that is substantially independent from the magnetic influence, because the orientation of the one first electrode 210 and the one second electrode 410 is arranged to be either parallel to the magnetic field B or parallel to the flow F of the fluid and thus be less affected by the magnetic field B. This ensures that a minimum of the induced tension is detected but overweighing the noise tension that is induced by electro-chemical effects.

[0188] The first measuring circuit 500 and/or an evaluation unit (not depicted) may store the value of the noise tension.

[0189] In a second state S2 of the switch 300 the one second electrode 410 is short circuited with one of the first electrodes 210. In this state S2, no tension can be conveyed to the first measuring circuit 500, but only the tension between the first electrodes 210 can be detected by the first measuring circuit 500.

[0190] In the state S2, when the tension between the first electrodes 210 is detected, this is the tension that is induced by the flow F of the fluid in the magnetic field B plus the tension that is induced by electro-chemical affect. Thus, the tension measured between the first electrodes 210 is a resultant (usually the sum) of the induced, useful signal and the electro-chemically induced noise tension. A subsequent logic component can substantially subtract the two values and thus harvest the useful tension. The relation of the useful tension, the noise tension and the resultant tension is depicted as family of curves in FIG. 4a.

[0191] Generally, it should be clear to the person skilled in the art that an induced tension is substantially in direct relation to an induced current. Thus, for the results sake it doesn't matter whether a tension or a current is measured.

[0192] The analogue value(s) delivered by the first electrodes 210 and the second electrode 410, via the switch 300, is fed into the first measuring circuit 500. In this embodiment, a second measuring circuit 600 is not provided.

[0193] The digital value delivered by the first measuring circuit 500 is conveyed to a subordinate arrangement or device.

[0194] FIG. 3b depicts a portion of an arrangement where only one first measuring circuit 500 is provided. The switches S1, S2 and S3 are coordinated. S3 selects the circuit that is to be analyzed (either the combination of a first electrode 210 with a second electrode 410, or by the combination of two first electrodes 210) the subordinate arrangement or device, in this embodiment the first measuring device 500. As can be determined from the two resistors R1 and R2, a voltage (or tension) is measured.

[0195] FIG. 4a depicts a family of theoretical curves that represent the components of tensions or currents that are induced by varied cause.

[0196] The first electrodes 210 detect a resultant tension M3—the one tension M1 that is induced by the flow F (FIG. 5) of the fluid within the magnetic field B (FIG. 5) and further a tension M2 that is induced by electro-chemical effect. This tension M3 illustrated over the time t is represented by the steady line.

[0197] The second electrodes 410 (FIG. 1) detect a noise tension M2 only, as explained in detail elsewhere. As can be seen from the curves, the tension M1 rises earlier than tension M2.

[0198] A subsequent evaluation unit (see FIGS. 2a and 2b) takes care of those two tensions M2 and M3 and evaluates the useful signal M1 that is displayed as a dotted line. Usually, the noise tension M2 that is harvested from the second electrodes (not depicted) is subtracted from the overall tension M3 that is harvested from the first electrodes (not depicted). The result is a useful tension M1.

[0199] It should be clear that this description is a simplified representation only. Filter and/or selection algorithms may be applied, consistency checks may be carried out; certain values may be neglected, other values may be applied with factors that may improve the quality of the resulting tension curve M1.

[0200] FIG. 4b depicts a diagram of an induced tension M3 over the time t in one embodiment. In the below portion of the diagram a state of a switch is shown. The upper state means the switch is closed (short circuit on the first electrodes), the lower state means the switch is opened (short circuit of the first electrodes released).

[0201] At the position in the diagram of t.sub.0 the short circuit between the first electrodes is released for a period of time that ends at t.sub.2. At t.sub.2 the short circuit is established again. Between t.sub.1 and t.sub.2 the measurements of M3 are taken.

[0202] The measuring cycle between two time stamps t.sub.0can be repeated multiply according to the discretion of the manufacturer. Usually, a certain amount of measurement cycles should be taken to allow the evaluation unit (not depicted) to detect irregularities and/or developments and to reduce noise.

[0203] FIG. 4c A sequence of measurement cycles can be initiated by a controlling instance (not depicted) like a timer module. In this embodiment, a sequence of measurements has been selected to measure three times per second. It should be clear that this represents one example only. More cycles may be selected or less, according to the specific needs.

[0204] FIG. 5 depicts a 3D embodiment where only the first electrodes 210 are in use. The permanent magnets 100 (the numbering “N” and “S” shall represent the polarities of the magnets) are situated at the tubal measuring arrangement 1 on the outer surface 10 of the tube. The small letter d shall indicate the inner diameter of a tube-shaped measuring arrangement 1. The first electrodes 210 in this embodiment pass through the wall of the tube to get in touch with the fluid. The first electrodes 210 are positioned in a way to comprise a substantially orthogonal orientation to both, the magnetic field B and the flow F of the fluid. The electrodes can be positioned eccentrically, as can be seen. A resistor R in this embodiment can be a discrete element or be achieved by the inner resistance of the first measuring circuit 500. A switch 300 is positioned parallel to the first electrodes 210 and to the resistor R. The switch 300 is adapted to short circuit the tension/current that is induced by the flow F of the fluid while it flows through the magnetic field B and an electro-chemically induced tension. The harvested tension that is detected by the first electrodes 210 is a resultant of the two sources of tension. In this embodiment, the electro-chemically induced tension cannot be detected directly. An evaluation unit (not depicted) that is logically positioned behind the first measuring circuit 500 may have tabular dates about the characteristics of the electro-chemical tension over the time lapsed during measurement to reduce the detected tension (see FIG. 4a, there marked as M3). Such a look-up table may be stored in an element of the evaluation unit (not depicted) and thus acquire data that can be assumed to be useful data, useful for various reasons.

[0205] It should be clear that the magnets can be configured also opposite of the depicted arrangement, i.e., the North—and the South poles of the magnets can be reversed, as long as a substantially homogeneous magnet field is achieved.

[0206] FIG. 6 shows a representation of a three-dimensional coordinate system. The person skilled in the art will know about the Lorentz rule, which says that the flow F of a fluid must be substantially orthogonal to a magnetic field B and also substantially orthogonal to the imaginary line between the electrodes E.

[0207] FIG. 7 represents a detailed view of how the first electrodes 210 (not depicted) can be arranged. The tension between the first electrode 210a and 210c is comparable, if not equal, to a tension measured between an allocation of a first electrode 210c and 210b. Thus, the pair of first electrodes 210 (not depicted here) doesn't need to be located opposingly.

[0208] FIG. 8 demonstrates that the first electrodes 210 do not necessarily have to be placed orthogonally to the magnetic flux. If the first electrodes 210 mod are placed angled to the magnetic flux, a sine value of the angle α can be applied to the measured value to receive a more suitable value for further calculations.