Flowmeter

Abstract

The invention relates to a flowmeter (1), comprising: - a plastics measuring tube (2), wherein the plastics measuring tube (2) comprises a measuring portion (MA), wherein the plastics measuring tube (2) comprises a measuring-tube channel (3) for conveying a flowable medium; - a support sleeve (4) for minimising an expansion of the plastics measuring tube (2) in the measuring portion (MA), the support sleeve (4) encompassing part of the plastics measuring tube (2); and - a housing (5), wherein the housing (5), together with the plastics measuring tube (2), defines a cavity (6) that extends around part of the plastics measuring tube (2), the support sleeve (4) being located in the cavity (6), characterised in that for a temperature T A from a temperature range of –10°C ≤ T A ≤ 10°C and for a medium-free measuring-tube channel (3), the plastics measuring tube (2) is radially clamped in the radial direction due to the support sleeve (4).

Description

[0001] flow meter

[0002] The invention relates to a flow meter, in particular a magnetic-inductive flow meter for determining a flow velocity-dependent measured variable and two methods for producing a flow meter.

[0003] Flowmeters are widely used and well-known, particularly in process measurement technology. For example, magnetic-inductive flowmeters for volumetric flow measurement utilize the principle of electrodynamic induction and are well-known from numerous publications. Charge carriers in the medium moving perpendicular to a magnetic field induce a measuring voltage in measuring electrodes arranged essentially perpendicular to the direction of flow of the medium and perpendicular to the direction of the magnetic field. The measuring voltage induced in the measuring electrodes is proportional to the flow velocity of the medium averaged over the cross-section of the measuring tube, i.e., proportional to the volume flow. If the density of the medium is known, the mass flow in the pipeline or measuring tube can be determined.The measuring voltage is usually tapped via a pair of measuring electrodes which are arranged with respect to the coordinate along the measuring tube axis in the area of ​​maximum magnetic field strength and where consequently the maximum measuring voltage is to be expected.

[0004] Magnetic-inductive flowmeters with a plastic measuring tube are known. Such plastic measuring tubes are known, among others, from DE 103 40 056 B4 and DE 10 2010 029 119 A1. The use of plastic measuring tubes in flowmeters is particularly advantageous when connected to plastic pipe systems, as installation is easier. For example, flangeless welding of the plastic measuring tube to a plastic pipe is possible for connecting the flowmeter. However, the use of plastic measuring tubes also brings with it new problems that do not occur with stainless steel pipes.

[0005] DE 10 2010 029 119 A1 addresses the problem of the expansion of a plastic pipe, which leads to a change in the pipe's internal cross-section due to pressure fluctuations. In DE 10 2010 029 119 A1, this problem is solved by compensating the measured values. The change in the pipe's cross-section is determined using strain gauges or similar devices and incorporated into the evaluation of the measured values.

[0006] DE 103 40 056 B4 discloses a so-called tube-in-tube housing variant with a plastic inner tube, an outer tube, a cylindrical shielding element, and a thermoplastic potting material between the outer and inner tubes. In the case of DE 103 40 056 B4, the inner tube is supported by the outer tube and the potting material. DE 10 2005 009 675 B3 discloses another variant of a tube-in-tube housing variant with a shielding plate. In this variant, the magnetic coils are simply mounted on the plastic tube. This can lead to the magnet system becoming detached and slipping along the circumference of the plastic tube during measurement.

[0007] DE 10 2013 102 544 A1 discloses a flowmeter with a plastic measuring tube and a support sleeve that prevents temperature and pressure fluctuations from distorting the measurement result. A disadvantage of this solution is that additional anti-twist devices and fastening elements are required to hold the support sleeve in position.

[0008] The object of the invention is to remedy the problem.

[0009] The object is achieved by the flow meter according to claim 1 and the method for producing a flow meter according to claims 13 and 14.

[0010] The flow meter according to the invention comprises:

[0011] - a plastic measuring tube, wherein the plastic measuring tube has a measuring section, wherein the plastic measuring tube comprises a measuring tube channel for guiding a flowable medium;

[0012] - a support sleeve to minimize expansion of the plastic measuring tube in the measuring section, wherein the support sleeve encompasses the plastic measuring tube in sections;

[0013] - a housing, wherein the housing together with the plastic measuring tube defines a hollow space which partially surrounds the plastic measuring tube, wherein the support sleeve is arranged in the hollow space, characterized in that for a temperature T A from a temperature range of -10°C < T A < 10°C and a medium-free measuring tube channel, the plastic measuring tube experiences mechanical radial stress in the radial direction towards the measuring tube channel center point due to the support sleeve.

[0014] The radial stress can be caused by the plastic measuring tube being cooled to a temperature below -10°C prior to installation, causing it to mechanically contract. The support sleeve is then pushed onto the cooled plastic measuring tube at room temperature, for example, or attached to the outer surface. When the cooled plastic measuring tube warms up and reaches a temperature within the temperature range specified by the manufacturer, it expands radially. However, the support sleeve limits the degree of expansion within the measuring section, so that radial stress acts on the plastic measuring tube there.

[0015] Alternatively, the radial stress can be caused by the support sleeve being compressed during assembly on the plastic measuring tube in the measuring section or being fastened in such a force-locking manner that the measuring tube cross-section of the plastic measuring tube is reduced in the measuring section and a permanent radial force is present in the direction of a center point of the plastic measuring tube lying on the longitudinal axis of the measuring tube channel.

[0016] Advantageous embodiments of the invention are the subject of the subclaims.

[0017] One embodiment provides that the plastic measuring tube in the measuring section has a first outer diameter D t wherein the plastic measuring tube has a measuring tube section outside the measuring section, in which the plastic measuring tube has a second outer diameter D2, wherein for the temperature T A the first diameter D is smaller than the second diameter Di, where for a temperature TB which is less than the temperature T A the first diameter D and the second diameter D2 are equal.

[0018] One embodiment provides that the plastic measuring tube has a process connection at each end, with the measuring tube section being located between the measuring section and the process connection.

[0019] One design provides that the flowmeter is free of a process connection.

[0020] One embodiment provides that the support sleeve has an inner diameter D in wherein the inner diameter D in is smaller than the second diameter D2.

[0021] One embodiment provides that the radial clamping provides anti-twist and axial displacement protection for the support sleeve.

[0022] This has the advantage that no additional fasteners are required to attach the plastic measuring tube. This also reduces the processing steps required for the plastic measuring tube. One embodiment provides for the support sleeve to be made of a fiber composite material.

[0023] A fiber composite material, as defined by the invention, is a composite material comprising a multiphase or mixed material, i.e., one that generally consists of at least two main components: the reinforcing fibers and a supporting matrix. The matrix can be the filler and adhesive between the fibers. The fibers can be glass fibers, carbon fibers, ceramic fibers, aramid fibers, nylon fibers, or similar fiber types. Suitable fillers and adhesives include thermosets, synthetic resins, elastomers, and thermoplastics.

[0024] One embodiment provides that the radial tension is caused by compressing the plastic measuring tube by means of the support sleeve.

[0025] The pressing can be done using an assembly tool. A suitable assembly tool would be a crimping pliers or a press, especially a hydraulic one.

[0026] One embodiment provides that the support sleeve is formed in one piece and is flexible, wherein the support sleeve comprises a connecting element which is designed to mechanically connect two ends of the support sleeve in such a way that the support body thereby effects the radial tension on the plastic measuring tube.

[0027] For an alternative option for applying radial stress, at least one connecting element is provided, which is part of the support sleeve and with which both ends of the support sleeve can be pulled together. In this case, the support sleeve can be a pipe clamp consisting of at least two clamps or a hose clamp, which is designed and attachable to the plastic measuring tube in such a way that radial stress is created in the plastic measuring tube.

[0028] One embodiment provides that the support sleeve comprises two half-shells which are mechanically connected to one another via at least one connecting element, wherein two half-shells are connected to one another in such a way that the support sleeve or the two half-shells cause or cause the radial tension on the plastic measuring tube.

[0029] One design provides that the support sleeve is pressed onto the plastic measuring tube by means of a press fitting.

[0030] With a press fitting, a sleeve or connection of an intermediate piece is typically attached to or with a plastic pipe. The sleeve or connection is deformed or pressed in such a way that it is permanently fixed to the plastic pipe. A further design includes:

[0031] - a magnetic field generating device for generating a magnetic field penetrating the plastic measuring tube in the measuring section, wherein the magnetic field generating device is arranged in the measuring section, wherein the magnetic field generating device is arranged in the cavity;

[0032] - at least two measuring electrodes, wherein the at least two measuring electrodes are arranged in the measuring section.

[0033] The method according to the invention for producing a flowmeter, in particular a magnetic-inductive flowmeter, which comprises a plastic measuring tube and a support sleeve, preferably the flowmeter according to one of the preceding claims, comprises the method steps:

[0034] - Cooling of a plastic measuring tube below a cooling temperature T cool , where cooling temperature T cool is selected from a temperature range of -60°C < Tcooi < -10°C, in particular -55°C < T cool < -10°C;

[0035] - sliding a support sleeve onto the plastic measuring tube and positioning the support sleeve in a measuring section of the plastic measuring tube; and

[0036] - Warming up the plastic measuring tube to a temperature ^ to fix the support sleeve in the measuring section.

[0037] The method according to the invention for producing a flowmeter, in particular a magnetic-inductive flowmeter, which comprises a plastic measuring tube and a support sleeve, preferably the flowmeter according to one of the preceding claims, comprises the method steps:

[0038] - Positioning the support sleeve on the plastic measuring tube in a measuring section of the plastic measuring tube;

[0039] - mechanical pressing of the entire support sleeve or pressing of the support sleeve in sections.

[0040] A further design includes the following procedural steps:

[0041] - Attaching a magnetic field generating device to the support sleeve; and

[0042] - Attaching at least two electrodes in the measuring section. The invention is explained in more detail with reference to the following figures. It shows:

[0043] Fig. 1 : a perspective view of a longitudinal section through a flow meter;

[0044] Fig. 2 : a perspective view of a longitudinal section through a magnetic-inductive flow meter;

[0045] Fig. 3a-b: two side views of a support sleeve;

[0046] Fig. 4 : an alternative support sleeve;

[0047] Fig. 5a-c: individual process steps for attaching a support sleeve to the plastic measuring tube; and

[0048] Fig. 6 : Process steps of a process for manufacturing a flow meter.

[0049] Some embodiments of the present disclosure are described in more detail below with reference to the accompanying figures. The figures illustrate some, but not all, embodiments of the disclosure. Indeed, these disclosures may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Different embodiments, each illustrating individual details of the inventive subject matter, may be combined with one another to form new embodiments not shown in the figures. Like numbers refer to like elements throughout.

[0050] The components illustrated in the figures represent components that may or may not be present in various embodiments of the present disclosure described herein, so that the embodiments may include fewer or more components than those illustrated in the figures without departing from the scope of the present disclosure. Some components may be omitted or shown in phantom in one or more figures to reveal underlying components.

[0051] The phrases "in an exemplary embodiment," "some embodiments," "various embodiments," and the like generally mean that the particular feature, structure, or characteristic following the phrase may be included in at least one embodiment of the present disclosure and may be included in more than one embodiment of the present disclosure. Such phrases do not necessarily refer to the same embodiment.

[0052] The word "example" or "exemplary" is used herein to mean "serving as an example or illustration." Any implementation described herein as "exemplary" is not necessarily preferred or advantageous over other implementations. When the figure description indicates that a component, part, or feature is "preferably," "may," "typically," "optionally," or "for example" (or other such wording) included, or that a feature "may" or "could" have a characteristic, it is not required that a particular component or feature be included or exhibit the characteristic. Such components or features may be optionally included in some embodiments, but they may also be excluded.An embodiment not included in the figures may also contain all features - as long as they do not contradict each other - of the embodiments shown.

[0053] Fig. 1 shows a perspective view of a longitudinal section through a flowmeter 1. The flowmeter 1 comprises a plastic measuring tube 2. The plastic measuring tube 2 can be a tube made exclusively or predominantly of a plastic. A suitable tube would be a PE pipe made of polyethylene. Another alternative would be a PEEK pipe made of polyetheretherketone. A plastic measuring tube 2 made predominantly of plastic can be a tube made of a fiber composite material.

[0054] The plastic measuring tube 2 has a measuring section MA (dashed area) in which a flow velocity-dependent measured variable is measured. The components of a sensor 15 required to determine the flow velocity-dependent measured variable are arranged in the measuring section MA. The flow velocity-dependent measured variable can be the current flow velocity, the volume flow rate, or the mass flow rate.

[0055] The plastic measuring tube 2 comprises a measuring tube channel 3 for conveying a flowable medium. The measuring tube channel 3 is defined by the measuring tube body and has an inlet and an outlet.

[0056] According to the invention, a support sleeve 4 is provided to minimize expansion of the plastic measuring tube 2 in the measuring section MA. The support sleeve 4 surrounds the plastic measuring tube 2 at least in the measuring section MA and thus ensures that the measuring cross-section (measuring tube channel cross-section in the measuring section MA) does not change due to temperature or pressure fluctuations. This ensures a more stable and accurate measured value.

[0057] The flowmeter 1 also has a housing 5, which serves to protect the components of the sensor 15 and, alternatively, electronic components from external influences. For this purpose, the housing 5 is arranged on the outer surface of the plastic measuring tube 2 and, together with the plastic measuring tube 2, defines a cavity 6 that partially surrounds the plastic measuring tube 2. The electronic components can be arranged in this cavity 6. The support sleeve 4 is positioned in the cavity 6. The cavity 6 can be filled with a filler, such as PU foam.

[0058] For a temperature ^ from a temperature range of -10°C < T A < 10°C, especially -8°C < T A < 5°C and preferably -5°C < T A< 2°C, and a medium-free measuring tube channel 3, the plastic measuring tube 2 experiences radial stress in the radial direction due to the support sleeve 4. This means that the plastic measuring tube 2 tends to return to its original state, but this is inhibited by the support sleeve 4. Thus, a radial stress builds up in the measuring section of the plastic measuring tube 2.

[0059] The advantage is that the radial clamping provides anti-twist and axial displacement protection of the support sleeve 4 without the need for additional fastening means such as screws or bolts.

[0060] The plastic measuring tube 2 has a first outer diameter D in a cross section in the measuring section MA and a second outer diameter D2 in a cross section outside the measuring section MA. For the temperature 7^ and an empty measuring tube channel 3, the first diameter smaller than the second diameter D2. This is due to the fact that the plastic measuring tube 2 outside the measuring section MA can freely expand and contract according to the temperature, while the expansion capability of the plastic measuring tube 2 in the measuring section MA is already limited from the outset by the support sleeve, even for the lower limit of the application range.

[0061] The support sleeve 4, which is hollow-cylindrical in the illustrated embodiment, has an inner diameter D in (see Fig. 3b). This can be smaller than the second diameter D2 of the plastic measuring tube 2. In this case, the outer diameter of the plastic measuring tube 2 after cooling assumes a value that is smaller than the inner diameter D in the support sleeve 4 at a temperature within the working range.

[0062] For a temperature T Bwhich is smaller than the temperature 7^, and an empty measuring tube channel 3, the first diameter and the second diameter D2 must be equal. This means that the plastic measuring tube 2 has an essentially constant outer diameter below the temperature 7^, ie, within the usual manufacturing tolerances.

[0063] The plastic measuring tube 2 can have a process connection 7 at each end. In this case, the measuring tube section can be located between the measuring section MA and the process connection 7. Alternatively, the flowmeter 1 can be free of a process connection (not shown).

[0064] The support sleeve 4 can be formed from a fiber composite material or at least partially encompass it. Alternatively, the support sleeve can be metallic or made of ceramic. The sensor 15 can be a vortex flowmeter, an ultrasonic flowmeter, a magnetic-inductive flowmeter, or a thermal flowmeter. The sensor 15 or components of the sensor 15 can be attached to the support sleeve 4. For this purpose, the support sleeve 4 itself can have fastening means, such as bolts or screws (see reference numeral 11 in Fig. 2 and Fig. 3a).

[0065] Fig. 2 shows a perspective view of a longitudinal section through a magnetic inductive flowmeter 20. Magnetic inductive flowmeters 20 are used to determine the flow velocity and / or the volume flow of a medium in a measuring tube, here a plastic measuring tube 2, in particular in the measuring tube channel 3. A magnetic inductive flowmeter 20 comprises a magnetic field generating device 21 which generates a magnetic field perpendicular to the transverse axis of the measuring tube. For this purpose, individual or multiple coils 22, each with at least one coil core 24, are typically used. In order to realize a predominantly homogeneous magnetic field, additional pole shoes 26 are shaped and attached such that the magnetic field lines run essentially perpendicular to the transverse axis across the entire measuring tube cross-section.Two measuring electrodes 23 attached to the outer surface of the plastic measuring tube 2 tap an inductively generated electrical measuring voltage, which arises when a conductive medium flows in the direction of the longitudinal axis when a magnetic field is applied. Since the tapped measuring voltage depends on the velocity of the flowing medium according to Faraday's law of induction, the flow velocity and, with the addition of a known measuring tube cross-section, the volumetric flow of the medium can be determined from the measuring voltage.

[0066] The magnetic field-generating device 21 for generating a magnetic field penetrating the plastic measuring tube 2 in the measuring section MA is itself arranged in the cavity 6 of the housing 5 in the measuring section MA. The housing 5 shown has a hollow cylindrical frame, which is closed at each end by a housing disc 12. Furthermore, the housing 5 can have an opening in which a transmitter adapter 13 for arranging a transmitter (not shown) is arranged and through which connecting cables run, connecting the magnetic field-generating device 21 and the measuring electrodes 23 to a transmitter electronics system.

[0067] The measuring electrodes 23 are also arranged in the measuring section MA. In addition to the measuring electrode 23, the magnetic-inductive flowmeter 20 can have a potential electrode 25 and / or a level monitoring electrode. The support sleeve 4 according to the invention can have openings for the measuring electrodes 23 and the potential electrode 25 and / or the level monitoring electrode.

[0068] Fig. 3a-b each show a side view of a support sleeve 4. The illustrated support sleeve 4 is hollow-cylindrical and has a mechanical strength selected such that the plastic measuring tube's expansion behavior in the measuring section is limited by the support sleeve 4 itself. However, the shape of the support sleeve 4 depends on the outer shape of the plastic measuring tube.

[0069] Fig. 4 shows an alternative support sleeve 40 which allows radial tension to be applied to the plastic measuring tube 2 without the latter having to be cooled down beforehand. The support sleeve 40 shown is flexible and comprises an annular component 41 with open ends. The open ends can be mechanically connected via a connecting element 8 such that the support sleeve 40 can thereby apply radial tension to the plastic measuring tube 2. In the embodiment shown, the connecting element 8 comprises two screws via which radial tension can be applied to the plastic measuring tube 2. The annular component 42 is arranged on an annular guide 42 and interacts with it.

[0070] Alternatively, the support sleeve 4 can comprise two half-shells (not shown) that can be mechanically connected to one another via two connecting elements in such a way that, when connected to one another, they exert a radial stress on the plastic measuring tube 2. The radial stress is thereby caused by compressing the plastic measuring tube 2 by means of the support sleeve 4, in particular the two half-shells.

[0071] Fig. 5a-c show individual method steps for attaching a support sleeve 4 to a plastic measuring tube 2. In a first method step, the support sleeve 4 is arranged on the plastic measuring tube 2 in a measuring section MA of the plastic measuring tube 2. This can be done by sliding the support sleeve on or by radial attachment. Once the support sleeve 4 is positioned in the desired position, the entire support sleeve 4 or at least a section of the support sleeve 4 is mechanically pressed in the second method step. This can be done using a pressing device 30.

[0072] Fig. 6 shows process steps of a method for manufacturing a magnetic-inductive flowmeter.

[0073] In a first process step I, a plastic measuring tube is cooled below a cooling temperature T cool cooled. The cooling temperature T cooi is selected from a temperature range of -60°C < T cool< -10°C, especially -55°C < T cool < -10°C. Cooling can be achieved using a cooling device or liquid nitrogen.

[0074] In a second process step, a support sleeve is slid onto the plastic measuring tube and placed in a fixed position within a measuring section MA of the plastic measuring tube. The support sleeve itself can be cooled beforehand. Alternatively, the support sleeve can be cooled to a temperature corresponding to the ambient temperature, e.g., room temperature (15-17°C for warehouses and 17-22°C for offices).

[0075] In a third process step, the plastic measuring tube is heated to a temperature ^ necessary to secure the support sleeve in the measuring section. The warming process can be achieved by acclimatizing the previously cooled plastic measuring tube to the ambient temperature. Alternatively, the warming process can be accelerated using a heating device.

[0076] In a fourth step, a magnetic field generating device is attached to the support sleeve. In a fifth step, at least two measuring electrodes are

[0077] Measuring section arranged and fixed medium-tight.

[0078] The fifth method step can also be performed before the fourth method step. Furthermore, further method steps can be provided, which include connecting the magnetic field-generating device and the at least two measuring electrodes to a measuring and / or operating circuit, attaching a housing to the plastic measuring tube, and filling a cavity between the housing wall and the outer surface of the plastic measuring tube with a potting compound.

Claims

PATENT CLAIMS 1. Flow meter (1), comprising: - a plastic measuring tube (2), wherein the plastic measuring tube (2) has a measuring section (MA), wherein the plastic measuring tube (2) comprises a measuring tube channel (3) for guiding a flowable medium; - a support sleeve (4) for minimizing expansion of the plastic measuring tube (2) in the measuring section (MA), wherein the support sleeve (4) encompasses the plastic measuring tube (2) in sections; - a housing (5), wherein the housing (5) together with the plastic measuring tube (2) defines a cavity (6) which partially surrounds the plastic measuring tube (2), wherein the support sleeve (4) is arranged in the cavity (6), characterized in that for a temperature ^ from a temperature range of -10°C < T A< 10°C and a medium-free measuring tube channel (3), the plastic measuring tube (2) experiences radial stress in the radial direction due to the support sleeve (4).

2. Flowmeter (1) according to claim 1, wherein the plastic measuring tube (2) in the measuring section (MA) has a first outer diameter, wherein the plastic measuring tube (2) outside the measuring section (MA) has a measuring tube section in which the plastic measuring tube (2) has a second outer diameter D2, wherein for the temperature ^ the first diameter is smaller than the second diameter D2, wherein for a temperature T B which is less than the temperature 7^, the first diameter and the second diameter D2 are equal.

3. Flow meter (1) according to claim 1 or 2, wherein the plastic measuring tube (2) has a process connection (7) at each end, the measuring tube section being located between the measuring section (MA) and the process connection (7).

4. Flowmeter (1) according to claim 1 or 2, wherein the flowmeter (1) is free of a process connection.

5. Flowmeter (1) according to claim 2 to 4, wherein the support sleeve (4) has an inner diameter D in wherein the inner diameter D in is smaller than the second diameter D2.

6. Flow meter (1) according to one of the preceding claims, wherein the radial clamping provides an anti-rotation and an axial displacement lock for the support sleeve (4).

7. Flow meter (1) according to one of the preceding claims, wherein a material of the support sleeve (4) comprises a fiber composite material.

8. Flow meter (1) according to one of the preceding claims, wherein the radial tension is caused by compressing the plastic measuring tube (2) by means of the support sleeve (4).

9. Flowmeter (1) according to claim 8, wherein the support sleeve (4) is formed in one piece and is flexible, wherein the support sleeve (4) comprises at least one connecting element (8) which is designed to mechanically connect two ends of the support sleeve (4) in such a way that the support sleeve (4) thereby effects the radial tension on the plastic measuring tube (2).

10. Flowmeter (1) according to claim 8, wherein the support sleeve (4) comprises two half-shells (10a, 10b) which are mechanically connected to one another via at least one connecting element (8), wherein two half-shells (10a, 10b) are connected to one another in such a way that the support sleeve (4) effects the radial tension on the plastic measuring tube (2).

11. Flow meter (1) according to claim 8, wherein the support sleeve (4) is pressed onto the plastic measuring tube (2) by means of a press fitting.

12. Flowmeter (1) according to one of the preceding claims, further comprising: - a magnetic field generating device (21) for generating a magnetic field penetrating the plastic measuring tube (2) in the measuring section (MA), wherein the magnetic field generating device (21) is arranged in the measuring section (MA), wherein the magnetic field generating device (21) is arranged in the cavity (6); - at least two measuring electrodes (23), wherein the at least two measuring electrodes (23) are arranged in the measuring section (MA).

13. A method for producing a flowmeter (1), in particular a magnetic inductive flowmeter (20), which comprises a plastic measuring tube (2) and a support sleeve (4), preferably according to one of the preceding claims, comprising the method steps: - Cooling of a plastic measuring tube (2) below a cooling temperature T cool , where cooling temperature T cool selected from a temperature range of -60°C < T cool < — 10°C, especially -55°C < T cool< -10°C; - sliding a support sleeve (4) onto the plastic measuring tube (2) and positioning the support sleeve (4) in a measuring section (MA) of the plastic measuring tube (2); and - Heating the plastic measuring tube (2) to a temperature ^ to fix the support sleeve (4) in the measuring section (MA).

14. A method for producing a flowmeter (1), in particular a magnetic inductive flowmeter (1), which comprises a plastic measuring tube (2) and a support sleeve (4), preferably according to one of the preceding claims, comprising the method steps: - Positioning the support sleeve (4) on the plastic measuring tube (2) in a measuring section (MA) of the plastic measuring tube (2); - mechanical pressing of the entire support sleeve (4) or pressing of the support sleeve (4) in sections.

15. The method according to claim 13 or 14, comprising the method steps: - attaching a magnetic field generating device (21) to the support sleeve (4); and - Attaching at least two measuring electrodes (23) in the measuring section (MA).

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