In-line measuring device with measuring tube lined internally with polyurethane and method for manufacture thereof
09782798 · 2017-10-10
Assignee
Inventors
Cpc classification
International classification
Abstract
The measuring tube of the in-line measuring device is formed by means of a support tube and a liner internally lining the support tube. The liner adheres to the support tube, with interposition of a mediating primer. Both the primer and the liner are composed, at least in part, of polyurethane. Especially, both the polyurethane of the liner and also the polyurethane of the primer are suitable for drinking water applications, so that the in-line measuring device itself is also suited for measuring drinking water.
Claims
1. A method for manufacturing a measuring tube of an in-line measuring device, wherein the measuring tube includes a support tube and a liner internally lining the support tube, said method comprising: forming a flowable first multicomponent system, which contains isocyanate as well as a di-, or more-, valent alcohol; applying the first multicomponent system onto an inner wall of a support tube serving as a component of the measuring tube; allowing at least parts of the first multicomponent system to cure on the inner wall of the support tube for forming a primer adhering to the support tube; forming a flowable, second multicomponent system, which contains isocyanate, a di-, or more-, valent alcohol, and a catalyst; applying the second multicomponent system onto the primer formed on the inner wall of the support tube; and allowing the second multicomponent system to cure in the support tube for forming the liner.
2. The method as claimed in claim 1, wherein: the catalyst of the second multicomponent system contains metal-organic compounds.
3. The method as claimed in claim 2, wherein: the catalyst of the second multicomponent system contains metal-organic compounds formed of a physiologically safe metal.
4. The method as claimed in claim 3, wherein: the catalyst of the second multicomponent system contains organotin compounds.
5. The method as claimed in claim 4, wherein: the catalyst of the second multicomponent system contains di-n-octyl tin compounds.
6. The method as claimed in claim 4, wherein: the catalyst of the second multicomponent system comprises a di-n-octyl tin dilaurate; and/or the catalyst of the second multicomponent system comprises a di-n-octyl tin dimalinate.
7. The method as claimed in claim 2, wherein: the first multicomponent system contains a catalyst containing metal-organic compounds.
8. The method as claimed in claim 7, wherein: the catalyst of the first multicomponent system contains organotin compounds.
9. The method as claimed in claim 8, wherein: the catalyst of the first multicomponent system contains metal-organic compounds formed of a physiologically safe metal.
10. The method as claimed in claim 9, wherein: the catalyst of the first multicomponent system contains di-n-octyl tin compounds.
11. The method as claimed in claim 10, wherein: the catalyst of the first multicomponent system comprises a di-n-octyl tin dilaurate; and/or the catalyst of the first multicomponent system comprises a di-n-octyl tin dimalinate.
12. The method as claimed in claim 8, wherein: the catalyst of the first multicomponent system contains organotin compounds.
13. The method as claimed in claim 2, wherein: the catalyst of the second multicomponent system contains organotin compounds.
14. The method as claimed in claim 1, wherein: the first multicomponent system contains at least two reactive NCO groups; and/or the second multicomponent system contains at least two reactive NCO groups; and/or the first multicomponent system contains aromatic isocyanate groups; and/or the first multicomponent system contains aliphatic isocyanate groups; and/or the second multicomponent system contains aromatic isocyanate groups; and/or the second multicomponent system contains aliphatic isocyanate groups; and/or the first multicomponent system contains monomeric isocyanate; and/or the first multicomponent system contains prepolymeric isocyanate; and/or the first multicomponent system contains polymeric isocyanate; and/or the second multicomponent system contains monomeric isocyanate; and/or the second multicomponent system contains prepolymeric isocyanate; and/or the second multicomponent system contains polymeric isocyanate; and/or the first multicomponent system is formed using a prepolymer based on diisocyanate; and/or the second multicomponent system is formed using a prepolymer based on diisocyanate; and/or the first multicomponent system contains ether groups, and/or the first multicomponent system contains ester groups; and/or the second multicomponent system contains ether groups; and/or the second multicomponent system contains ester groups; and/or the alcohol of the first multicomponent system comprises a diol; and/or the alcohol of the second multicomponent system comprises a diol; and/or the alcohol of the first multicomponent system comprises a prepolymer based on castor oil; and/or, the alcohol of the second multicomponent system comprises a prepolymer based on castor oil; and/or the first multicomponent system also contains a catalyst.
15. The method as claimed in claim 14, wherein: the first multicomponent system contains aliphatic ether groups, and/or the first multicomponent system contains aromatic ether groups, and/or the first multicomponent system contains aliphatic ester groups; and/or the first multicomponent system contains aromatic ester groups; and/or the second multicomponent system contains aliphatic ether groups, and/or the second multicomponent system contains aromatic ether groups, and/or the second multicomponent system contains aliphatic ester groups; and/or the second multicomponent system contains aromatic ester groups; and/or the alcohol of the first multicomponent system comprises a butanediol; and/or the alcohol of the second multicomponent system comprises a butanediol; and/or the first multicomponent system contains a catalyst containing metal-organic compounds.
16. The method as claimed in claim 1, wherein: at least one of said first and second multicomponent systems is based on diphenylmethane diisocyanate (MDI), hexane diisocyanate (HDI), toluene diisocyanate (TDI) and/or isophorone diisocyanate (IPDI).
17. The method as claimed in claim 1, wherein: the first multicomponent system contains a catalyst containing metal-organic compounds.
18. The method as claimed in claim 17, wherein: the catalyst of the first multicomponent system contains metal-organic compounds formed of a physiologically safe metal.
19. The method as claimed in claim 18, wherein: the catalyst of the first multicomponent system contains organotin compounds.
20. The method as claimed in claim 19, wherein: the catalyst of the first multicomponent system contains di-n-octyl tin compounds.
21. The method as claimed in claim 20, wherein: the catalyst of the first multicomponent system comprises a di-n-octyl tin dilaurate; and/or the catalyst of the first multicomponent system comprises a di-n-octyl tin dimalinate.
22. The method as claimed in claim 17, wherein: the catalyst of the first multicomponent system contains organotin compounds.
23. The method as claimed in claim 1, wherein: the method is performed at a working temperature of less than 100° C.
24. The method as claimed in claim 23, wherein: the method is performed at a working temperature at about 25° C.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) The invention and advantageous embodiments are described in further detail in the following on the basis of the figures of the drawing. Equal components are provided with equal reference characters. If it is required for purposes of clarity, however, reference characters are omitted in subsequent figures.
(2)
(3)
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
(4) While the invention is susceptible to various modifications and alternative forms, exemplary embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the intended claims.
(5)
(6) Measuring tube 1 is composed of an, especially metal, support tube 2 of predeterminable lumen and a tubular liner 3 having a predeterminable diameter and made of an insulating material. Support tube 2 is composed of a non-ferromagnetic material, for example stainless steel or another rust-free metal, and surrounds the liner 3 coaxially. The liner completely lines the support tube 2, and, in this respect, essentially completely isolates the support tube 2 from fluid flowing through during operation.
(7) The liner 3 of the in-line measuring device of the invention is composed, at least in part, of a polyurethane (PUR.sub.3). For facilitating adherence of liner 3 to support tube 2, a primer 4, likewise at least in part of a polyurethane (PUR.sub.4), is provided therebetween. Primer 4 can, for instance, be applied by spraying or painted with a brush or other applicator in a liquid state as a thin layer to the inner wall of the support tube 2 during manufacture of the measuring tube. After the polyurethane (PUR.sub.4) forming the primer 4 has been allowed to cure, at least partially, at least to a degree sufficient for the subsequent processing, on the inner wall of the support tube 2, then the actual liner 3 can be manufactured, for example, by applying flowable polyurethane (PUR.sub.3) in a centrifugal process or in a so-called ribbon-flow process to the inner wall of the support tube 2 and distributing such there in a surface-covering manner, as uniformly as possible.
(8) In an embodiment of the invention, it is provided that, used for the manufacture of the liner 3, is a polyurethane which is different from the polyurethane used for primer 4. Alternatively thereto, especially for the case in which liner 3 and primer 4 are to exhibit essentially the same chemical properties, it is, however, also possible to use essentially equal polyurethanes for manufacture of liner and primer.
(9) In an embodiment of the invention, the measuring tube is provided for use in an in-line measuring device having a magneto-inductive measuring transducer. Accordingly, the measuring transducer encompasses, furthermore, a magnetic circuit arranged at the measuring tube to create and convey a magnetic field inducing an electrical voltage in the flowing—in this case, electrically conductive—fluid, as well as measuring electrodes for sensing voltages induced in the flowing fluid.
(10) The magnetic circuit arrangement usually has two field coils that, in measurement operation, are connected with an—not shown here—exciter electronics of the in-line measuring device that creates variable electrical currents of predeterminable current strength, such that the coils are, at least at times, flowed-through by a corresponding exciter current. The magnetic field created thereby passes through the fluid flowing in the measuring tube 1 at least sectionally perpendicularly to its stream direction of flow. To read the corresponding, induced, electrical voltage in the flowing fluid, the transducer has a sensor assembly arrangement attached to the measuring tube 1. The sensor arrangement includes first and second measuring electrodes 31, 32. These lie diametrically opposite one another, on a diameter of the measuring tube 1 imaginarily connecting the measuring electrodes running, or extending, perpendicularly to a diameter of the measuring tube 1 imaginarily connecting the field coils.
(11) Of course, the measuring electrodes 31, 32 can, if required, especially in the case of more than two measuring electrodes, be arranged separately and with clearance from each other, but not diametrically opposed. This can be the case, for example, if additional measuring electrodes are provided for reference potentials or, in the case of a horizontal, installed position of the measuring tube 1, measuring electrodes are provided for monitoring a minimum level of fluid in measuring tube 1. For fluid-tight insertion into the pipeline, the measuring tube 1 has, further, a first flange 4 on a first measuring tube end and a second flange 5 on a second measuring tube end. Support tube 2 and flanges 4, 5 all have circular cross-sections.
(12) In production of the measuring tube 1, support tube 2 is first provided with the desired length, and the metal flanges 4, 5 are prepared to fit with the support tube 2. Then, flange 4 is pushed onto one end of the support tube 2 and flange 5 onto the other end. Thereupon a rear side of each of the metal flanges 4, 5 is connected firmly and tightly with the exterior of the support tube 2. This can be done when using a metal support tube and metal flanges, for example, by soldering, brazing or welding, which leads to corresponding solder, braze, or weld seams 6. The space between the flanges 4, 5 and the support tube 2 can, as is usual especially in the case of magneto-inductive measurement pickups, be closed by means of a surrounding piece of sheet metal. The space, in the case that the measuring tube will be used for a magneto-inductive measurement pickup, can serve, for example, to accommodate the field coils producing the mentioned magnetic field and further components of the above-mentioned, magnetic circuit arrangement. If the sheet metal is to serve, in such case, as a component of the magnetic circuit, it is preferably built of ferromagnetic material.
(13) As already indicated, the in-line measuring device serves, especially, also for measuring fluids, such as drinking water, which are subject to increased requirements as regards chemical-biological, as well as also bacteriological, purity. Consequently, it is additionally provided in the case of the measuring tube 1 of the invention, that both the polyurethane (PUR.sub.3) for the liner 3 and also the polyurethane (PUR.sub.4) for the primer 4 are, in each case, suited, especially also permitted, per se for application in the drinking water field. In other words, the polyurethane (PUR.sub.3) for the liner 3 and the polyurethane (PUR.sub.4) for the primer 4 are, in each case, so developed, that in spite of sustained contact with the fluid, especially drinking water, to be measured, at least no unallowably high, as much as possible, however, no, contamination of the fluid would be caused by ingredients contained in the liner and/or in the primer, be it, for instance, the reacted polyurethane itself or possibly unreacted residues of individual starting components, intermediate reaction products and/or reaction by-products thereof or possibly introduced metals or metal compounds possibly contained therein. Used as materials for the liner 3 and also for the primer 4 can be, for example, a polyurethane containing aliphatic and/or aromatic, ether groups, and/or aliphatic and/or aromatic, ester groups. Additionally, the polyurethane (PUR.sub.3) for the liner 3, as well as also the polyurethane (PUR.sub.4) for the primer, can be formed on the basis of monomeric and/or prepolymeric and/or polymeric isocyanates, as required, also trimers (trimerizates or trimerisates) derived therefrom.
(14) In a further embodiment of the invention, it is provided, in such case, that the polyurethane (PUR.sub.3) of the liner 3 is produced on the basis of a multicomponent system formed of a first liner starting component (A.sub.3) containing an isocyanate, especially diisocyanate, and a second liner starting component (B.sub.3) containing a di-, or more-, valent alcohol. Alternatively or in supplementation thereof, it is further provided that the polyurethane (PUR.sub.4) of the primer 4 is produced on the basis of a multicomponent system formed by means of a first primer starting component (A.sub.3) containing an isocyanate, especially a diisocyanate and/or a higher-valent isocyanate, as well as a second primer starting component (B.sub.3) containing a di-, or more-, valent alcohol.
(15) In order to make liner 3 and primer 4 drinking-water suitable, in each case, in the above sense, in a further embodiment of the invention for manufacturing the polyurethane (PUR.sub.3) used for the liner 3, as well as also for the manufacture of the polyurethane (PUR.sub.4) used for the primer 4, among other things, in each case, use of a heavy metal containing and/or amine containing catalyst is declined, although these types of catalysts would actually be very advantageous for the proper manufacture of liner 3 and for primer 4, because of their good reactivity. Instead, in the case of the in-line measuring device of the invention, for manufacture at least of its liner 3, a polyurethane (PUR.sub.3) is used, which is formed by inclusion of a catalyst (C.sub.3) containing metal-organic compounds and serving, in effect, as a third liner starting component. Moreover, the polyurethane (PUR.sub.3) for the liner 3 is so chosen that the metal (Me) brought into the liner with the catalyst (C.sub.3) and remaining there, is bonded chemically, especially atomically, and/or physically, especially by crosslinking, to carbon chains formed in the liner. An advantage of this catalyst (C.sub.3) is that its organo-metal compounds are incorporated into the material of the liner in such a manner that, even under the action of water during operation of the in-line measuring device, such are not leached out of the liner, or, if at all, then only in physiologically safe amounts and rates. In supplementation thereof, in a further development of the invention, it is provided to use, also for the primer 4, such a polyurethane (PUR.sub.4) also produced with the help of a catalyst (C.sub.4), likewise containing metal-organic compounds. However, in view of the fact that, in the case of manufacture of the primer 4, not necessarily the same requirements must be set as regards speed of manufacture and/or accuracy of dimensions, as must be done for liner 3, it can be possible in the manufacture of the primer 4 even to omit completely the use of a catalyst (C.sub.4). However, it is clearly possible, in case required, to include for the polyurethane (PUR.sub.4) of the primer 4, thus serving as a third primer starting component, an equally drinking-water-suitable catalyst (C.sub.4). This can be, for example, essentially the catalyst (C.sub.3) for the polyurethane (PUR.sub.3) of the liner 3,
(16) In an embodiment of the invention, the catalyst used, at least for the manufacture of the polyurethane (PUR.sub.3) of the liner 3, contains organotin compounds, especially di-n-octyl tin compounds, whereby it can be assured that the tin (Sn) brought into the finished liner 3 via the catalyst and, in the end, remaining there, is itself chemically and/or physically bound in the liner 3 and is, as a result, lastingly embedded therein. In an embodiment of the invention, the following organotin compound is used as catalyst (C.sub.3) for manufacture of the polyurethane (PUR.sub.3) for the liner 3:
C.sub.40H.sub.80O.sub.4Sn (1)
(17) Proven to be especially advantageous as catalyst (C.sub.3) for manufacture of the liner 3 is, for example, di-n-octyl tin dilaurate (DOTL), especially that with CAS No. 3648-18-8, whose structure can be represented schematically as follows:
(18) ##STR00001##
(19) Moreover, also, for example, dioctyltin dimalinates or similar metal-organic compounds can be used as catalysts (C3) for manufacture of liner 3.
(20) In an embodiment of the invention, at least the polyurethane (PUR.sub.3) of the liner is an elastomer manufactured on the basis of a multicomponent system (A.sub.3+B.sub.3+C.sub.3), which has been formed by means of a prepolymer as first liner starting component (A.sub.3) and an alcohol, especially a di-, or more-, valent alcohol, as second liner starting component (B.sub.3), as well as with use of a catalyst (C.sub.3) of the aforementioned kind serving as third liner starting component.
(21) For example, the polyurethane (PUR.sub.3) for the liner can be an elastomer that, at least in part, exhibits essentially the following structure:
(22) ##STR00002##
(23) In a further embodiment of the invention, the alcohol (B.sub.3) used for manufacture of the liner 3 is one having at least two functional OH-groups, for example a diol. Especially good results can be obtained, in such case, for example through use of butanediol, especially that having CAS No. 110-63-4.
(24) In another embodiment, it is further provided to develop the alcohol for the polyurethane (PUR.sub.3) of the liner 3 and/or the polyurethane (PUR.sub.4) of the primer 4 as a prepolymer. Found to be advantageous in this case is, for example, the use of prepolymeric alcohol based on castor oil. In a further embodiment of the invention, the alcohol (B.sub.4) at least used for the manufacture of the primer 4 is a polyester polyol, such as e.g. Baycoll® AD 1122 or Baycoll® CD 2084 of Bayer MaterialScience AG, Leverkusen, DE, and/or a polyether polyol, such as e.g. Desmophen® 1380 BT of Bayer MaterialScience AG, Leverkusen, DE, and/or an appropriately hydroxyl-groups-containing polyester, especially a branched one, such as e.g. Desmophen® 650 MPA of Bayer MaterialScience AG, Leverkusen, DE.
(25) Additionally, prepolymers or polymers with two or more, reactive NCO-groups, especially those with aromatic isocyanates, have proven to be especially advantageous for the manufacture of the liner 3, as well as also the primer 4. Alternatively or in supplementation thereof, it is, however, also possible to use corresponding isocyanate monomers or also prepolymers or polymers based on aliphatic, as required also cycloaliphatic, isocyanate groups for manufacture of the polyurethane (PUR.sub.3) of the liner 3 and/or the polyurethane (PUR.sub.4) of the primer 4.
(26) In another embodiment of the invention, at least the first liner starting component (A.sub.3) used for manufacture of the liner 3 is formed by means of a prepolymer, which is, at least in part, built on the basis of the following structural formula:
(27) ##STR00003##
(28) For producing such a prepolymer, in a further development of the invention, a polypropylene oxide is used, which is allowed to react with an aromatic and/or aliphatic diisocyanate, especially such added in excess. In another embodiment of the invention, the polypropylene oxide, at least for the liner 3, is a polypropylene glycol (PPG), whose simplified structure can be described about as follows:
(29) ##STR00004##
(30) Alternatively or in supplementation to polypropylene oxide, also a polytetramethylene-ether-glycol (PTMEG) of the following structural formula can, for example, serve for the manufacture at least of the prepolymer (A.sub.3) for the liner 3:
(31) ##STR00005##
(32) Moreover, alternatively or in supplementation, it is also possible to use other aliphatically constructed glycol compounds containing polymeric ether groups and terminal OH-groups for manufacture of the prepolymer serving as liner starting component (A.sub.3) or, however, also for manufacture of the prepolymer serving as primer starting component (A.sub.4).
(33) In another embodiment of the invention, the diisocyanate used for manufacture of the polyurethane (PUR.sub.3) for the liner 3 and/or for manufacture of the polyurethane (PUR.sub.4) for the primer 4 is one based on an aromatic diphenylmethane diisocyanate (MDI), especially according to CAS No. 101-68-8 and having at least one of the following isomeric structures:
(34) ##STR00006##
(35) Monomeric isocyanates, especially those based on diphenylmethane diisocyanate, are available, for example, as Desmodur® 44 M or Desmodur® 2460 M from Bayer MaterialScience AG, Leverkusen, DE. Alternatively to or in supplementation of the monomeric diisocyanates, it is possible, however, also to use their homologs and/or also corresponding prepolymers, as required also polymers based on such diisocyanates, for the manufacture of the polyurethane (PUR.sub.3) for the liner 3 and/or for manufacture of the polyurethane (PUR.sub.4) for the primer 4, especially with the following structure:
(36) ##STR00007##
(37) Prepolymers of the aforementioned type based on diphenylmethane diisocyanate (MDI) are available, for example, as Desmodur® E 23 from Bayer MaterialScience AG, Leverkusen, DE.
(38) Alternatively or in supplementation thereto, it is, however, also possible to use a prepolymer and/or a polymer based on aromatic toluene diisocyanate (TDI, CAS No. 584-84-9),
(39) ##STR00008##
such as e.g. Desmodur® L 67 MPA/X or Desmodur® L 75 of Bayer MaterialScience AG, Leverkusen, DE, for at least one of the polyurethanes (PUR.sub.3), (PUR.sub.4) for the manufacture of the measuring tube, at least to the extent that the toluene diisocyanate is permitted for applications in the drinking water field.
(40) Additionally, however, it is also possible to apply for the manufacture of the liner 3 and/or the primer 4 a prepolymer and/or a polymer based on an aliphatic hexane diisocyanate (HDI, CAS No. 822-06-0), especially also allowable for applications in the drinking water field, of structure
(41) ##STR00009##
and/or based on an aliphatic isophorone diisocyanate (IPDI, CAS No. 4098-71-9), especially also allowable for applications in the drinking water field, of structure
(42) ##STR00010##
(43) An isophorone diisocyanate suitable in the above sense is e.g. the IPDI-trimer Desmodur® Z 4470 MPA/X of Bayer MaterialScience AG, Leverkusen, DE, while a successful example of hexane diisocyanate is provided by the HDI-trimer Desmodur® N 3300 of Bayer MaterialScience AG, Leverkusen, DE.
(44) Additionally, also other homologs and/or isomers of the aforementioned diisocyanates can be used for producing the polyurethane (PUR.sub.3) of the liner 3 and/or the polyurethane (PUR.sub.4) of the primer 4. Alternatively or in supplementation thereto, the polyurethane (PUR.sub.3) of the liner 3 and/or the polyurethane (PUR.sub.4) of the primer 4 can be formed on the basis of aromatic and/or aliphatic, monomeric diisocyanates, especially monomeric MDI, HDI, IPDI and/or TDI. Moreover, it has been found to be advantageous, at least for manufacture of the primer 4, to produce the polyurethane (PUR.sub.4) using a mixture of monomeric and homologous diisocyanate, for example one according to CAS No. 9016-87-9 based on diphenylmethane diisocyanate (MDI).
(45) In a further development of the invention, for producing the primer 4, first, a flowable, especially sprayable and/or brushable, first multicomponent system (A.sub.4+B.sub.4) is formed, which contains the isocyanate (A.sub.4), for example, in the form of diisocyanate, according to one of the aforementioned configurations, as well as di-, or more-, valent alcohol (B.sub.4). If required, the first multicomponent system can, for accelerating the manufacturing process, be provided also with one of the aforementioned catalysts (C.sub.4), especially one suitable for drinking-water applications. Once the first multicomponent system has been prepared, it is applied, for example painted or sprayed, onto an internal wall of the support tube, especially a metal support tube, serving as foundation of the measuring tube, and there allowed to cure, at least partially, for forming the primer 4 secured to the support tube 2. In an embodiment of the method, the first multicomponent system (A.sub.4+B.sub.4) is so applied to the inner wall of the support tube 2, taking into consideration possible volume changes, such that the primer 4 ends with a thickness of less than 500 μm, especially less than 300 μm.
(46) For manufacturing the polyurethane (PUR.sub.3) for the liner 3, additionally, the second multicomponent system (A.sub.3+B.sub.3+C.sub.3) containing isocyanate (A.sub.3), especially diisocyanate, di-, or more-, valent alcohol (B.sub.3), and a catalyst (C.sub.3) is mixed. After the first-formed primer 4 has cured sufficiently on the inner wall of the support tube 2, the first still flowable, second multicomponent system is applied onto the primer 4 formed on the inner wall of the support tube 2 and then allowed to cure quickly based on the effect of the catalyst (C.sub.3), whereby, finally, the liner 3 is formed in-situ.
(47) The second multicomponent system (A.sub.3+B.sub.3+C.sub.3) can be applied, for example, in the so-called ribbon-flow process using a flow or spray head, which can travel within the lumen of the support tube 2, onto the primer 4 already adhered to the inner wall of the support tube 2. By simultaneous rotating of the support tube 2 about its longitudinal axis and traveling of the flow or spray head essentially parallel to the longitudinal axis, the liquid, multicomponent system (A.sub.3+B.sub.3+C.sub.3) can be distributed in very simple and well reproducible manner uniformly over the entire inner wall.
(48) In an advantageous embodiment of the invention, concentration and amount of the added catalyst (C.sub.3) are so selected, that the multicomponent system (A.sub.3+B.sub.3+C.sub.3) applied to the support tube 2 equipped with primer 4 can cure within a comparatively short reaction time of less than one minute, especially under 30 seconds, and at a working temperature of less than 100° C., for example 25° C.
(49) Experimental investigations have, in such case, shown, for example, that, especially in the case of use of the above-described prepolymer systems (PPG+MDI and/or PTMEG+MDI), such short reaction times can be achieved by addition of the catalyst (C.sub.3) at a mass fraction of less than 2% of the total mass of the multicomponent system (A.sub.3+B.sub.3+C.sub.3). Further-going investigations have additionally shown that especially good results can be achieved in the case of manufacture of the liner 3, when alcohol (B.sub.3) and prepolymer (A.sub.3) for the polyurethane (PUR.sub.3) of the liner 3 are added in a mixing ratio B:A of about 15:100 or less, especially a mixing ratio B:A of less than 10:100. Methods especially suited for manufacture of the polyurethane (PUR.sub.3) for the liner 3, and, as a result, also for its manufacture, especially also for metering of the catalyst, are, moreover, described, for example, in the non-prepublished patent applications DE 102005044972.7 and U.S. 60/718,308.
(50) In case required, multicomponent systems used for manufacture of the polyurethane (PUR.sub.3) for the liner 3 and/or the polyurethane (PUR.sub.4) for the primer 4 can be extended by means of one or more, suitable, especially color-giving and/or strengthening, fillers. The filler can be, for example, a reactive colorant or a pigment e.g. containing, or derived from, carbon particles. Thus, for example, use of black pigment, for example PRINTEX® F 80 of the firm Degussa AG, Düsseldorf, DE, has proven to be very advantageous for manufacture of liners of the described kind, especially also liners which are suitable for drinking-water applications. However, also use of the reactive colorant Reactint® Black X95AB has been found to be very successful, such as is currently offered for the coloring of polyurethanes by the firm Milliken Chemical, a subsidiary of Milliken & Company, Spartanburg, S.C. Alternatively to or in supplementation of the aforementioned coloring materials, also carbonates, especially calcium carbonate, silicates, such as e.g. talc, clay and/or glimmer, silaceous earth, calcium- and barium-sulfate, aluminum hydroxide, glass fibers and spheres, as well as wood dust and cellulose, can be used for manufacture of the polyurethane (PUR.sub.3) for the liner 3 and/or the polyurethane (PUR.sub.4) for the primer 4. By suitable selection of such, especially equally drinking-water suitable, fillers as regards composition and/or particle size, additionally, as required, also a further improvement of the chemical-biological and/or mechanical properties, e.g. strength or surface hardness, etc. of the respective polyurethanes (PUR.sub.3), (PUR.sub.4) can be achieved.
(51) By using polyurethanes (PUR.sub.3) of the above-described kind as material for the liner 3, the measuring tube 1 can be manufactured, without more, with nominal diameters in the range between 25 mm and 2000 mm. Equally, consequently, especially using the above-described, ribbon-flow method for the manufacture of the liner 3, it can be assured that the liner 3 displays a thickness, as uniform as possible, of less than 8 mm, especially less than 4 mm.
(52) A further advantage of the in-line measuring device of the invention is that, by using a polyurethane (PUR.sub.3) of the above-described kind for the liner 3 and a polyurethane (PUR.sub.4) of the above-described kind for the primer 4, even the requirements posed for applications in the drinking-water field, especially the, also as compared to other foods applications, very high hygienic requirements, can be fulfilled. Investigations has shown, for example, that the migration rate (M.sub.max, TOC) as regards total organic carbon content (TOC) can lie below 0.25 milligrams per liter and day, while, for the chlorine consumption rate (M.sub.max, Cl), it is quite possible to achieve values of less than 0.2 milligrams per liter and day. As a result, the in-line measuring device of the invention can meet, for example, the requirements established in the “Leitlinie zur hygienischen Beurteilung von Epoxidharzbeschichtungen in Kontakt mit Trinkwasser” (translation: “Guideline for hygienic evaluation of epoxy resin coatings in contact with drinking water”) relevant at least for Germany for equipment in the distribution network, especially also in main lines, and/or the NSF/ANSI Standard 61 relevant at least for the USA for drinking-water system components. Equally, the in-line measuring device can thoroughly meet also the requirements of the test specifications for permitting for drinking-water applications for Great Briton, “Water Regulation Advisory Scheme BS 9620” and/or for France, “Dossier de Demande d'Acs pour Accesoires”. In-line measuring devices of the invention with a liner of polyurethane can, thus, be used quite conventionally in the drinking water field or replace in-line measuring devices of the described kind having relatively expensive liners of PFA, PTFE, hard rubber or the like provided therefor.
(53) While the invention has been illustrated and described in detail in the drawings and forgoing description, such illustration and description is to be considered as exemplary not restrictive in character, it being understood that only exemplary embodiments have been shown and described and that all changes and modifications that come within the spirit and scope of the invention as described herein are desired to protected.