CH684806A5 - Measuring the degree of filling of conductive liquids in a pipe - Google Patents
Measuring the degree of filling of conductive liquids in a pipe Download PDFInfo
- Publication number
- CH684806A5 CH684806A5 CH378792A CH378792A CH684806A5 CH 684806 A5 CH684806 A5 CH 684806A5 CH 378792 A CH378792 A CH 378792A CH 378792 A CH378792 A CH 378792A CH 684806 A5 CH684806 A5 CH 684806A5
- Authority
- CH
- Switzerland
- Prior art keywords
- measuring
- reference electrode
- arrangement according
- filling
- degree
- Prior art date
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
- G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
- G01F23/24—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid
- G01F23/241—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid for discrete levels
- G01F23/242—Mounting arrangements for electrodes
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
- G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
- G01F23/24—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid
- G01F23/241—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid for discrete levels
- G01F23/243—Schematic arrangements of probes combined with measuring circuits
Landscapes
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Fluid Mechanics (AREA)
- General Physics & Mathematics (AREA)
- Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
Abstract
Description
1 1
CH 684 806 A5 CH 684 806 A5
2 2nd
Beschreibung description
Die Erfindung bezieht sich auf eine Anordnung der im Oberbegriff des Patentanspruches 1 genannten Art zum Messen des Füllgrades eines Rohrquerschnittes, der von einer elektrisch leitenden Flüssigkeit durchflössen wird. The invention relates to an arrangement of the type mentioned in the preamble of claim 1 for measuring the degree of filling of a pipe cross section through which an electrically conductive liquid flows.
Zum Messen der Leitfähigkeit einer Flüssigkeit, wie etwa Wasser oder Milch ist es bekannt, das zwischen zwei Elektroden befindliche Medium mit einer Wechselspannung zu beaufschlagen und den Strom zu messen, sodass nach dem ohmschen Gesetz die Leitfähigkeit als Kehrwert des Widerstandes bestimmt werden kann. Ist das Medium mit Luft durchsetzt, so ist die Leitfähigkeit proportional zum Flüssigkeitsanteil oder Füllgrad. Wenn also der Durchfluss gemessen werden soll, so kann die gemessene Durchflussgeschwindigkeit mit der Füllstandhöhe des Rohrquerschnittes multipliziert werden, um den effektiven Durchfluss ohne Luftbeimischung zu erhalten. To measure the conductivity of a liquid, such as water or milk, it is known to apply an alternating voltage to the medium located between two electrodes and to measure the current so that, according to Ohm's law, the conductivity can be determined as the reciprocal of the resistance. If the medium is permeated with air, the conductivity is proportional to the liquid content or degree of filling. If the flow is to be measured, the measured flow rate can be multiplied by the level of the pipe cross-section in order to obtain the effective flow without adding air.
Es ist eine Anordnung nach dem Oberbegriff des Patentanspruches 1 bekannt bei der zu einem vorgegebenen Zeitpunkt bei vollständig gefüllter Leitung eine Kalibrierung des erfassten Flüssigkeitsmengenvolumens erfolgt, damit der spezifische Widerstand von beispielsweise Milch, welcher sich pro 10°C halbiert und auch wesentlich von Salzgehalt bestimmt wird, für die Zeit des Messvorganges als gegeben angenommen werden kann und so das Messresultat für den Füllgrad unabhängig von Salzgehalt und Temperatur erhalten wird. Es ist jedoch nicht in jedem Fall gewährleistet, dass in diesem Moment der Kalibrierung der Füllstand 100% ist. Besonders bei kleinen abzusaugenden Flüssigkeitsmengen die nur einige Sekunden Absaugzeit benötigen, kann in den 2 Sekunden vor dem Kalibrierzeitpunkt durch eine andere Temperatur als angenommen während der Kalibration ein erheblicher Messfehler entstehen. An arrangement according to the preamble of claim 1 is known in which, at a predetermined point in time when the line is completely full, the recorded volume of liquid is calibrated so that the specific resistance of, for example, milk, which is halved per 10 ° C. and is also essentially determined by salinity , can be taken as given for the time of the measurement process and so the measurement result for the degree of filling is obtained regardless of salinity and temperature. However, it is not always guaranteed that the level is 100% at this moment of calibration. Especially with small amounts of liquid to be aspirated that only require a few seconds of suction time, a significant measurement error can occur in the 2 seconds before the calibration time due to a different temperature than assumed during the calibration.
Der Erfindung liegt die Aufgabe zugrunde, eine einfache Anordung der eingangs genannten Art zu schaffen, bei welcher der Einfluss von Temperatur-und Salzgehalt auf den spezifischen Widerstand der Flüssigkeit sofort und in jedem Moment kompensiert wird. The invention has for its object to provide a simple arrangement of the type mentioned, in which the influence of temperature and salt content on the specific resistance of the liquid is compensated for immediately and at any moment.
Nachfolgend wird ein Ausführungsbeispiel der Erfindung anhand der Zeichnungen erläutert. An exemplary embodiment of the invention is explained below with reference to the drawings.
Es zeigen: Show it:
Fig. 1: Ein Prinzipschaltbild der Anordnung in einem eckigen Rohr. Fig. 1: A basic circuit diagram of the arrangement in an angular tube.
Fig. 2: Ein Schema zum ausführlichen Erläutern des Verstärkerteiles. Fig. 2: A diagram for a detailed explanation of the amplifier part.
Fig. 3: Eine Variante in Ansicht der Anordnung mit einem runden Rohr. Fig. 3: A variant in view of the arrangement with a round tube.
Ein Oszillator 1 mit einer Frequenz von z.B. 10 KHz liefert eine Wechselspannung 15 von z.B. 0,5 Veff der einen dem Leitwert 10 von Rx zwischen den beiden, vorzugsweise rechteckigen Elektroden 3 und 4 entsprechenden Strom fliessen lässt. Von der Elektrode 4 fliesst der Strom Im 2 weiter über eine sehr kurze Flüssigkeitsstrecke 13 z.B. 0,5 mm auf die sehr kleine Referenzelektrode 5 und erzeugt dabei eine Spannung 7 am Ausgang des Operationsverstärkers 6, die proportional zum Füllgrad der Flüssigkeit 11 ist, und nach dem Gleichrichter 8 am Ausgang 14 z.B. zur analogen oder digitalen elektronischen Multiplikation mit der Durchflussgeschwindigkeit ansteht. An oscillator 1 with a frequency of e.g. 10 KHz supplies an AC voltage 15 of e.g. 0.5 Veff which allows a current corresponding to the conductance 10 of Rx to flow between the two, preferably rectangular electrodes 3 and 4. The current Im 2 continues to flow from the electrode 4 over a very short liquid path 13, e.g. 0.5 mm on the very small reference electrode 5 and thereby generates a voltage 7 at the output of the operational amplifier 6, which is proportional to the degree of filling of the liquid 11, and after the rectifier 8 at the output 14 e.g. for analog or digital electronic multiplication with the flow rate.
Da die Referenzelektrode 5 an der Sohle, vorzugsweise in einer Ecke des Rohres 10 angebracht ist, wo keine Luftblasen sind, ist der Widerstand 12 dieser Messstrecke 13 entsprechend 100% Flüssigkeit ohne Luft. Since the reference electrode 5 is attached to the base, preferably in a corner of the tube 10, where there are no air bubbles, the resistance 12 of this measuring section 13 is correspondingly 100% liquid without air.
Vorzugsweise wird der Referenzelektrodenab-stand 13 von 4 zu 5 kleiner als 1 mm und die Elektrodenfläche kleiner als 3 mm2 also z.B. ein Drahtende von 2 mm Länge bei 0,5 mm Durchmesser gewählt, sodass bei einem Messelektrodenabstand von 30 mm und einer Elektrodenfläche von 300 mm2 ein Verhältnis von Messwiderstand 10 zu Referenzwiderstand 12 von z.B. 1 zu 2 entsteht, was zur Folge hat, dass der Operationsverstärker 6 durch die Beschaltung mit Rx 10 und RRef 12 eine 2-fache Verstärkung aufweist, die unabhängig ist von den Temperaturen und dem Salzgehalt der Flüssigkeit 11, die weitgehend den spezifischen Widerstand bestimmen. The reference electrode spacing 13 from 4 to 5 is preferably less than 1 mm and the electrode area is less than 3 mm 2, e.g. a wire end of 2 mm length with 0.5 mm diameter is selected so that with a measuring electrode distance of 30 mm and an electrode area of 300 mm2 a ratio of measuring resistor 10 to reference resistor 12 of e.g. 1 to 2 arises, which means that the operational amplifier 6 has a double amplification due to the connection with Rx 10 and RRef 12, which is independent of the temperatures and the salinity of the liquid 11, which largely determine the specific resistance.
Da in runden Rohren die benetzte Fläche von rechteckigen Elektroden im Verhältnis zum Widerstand der Flüssigkeit zu gross, respektive der Elektrodenabstand 14 variert wird, soll bei runden Rohren eine zum Rohrboden schmäler werdende Elektrodenform gemäss Fig. 3 gewählt werden. Since in circular tubes the wetted area of rectangular electrodes is too large in relation to the resistance of the liquid, or the electrode spacing 14 is varied, in the case of round tubes an electrode shape narrowing towards the tube sheet should be selected according to FIG. 3.
Die Referenzelektrode 5 soll auch hier wieder sehr nahe, beispielsweise im Abstand 13 an der Elektrode 4 plaziert sein. The reference electrode 5 should again be placed very close to the electrode 4, for example at a distance 13.
Die vorliegende Anordnung ist dank ihrer kompakten Bauweise speziell für Messungen an Milchprobeentnahmegeräten geeignet. Für andere Applikationen kann das Ausgangssignal 16 so konditioniert werden, dass es jederzeit mit einem Durch-flussmessgerät multiplikativ verknüpft werden kann. Thanks to its compact design, the present arrangement is particularly suitable for measurements on milk sampling devices. For other applications, the output signal 16 can be conditioned in such a way that it can be multiplicatively linked to a flow meter at any time.
Claims (7)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH378792A CH684806A5 (en) | 1992-12-11 | 1992-12-11 | Measuring the degree of filling of conductive liquids in a pipe |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH378792A CH684806A5 (en) | 1992-12-11 | 1992-12-11 | Measuring the degree of filling of conductive liquids in a pipe |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CH684806A5 true CH684806A5 (en) | 1994-12-30 |
Family
ID=4263470
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CH378792A CH684806A5 (en) | 1992-12-11 | 1992-12-11 | Measuring the degree of filling of conductive liquids in a pipe |
Country Status (1)
| Country | Link |
|---|---|
| CH (1) | CH684806A5 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102008020647A1 (en) * | 2008-04-24 | 2009-11-12 | Continental Automotive Gmbh | Device for measuring a probe impedance |
| WO2024132779A1 (en) * | 2022-12-20 | 2024-06-27 | Endress+Hauser Flowtec Ag | Magnetic-inductive flow meter |
-
1992
- 1992-12-11 CH CH378792A patent/CH684806A5/en not_active IP Right Cessation
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102008020647A1 (en) * | 2008-04-24 | 2009-11-12 | Continental Automotive Gmbh | Device for measuring a probe impedance |
| EP2113753B1 (en) * | 2008-04-24 | 2011-06-29 | Continental Automotive GmbH | Device for measuring a probe impedance |
| WO2024132779A1 (en) * | 2022-12-20 | 2024-06-27 | Endress+Hauser Flowtec Ag | Magnetic-inductive flow meter |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PFA | Name/firm changed |
Owner name: PROMYX AG |
|
| PFA | Name/firm changed |
Owner name: SCHLAEPFER MESSTECHNIK AG |
|
| PL | Patent ceased |