CH683375A5 - Detecting presence, level or condition of fluid - using evaluation circuit to register frequency of diaphragm inserted flush into wall of vessel - Google Patents

Detecting presence, level or condition of fluid - using evaluation circuit to register frequency of diaphragm inserted flush into wall of vessel Download PDF

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Publication number
CH683375A5
CH683375A5 CH2901/91A CH290191A CH683375A5 CH 683375 A5 CH683375 A5 CH 683375A5 CH 2901/91 A CH2901/91 A CH 2901/91A CH 290191 A CH290191 A CH 290191A CH 683375 A5 CH683375 A5 CH 683375A5
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CH
Switzerland
Prior art keywords
frequency
membrane
diaphragm
liquid
vessel
Prior art date
Application number
CH2901/91A
Other languages
German (de)
Inventor
Pierre-Yves Mueller
Original Assignee
Vibro Meter Ag
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Vibro Meter Ag filed Critical Vibro Meter Ag
Priority to CH2901/91A priority Critical patent/CH683375A5/en
Publication of CH683375A5 publication Critical patent/CH683375A5/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/02—Analysing fluids
    • G01N29/036—Analysing fluids by measuring frequency or resonance of acoustic waves
    • 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
    • G01F23/28—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 the variations of parameters of electromagnetic or acoustic waves applied directly to the liquid or fluent solid material
    • G01F23/296—Acoustic waves
    • G01F23/2965—Measuring attenuation of transmitted waves
    • 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
    • G01F23/28—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 the variations of parameters of electromagnetic or acoustic waves applied directly to the liquid or fluent solid material
    • G01F23/296—Acoustic waves
    • G01F23/2966—Acoustic waves making use of acoustical resonance or standing waves
    • 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
    • G01F23/28—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 the variations of parameters of electromagnetic or acoustic waves applied directly to the liquid or fluent solid material
    • G01F23/296—Acoustic waves
    • G01F23/2966—Acoustic waves making use of acoustical resonance or standing waves
    • G01F23/2967—Acoustic waves making use of acoustical resonance or standing waves for discrete levels
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/02—Analysing fluids
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/22—Details, e.g. general constructional or apparatus details
    • G01N29/222—Constructional or flow details for analysing fluids
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/02—Indexing codes associated with the analysed material
    • G01N2291/024—Mixtures
    • G01N2291/02408—Solids in gases, e.g. particle suspensions
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/02—Indexing codes associated with the analysed material
    • G01N2291/024—Mixtures
    • G01N2291/02416—Solids in liquids
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/02—Indexing codes associated with the analysed material
    • G01N2291/028—Material parameters
    • G01N2291/02836—Flow rate, liquid level

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Health & Medical Sciences (AREA)
  • Fluid Mechanics (AREA)
  • Thermal Sciences (AREA)
  • Electromagnetism (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Measurement Of Levels Of Liquids Or Fluent Solid Materials (AREA)

Abstract

The diaphragm (5) is excited to vibrate at its natural frequency by a piezo-electric transducer (6,7) and an amplifier (8). When the diaphragm is covered by a fluid its frequency falls. This is detected by an evaluating circuit (9). The diaphragm is pref. of stainless steel with its natural frequency of vibration lying above expected basic frequencies of interference sources such as vibrations from pumps, vibrators and acoustic oscillations. The circuit registers the frequency and/or amplitude or a change in either of them. This allows conclusions to be drawn regarding certain characteristics of the medium, e.g. density, viscosity. or the inclusion of solid particles, bubbles or deposits on the diaphragm. This could indicate that the vessel needs cleaning. ADVANTAGE - Diaphragm operates reliably, can be cleaned and is resistant to disturbances from liq. itself or surroundings.

Description

1 1

CH 683 375 A5 CH 683 375 A5

2 2nd

Beschreibung description

Zur Erfassung der Anwesenheit von Flüssigkeit bzw. eines Niveaus in einem Gefäss sind Flüssigkeitsdetektoren bekannt, die in die Flüssigkeit eintauchen. Die CH-A 665 904 zeigt z.B. einen Füllstandsdetektor, der als Schwinger in der Art einer Stimmgabel ausgebildet ist und in ein Gefäss eingesetzt ist. Aus der Frequenz bzw. Frequenzänderung des Schwingers wird darauf geschlossen, ob er in Flüssigkeit eintaucht oder nicht. Es sind auch andere, ähnliche Detektoren oder Schwimmerschalter bekannt, die in den Gefässraum einragen. All diese Geräte haben den Nachteil, dass das Messelement schwer zu reinigen ist, und dass eventuell in der Flüssigkeit vorhandene kolloidale Teile oder Fasern den Mechanismus verstopfen und zum Ausfall oder zur Verfälschung der Messung führen können. To detect the presence of liquid or a level in a vessel, liquid detectors are known which are immersed in the liquid. CH-A 665 904 shows e.g. a level detector, which is designed as an oscillator in the manner of a tuning fork and is inserted into a vessel. From the frequency or frequency change of the transducer, it is concluded whether it is immersed in liquid or not. Other, similar detectors or float switches are known which protrude into the vessel space. All these devices have the disadvantage that the measuring element is difficult to clean and that any colloidal parts or fibers present in the liquid can clog the mechanism and lead to failure or falsification of the measurement.

Es sind auch Ultraschalldetektoren bekannt, die an der Aussenseite eines Gefässes angebracht werden können (CH-A 635 676). In diesem Falle können zwar die oben erwähnten Nachteile nicht auftreten, aber die Empfindlichkeit und Messgenauigkeit ist gering. Insbesondere stellt die korrekte An-koppelung eines Ultraschalldetektors im industriellen Bereich ein Problem dar. Ultrasonic detectors are also known which can be attached to the outside of a vessel (CH-A 635 676). In this case, the disadvantages mentioned above cannot occur, but the sensitivity and measuring accuracy is low. In particular, the correct coupling of an ultrasonic detector in the industrial area is a problem.

Ziel vorliegender Erfindung ist es, eine genaue Anwesenheits- bzw. Niveauerfassung oder die Beurteilung von Eigenschaften der Flüssigkeit ohne störende Einflüsse der Flüssigkeit oder der Umgebung zu ermöglichen. Dieses Ziel wird gemäss den Ansprüchen 1 und 4 erreicht. Die Membran kann keinesfalls verstopft werden, und sie kann nötigenfalls leicht gereinigt werden. Sie kann vorzugsweise relativ kleine Abmessungen aufweisen und somit rasch und empfindlich reagieren, wenn die Flüssigkeit sie zu bedecken beginnt. Die Eigenfrequenz der Membran kann in einem günstigen Bereiche gewählt werden, in welchem kaum äussere Störeinflüsse zu erwarten sind. The aim of the present invention is to enable a precise presence or level detection or the assessment of properties of the liquid without disruptive influences of the liquid or the environment. This goal is achieved according to claims 1 and 4. The membrane can never be clogged and, if necessary, it can be easily cleaned. It can preferably have relatively small dimensions and thus react quickly and sensitively when the liquid begins to cover it. The natural frequency of the membrane can be selected in a favorable range in which hardly any external interference can be expected.

Die Erfindung wird nun anhand eines in der Zeichnung dargestellten Ausführungsbeispiels näher erläutert. The invention will now be explained in more detail with reference to an embodiment shown in the drawing.

Die Wand 1 eines Gefässes, das ein Behälter oder eine Leitung sein kann, weist eine mit Gewinde versehene Öffnung 2 auf, in die das Gehäuse 3 des erfindungsgemässen Flüssigkeitsdetektors eingeschraubt ist. Eine Dichtung 4 dient der dichten Verbindung zwischen Gefässwand und Detektorgehäuse. Die Innenfläche des Gehäuses 3 sowie eine in dieselbe eingesetzte Membran 5 liegen bündig in der Innenfläche der Gefässwand 1. An der Innenseite der Membran 5 sind zwei piezoelektrische Wandler angebracht, nämlich ein kreisförmiger, innerer Wandler 6 und ein denselben ringförmig umgebender Wandler 7. Der Wandler 6 ist mit einem Eingang, der Wandler 7 mit dem Ausgang eines Verstärkers 8 verbunden. Ein weiterer Eingang des Verstärkers und sein Ausgang sind über ein abgeschirmtes Kabel 10 mit der Elektronik 9 verbunden, die unter anderem einen Frequenzdiskriminator aufweist. Das Kabel 10 ist mittels einer Dichtung 11 dicht in das Gehäuse 3 eingeführt. The wall 1 of a vessel, which can be a container or a line, has a threaded opening 2, into which the housing 3 of the liquid detector according to the invention is screwed. A seal 4 serves for the tight connection between the vessel wall and the detector housing. The inner surface of the housing 3 and a membrane 5 inserted into it lie flush in the inner surface of the vessel wall 1. On the inside of the membrane 5, two piezoelectric transducers are attached, namely a circular, inner transducer 6 and a transducer 7 surrounding it in a ring. The transducer 6 is connected to an input, the converter 7 to the output of an amplifier 8. Another input of the amplifier and its output are connected to the electronics 9 via a shielded cable 10, which has, among other things, a frequency discriminator. The cable 10 is inserted tightly into the housing 3 by means of a seal 11.

Wenn der Verstärker 8 über eine nicht dargestellte Leitung gespeist wird, regt er über den Wandler If the amplifier 8 is fed via a line, not shown, it excites through the converter

7 und den Rückkopplungswandler 6 die Membran 5 zur Schwingung mit ihrer Eigenfrequenz an. Die Membran kann z.B. aus rostfreiem Stahl bestehen und einen Durchmesser von etwa 15 mm und eine Stärke von etwa 2 mm aufweisen. Ihre Eigenfrequenz liegt dann im Bereiche von etwa 30 bis 40 kHz. Diese Frequenz ist ideal, da sie einerseits weit höher liegt als zu erwartende Störgeräusche, wie sie durch Druckschwankungen in der Flüssigkeit oder durch Strömungsvibrationen oder aber äussere Störvibrationen auftreten können. Andererseits liegt diese Frequenz wesentlich tiefer als Frequenzen von elektromagnetischen Störfeldern. Es ist somit möglich, mit einfachen Mitteln ein äusserst störungsunempfindliches und doch für die zu erfassende Grösse empfindliches Gerät zu bauen. Die Abmessung der Membran von nur etwa 15 mm führt dazu, dass das Gerät schnell anspricht, wenn Flüssigkeit die Membran 5 zu bedecken beginnt. Die die Membran bedeckende Flüssigkeit bewirkt ein Absinken der Frequenz, was durch den erwähnten Diskriminator ermittelt wird. Es wird dann ein Ausgangssignal erzeugt, das anzeigt, dass der Flüssigkeitsstand erreicht ist, und es kann z.B. die Flüssigkeitszufuhr unterbrochen werden. Es kann aber auch ermittelt werden, wann keine Flüssigkeit mehr an der Membran liegt, und es kann entsprechend z.B. die Zufuhr eingeleitet werden. Es ist aber auch möglich, den Detektor zur eigentlichen Niveaumessung zu verwenden, indem die Änderung der Frequenz erfasst und damit nicht nur die Anwesenheit oder Abwesenheit von Flüssigkeit, sondern deren wirklicher Stand ermittelt wird. In diesem Falle kann die Membran grössere Abmessungen aufweisen. Die Schwingung der Membran kann auch in anderer Weise angeregt werden, z.B. mittels elektromagnetischer Wandler. Die Membran kann vorzugsweise in eine vertikal orientierte Gefässwand eingesetzt werden, von welcher die Flüssigkeit selbständig abfliessen kann. Obwohl die Membran vorzugsweise bündig in eine Gefässwand eingesetzt sein kann, ist es auch möglich, ein in den Gefässraum einbringbares Messgerät vorzusehen, dessen eine Wand als Membran ausgebildet ist. Die Erfassung der Frequenz bzw. Frequenzänderung der Membranschwingung ist zuverlässig und empfindlich, aber es wäre auch möglich, die Schwingungsamplitude zu erfassen und daraus auf die Anwesenheit bzw. Abwesenheit oder den Stand der Flüssigkeit zu schliessen. Die Membran 5 wird vorzugsweise eben ausgeführt und in eine ebene Gefässwand eingesetzt. Es ist aber auch möglich, eine unebene Membran vorzusehen, die in eine entsprechend unebene Gefässwand bündig eingesetzt ist. 7 and the feedback converter 6, the membrane 5 for oscillation at its natural frequency. The membrane can e.g. are made of stainless steel and have a diameter of approximately 15 mm and a thickness of approximately 2 mm. Your natural frequency is then in the range of about 30 to 40 kHz. This frequency is ideal because, on the one hand, it is far higher than expected noise, such as can occur due to pressure fluctuations in the liquid or due to flow vibrations or external interference vibrations. On the other hand, this frequency is much lower than the frequencies of electromagnetic interference fields. It is thus possible to use simple means to build a device that is extremely insensitive to faults and yet sensitive to the size to be detected. The dimension of the membrane of only about 15 mm means that the device responds quickly when liquid begins to cover the membrane 5. The liquid covering the membrane causes the frequency to drop, which is determined by the discriminator mentioned. An output signal is then generated which indicates that the liquid level has been reached, and e.g. the fluid supply should be interrupted. However, it can also be determined when there is no more liquid on the membrane, and accordingly it can e.g. the feed will be initiated. However, it is also possible to use the detector for the actual level measurement, in that the change in frequency is detected and thus not only the presence or absence of liquid, but its actual level is determined. In this case, the membrane can have larger dimensions. The vibration of the membrane can also be excited in other ways, e.g. by means of electromagnetic transducers. The membrane can preferably be inserted into a vertically oriented vessel wall, from which the liquid can flow off independently. Although the membrane can preferably be inserted flush into a vessel wall, it is also possible to provide a measuring device which can be inserted into the vessel space and whose one wall is designed as a membrane. The detection of the frequency or frequency change of the membrane vibration is reliable and sensitive, but it would also be possible to record the vibration amplitude and to infer the presence or absence or the level of the liquid. The membrane 5 is preferably made flat and inserted into a flat vessel wall. However, it is also possible to provide an uneven membrane which is inserted flush in a correspondingly uneven vessel wall.

Wenn der Einfluss des Mediums auf die Frequenz und Amplitude der Schwingung zugleich in Betracht gezogen wird, können Aussagen über gewisse Eigenschaften des Mediums gemacht werden. So kann z.B. die Dichte, die Viskosität, das Vorhandensein von Einschlüssen wie Gasblasen, Feststoffanteilen und dergleichen beurteilt werden. Es ist ferner möglich, bleibende Ablagerungen an der Membran bei Abwesenheit von Flüssigkeit festzustellen und damit z.B. zu beurteilen, wann eine Reinigung des Gefässes erforderlich ist. If the influence of the medium on the frequency and amplitude of the vibration is taken into account at the same time, statements can be made about certain properties of the medium. For example, the density, the viscosity, the presence of inclusions such as gas bubbles, solid contents and the like can be assessed. It is also possible to determine permanent deposits on the membrane in the absence of liquid and thus e.g. to assess when it is necessary to clean the vessel.

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CH 683 375 A5 CH 683 375 A5

Claims (7)

PatentansprücheClaims 1. Verfahren zur Erfassung der Anwesenheit oder des Standes oder Zustandes einer Flüssigkeit, dadurch gekennzeichnet, dass man eine der Flüssigkeit ausgesetzte Membran mit ihrer Eigenfrequenz zur Schwingung anregt und aus der ermittelten Frequenz bzw. Frequenzänderung und/oder Amplitude bzw. Amplitudenänderung auf die Anwesenheit bzw. Abwesenheit, den Stand oder den Zustand der Flüssigkeit schliesst.1. A method for detecting the presence or the state or condition of a liquid, characterized in that one excites a membrane exposed to the liquid with its natural frequency to vibrate and from the determined frequency or frequency change and / or amplitude or amplitude change to the presence or Absence, level or condition of the liquid closes. 2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass man eine Eigenfrequenz im Bereiche von etwa 30 bis 40 kHz wählt.2. The method according to claim 1, characterized in that one selects a natural frequency in the range of about 30 to 40 kHz. 3. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, dass man aus dem Einfluss auf die Frequenz und Amplitude auf bestimmte Eigenschaften des Mediums, z.B. auf seine Dichte oder Viskosität oder auf Feststoffeinschlüsse, oder aber auf Anlagerungen an der Membran schliesst.3. The method according to claim 1 or 2, characterized in that from the influence on the frequency and amplitude on certain properties of the medium, e.g. on its density or viscosity or on solid inclusions, or on deposits on the membrane. 4. Flüssigkeitsdetektor an einem Gefäss, zur Durchführung des Verfahrens nach Anspruch 1, dadurch gekennzeichnet, dass eine Membran (5) bündig in die Gefässwand (1) eingesetzt ist, dass Mittel (6, 7, 8) zur Anregung der Membran zur Schwingung mit Eigenfrequenz sowie Mittel (9) zur Erfassung der Frequenz und/oder Amplitude oder von Änderungen derselben vorgesehen sind.4. Liquid detector on a vessel for carrying out the method according to claim 1, characterized in that a membrane (5) is inserted flush in the vessel wall (1), that means (6, 7, 8) for exciting the membrane to vibrate with Natural frequency and means (9) for detecting the frequency and / or amplitude or changes thereof are provided. 5. Detektor nach Anspruch 4, dadurch gekennzeichnet, dass die Membran (5) aus rostfreiem Stahl besteht.5. Detector according to claim 4, characterized in that the membrane (5) consists of stainless steel. 6. Detektor nach Anspruch 4 oder 5, dadurch gekennzeichnet, dass die Eigenfrequenz über den zu erwartenden Grundfrequenzen von störenden Umwelteinflüssen wie Pumpenschwingungen, Vibrationen und akustischen Schwingungen liegt.6. Detector according to claim 4 or 5, characterized in that the natural frequency lies above the expected basic frequencies of disturbing environmental influences such as pump vibrations, vibrations and acoustic vibrations. 7. Detektor nach einem der Ansprüche 4 bis 6, dadurch gekennzeichnet, dass auf der Membran (5) piezoelektrische Wandler (6, 7) angebracht sind, die mit dem Eingang bzw. Ausgang eines Verstärkers (8) verbunden sind.7. Detector according to one of claims 4 to 6, characterized in that on the membrane (5) piezoelectric transducers (6, 7) are attached, which are connected to the input or output of an amplifier (8). 55 1010th 1515 2020th 2525th 3030th 3535 4040 4545 5050 5555 6060 6565 33rd
CH2901/91A 1991-10-01 1991-10-01 Detecting presence, level or condition of fluid - using evaluation circuit to register frequency of diaphragm inserted flush into wall of vessel CH683375A5 (en)

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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997006433A1 (en) * 1995-08-03 1997-02-20 Milltronics Ltd. Method of detecting characteristics of liquids in pipes and pump controlling
NL1003654C2 (en) * 1996-07-22 1998-01-28 Matheus Jozef Maria Coolen Method for measuring properties of media.
US6044694A (en) * 1996-08-28 2000-04-04 Videojet Systems International, Inc. Resonator sensors employing piezoelectric benders for fluid property sensing
DE10242970A1 (en) * 2002-09-17 2004-04-01 Vega Grieshaber Kg Vibration level sensor compares mechanical oscillator amplitude and/or frequency with value and detects fault in mechanical oscillator if amplitude and/or frequency of value differs in defined manner
WO2005001392A2 (en) * 2003-06-23 2005-01-06 Endress+Hauser Gmbh+Co. Kg Alarm for field devices
WO2005019713A1 (en) * 2003-08-21 2005-03-03 Oliver Twinsafe Valves Limited Valve assembly
WO2008156423A1 (en) 2007-06-21 2008-12-24 Feldt & Meiton Marin Ab Device and method for determination regarding the liquid level in containers
DE102010028161A1 (en) * 2010-04-23 2011-10-27 Endress + Hauser Gmbh + Co. Kg Method for determining and/or monitoring limit level of outgassing liquid medium in container, involves generating signals for signalizing covering and idle conditions when variables fulfill criterion for conditions, respectively
RU2498234C1 (en) * 2012-03-06 2013-11-10 Федеральное государственное автономное образовательное учреждение высшего профессионального образования "Национальный исследовательский ядерный университет "МИФИ" (НИЯУ МИФИ) Liquid level measuring device
IT201900006274A1 (en) * 2019-04-23 2020-10-23 Nuovo Pignone Tecnologie Srl Arrangement with sensor and method for measuring fouling or erosion or corrosion as well as machine monitoring fouling or erosion or corrosion

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US3555880A (en) * 1967-04-12 1971-01-19 Industrial Nucleonics Corp Liquid density measuring system
DE2749077A1 (en) * 1976-12-09 1978-06-15 Kkf Corp PROBE
GB2114745A (en) * 1982-02-12 1983-08-24 Bestobell Electromagnetically driven tuning fork for determining fluid properties
JPS58205820A (en) * 1982-05-27 1983-11-30 Fuji Elelctrochem Co Ltd Liquid level sensor
FR2572519A1 (en) * 1984-10-25 1986-05-02 Jaeger Electromechemical transducer level detector

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Publication number Priority date Publication date Assignee Title
US3555880A (en) * 1967-04-12 1971-01-19 Industrial Nucleonics Corp Liquid density measuring system
DE2749077A1 (en) * 1976-12-09 1978-06-15 Kkf Corp PROBE
GB2114745A (en) * 1982-02-12 1983-08-24 Bestobell Electromagnetically driven tuning fork for determining fluid properties
JPS58205820A (en) * 1982-05-27 1983-11-30 Fuji Elelctrochem Co Ltd Liquid level sensor
FR2572519A1 (en) * 1984-10-25 1986-05-02 Jaeger Electromechemical transducer level detector

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Title
CHEMICAL PROCESSING. Bd. 16, Nr. 9, September 1970, LONDON GB Seiten 36 - 37; 'LEVEL CONTROLLERS FOR TANKS AND BINS' *
PATENT ABSTRACTS OF JAPAN vol. 8, no. 58 (P-261)(1495) 16. März 1984 & JP,A,58 205 820 ( FUJI DENKI KAGAKU K.K. ) 30. November 1983 *

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WO1997006433A1 (en) * 1995-08-03 1997-02-20 Milltronics Ltd. Method of detecting characteristics of liquids in pipes and pump controlling
NL1003654C2 (en) * 1996-07-22 1998-01-28 Matheus Jozef Maria Coolen Method for measuring properties of media.
WO1998003864A1 (en) * 1996-07-22 1998-01-29 Matheus Jozef Maria Coolen Method for measuring medium properties
US6044694A (en) * 1996-08-28 2000-04-04 Videojet Systems International, Inc. Resonator sensors employing piezoelectric benders for fluid property sensing
AU738267B2 (en) * 1996-08-28 2001-09-13 Videojet Systems International, Inc. Resonator sensors employing piezoelectric benders for fluid property sensing
DE10242970A1 (en) * 2002-09-17 2004-04-01 Vega Grieshaber Kg Vibration level sensor compares mechanical oscillator amplitude and/or frequency with value and detects fault in mechanical oscillator if amplitude and/or frequency of value differs in defined manner
US7665357B2 (en) 2003-06-23 2010-02-23 Endress + Hauser Gmbh + Co. Kg Accretion alarm for field devices
WO2005001392A2 (en) * 2003-06-23 2005-01-06 Endress+Hauser Gmbh+Co. Kg Alarm for field devices
WO2005001392A3 (en) * 2003-06-23 2005-04-07 Endress & Hauser Gmbh & Co Kg Alarm for field devices
CN100394148C (en) * 2003-06-23 2008-06-11 恩德莱斯和豪瑟尔两合公司 Alarm for field devices
WO2005019713A1 (en) * 2003-08-21 2005-03-03 Oliver Twinsafe Valves Limited Valve assembly
WO2008156423A1 (en) 2007-06-21 2008-12-24 Feldt & Meiton Marin Ab Device and method for determination regarding the liquid level in containers
US8448509B2 (en) 2007-06-21 2013-05-28 Feldt & Meiton Marin Ab Device and method for determination regarding the liquid level in containers
DE102010028161A1 (en) * 2010-04-23 2011-10-27 Endress + Hauser Gmbh + Co. Kg Method for determining and/or monitoring limit level of outgassing liquid medium in container, involves generating signals for signalizing covering and idle conditions when variables fulfill criterion for conditions, respectively
DE102010028161B4 (en) 2010-04-23 2023-08-17 Endress+Hauser SE+Co. KG Method and device for determining and/or monitoring a fill level limit
RU2498234C1 (en) * 2012-03-06 2013-11-10 Федеральное государственное автономное образовательное учреждение высшего профессионального образования "Национальный исследовательский ядерный университет "МИФИ" (НИЯУ МИФИ) Liquid level measuring device
IT201900006274A1 (en) * 2019-04-23 2020-10-23 Nuovo Pignone Tecnologie Srl Arrangement with sensor and method for measuring fouling or erosion or corrosion as well as machine monitoring fouling or erosion or corrosion
WO2020216469A1 (en) * 2019-04-23 2020-10-29 Nuovo Pignone Tecnologie - S.R.L. Sensor arrangement and method for measuring fouling and/or erosion, and machine monitoring fouling and/or erosion
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AU2020261165B2 (en) * 2019-04-23 2023-05-25 Nuovo Pignone Tecnologie - S.R.L. Sensor arrangement and method for measuring fouling and/or erosion, and machine monitoring fouling and/or erosion
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