FI93396B - Optical method for measuring the surface level of the liquid - Google Patents

Optical method for measuring the surface level of the liquid Download PDF

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Publication number
FI93396B
FI93396B FI933616A FI933616A FI93396B FI 93396 B FI93396 B FI 93396B FI 933616 A FI933616 A FI 933616A FI 933616 A FI933616 A FI 933616A FI 93396 B FI93396 B FI 93396B
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Prior art keywords
liquid
light
height
measuring
change
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FI933616A
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Finnish (fi)
Swedish (sv)
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FI93396C (en
FI933616A0 (en
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Pertti Puumalainen
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Petetronic Tmi P Kinnunen
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Priority to FI933616A priority Critical patent/FI93396C/en
Publication of FI933616A0 publication Critical patent/FI933616A0/en
Priority to AU74619/94A priority patent/AU7461994A/en
Priority to PCT/FI1994/000352 priority patent/WO1995005583A1/en
Application granted granted Critical
Publication of FI93396B publication Critical patent/FI93396B/en
Publication of FI93396C publication Critical patent/FI93396C/en

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    • 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
    • G01F23/284—Electromagnetic waves
    • G01F23/292—Light, e.g. infrared or ultraviolet

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Thermal Sciences (AREA)
  • Fluid Mechanics (AREA)
  • General Physics & Mathematics (AREA)
  • Measurement Of Levels Of Liquids Or Fluent Solid Materials (AREA)

Description

9339693396

OPTINEN MENETELMÄ NESTEEN PINNANKORKEUDEN MITTAAMISEKSIOPTICAL METHOD OF MEASURING THE LEVEL OF A LIQUID

Keksinnön kohteena on optinen menetelmä nesteen pinnan korkeuden mittaamiseksi.The invention relates to an optical method for measuring the height of a liquid surface.

5 i5 i

Tunnetuin menetelmä esim. säiliöissä tai vastaavissa olevan nesteen pinnan korkeuden määrittämiseksi on vieläkin mittatikun käyttö, missä kastumarajasta määritetään pinnankor-keus. Jonkin verran käytetään myös säiliöön asetettujen 10 elektrodien välisen induktion riippuvuutta nestemäärästä pinnankorkeuden mittaamiseen. Myös ultraäänellä on pyritty määräämään pinnankorkeus säiliössä. Näitä mittauksia rajoittaa huomattavasti polttoainesäiliössä räjähdysalttius, optisten anturien likantuminen varsinkin lyijypitoisten 15 bensiinien pinnankorkeuden mittauksissa sekä lämpötilan ja höyrynpaineen muutokset mittaustilassa.The best-known method for determining the surface height of a liquid, for example in tanks or the like, is still the use of a dipstick, where the level is determined from the wetting limit. The dependence of the induction between the 10 electrodes placed in the tank on the amount of liquid is also used to some extent to measure the surface height. Ultrasound has also been used to determine the surface height in the tank. These measurements are severely limited by the susceptibility of the fuel tank to explosion, the fouling of optical sensors, especially in the measurement of the surface height of leaded gasolines, and changes in temperature and vapor pressure in the measurement enclosure.

Keksinnön tarkoituksena on tuoda esiin menetelmä nesteen pinnan korkeuden mittaamiseksi, jonka menetelmän avulla 20 poistetaan tunnettuihin menetelmiin liittyviä epäkohtia. Erityisesti keksinnön tarkoituksena on tuoda esiin menetelmä, joka sopii polttoainesäiliöiden nesteen korkeuden mittaamiseen, ja on luotettava ja turvallinen.The object of the invention is to provide a method for measuring the height of the surface of a liquid, by means of which method the disadvantages associated with known methods are eliminated. In particular, it is an object of the invention to provide a method which is suitable for measuring the liquid level of fuel tanks and is reliable and safe.

25 Keksinnön tarkoitus saavutetaan menetelmällä, jolle on tunnusomaista se, mitä on esitetty patenttivaatimuksissa.The object of the invention is achieved by a method which is characterized by what is stated in the claims.

Keksinnön mukaisessa menetelmässä valoa johdetaan valokuidun kautta nesteeseen sijoitetussa anturissa olevaan sekundää-30 rinesteeseen, johon vaikuttaa tutkittavan nesteen hydrostaattinen paine, valo johdetaan anturista toisella valokuidulla fotodiodille ja nesteen pinnan korkeus mitataan se-kundäärinesteen nestepatsaan korkeuden aiheuttaman valon intense teettimuutoksen avulla siten, että valokuidusta saata-35 van valon intensiteetin muutos mitataan suhteessa normitus-valokuidusta saatavan valon intensiteettiin, mikä mitataan valitsijan avulla, ja lopullinen primäärikorkeus saadaan 2 93396 vertaamalla tätä suhteellista mittausarvoa kalibrointiku-vaajaan.In the method according to the invention, light is conducted via an optical fiber to a secondary fluid in a sensor placed in the liquid, which is affected by the hydrostatic pressure of the liquid under test, light is passed from the sensor to another photodiode The change in light intensity of 35 van is measured in relation to the intensity of light from the standardization optical fiber, which is measured by means of a selector, and the final primary height is obtained by comparing 2,93396 of this relative measured value with the calibration factor.

Kehitetyllä optisella menetelmällä päästään eroon likaan-5 tumisesta ja menetelmä on täysin optinen anturirakenteen osalta. Kehitetyn menetelmän keskeisimpänä käyttöalana on polttosäiliöiden nesteen pinnan korkeuden mittaus esimerkiksi huoltoasemilla. Polttoainesäiliöön ei tarvitse viedä minkäänlaisia sähköisiä tai mekaanisesti liikkuvia laitteita 10 tai niiden osia, ja kipinöiden muodostuminen ei ole mahdollista. Vain valoa liikutetaan säiliöön ja sieltä pois. Menetelmä myös normittaa itseään koko ajan. Keksintöä voidaan soveltaa myös muihin käyttökohteisiin.The developed optical method eliminates dirt-5 and is completely optical in terms of sensor structure. The main field of application of the developed method is the measurement of the liquid surface level of fuel tanks, for example at service stations. It is not necessary to introduce any electrical or mechanically moving devices 10 or parts thereof into the fuel tank, and the formation of sparks is not possible. Only the light is moved into and out of the tank. The method also normalizes itself all the time. The invention can also be applied to other applications.

15 Keksinnön edullisessa sovelluksessa nestepatsaan sisälle sijoitetaan valokuitu tai valokuitunippu, joka kastuu. Kastuminen aiheuttaa valon kulussa kuidussa muutoksen, joka havaitaan intensiteetin muutoksena, johon ulkoinen pinnan korkeus kalibroidaan. Tällöin saadaan aikaan tarkka ja 20 luotettava mittaustulos.In a preferred embodiment of the invention, an optical fiber or a bundle of optical fibers which is wetted is placed inside the liquid column. Wetting causes a change in the passage of light in the fiber, which is observed as a change in intensity to which the external surface height is calibrated. In this case, an accurate and reliable measurement result is obtained.

Keksinnön toisessa sovelluksessa valo johdetaan nestepatsan kohdalle ja suunnataan nestepatsaaseen, jolloin nestepatsaan sisällä valo heijastelee ja sen heijastuksen tehokkuus 25 muuttuu kun putken, jonka sisällä nestepatsas on, sisäpinta kastuu, jolloin määritys ulkoisen pinnan muutoksesta saadaan vertaamalla normituskuidusta tulevan valon intensiteettiin ja tästä suhteesta saadaan kalibrointikuvaajän avulla ulkoisen nesteen pinnan korkeus. Myös tällä tavalla saadaan 30 tarkka ja luotettava mittaustulos.In another embodiment of the invention, the light is directed to the liquid column and directed to the liquid column, whereby light is reflected inside the liquid column and its reflection efficiency changes when the inner surface of the tube containing the liquid column is wetted. the height of the surface of the external fluid. Also in this way, 30 accurate and reliable measurement results are obtained.

Keksinnön edullisessa lisäsovelluksessa mittausnesteeseen lisätään lisäaineita, jotka lisäävät optisten ominaisuuksien muutoksien aiheuttajia, kuten väriä ja taitekerrointa. Näin 35 saadaan nesteen pinnan korkeus vielä tarkemmin selville.In a further preferred embodiment of the invention, additives are added to the measuring liquid which increase the causes of changes in optical properties, such as color and refractive index. In this way, the height of the surface of the liquid is determined even more precisely.

Seuraavaksi keksintöä selvitetään tarkemmin viittaamalla 3 93396 oheiseen piirustukseen, joka esittää keksinnön mukaisen mittausmenetelmän periaatetta soveltavaa laitteistoa sivulta katsottuna ja sen toimintaa käytännössä.The invention will now be explained in more detail with reference to the accompanying drawing, which shows an apparatus applying the principle of the measuring method according to the invention, seen from the side, and its operation in practice.

5 Kuvan mukaisessa laitteistossa valolähteestä 1 ohjataan * valoa valokuituihin 2, 3. Valoa jaetaan kahteen kuituun; toisen kuidun 3 valoa käytetään normitukseen ja toisen kuidun 2 valoa puolestaan mittaukseen. Anturi on avoinna tilaan, jossa on sama ilmanpaine kuin pinnan mittaustilassa 10 mitattavan nesteen yläpuolella. Anturissa on joustavalla kumikalvolla 5 eristetty mitattavasta nesteestä 12 varsinaisen mittausnesteen tila 4. Kumikalvo on asennettu niin löysälle, että sen muutoksiin ei tule huomattavaia kimmovoi-mia mittaustilanteissa ulkoisen nestepinnan ollessa eri 15 korkeuksilla. Kumikalvo välittää hydrostaattisen paineen 11 avulla nestepatsaaseen 8 tutkittavan nesteen pinnankorkeu-den. Kun kumikalvon liikuttamiseen ei tarvita voimia ja nesteiden tiheydet anturin ulkopuolella ja anturissa ovat samat, on patsaan pinta yhtä korkealla kuin ulkopuolisen 20 nesteen pinta. Näin ei kuitenkaan tarvitse välttämättä olla, vaan anturi kalibroidaan sähköisen signaalin ja todellisen nesteen korkeuden avulla näyttämään oikeaa korkeutta.5 In the apparatus shown in the figure, light from the light source 1 is directed * to the optical fibers 2, 3. The light is divided into two fibers; the light of the second fiber 3 is used for normalization and the light of the second fiber 2 is used for the measurement. The sensor is open to a space with the same air pressure as in the surface measurement space 10 above the liquid to be measured. The sensor has a space 4 of the actual measuring liquid 12 isolated from the liquid to be measured 12 by means of a flexible rubber film. The rubber film is mounted so loosely that its changes do not cause considerable elastic forces in measuring situations at different liquid heights. By means of the hydrostatic pressure 11, the rubber film transmits to the liquid column 8 the surface height of the liquid to be examined. When no forces are required to move the rubber film and the densities of the fluids outside and inside the sensor are the same, the surface of the statue is as high as the surface of the outer 20 fluids. However, this does not necessarily have to be the case, but the sensor is calibrated using an electrical signal and the actual liquid level to show the correct height.

Valosignaali ohjataan kuidusta 2 putkimaiseen valojohtimeen 25 6, jossa se kulkee kuin optisessa kuidussa heijastellen pääosin sen sisäseinämistä. Kun putkeen nousee nestettä, heijastusominaisuudet muuttuvat ja intensiteetin pieneneminen on verrannollista nestepatsaan 8 korkeuteen.The light signal is directed from the fiber 2 to a tubular light guide 25 6, where it travels like an optical fiber, reflecting mainly from its inner walls. As liquid rises into the tube, the reflection properties change and the decrease in intensity is proportional to the height of the liquid column 8.

30 Mittaputki on suljettu yläpäästään elastisella kumipussilla hermeettisesti 9 haihtumisen eliminoimiseksi. Mittausneste-tila on suljettu siten, että sen sisällä oleva neste ei pääse haihtumaan, mutta sulkeminen ei estä nestepatsaan 8 korkeuden muuttumista. Mittaputken 6 yläpäästä otetaan valo 35 optiseen kuituun 10 ja viedään valitsimen 13 kautta foto-diodille 14 intensiteettimittaukseen. Fotodiodin signaali vahvistetaan ja luetaan normaalisti esimerkiksi mikrotieto- 4 93396 koneella. Mittaus tehdään aina suhteellisesti eli mitataan vuorotellen normituskuidun 3 kautta kulkevaa valoa ja mittalaitteen kautta 2 =#· 6 10 kulkevaa valoa. Suhteellisesta mittaustuloksesta kalibrointikuvaajän avulla saadaan sitten 5 lasketuksi ulkopuolisen nesteen korkeus. Mittauksen ollessa aina suhteellinen eliminoituu valolähteen ja vahvistimen ryömintä käytännössä kokonaan. Myös ulkoisen mitattavan nesteen likaava vaikutus eliminoituu sillä, että optisessa järjestelmässä on puhdas sekundäärineste, joka on hermeetti-10 sesti suljetussa tilassa.30 The measuring tube is hermetically sealed at its upper end with an elastic rubber bag 9 to eliminate evaporation. The measuring liquid space is closed in such a way that the liquid inside it cannot evaporate, but the closing does not prevent the height of the liquid column 8 from changing. Light 35 is taken from the upper end of the measuring tube 6 to the optical fiber 10 and passed through a selector 13 to the photodiode 14 for intensity measurement. The photodiode signal is normally amplified and read, for example, by a microcomputer. The measurement is always made proportionally, ie the light passing through the standardization fiber 3 and the light passing through the measuring device 2 = # · 6 10 are measured alternately. From the relative measurement result, the height of the external fluid is then calculated by means of a calibration graph. When the measurement is always relative, the creep of the light source and the amplifier is virtually eliminated. The contaminating effect of the external liquid to be measured is also eliminated by the presence in the optical system of a pure secondary liquid in a hermetically sealed state.

Keksintöä ei rajata esitettyyn polttoainesäiliön pinnan korkeuden mittaukseen, vaan se soveltuu mihin tahansa rajapinnan mittaukseen, kun mittaustilan paineistusaukko on 15 samassa paineessa säiliön ilmatilan kanssa.The invention is not limited to the above-mentioned measurement of the height of the surface of the fuel tank, but is suitable for any measurement of the interface when the pressure opening of the measuring space is at the same pressure as the air space of the tank.

Claims (8)

1. En optisk metod for mätande av höjden pä en vätskas yta, k ä n neteckriad av, att att ljus leds genoin en optisk fiber (2) till en 5 i en vätska (12) placerad givare (7) oefintlig sekundärvätska (4), pä vilken verkar den vätskas hydrostatiska tryck, som skall undersökas, ljuset leds frän givaren med en annan optisk fiber (ID) pä en fotodiod (14) och höjden pä vätskans yta mats 10 med tillhjälp av intensitetsforändringen i ljuset förorsakad av sekundärvätskans vätskepelares höjd sälunda, att förändringen i ljusets intensitet, som fäs ur den optiska fibern (10), mäts i förhällande tili den intensitet, som fäs ur en kaiibrerings-15 fiber (3), och som mäts med tillhjälp av en dikrimi-nator (13), och den slutgiltiga primärhöjden fäs genom att jämfora detta relativa rnätningsvärde med en grafisk kaiibreringsrepresentant.1. An optical method for measuring the height of the surface of a liquid, characterized in that light is guided by an optical fiber (2) to a sensor (7) located in a liquid (12), non-existent secondary liquid (4) , acting on the hydrostatic pressure of the liquid to be investigated, the light is passed from the sensor with another optical fiber (ID) onto a photodiode (14) and the height of the liquid surface is fed 10 by means of the intensity change in the light caused by the height of the secondary liquid liquid column , that the change in the intensity of light emitted from the optical fiber (10) is measured in proportion to the intensity emitted from a calibration fiber (3) and measured with the aid of a discriminator (13), and the final primary height is fixed by comparing this relative grid value with a graphical calibration representative. 2. En metod i enlighet med patentkrav 1, k ä n n etecknad av, att innanför vätske-pelaren placeras en optisk fiber eller en knippe av optiskafibrer, som blir vät, varvid vätan förorsakar en förändring i ljusets gäng i fibern, som observeras 25 soin en ändring i i ntens i teten, pä vilken den yttre höjden av ytan kalibreras.2. A method according to claim 1, characterized in that an optical fiber or a bundle of optical fibers which becomes wet is placed inside the liquid column, the hydrogen causing a change in the amount of light in the fiber observed. a change in density, at which the outer height of the surface is calibrated. 3. En metod i enlighet med patentkrav 1, k a n n e tecknad av, att ljuset leds tili 30 platsen av vätskepe1aren och riktas pä vätskepelaren, varvid innanför vätskepe1aren ljuset reflekteras och effektiviteten pä den reflekteringen ändras, när den inre ytan pä det rör (6), innanför vilket vätskepelaren befinner sig, blir vät, varvid bestäm-35 ningen av ändringen pä den yttre ytan fäs genom järnförelse med intensiteten i det ur kai i breri ngsfi - 8 93396 bern (3) kommande ljuset och ur detta förhällande far man med tillhjälp av en grafisk representant ytans höjd pä den yttre vätskan.3. A method according to claim 1, characterized in that the light is led to the location of the liquid column and directed to the liquid column, whereby the light is reflected inside the liquid collector and the efficiency of that reflection changes as the inner surface of that tube (6), within which the liquid column is located becomes wet, whereby the determination of the change on the outer surface is made by iron movement with the intensity of the light emanating from the light (3) and (3) this can be obtained with the aid of a graphic representative of the height of the surface of the outer fluid. 4. En metod i enlighet med nägot av patentkraven 1-3, kännetecknad av, att i mätnings- vatskan (4) tillsätts ti 11äggsämnen, som intesifierar ändringsförorsakande faktorerna pä de optiska egenska-perna, sasom färg och brytningskoefficient. 104. A method according to any of claims 1-3, characterized in that in the measuring vessel (4) there are added to eggs which identify the causative factors of the optical properties, such as color and refractive coefficient. 10 5. En metod i enlighet med nägot av patentkraven 1-4, k a n netecknad av, att utrymmet för mätningsvätskan tillsluts hermetiskt (9) sälunda, att vätskan (8) innanför den inte kan förflyktigas, 15 men vätskepelarens (8) höjd är föränderlig.5. A method according to any of claims 1-4, characterized in that the space for the measuring fluid is hermetically sealed (9) so that the liquid (8) inside it cannot be volatilized, but the height of the liquid column (8) is variable. 6. En metod i enlighet med nägot av patentkraven 1-5, k ä n n etecknad av, att givaren (7) stär öppen tili ett utrymme, dar lufttrycket 20 är detsamma soin i ytans mätni ngsutrymme ovanför den vätskeyta, soin skall mätäs.6. A method according to any of claims 1-5, characterized in that the sensor (7) is open to a space where the air pressure 20 is the same in the measurement space of the surface above the liquid surface to be measured. 7. En metod i enlighet med nägot av patentkraven 1-6, k ä nnetecknad av, att det yttre 25 hydrostatiska trycket förmedlas med en gummimembran (5), som placeras sä lost, att i dess ändringar inte inträder nagra märkbara elasticitetskrafter i mätningssituationer, da den yttre vätskeytan befinner sig pä olika höjder.7. A method according to any of claims 1-6, characterized in that the external hydrostatic pressure is conveyed with a rubber membrane (5) which is placed so securely that in its modifications no appreciable elasticity forces occur in measurement situations. since the outer liquid surface is at different heights.
FI933616A 1993-08-17 1993-08-17 Optical method for measuring the level of a liquid FI93396C (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
FI933616A FI93396C (en) 1993-08-17 1993-08-17 Optical method for measuring the level of a liquid
AU74619/94A AU7461994A (en) 1993-08-17 1994-08-15 Optic method for measuring of the level of the surface of a liquid
PCT/FI1994/000352 WO1995005583A1 (en) 1993-08-17 1994-08-15 Optic method for measuring of the level of the surface of a liquid

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI933616A FI93396C (en) 1993-08-17 1993-08-17 Optical method for measuring the level of a liquid
FI933616 1993-08-17

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FI933616A0 FI933616A0 (en) 1993-08-17
FI93396B true FI93396B (en) 1994-12-15
FI93396C FI93396C (en) 1995-03-27

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FI933616A FI93396C (en) 1993-08-17 1993-08-17 Optical method for measuring the level of a liquid

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WO (1) WO1995005583A1 (en)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6782122B1 (en) 2000-04-27 2004-08-24 Simmonds Precision Products, Inc. Apparatus for measuring height of a liquid in a container using area image pattern recognition techniques
JO2409B1 (en) 2000-11-21 2007-06-17 شركة جانسين فارماسوتيكا ان. في Biphenylcarboxamides useful as lipid lowering agents
CN100390507C (en) * 2004-05-20 2008-05-28 广州市敏通光电科技有限公司 Continuous fiber optic liquid level sensor
RU2503950C2 (en) * 2012-02-27 2014-01-10 Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Башкирский государственный университет" System to control liquid parameters

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB905228A (en) * 1958-03-14 1962-09-05 Pynford Ltd Improvements in or relating to apparatus operable in accordance with a fluid pressure or head
CA1174869A (en) * 1980-11-20 1984-09-25 Lloyd A. Baillie Liquid level indicator
US5303586A (en) * 1993-01-22 1994-04-19 Wayne State University Pressure or fluid level sensor

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FI93396C (en) 1995-03-27
AU7461994A (en) 1995-03-14
FI933616A0 (en) 1993-08-17
WO1995005583A1 (en) 1995-02-23

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