WO2017216743A1 - Sensor for monitoring liquid level - Google Patents
Sensor for monitoring liquid level Download PDFInfo
- Publication number
- WO2017216743A1 WO2017216743A1 PCT/IB2017/053537 IB2017053537W WO2017216743A1 WO 2017216743 A1 WO2017216743 A1 WO 2017216743A1 IB 2017053537 W IB2017053537 W IB 2017053537W WO 2017216743 A1 WO2017216743 A1 WO 2017216743A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- filament
- optical fiber
- sensor
- sensor according
- liquid level
- Prior art date
Links
- 239000007788 liquid Substances 0.000 title claims abstract description 25
- 238000012544 monitoring process Methods 0.000 title claims abstract description 9
- 239000013307 optical fiber Substances 0.000 claims abstract description 23
- 230000003287 optical effect Effects 0.000 claims description 17
- 229920003229 poly(methyl methacrylate) Polymers 0.000 claims description 2
- 239000004926 polymethyl methacrylate Substances 0.000 claims description 2
- 239000003673 groundwater Substances 0.000 claims 2
- 239000000835 fiber Substances 0.000 abstract description 15
- 238000005259 measurement Methods 0.000 abstract description 7
- 230000005672 electromagnetic field Effects 0.000 abstract description 2
- 230000007613 environmental effect Effects 0.000 abstract 1
- 238000002347 injection Methods 0.000 description 4
- 239000007924 injection Substances 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 2
- 238000001514 detection method Methods 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 239000002828 fuel tank Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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
- G01F23/28—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
Definitions
- the present application describes an optical fiber-based level sensor.
- the objective of the optical fiber-based sensor developed is to measure variations in liquid levels in hostile or flammable environments, in locations of hard access or where the existence of electromagnetic fields may influence the operation of electronic sensors. Said sensor is therefore useful for applications in monitoring the level of flammable liquids, such as oil and derivatives thereof, as there is no risk of short circuit and consequent explosion.
- the technology disclosed in the present application includes an alternative system for liquid level detection that uses polymer optic fiber with grooves along the length of the fiber, with a simple implementation of only one fiber, with no special mounting care, and at low cost.
- the measuring points may be of the order of tens and it does not require special care as far as the placement angle of the optical fiber, relative to the surface of the liquid is concerned.
- the present application describes an optical fiber sensor for measuring the liquid levels in hostile and flammable environments, constructed from an optical fiber filament provided with grooves along its length.
- the type of fiber whether made from plastic or glass, or the depth and/or spacing of the grooves, can be altered according to the intended resolution and application. In case of higher resolution in the measurement, for example in fuel tanks, it is possible to make a smaller grooves spacing. For coarser level measurements, greater spacing between grooves will provide a more stable sensor, but with lower resolution.
- one end of the optical fiber filament is coupled to an optical signal injector device, and the opposite end to a signal receiving unit.
- the optical fiber filament is divided into two different segments: a first segment associated with the end connected to the optical signal injector, which is devoid of grooves, and whose length is such that it allows complying with the distance between the signal injector and the base of the container where the liquid is stored; and a second segment, associated with the end connected to the signal receiving unit, which has spaced grooves etched along said segment, and whose length is such that it allows complying with the distance between the base of the container and the signal receiving unit.
- one end of the filament is connected to a reflecting element, for example an optical coupler, which redirects the radiation transmitted by the fiber, in the region of the grooves, to the photodetector present in a signal in ection and receiving unit, coupled to the opposite end.
- the filament is provided with grooves along the entire length thereof, which extends from the signal injection and receiving unit, to the base of the container where the reflecting element is placed.
- the introduction of grooves along the fiber filament is responsible for causing a loss in the optical signal received by the receiver unit due to the change in refractive index between the fiber core and the environment.
- the groove is filled by a material having a refractive index similar or closer to that of the fiber core, compared to that of air, such as for example water, the signal losses decrease.
- the presence of the grooves allows detecting changes in the power of the optical signal transmitted along the filament, according to the rise of the liquid and consequent filling of each groove.
- Figure 1 shows the structure of the optical fiber-based liquid level sensor wherein reference numbers refer to:
- Figure 2 shows a schematic of the fiber configuration by applying a reflecting element at the end of the filament, wherein reference numbers refer to:
- FIG. 3 shows the schematic of a practical application of the liquid level sensor in the oil industry, wherein reference numbers refer to:
- one end (1) of the optical fiber filament is coupled to an optical signal injector device, and the opposite end (2) to a signal receiving unit.
- the signal is injected at the end of the filament, runs through the first segment (3) without grooves, which extends to the base of the container (11) containing the liquid, and enters into the second segment (4), which is provided with grooves (5), runs through the respective fiber filament until it is collected, at the other end (2), by the data receiving unit for further processing.
- a reflecting element (6) is arranged at the end of the fiber filament (4), the optical signal being inserted and collected only by the opposite end, in the signal injection and receiving unit (7) .
- the liquid level measurement sensor developed is characterized by the use of an optical fiber composed of polymethylmethacrylate, having a thickness of 1 mm and with grooves having a depth of 0.01 mm to 0.50 mm, spaced apart between 1.00 mm and 200 mm.
Abstract
The present application describes an optical fiber-based liquid level sensor, characterized by the use of grooves along the length of the fiber, having engineering applications for liquid level measurements in locations of hard access under hostile conditions, with electromagnetic field interference, and without risk of short circuit in flammable environments. The liquid level sensor developed allows monitoring the rise or fall variation of the liquid level, with low signal loss, in environments with high environmental aggressiveness or flammable, where the use of electronic sensors is limited. In addition, this sensor can be used for various applications in the context of continuous and real-time monitoring through synchronization with other monitoring systems.
Description
DESCRIPTION
SENSOR FOR MONITORING LIQUID LEVEL
Technical Field
The present application describes an optical fiber-based level sensor.
Background art
Documents EP0393144 Al, EP2685226 Al , US3713338 Al and US4354180 Al disclose optical sensors for liquid level measurements. Essentially, the sensors presented and currently available in the market make use of very complex forms, making the sensors an expensive product. As an example, the sensor disclosed in document US4069838 requires the arrangement thereof at a certain angle relative to the surface of the liquid and has only two measurement points, or fiber interruptions. In this case, only when the liquid reaches the level of these fiber interruption points does a variation in the optical signal occur and a change in the sensor signal.
An example of complexity is the patent US3713338 Al, which shows the need for 333 fibers for a resolution of 1.5 mm over a measurement range of 500 mm.
Summary
The objective of the optical fiber-based sensor developed is to measure variations in liquid levels in hostile or flammable environments, in locations of hard access or where the existence of electromagnetic fields may influence the operation of electronic sensors. Said sensor is therefore useful for applications in monitoring the level of flammable
liquids, such as oil and derivatives thereof, as there is no risk of short circuit and consequent explosion.
The technology disclosed in the present application includes an alternative system for liquid level detection that uses polymer optic fiber with grooves along the length of the fiber, with a simple implementation of only one fiber, with no special mounting care, and at low cost. The measuring points may be of the order of tens and it does not require special care as far as the placement angle of the optical fiber, relative to the surface of the liquid is concerned.
General Description
The present application describes an optical fiber sensor for measuring the liquid levels in hostile and flammable environments, constructed from an optical fiber filament provided with grooves along its length. The type of fiber, whether made from plastic or glass, or the depth and/or spacing of the grooves, can be altered according to the intended resolution and application. In case of higher resolution in the measurement, for example in fuel tanks, it is possible to make a smaller grooves spacing. For coarser level measurements, greater spacing between grooves will provide a more stable sensor, but with lower resolution.
In one embodiment of the sensor developed, one end of the optical fiber filament is coupled to an optical signal injector device, and the opposite end to a signal receiving unit. In this configuration, the optical fiber filament is divided into two different segments: a first segment associated with the end connected to the optical signal injector, which is devoid of grooves, and whose length is such that it allows complying with the distance between the
signal injector and the base of the container where the liquid is stored; and a second segment, associated with the end connected to the signal receiving unit, which has spaced grooves etched along said segment, and whose length is such that it allows complying with the distance between the base of the container and the signal receiving unit.
In another embodiment of the sensor developed, one end of the filament is connected to a reflecting element, for example an optical coupler, which redirects the radiation transmitted by the fiber, in the region of the grooves, to the photodetector present in a signal in ection and receiving unit, coupled to the opposite end. In this embodiment, the filament is provided with grooves along the entire length thereof, which extends from the signal injection and receiving unit, to the base of the container where the reflecting element is placed.
The introduction of grooves along the fiber filament is responsible for causing a loss in the optical signal received by the receiver unit due to the change in refractive index between the fiber core and the environment. Whenever the groove is filled by a material having a refractive index similar or closer to that of the fiber core, compared to that of air, such as for example water, the signal losses decrease. Thus, by inserting an optical fiber filament with these characteristics, the presence of the grooves allows detecting changes in the power of the optical signal transmitted along the filament, according to the rise of the liquid and consequent filling of each groove.
Description of the Figures
For ease of understanding of the present application, figures are herein attached which represent exemplary embodiments which, however, are not intended to limit the technology herein disclosed.
Figure 1 shows the structure of the optical fiber-based liquid level sensor wherein reference numbers refer to:
1 - end of the optical fiber filament for connection to an optical signal injector;
2 - end of the optical fiber filament for connection to a signal receiving unit;
3 - segment of the optical fiber filament without grooves etched on the surface;
4 - segment of the optical fiber filament with grooves etched on the surface;
5 - groove .
Figure 2 shows a schematic of the fiber configuration by applying a reflecting element at the end of the filament, wherein reference numbers refer to:
4 - segment of the optical fiber filament with grooves etched on the surface;
5 - groove;
6 - reflecting element;
7 - optical signal injection and receiving unit.
Figure 3 shows the schematic of a practical application of the liquid level sensor in the oil industry, wherein reference numbers refer to:
4 - segment of the optical fiber filament with grooves etched on the surface;
7 - optical signal injection and receiving unit;
8 - liquid inlet;
9 - liquid collection system;
10 - liquid drain tube into the container;
11 - liquid container;
Description of the embodiments
With reference to the figures, some embodiments are now described in more detail, which are however not intended to limit the scope of the present application.
In one embodiment, one end (1) of the optical fiber filament is coupled to an optical signal injector device, and the opposite end (2) to a signal receiving unit. In this embodiment, the signal is injected at the end of the filament, runs through the first segment (3) without grooves, which extends to the base of the container (11) containing the liquid, and enters into the second segment (4), which is provided with grooves (5), runs through the respective fiber filament until it is collected, at the other end (2), by the data receiving unit for further processing.
In a further particular embodiment of the sensor, a reflecting element (6) is arranged at the end of the fiber filament (4), the optical signal being inserted and collected only by the opposite end, in the signal injection and receiving unit (7) .
In a particular embodiment, the liquid level measurement sensor developed is characterized by the use of an optical fiber composed of polymethylmethacrylate, having a thickness of 1 mm and with grooves having a depth of 0.01 mm to 0.50 mm, spaced apart between 1.00 mm and 200 mm.
Claims
1. Liquid level monitoring sensor comprising an optical fiber filament, said optical fiber filament comprising at least one segment arranged between the two ends of said filament, having at least one groove etched along the length thereof .
2. Sensor according to claim 1, wherein the spacing and depth of the grooves is adjustable.
3. Sensor according to claim 2, wherein the end of the filament opposite the end where the optical signal is injected is connected to a reflecting element.
4. Sensor according to claim 2, wherein the optical fiber filament comprises two segments, arranged between the two ends of the filament, wherein one of the filament segments has at least one etched groove and the other segment does not .
5. Sensor according to claim 4, wherein the non-grooved filament segment is associated with the end of the filament where the optical signal is injected, and the grooved filament segment is associated with the end of the filament where the optical signal is received.
6. Sensor according to claim 1, wherein the optical fiber filament is made of polymethylmethacrylate.
7. Sensor according to claim 1, wherein the optical fiber filament has a thickness of 1 mm and the grooves have a depth
between 0.01 mm and 0.50 mm and are spaced apart between 1.00 mm and 200 mm.
8. Use of the sensor according to any claim 1 to 7, characterized in that it is integrated together with other optical and electrical monitoring systems and/or is applied to groundwater or underground environments, to oil tanks and derivatives thereof.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PT109456 | 2016-06-14 | ||
| PT10945616 | 2016-06-14 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2017216743A1 true WO2017216743A1 (en) | 2017-12-21 |
Family
ID=59337735
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/IB2017/053537 WO2017216743A1 (en) | 2016-06-14 | 2017-06-14 | Sensor for monitoring liquid level |
Country Status (1)
| Country | Link |
|---|---|
| WO (1) | WO2017216743A1 (en) |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3713338A (en) | 1971-01-18 | 1973-01-30 | Gen Motors Corp | Fiber optic liquid level indicator |
| US4069838A (en) | 1976-05-26 | 1978-01-24 | Sun Oil Company Of Pennsylvania | Fiber optic liquid level sensor |
| DE2809087A1 (en) * | 1978-03-02 | 1979-09-06 | Siemens Ag | Fuel level gauge - has vertical bar of light-transmitting plastics material fitted with light-transmitting diode and photocell of photodiode |
| US4354180A (en) | 1980-12-19 | 1982-10-12 | Genelco, Inc. | Electro-optical liquid level sensor |
| EP0393144A1 (en) | 1988-10-20 | 1990-10-24 | Conax Buffalo Corporation | Optical liquid level sensors |
| US20090216419A1 (en) * | 2004-11-19 | 2009-08-27 | Andrew Mark Shaw | Methods and Apparatus for Optical Monitoring of Fluid |
| EP2685226A1 (en) | 2012-07-11 | 2014-01-15 | Eurocopter Deutschland GmbH | Optical liquid level sensor |
| US20160116323A1 (en) * | 2013-03-25 | 2016-04-28 | Luxtec - Sistemas Ópticos Ltda - Me | Multiparameter device for measuring by optical means the filling level of tanks and reservoirs of liquids and liquefied products, the index of refraction, and for image analysis, without moving parts |
-
2017
- 2017-06-14 WO PCT/IB2017/053537 patent/WO2017216743A1/en active Application Filing
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3713338A (en) | 1971-01-18 | 1973-01-30 | Gen Motors Corp | Fiber optic liquid level indicator |
| US4069838A (en) | 1976-05-26 | 1978-01-24 | Sun Oil Company Of Pennsylvania | Fiber optic liquid level sensor |
| DE2809087A1 (en) * | 1978-03-02 | 1979-09-06 | Siemens Ag | Fuel level gauge - has vertical bar of light-transmitting plastics material fitted with light-transmitting diode and photocell of photodiode |
| US4354180A (en) | 1980-12-19 | 1982-10-12 | Genelco, Inc. | Electro-optical liquid level sensor |
| EP0393144A1 (en) | 1988-10-20 | 1990-10-24 | Conax Buffalo Corporation | Optical liquid level sensors |
| US20090216419A1 (en) * | 2004-11-19 | 2009-08-27 | Andrew Mark Shaw | Methods and Apparatus for Optical Monitoring of Fluid |
| EP2685226A1 (en) | 2012-07-11 | 2014-01-15 | Eurocopter Deutschland GmbH | Optical liquid level sensor |
| US20160116323A1 (en) * | 2013-03-25 | 2016-04-28 | Luxtec - Sistemas Ópticos Ltda - Me | Multiparameter device for measuring by optical means the filling level of tanks and reservoirs of liquids and liquefied products, the index of refraction, and for image analysis, without moving parts |
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