WO1982004316A1 - Fluid level indicator - Google Patents
Fluid level indicator Download PDFInfo
- Publication number
- WO1982004316A1 WO1982004316A1 PCT/GB1982/000165 GB8200165W WO8204316A1 WO 1982004316 A1 WO1982004316 A1 WO 1982004316A1 GB 8200165 W GB8200165 W GB 8200165W WO 8204316 A1 WO8204316 A1 WO 8204316A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- tube
- fluid level
- reflector
- level indicator
- fluid
- Prior art date
Links
- 239000012530 fluid Substances 0.000 title claims abstract description 40
- 238000005305 interferometry Methods 0.000 claims abstract description 3
- 239000007788 liquid Substances 0.000 claims description 11
- KKEBXNMGHUCPEZ-UHFFFAOYSA-N 4-phenyl-1-(2-sulfanylethyl)imidazolidin-2-one Chemical compound N1C(=O)N(CCS)CC1C1=CC=CC=C1 KKEBXNMGHUCPEZ-UHFFFAOYSA-N 0.000 claims description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims 1
- 230000003749 cleanliness Effects 0.000 claims 1
- 239000000741 silica gel Substances 0.000 claims 1
- 229910002027 silica gel Inorganic materials 0.000 claims 1
- 238000001514 detection method Methods 0.000 abstract description 2
- 239000003570 air Substances 0.000 description 9
- 238000005259 measurement Methods 0.000 description 9
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 6
- 238000006073 displacement reaction Methods 0.000 description 5
- 238000004458 analytical method Methods 0.000 description 3
- 229910052742 iron Inorganic materials 0.000 description 3
- 230000010287 polarization Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 1
- 229920005439 Perspex® Polymers 0.000 description 1
- 239000012080 ambient air Substances 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 239000000284 extract Substances 0.000 description 1
- 229940020445 flector Drugs 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 230000010363 phase shift Effects 0.000 description 1
- 239000004926 polymethyl methacrylate Substances 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 230000002123 temporal effect Effects 0.000 description 1
- 238000012360 testing method Methods 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
-
- 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
- G01F23/30—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 floats
- G01F23/64—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 floats of the free float type without mechanical transmission elements
- G01F23/68—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 floats of the free float type without mechanical transmission elements using electrically actuated indicating means
- G01F23/686—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 floats of the free float type without mechanical transmission elements using electrically actuated indicating means using opto-electrically actuated indicating means
-
- 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
- G01F23/30—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 floats
- G01F23/64—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 floats of the free float type without mechanical transmission elements
- G01F23/72—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 floats of the free float type without mechanical transmission elements using magnetically actuated indicating means
Definitions
- the present invention relates to fluid level indicators.
- a fluid level indicator for fluid level detection using laser beam interferometry comprising a tube for vertical arrangement in a fluid whose level is to be monitored, a reflector arranged for movement long- itudinally of the tube for reflecting a laser beam trans ⁇ mitted to the reflector from the top of the tube and a float member movable with the fluid,for moving the reflector in response to fluid level.changes.
- the reflector is mounted on the float member which is located in the tube and the tube wall is provided with one or more inlets for entry of fluid from the tank into the tube.
- the float member is annular in shape and carries a magnet on its inner surface.
- the reflector is mounted on a disc containing or coated with iron inside the tube which is sealed. As the float member moves with the fluid on the outside of the tube, the disc with the re lector is carried along with it due to magnetic attraction between the magnet and disc.
- the reflector may be mounted on a magnet and the inner surface of the float be coated with iron.
- the tube is sealed at both ends, being provided at the top with a transparent plate or disc through which the laser beam is transmitted and reflected from the reflector.
- This tube preferably contains dry air or other gas at low pressure.
- an attemporator is provided on the tube to regulate the temperature of the air/gas in the tube.
- a further aspect of the present invention provides a fluid level indicator system comprising the fluid level indicator according to the present invention, a laser and an interferometric detector respectively aligned with the reflector to transmit a beam thereto and receive a beam reflected therefrom.
- Fig. 1 is a schematic diagram illustrating the principle of interferometric measurement
- Fig. 2 illustrates an embodiment of the present invention
- Fig. 3 illustrates a further embodiment of the present invention.
- the fluid level indicator of the present invention is intended for incorporation in a laser beam inter ⁇ ferometric system.
- the high intensity and temporal coherence of laser beams offer advantages in inter- ferometric measurement over those of conventional light sources, and provide for high accuracy and speed of measurement.
- FIG. 1 is a schematic diagram showing such an interferometer.
- a laser beam -i is split into two parts by a beam splitter A to produce a measurement beam on and a reference beam R.
- the measurement beam travels to a movable reflector B whose displacement is to be measured.
- the reflector B is usually a corner cube re ⁇ flector which provides an accurate return of the beam.
- the return beam *v and reference beam R are combined at the beam splitter A and travel to a detector C.
- the combined beams form an interference pattern.
- the amplitude of the light at the detector C depends on the phase difference between the reference beam and the measurement beam which in turn depends on the difference in the optical path that the two beams have travelled.
- the phase The phase difference
- Electronic circuitry can then count the period of amplitude modulation detected by the interferometer and feed this information to a computer which calculates the distance through which the reflector has moved and/or velocity of motion of the reflector.
- the computer out ⁇ put can then be transmitted to- a display unit where it is displayed digitally or graphically, by for example a print out or cathode ray tube, and/or recorded on magnetic tape for subsequent analysis.
- the output of the computer may also or alternatively, be used to operate warning and/or control devices.
- two detectors are provided which respectively collect light from regions of the fringe pattern where the phase difference of the interfering beams differ by " -./2.
- the relative phase of the amplitude modulation viewed by the two detectors will therefore be different depending on the direction of the reflector motion and this is used to determine the correct displacement, and/or velocity.
- the laser beam is circularly polarized and split into a reference beam and measuring
- a ' series of reflectors of the reference and measuring beams result in their being of opposite circular polarization when they are combined. These beams combine to form a linear polarization vector whose orientation will depend on the relative phase of the two circularly polarized beams and which therefore rotates as a function of reflector position.
- An alternative interferometer employs a two fre-quency laser system,in which the Doppler shift of the beam reflected from the moving reflector is measured.
- the laser emits light of two slightly different fre ⁇ quencies fl and f2 with different polarization properties allowing the beam to be split into these two frequencies.
- the frequency f2 travels to a fixed reflector and frequency f1 to the movable reflector whose displacement is to be measured.
- Light reflected from the moving reflector has a frequency shifted by an amount ⁇ f, where:
- the beams are reflected from the fixed and movable reflectors are combined and produce an amplitude modulation of the light, of modulation fre ⁇ quency f2-(fl ⁇ _ f1) .
- a reference signal f2 - fl is generated and is fed with the modulation frequency to a converter which extracts ⁇ f1 and hence v ⁇ .
- the velocityt " can then be integrated to obtain linear displacements.
- the laser beam is amplitude modulated and the phase of the reflected light beam is compared with that of the emitted beam. The difference in phase occurs because of the finite time required for the light to travel to the movable reflector and return to the detector.
- the phase shift 0 is related
- laser interferometers provide measure- ent of displacement from an arbitrary zero, rather than an absolute measurement of distance.
- the instrument reading is set to zero at the initial position of the movable reflector and its motion is measured relative to this present zero.
- systems on market such as, for example, the "Hewlett-Packard 3850A industrial distance meter” which measure absolute distance.
- the Hewlett-Packard meter is also self-correcting for ambient air conditions based on an operator's presetting. Any of the above interferometric measurement systems may be employed with the fluid level indicator of the present invention, the selection of the appropriate system being dependent on the specific application and accuracy of measurement desired.
- a tube 1 is shown in Fig. 2 located in a liquid containing tank 2.
- the bottom of the tube 1 rests on the tank bottom while the top is mounted in the top wall of the tank or the ships deck and is sealed by a transparent sealing plate 3, of, for example, glass or perspex.
- Perforations 9 are provided in the wall of the tube 1 in the region of its bottom end through which liquid in the tank can pass. Preferably these perforations 9 are sufficiently small to act as a strainer to prevent entry of foreign bodies into the tube 1.
- a safety gauze 4 is provided in the tube 1 above the deck and serves as an outlet/inlet for air displaced/ replacement as the liquid in the tube rises/falls.
- OMP gauze 4 preferably contains silicate gel to dry the air drawn into the tube 1.
- a reflector 5 is mounted on the top of a float 6
- the float 6 is located in the tube 1
- Seal and scraper members 8 extend obliquely from the side surface of the float 6 above the liquid surface level and are biased against the inner surface of the tube 1.
- the seal and scraper members 8 10 act to maintain dry air above the float 6, providing a substantially constant refractive index medium above the reflector, and to keep the tube wall clean above the liquid level.
- a laser 10 and an interferometric detector 11 are 15 mounted directly above the transparent plate 3, respectivel aligned with the retroreflector 5. Lighttransmitted from the laser 10 is reflected by the retroreflector 5 and returned to a receiving lens of the detector 11 which surrounds the laser's transmitting lens.
- Electronic 20 circuitry determines the position of the retroreflector and this information is fed, for analysis, to a computer, such as, a desk-top computer in a single or multiple units. Information such as the amount and speed of filling/discharge may be computed either by height or 25 weight of liquid in the tank or by reference to permissible structural stress levels.
- FIG. 3 shows another embodiment of the present invention located in a liquid containing tank 2.
- the tube 1 is sealed and contains dry air or other
- An attemporator 12 surrounds the top end of the tube 1 above the ships deck to control the temperature of the air/gas in the tube so as to maintain the temp ⁇ erature, and hence the refractive index of the air/gas constant.
- the retroreflector 5 is mounted on an iron cont ⁇ aining/coated disc 13 which is free to move longitudinally of the tube.
- An annular float 6a surrounds the tube 1 and has a magnet 14 provided on its inner surface.
- the float 6a is preferably in two parts to facilitate its easy replacement.
- the float 6a_ is borne by and moves with the liquid in the tank.
- the magnet 14 attracts the disc 13 which therefore follows the movement of the float 6a_, carrying the retroreflector 5 with it.
- a laser 10 and.an interferometric detector 11 are mounted and operated as described in relation to the previous embodiment.
Landscapes
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- General Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Thermal Sciences (AREA)
- Length Measuring Devices By Optical Means (AREA)
Abstract
A fluid level indicator for fluid level detection using laser beam interferometry. The indicator comprising a tube (1) for vertical arrangement in a fluid whose level is to be monitored, a reflector (5) arranged for movement longitudinally of the tube for reflecting a laser beam transmitted to the reflector (5) from the top of the tube and a float member (6, 6a) movable with the fluid, for moving the reflector (5) in response to fluid level changes. The reflector may be mounted on the float member in the tube which is provided with one or more inlets for the fluid or on a disc in a sealed tube which is moved with the float on the outside of the tube through magnetic attraction.
Description
Title: FLUID LEVEL INDICATOR
Technical Field:
The present invention relates to fluid level indicators.
Background Art: Various fluid level indicators are known which employ mechanical sensors for detecting the rate and extent of filling/discharge of containers, such as, for example, the tanks of an oil tanker. However, the sensitivity and speed of response of such systems are not sufficient to permit the accurate control of fluid supply to or discharge from very large containers," such as, those of a tanker, in which the rate of rise or fall of the level is very small, but the quantities of fluid concerned are large. Such control is particularly im- portant in tankers in order to ensure that the sequence and/or rate of loading/unloading does not set up structural stresses in the tanker's hull, leading to fatigue and eventual fracture.
It has now been found that light, and in particular a laser beam, can be used to accurately and rapidly monitor the rate and/or extent of filling/discharging of a con¬ tainer.
Disclosure of the Invention: According to the present- invention there is pro¬ vided a fluid level indicator for fluid level detection using laser beam interferometry, the indicator comprising a tube for vertical arrangement in a fluid whose level is to be monitored, a reflector arranged for movement long- itudinally of the tube for reflecting a laser beam trans¬ mitted to the reflector from the top of the tube and a
float member movable with the fluid,for moving the reflector in response to fluid level.changes.
In one embodiment of the invention, the reflector is mounted on the float member which is located in the tube and the tube wall is provided with one or more inlets for entry of fluid from the tank into the tube.
In another embodiment, the float member is annular in shape and carries a magnet on its inner surface. The reflector is mounted on a disc containing or coated with iron inside the tube which is sealed. As the float member moves with the fluid on the outside of the tube, the disc with the re lector is carried along with it due to magnetic attraction between the magnet and disc. Alternatively, the reflector may be mounted on a magnet and the inner surface of the float be coated with iron. The tube is sealed at both ends, being provided at the top with a transparent plate or disc through which the laser beam is transmitted and reflected from the reflector. This tube preferably contains dry air or other gas at low pressure. Further, an attemporator is provided on the tube to regulate the temperature of the air/gas in the tube. These measures serve to maintain the refractive index of the air/gas in the tube substantially constant so as to mitigate errors in the measured path length travelled by the beam due to changes in the refractive index which occur with variations in humidity, temperature and pressure.
A further aspect of the present invention provides a fluid level indicator system comprising the fluid level indicator according to the present invention, a laser and an interferometric detector respectively aligned with the reflector to transmit a beam thereto and receive a beam reflected therefrom.
Brief Description of the Drawings:
Embodiments of the present invention will now be described with reference to the accompanying drawings, in which: Fig. 1 is a schematic diagram illustrating the principle of interferometric measurement;
Fig. 2 illustrates an embodiment of the present invention;
Fig. 3 illustrates a further embodiment of the present invention.
The fluid level indicator of the present invention is intended for incorporation in a laser beam inter¬ ferometric system. The high intensity and temporal coherence of laser beams offer advantages in inter- ferometric measurement over those of conventional light sources, and provide for high accuracy and speed of measurement.
An interferometric method based on A«_A. Michelson's interferometer will first be described in order to outline the basic operation of interferometric laser dis¬ tance measuring systems.
Figure 1 is a schematic diagram showing such an interferometer. A laser beam -i is split into two parts by a beam splitter A to produce a measurement beam on and a reference beam R. The measurement beam travels to a movable reflector B whose displacement is to be measured. The reflector B is usually a corner cube re¬ flector which provides an accurate return of the beam. The return beam *v and reference beam R are combined at the beam splitter A and travel to a detector C. The combined beams form an interference pattern. The amplitude of the light at the detector C depends on the phase difference between the reference beam and the measurement beam which in turn depends on the difference in the optical path that the two beams have travelled. The phase
OMPI
difference ^ is given by = 2ks Cos θ where k = 2 ^ "X and S = wavelength; s = the path difference, and θ = the angle between the common axis of the beam and the direction of observ- ation which, in this case, is zero. When the moving part travels one half wavelength of light, the total difference in optical path goes through one wavelength and the fringe pattern obtained will go through one period, corresponding to a change from light to dark to light at the position of the detector. Thus, the motion of the moving part leads to amplitude modulation of the light which is sensed by the detector.
Electronic circuitry can then count the period of amplitude modulation detected by the interferometer and feed this information to a computer which calculates the distance through which the reflector has moved and/or velocity of motion of the reflector. The computer out¬ put can then be transmitted to- a display unit where it is displayed digitally or graphically, by for example a print out or cathode ray tube, and/or recorded on magnetic tape for subsequent analysis. The output of the computer may also or alternatively, be used to operate warning and/or control devices.
Various interferometic arrangements for measuring direction of motion have been developed. In one such system, two detectors are provided which respectively collect light from regions of the fringe pattern where the phase difference of the interfering beams differ by " -./2. The relative phase of the amplitude modulation viewed by the two detectors will therefore be different depending on the direction of the reflector motion and this is used to determine the correct displacement, and/or velocity.
In another such system, the laser beam is circularly polarized and split into a reference beam and measuring
beam. A' series of reflectors of the reference and measuring beams result in their being of opposite circular polarization when they are combined. These beams combine to form a linear polarization vector whose orientation will depend on the relative phase of the two circularly polarized beams and which therefore rotates as a function of reflector position.
An alternative interferometer employs a two fre-quency laser system,in which the Doppler shift of the beam reflected from the moving reflector is measured. The laser emits light of two slightly different fre¬ quencies fl and f2 with different polarization properties allowing the beam to be split into these two frequencies. The frequency f2 travels to a fixed reflector and frequency f1 to the movable reflector whose displacement is to be measured. Light reflected from the moving reflector has a frequency shifted by an amount Δf, where:
> f/f = -s/
being the velocity of motion of the reflector and c the velocity of light. The beams are reflected from the fixed and movable reflectors are combined and produce an amplitude modulation of the light, of modulation fre¬ quency f2-(fl ± _ f1) . A reference signal f2 - fl is generated and is fed with the modulation frequency to a converter which extracts Δf1 and hence v ~ . The velocityt " can then be integrated to obtain linear displacements. In yet another type of interferometer the laser beam is amplitude modulated and the phase of the reflected light beam is compared with that of the emitted beam. The difference in phase occurs because of the finite time required for the light to travel to the movable reflector and return to the detector. The phase shift 0 is related
O PI
to the .total path length L by the equation β — 2
(2n L/>"-g) where is the vacuum wavelength of the laser and n is the group index of refraction.
Generally, laser interferometers provide measure- ent of displacement from an arbitrary zero, rather than an absolute measurement of distance. Thus, the instrument reading is set to zero at the initial position of the movable reflector and its motion is measured relative to this present zero. However, there are systems on market such as, for example, the "Hewlett-Packard 3850A industrial distance meter" which measure absolute distance. The Hewlett-Packard meter is also self-correcting for ambient air conditions based on an operator's presetting. Any of the above interferometric measurement systems may be employed with the fluid level indicator of the present invention, the selection of the appropriate system being dependent on the specific application and accuracy of measurement desired.
Fr rerred Modes of Carrying Out the Invention:
Embodiments of the fluid level indicator of the present invention will now be described.
A tube 1 is shown in Fig. 2 located in a liquid containing tank 2. The bottom of the tube 1 rests on the tank bottom while the top is mounted in the top wall of the tank or the ships deck and is sealed by a transparent sealing plate 3, of, for example, glass or perspex.
Perforations 9 are provided in the wall of the tube 1 in the region of its bottom end through which liquid in the tank can pass. Preferably these perforations 9 are sufficiently small to act as a strainer to prevent entry of foreign bodies into the tube 1.
A safety gauze 4 is provided in the tube 1 above the deck and serves as an outlet/inlet for air displaced/ replacement as the liquid in the tube rises/falls. The
' OMP
gauze 4 preferably contains silicate gel to dry the air drawn into the tube 1. , A reflector 5 is mounted on the top of a float 6
^ within the tube 1. The float 6 is located in the tube 1
5 on alignment rollers 7 which run on the inner surface of the tube 1. Seal and scraper members 8 extend obliquely from the side surface of the float 6 above the liquid surface level and are biased against the inner surface of the tube 1. The seal and scraper members 8 10 act to maintain dry air above the float 6, providing a substantially constant refractive index medium above the reflector, and to keep the tube wall clean above the liquid level.
A laser 10 and an interferometric detector 11 are 15 mounted directly above the transparent plate 3, respectivel aligned with the retroreflector 5. Lighttransmitted from the laser 10 is reflected by the retroreflector 5 and returned to a receiving lens of the detector 11 which surrounds the laser's transmitting lens. Electronic 20 circuitry determines the position of the retroreflector and this information is fed, for analysis, to a computer, such as, a desk-top computer in a single or multiple units. Information such as the amount and speed of filling/discharge may be computed either by height or 25 weight of liquid in the tank or by reference to permissible structural stress levels. This may then be recorded on magnetic tape for subsequent analysis , in the manner of an aeroplane flight recorded and/or be used to operate low and high level alarms and/or control the rate of 30 filling/discharge of liquid. Further, this information can be used in the testing of filling/discharge equipment, and in ascertaining the instantaneous weight of cargo in any tank, enabling tanker specific gravity corrections to be made during loading and unloading using ballast. 35 Figure 3 shows another embodiment of the present invention located in a liquid containing tank 2. In this case, the tube 1 is sealed and contains dry air or other
_O PI
gas at low pressure throughout. The sealed bottom of tube 1 rests on the tank bottom while the top of the tube is mounted in the tank's top/ship's deck and is sealed by a transparent plate 3 as in the previous embodiment.
An attemporator 12 surrounds the top end of the tube 1 above the ships deck to control the temperature of the air/gas in the tube so as to maintain the temp¬ erature, and hence the refractive index of the air/gas constant.
The retroreflector 5 is mounted on an iron cont¬ aining/coated disc 13 which is free to move longitudinally of the tube. An annular float 6a surrounds the tube 1 and has a magnet 14 provided on its inner surface. The float 6a is preferably in two parts to facilitate its easy replacement. The float 6a_ is borne by and moves with the liquid in the tank. The magnet 14 attracts the disc 13 which therefore follows the movement of the float 6a_, carrying the retroreflector 5 with it. A laser 10 and.an interferometric detector 11 are mounted and operated as described in relation to the previous embodiment.
Claims
1. A fluid level indicator for fluid level de¬ tection using laser beam interferometry, the indicator comprising a tube for vertical arrangement in a fluid whose level is to be monitored, a reflector arranged for movement longitudinally of the tube for reflecting a laser beam transmitted to the reflector from the top of the tube and a float member movable with the fluid, for moving the reflector in response to fluid level changes.
2. A fluid level indicator according to claim 1 wherein the reflector is mounted on the float member which is located in the tube and the tube wall is provided with one or more inlets for entry of fluid into the tube.
3. A fluid level indicator according to claim 2 wherein the top of said tube has a transparent plate through which the laser beam is transmitted and reflected and an air inlet/outlet.
4. A fluid level indicator according to claim 3 wherein a gauze containing silica gel is provided across said air inlet/outlet.
5. A fluid level indicator according to claim 2, 3 or 4 wherein the float member is located in the tube on alignment rollers.
6. A fluid level indicator according to any of claims 2 to 5 wherein seal members for preventing evaporated liquid entering the region above the float, extend obliquely from the side surface of the float member above the liquid level line thereof and are biassed against the inner surface of the tube.
^TJRE
OMPI IP
7. 'A fluid level indicator according to claim 6, wherein said seal members also act as scraper; members for maintaining the cleanliness of the inner walls of the tube.
8. A fluid level indicator according to claim 1, wherein the float member is annular in shape and located on the outside wall of the tube, co-axial therewith, and the reflector is mounted on a disc inside the tube which is sealed, the float moving the reflector through magnetic attraction between the float and the disc.
9. A fluid level indicator according to claim 8 wherein the tube contains dry air or other gas at low pressure.
10. A fluid level indicator according to claim 8 or 9, wherein an attemprator is provided on the tube to regulate the temperature of the air or other gas in the tube.
11. A fluid level indicator system comprising the fruid level indicator according to any preceding claim, a laser and an interferometric detector respectively aligned with the reflector to transmit a beam thereto and receive a beam reflected therefrom.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB8117241 | 1981-06-05 | ||
GB8117241810605 | 1981-06-05 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1982004316A1 true WO1982004316A1 (en) | 1982-12-09 |
Family
ID=10522293
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/GB1982/000165 WO1982004316A1 (en) | 1981-06-05 | 1982-06-04 | Fluid level indicator |
Country Status (1)
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WO (1) | WO1982004316A1 (en) |
Cited By (17)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4773265A (en) * | 1980-11-20 | 1988-09-27 | Atlantic Richfield Company | Method for detecting leaks |
US4850223A (en) * | 1987-07-17 | 1989-07-25 | Tanktech, Inc. | Leak detector |
US5156042A (en) * | 1987-07-17 | 1992-10-20 | Proeco, Inc. | Leak detector |
NL1030093C2 (en) * | 2005-10-03 | 2007-04-04 | Petroplus Internat B V | Monitoring system for level of contents inside storage tank for e.g. oil, shines laser onto surface of tank contents |
CN100427900C (en) * | 2006-08-08 | 2008-10-22 | 浙江天保利科技开发有限公司 | Sealing rod type laser liquid level gauge |
EP2220465A2 (en) * | 2007-11-12 | 2010-08-25 | Pricol Limited | A fluid level sensor |
US7845813B1 (en) | 2007-08-14 | 2010-12-07 | Beck Lewis H | Positional setting tool for use in an oil sump lubrication system |
CN102426044A (en) * | 2011-11-08 | 2012-04-25 | 西安航天自动化股份有限公司 | Liquid level measurement system for float bowl of hydraulic power floating type ship elevator |
CN101285380B (en) * | 2008-05-27 | 2012-12-19 | 张炳爱 | Measuring method for water level of drilled shaft |
WO2014023061A1 (en) * | 2012-08-07 | 2014-02-13 | 付建国 | Laser automatic tide gauge |
WO2015049346A1 (en) | 2013-10-02 | 2015-04-09 | E. I. P. | Device for absolute optical measurement of a liquid level in a container |
CN106415219A (en) * | 2014-07-07 | 2017-02-15 | Vega格里沙贝两合公司 | Radar level gauge comprising a safety device |
WO2017220630A1 (en) | 2016-06-24 | 2017-12-28 | Bruno Morel-Fatio | Digital system for absolute optical measurement of a level of liquid in a container by correlation of photographs |
CN108593052A (en) * | 2018-03-30 | 2018-09-28 | 武汉理工大学 | A kind of laser water level monitoring early-warning system |
CN110081951A (en) * | 2019-04-16 | 2019-08-02 | 江苏大学 | A kind of supersonic range finder |
KR102007527B1 (en) * | 2019-03-26 | 2019-10-21 | (주)혜성티앤시 | level sensing device |
CN118089887A (en) * | 2024-04-28 | 2024-05-28 | 山东省薛风压力容器有限责任公司 | Measuring device for preventing liquid level fluctuation for pressure container |
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US4773265A (en) * | 1980-11-20 | 1988-09-27 | Atlantic Richfield Company | Method for detecting leaks |
US4850223A (en) * | 1987-07-17 | 1989-07-25 | Tanktech, Inc. | Leak detector |
US5156042A (en) * | 1987-07-17 | 1992-10-20 | Proeco, Inc. | Leak detector |
NL1030093C2 (en) * | 2005-10-03 | 2007-04-04 | Petroplus Internat B V | Monitoring system for level of contents inside storage tank for e.g. oil, shines laser onto surface of tank contents |
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US7845813B1 (en) | 2007-08-14 | 2010-12-07 | Beck Lewis H | Positional setting tool for use in an oil sump lubrication system |
EP2220465A2 (en) * | 2007-11-12 | 2010-08-25 | Pricol Limited | A fluid level sensor |
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WO2015049346A1 (en) | 2013-10-02 | 2015-04-09 | E. I. P. | Device for absolute optical measurement of a liquid level in a container |
CN106415219A (en) * | 2014-07-07 | 2017-02-15 | Vega格里沙贝两合公司 | Radar level gauge comprising a safety device |
CN106415219B (en) * | 2014-07-07 | 2019-11-29 | Vega格里沙贝两合公司 | Radar level measurement instrument including safety device |
WO2017220630A1 (en) | 2016-06-24 | 2017-12-28 | Bruno Morel-Fatio | Digital system for absolute optical measurement of a level of liquid in a container by correlation of photographs |
CN108593052A (en) * | 2018-03-30 | 2018-09-28 | 武汉理工大学 | A kind of laser water level monitoring early-warning system |
KR102007527B1 (en) * | 2019-03-26 | 2019-10-21 | (주)혜성티앤시 | level sensing device |
CN110081951A (en) * | 2019-04-16 | 2019-08-02 | 江苏大学 | A kind of supersonic range finder |
CN118089887A (en) * | 2024-04-28 | 2024-05-28 | 山东省薛风压力容器有限责任公司 | Measuring device for preventing liquid level fluctuation for pressure container |
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