GB2205405A - Level sensing device - Google Patents
Level sensing device Download PDFInfo
- Publication number
- GB2205405A GB2205405A GB08712816A GB8712816A GB2205405A GB 2205405 A GB2205405 A GB 2205405A GB 08712816 A GB08712816 A GB 08712816A GB 8712816 A GB8712816 A GB 8712816A GB 2205405 A GB2205405 A GB 2205405A
- Authority
- GB
- United Kingdom
- Prior art keywords
- level
- sight glass
- ana
- sensing device
- capacitor
- Prior art date
- Legal status (The legal status 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 status listed.)
- Withdrawn
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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
- G01F23/26—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields
- G01F23/263—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields by measuring variations in capacitance of capacitors
- G01F23/268—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields by measuring variations in capacitance of capacitors mounting arrangements of probes
-
- 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
- G01F23/02—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 gauge glasses or other apparatus involving a window or transparent tube for directly observing the level to be measured or the level of a liquid column in free communication with the main body of the liquid
-
- 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
- G01F23/26—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields
- G01F23/263—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields by measuring variations in capacitance of capacitors
- G01F23/266—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields by measuring variations in capacitance of capacitors measuring circuits therefor
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Fluid Mechanics (AREA)
- General Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Thermal Sciences (AREA)
- Measurement Of Levels Of Liquids Or Fluent Solid Materials (AREA)
Abstract
A capacitor plate in the form of a transparent stannous oxide layer 22 is deposited on the external surface of a boiler tube sight glass 12 preserving visual observation of the feed water level and 10K Hertz electric signal is applied through a conductive 24 between the earthed water and stannous oxide layer in suitable circuitry to provide an electric analogue signal of water level for remote indication and/or control. An adaptation with a thin wire 24 or rod inside the sight glass allows operation with very pure water or petroleum products. Alternatively rather than a transparent layer 22 an opaque layer with a longitudinal slot may be employed to allow visual observation. <IMAGE>
Description
LEVEL SENSING DEVICE
Introduction
This invention relates to a level sensing device for sensing the level of a liquia in a vessel or container ana to an apparatus adapted to inaicate, recora ana/or control the level of liquid in tne vessel or container in conjunction with associated indicating, recording'and/or controlling means. The invention in particular relates to such sensing device in a vessel which is equipped with a gauge glass or sight glass to give a visual indication of the level of liquid within the vessel or container. An alarm triggered when the level of the liquid either falls below or rises above predetermined positions in the sight glass can be proviaed.
Background of the Invention
Sight or gauge glass level indicators are widely usea to provide a visual inaication of water level in for instance, steam boilers. For safety reasons it is compulsory, in most countries, for steam boiler installations to be provided with sight glasses of the aforementioned type, irrespective of whether such boiler installations are equippea with level sensing and/or controlling apparatus. This is considered essential Decause automatic sensing devices are subject to mechanical ana/or electrical failure and in the event of such failure, it is arguea, it shoula still be possible to visually verify the level indicated by a sensing device.
Various types of level sensing aevices are known in the art. Tnus for instance, float operatea, capacitave, reflector type, conductivity proDe type ana other types of level sensing devices are available on tne market. However, many of these aevices are incapable of being usea in conjunction with a visual sight glass.
U.S. patent 2 743 340, Zoltanski described a glass tube internally coatea with a resistive coating ana containing mercury; an electrical circuit connectea across the coating as a variable resistance gives an analogue signal of the mercury level. U.S. patent 3 190 122 Eawards describes mercury in a tube coatea externally with a conductive layer, an electrical circuit connectea across the coating ana mercury as a variable area capacitor gives an analogue signal of the mercury level.
In Doth these approaches the mercury column in a glass tuDe was maae responsive to temperature or pressure variations to give a continuous analogue signal of these variables, e.g. for chart recoraing.
Objects and Summary of the Invention
This invention Dy contrast provides a level sensing device by means of which tne level of liquid in a vessel can De aetermined Doth Dy visual observation of the level of said liquid in a sight glass which is in communication with the interior of the vessel, and by detection of the level of the liquia in the sight glass Dy the use of an electrically conductive layer on the external surface of the sight glass.
This approach can provide a level sensing device which is aaaptea to provide a warning alarm when the level of the liquid in a vessel either arops below or exceeds a predetermined low or high level in the vessel respectively.
This invention in addition provides a level sensing device by means of which the level of liquia in a vessel can De determinea both Dy visual observation of the level of saia liquid in a sight glass which is in communication with tne interior of the vessal, and also at the same time provides a continuous remote indication of the level of saia liquia in the vessel, whether the liquia is electrically conductive, or not.
Thus in accordance with the invention there is provided a level sensing device for sensing the level of a liquid whether electrically conductive or not, in a vessel or container, e.g. comprising a transparent tubular sight glass, conduits for communication between the sight glass ana the vessel or container, a layer of conductive material applied to the external surface of the sight glass, electrical connectors for connecting the layer to an electric (including electronic) circuit ana a conductor of a diameter selectea accoraing to resistance of the liquid for connecting the liquid (which is normally earthea), with the electric or electronic circuit a selectea one or more of the liquia ana/or air with the sight glass wall constituting a variable dielectric of a capacitor in the circuit, the value of the capacitance of the capacitor so formea being relatea to the level of the liquid in the sight glass.
The great advantage of this invention is that it can De appliea to boilers in which the conductivity of the water varies tremendously (e.g. Dy a factor of 100) according to the stage of the operating cycle of the boiler which is punctuatea by blow aown; moreover the invention can also De applied to non-conductive liquids, for example petroleum products.
The electrically conductive layer may be provided longitudinally along at least a portion of the length of the sight glass. It may be opaque or transparent. However, when it is opaque, it should preferably not cover the entire circumference of the sight glass, but leaves uncoverea at least a longitudinal slot or slots along the length of the sight glass, so as to permit visual observation of the level of the liquid therein.
It has Deen founa by the applicant that a thin layer of a material such as stannous oxide can be aepositea on one or more of the exterior surfaces of a sight glass, which layer surprisingly offers excellent transparency characteristics for visual observance of the level of the liquid in the sight glass whilst still remaining sufficiently electrically conductive for suitable circuitry as provided by this invention.
In all embodiments of the invention the conductive layer appliea to the external surface of the sight glass constitutes one plate of an electrical capacitor in the electric or electronic circuit. Where the liquia is of high conductivity the liquia primarily forms the other plate of (variable area according to the level) the capacitor ana the glass wall of the sight glass primarily constitutes the dielectric medium of the capacitor. Where the resistance of the liquid, such as water having a high aegree of purity, is high this may be compensatea for oy the introduction in one embodiment of the invention, of a metal conductor of small cross-sectional area within and along the length of the sight glass.It is connectea to the conductor which provides connection with the electric or electronic circuit and, on account of its small cross-sectional area ana comparatively great distance from the conductive layer on the external surface of the sight glass, provides a compensating effect on the capacitance of the sight glass capacitor even when the level of liquid which is a poor conductor is at the lowest level.
In another emDoaiment of the invention where the resistance of the liquid is very high and it may be regardea as essentially nonconductive, e.g. oil, petrol, benzine, etc., it constitutes a variable component of the aielectric medium. In this embodiment the one plate consists of the conductive layer on the external surface of the sight glass ana the other plate of the capacitor comprises of a metal conductor, preferaDly of circular cross-section placea longitudinally within the sight glass so arrangea that a narrow space exists between the external surface of saia conductor and the internal surface of the sight glass.The void so formed between the two plates of the capacitor will have the effect of reducing the capacitance thereof which effect will be counteracted when said void is filled with the non-conductive liquid (oil, etc.) resulting in the capacitance of the capacitor being variable in accordance with variations in the level of saia liquia in the sight glass.
The metal conductor of small cross sectional area for poorly conducting liquids is preferably a fine wire thus leaving an annular space between it ana the glass walls of greater radial dimension than twice the radius of the wire, e.g. 10 x to 100 x as great.
The metal conductor leaving a narrow space between it ano the glass walls for non-conaucting liquias has a radius greater than half the radial aimension of the narrow space.
In a further embodiment of the invention the conductive layer on the external surface of the sight glass may De substituted by deposition onto the internal or external surface of two halves or sections of a glass tube cut along its length, having an internal aiameter compatible with the external aiameter of the sight glass for attachment thereto in wrap arouna fashion. In all embodiments the conductive layer may be encapsulatea in a transparent medium to prevent malfunction of the capacitor from the effects of airt or leakage on the external surface of the sight glass.
In accordance with the invention the sensing device for sensing the level of a liquid in a container or vessel further comprises means to apply an alternating or fluctuating electromotive force across the plates of the capacitor hereinDefore described ana means for aetecting a variation in the capacitance of the capacitor.
Brief description of the drawings
The invention is now described by way of example with reference to tne attachea drawings in which
Figure 1 shows a part sectional side elevation of a sight glass attachable to a vessel forming part of one embodiment of a sensing device in accoraance with the invention in terms of which the conductive liquid constitutes the variable component (plate) of the capacitor.
Figure 2 snows a part sectional side elevation of a sight glass attachable to a vessel forming part of another embodiment of a sensing device in accoraance with the invention in terms of which the resistance of the liquia, such as water having a high aegree of purity, methylated spirits, etc., is compensated for by the introduction of a metal conductor of small cross-sectional area into the sight glass along the length thereof with provision for electrical contact between saia metal conductor and tne metal parts of the gauge column which parts are normally in contact with the liquid and tne vessel at earth potential. Methylated spirits is a mixture of preaominantly ethanol, methanol ana water with small amounts of pyridine and colouring matter.
Figure 3 snows a part sectional side elevation of a sight glass attachable to a vessel forming part of another embodiment of a sensing aevice in accordance with the invention in terms of which the variable component of the capacitor is represented by a non-conductive liquid (e.g. constituting part of the dielectric medium).In this embodiment a central conductor of relatively large cross-sectional area, preferably circular, constituting one plate of the capacitor, is positioned longitudinally within the sight glass providing a gap or Dreak in the dielectric medium between said conductor ana the inner wall of the sight glass, the glass wall of which constitutes the remainder of the dielectric medium between the two plates of the capacitor as representea by the aforementionea conductor ana the conductive layer on the external surface of the sight glass, thereby providing for variation in the capacitance of the capacitor in accordance with variations in the level of the non-conauctive liquia in the vessel ana the sight glass.Examples of non-conductive liquids are water-free petroleum proaucts.
Figure 4 shows a part sectional side elevation of a sight glass attachaDle to a vessel forming part of another embodiment of a sensing device in accordance with the invention in terms of which the conductive layer is aepositea on the internal or external surface of a glass tube having a suitable internal aiameter for fitting of said glass tuDe over the sight glass or cut in half along its length ana clampea to the sight glass in wrap arouna fashion. In this embodiment no conaucting layer is aepositea on the external surface of the sight glass ana the arrangmeent is suitable for use in conjunction with emoodiments aepictea in figures 1, 2 ana 3.
Figure 5 shows a schematic circuit diagram for use with sight glasses shown in figures 1, 2, 3 ana 4.
Detailed description of the drawings and embodiments
Referring to figure 1 reference numeral 10 generally indicates a portion of sensing device for sensing the level of an electrically conductive liquid such as water in, for example, a steam boiler (not snown). The device 10 is mounted on tne outside of the boiler ana comprises a cylindrical tubular sight glass 12 hela between a top connecting member 14 and a Dottom connecting member 16, the memDers 14, 16 having conduits 18, 20 respectively for communication between the box of the sight glass 12 and the interior of the boiler.
The length of the sight glass 12 ana the position in which it is mountea to the Doiler are selected such as to permit the sight glass 12 to indicate the aesirea normal operating level of water in the boiler about halfway between the members 14, 16. Furthermore, the sight glass 12 should be of sufficient length as to enble it to indicate a minimum operating level 26 ana a maximum operating level 28 respectively Delow and above the normal operating level.
The metal conductors 24 and 25 shown in figures 2 ana 3 respectively are attacnea to a metal plug in connecting member 14 thereDy providing good electrical contact with the body of the vessel to which the connecting members are attachea.
The wrap arouna coatea glass sections 29 shown in figure 4 are suitable for use in all embodiments ana provide the facility of ease of application in that sight glasses of the correct length for the application neea not be specially prepared and the transparent characteristic is maintained.
A thin transparent conductive coating 22 is aepositea on the external surface of the sight glass 12 along the length and circumference thereof terminating about 25 mm from the metal parts of the members 14 and 16 in figures i to 3, alternatively said coating may be appliea to the wrap arouna glass sections as illustratea in figure 4.
The aeposition of the transparent conductive layer 22 on the sight glass 12 or glass segments 29 may be achievea Dy heating tin chloride powder (either stannous or stannic chloride) in a flask (not snown) until fumes are produced. Oxygen'is then fed into the flask, for example, at a rate of 1 to 5 litres per minute. The oxygen reacts with the tin chloride to form tin oxide fumes which are fed from the flask into a furnace (not shown), hela for example at approximately 50U0C. The fumes are deposited onto the outsiae surface of the sight glass 12, alternatlvely onto the inside or outside surface of the wrap arouna sections for the figure 4 embodiment.
The surface to De coatea is preparea by etching it, for example, with hydrofluoric acia of about 3t strength for aDut 60 secondS. The thickness of the tin oxide layer need not De more than a few microns ana may De cneckea by means of interference patterns of different colours formea by tne reflection of light from the coatea surface.
The conductive coating on the external surface of the sight glass as well as the metal parts of the vessel, which are normally earthed, are connectea to an electric circuit 100 (see figure 5).
The circuit 100 (figure 5) comprises the sight glass capacitor embodiment 202 which is fea with an alternating current supply at aDout 10 volts from oscillator 201 at 10K Hertz ana connectea to aioaes 203 ana 204, feeaing capacitor 205, with discharge resistance 206 connectea as shown. The capacitor 205 will receive a half wave direct current supply charging said capacitor to a voltage value which will De dependant upon the capacitance of capacitor 2U2.This voltage value will in turn be aepenaant upon the level of liquia within the sight glass thereDy proviaing saia voltage reference across capacitor 205 which will increase or aecrease in accordance with increasiny or aecreasing level in the sight glass 12 for all embodiments.
The saia voltage across capacitor 205 is fea to a series of operational amplifiers 205, 206 and comparators 20-7, 208 with adjustable reference to provide an adjustable trigger point for the capacitor 202 controlling relays 209, 210 which may be employea to actuate low ana high water alarm devices.
The output from amplifier 206 may be employea to drive a remotely situatea level indicating device 211 comprising a meter, LED display, recording instrument, etc.
It will De appreciated that any numDer of signals via comparator/relay facilities may be incorporatea into the control system, for example for starting ana stopping of boiler feea pumps, operation of solenoid valves for isolation of gas or fuel supply on gas or oil fired boilers under conditions of low water level as well as a multitude of functions in other spheres of industry, e.g. chemical, petroleum, etc.
It will also be appreciated that the signal produced by the capacitor 202 may De utilised in any number of different methods with respect to circuit aesiyn ana principle of operation to achieve the aesirea result.
In the circuitry employea in figure 5 the one plate of tne gauge glass capacitor 202 is earthea, of necessity in the case of boiler applications, resulting in the conductors of the circuitry as shown being suDjectea to a capacitive influence to "earth" with detrimental effect on the operation of capacitor 202 necessitating electrical isolation Dy means of relays etc., for conductors in close proximity to earth. In the case of the supply to the display unit 211 the proDlem may De eliminatea by the use of an optical transducer (not shown).
Any residual output resulting from the gauge glass capacitor embodiment, for instance when employed in the figure 3 configuration, may De eliminated by the introduction of an offset facility in the input stage to amplifier 205 (not shown).
The term "sight glass" as used herein is intended to cover similar level indicators made of suitable transparent or translucent materials other than glass.
Modifications to the embodiments described may be apparent to those of relevant skill which retain one or more of the advantages associated therewith. The disclosure hereof
is intended to encompass such modifications.
Claims (12)
1. A level sensing device for sensing the level of a liquia whether
electrically conductive or not in a vessel or container
comprising a transparent tuDular sight glass, conduits for
communication between the bore of the sight glass and the vessel
or container, a layer of conductive material associated with the
external surface of the sight glass, a first conductor for
electrical connection of the layer as one plate of a capacitor to
an electric circuit, and a secona conductor of a diameter
selectea accoraing to resistance of the liquid for electrical
connection of the liquid to the electric circuit, a selectea one
or more of tne liquia ana/or air with the sight glass wall
constituting variable dielectric of a capacitor in a circuit, the
value of tne capacitance of said capacitor being relatea to the
level of the liquid in the sight glass, the circuit being adapted to
apply an electric signal having an alternating component which
senses the value of capacitance as an analogue of level.
2. A level sensing device as claimed in claim 1, in which the layer
of conductive material is transparent.
3. A level sensing device as claimed in claim 1, in which tne
conductive layer comprises stannous oxide.
4. A level sensing device as claimed in any one of claims 1 to 3, in
which the conductive layer is opaque ana does not cover the
entire circumference of the sight glass, Dut leaves uncoverea at
least a longitudinal slot or slots along the length of the sight
glass, so as to permit visual observation of the level of the
liquid therein.
5. A level sensing device as claimea in any one of claims 1 to 4, in
which the conductive layer is applied to the internal or external
surface of a glass tuDe having an internal diameter compatible to
the external diameter of the sight glass to be fittea over the
sight glass or attachea to the sight glass in wrap around
fashion when cut in half along its length.
6. A sensing device for sensiny the level of an electrically
conductive liquid in a container or vessel which comprises:
- a dielectric component having a conductive surface
electrically isolated from the liquid ana a non-conducting
surface spacea from the conductive surface ana being adapted
to De in continuous electrical contact with the liquia for
variations in its level between at least a low ana a high
level, the component constituting a capacitor of which one
plate is represented by the conductive surface
- means for applying an electromotive force between the liquia
ana the conductive surface, ana
- means for aetecting a variation in the capacitance of the capacitor
7.A level sensiny device as claimed in any one of claims 1 to 6,
for sensing tne level of an electrically poorly conductive liquid
comprising additionally a metal conductor placea longitudinally
within the Dore of the sight glass of small cross-sectional
area, connectea with tne electric circuit as the secona plate of
the capacitor.
8. A sensing device as claimed in any one of claims 1 to 6, for
sensing the level of an electrically non-conductive liquid in a
container or vessel which comprises additionally an electrical
conductor placed longitudinally within the sight glass comprising
the secona plate of the capacitor ana leaving only a narrow space
between the conductor ana the glass wall of the sight glass.
9. A sensing device substantially as herein described
with reference to Figure 1 of the accompanying drawings.
10. A sensing device substantially as herein described
with reference to Figure 2 of the accompanying drawings.
11. A sensing device substantially as herein described
with reference to Figure 3 of the accompanying drawings.
12. A sensing device substantially as herein described
with reference to Figure 4 of the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08712816A GB2205405A (en) | 1987-06-01 | 1987-06-01 | Level sensing device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08712816A GB2205405A (en) | 1987-06-01 | 1987-06-01 | Level sensing device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8712816D0 GB8712816D0 (en) | 1987-07-08 |
| GB2205405A true GB2205405A (en) | 1988-12-07 |
Family
ID=10618216
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08712816A Withdrawn GB2205405A (en) | 1987-06-01 | 1987-06-01 | Level sensing device |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2205405A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2782804A1 (en) * | 1998-09-01 | 2000-03-03 | Inst Francais Du Petrole | Device for separating and measuring volume of different phases of a mixture of fluids comprises tubular receiver having conducting external wall and dielectric inner wall, and conducting element and measurement assembly |
Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB674034A (en) * | 1939-05-03 | 1952-06-18 | Wheelco Instr Company | Improvements in or relating to liquid level sensitive apparatus |
| GB696907A (en) * | 1949-10-29 | 1953-09-09 | Dag Sigurdsson Schreiber | Improved device for regulating the level of liquids |
| GB1208060A (en) * | 1967-12-29 | 1970-10-07 | Siemens Ag | Evaporimeters |
| US3553575A (en) * | 1967-11-27 | 1971-01-05 | Sonic Eng Corp | Capacitive sensing device having a slidable probe |
| GB2040464A (en) * | 1979-01-05 | 1980-08-28 | Larson R G | Measuring Liquid Level |
| GB1585188A (en) * | 1977-02-10 | 1981-02-25 | Mallory & Co Inc P R | Means for measuring the level of fluids |
| US4295370A (en) * | 1979-03-12 | 1981-10-20 | Emhart Industries, Inc. | Capacitive scheme for measuring the level of a liquid |
| GB2125553A (en) * | 1982-08-10 | 1984-03-07 | Standard Telephones Cables Ltd | Multi-purpose sensor/detector for fluid |
| GB2156993A (en) * | 1984-03-31 | 1985-10-16 | Glaverbel | Proximity control switches |
-
1987
- 1987-06-01 GB GB08712816A patent/GB2205405A/en not_active Withdrawn
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB674034A (en) * | 1939-05-03 | 1952-06-18 | Wheelco Instr Company | Improvements in or relating to liquid level sensitive apparatus |
| GB696907A (en) * | 1949-10-29 | 1953-09-09 | Dag Sigurdsson Schreiber | Improved device for regulating the level of liquids |
| US3553575A (en) * | 1967-11-27 | 1971-01-05 | Sonic Eng Corp | Capacitive sensing device having a slidable probe |
| GB1208060A (en) * | 1967-12-29 | 1970-10-07 | Siemens Ag | Evaporimeters |
| GB1585188A (en) * | 1977-02-10 | 1981-02-25 | Mallory & Co Inc P R | Means for measuring the level of fluids |
| GB2040464A (en) * | 1979-01-05 | 1980-08-28 | Larson R G | Measuring Liquid Level |
| US4295370A (en) * | 1979-03-12 | 1981-10-20 | Emhart Industries, Inc. | Capacitive scheme for measuring the level of a liquid |
| GB2125553A (en) * | 1982-08-10 | 1984-03-07 | Standard Telephones Cables Ltd | Multi-purpose sensor/detector for fluid |
| GB2156993A (en) * | 1984-03-31 | 1985-10-16 | Glaverbel | Proximity control switches |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2782804A1 (en) * | 1998-09-01 | 2000-03-03 | Inst Francais Du Petrole | Device for separating and measuring volume of different phases of a mixture of fluids comprises tubular receiver having conducting external wall and dielectric inner wall, and conducting element and measurement assembly |
| US6272906B1 (en) | 1998-09-01 | 2001-08-14 | Institut Francais Du Petrole | Device for separating and for measuring the volume of the various phases of a mixture of fluids |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8712816D0 (en) | 1987-07-08 |
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