GB2057141A - Method and apparatus for sensing fluid flow - Google Patents
Method and apparatus for sensing fluid flow Download PDFInfo
- Publication number
- GB2057141A GB2057141A GB8024819A GB8024819A GB2057141A GB 2057141 A GB2057141 A GB 2057141A GB 8024819 A GB8024819 A GB 8024819A GB 8024819 A GB8024819 A GB 8024819A GB 2057141 A GB2057141 A GB 2057141A
- Authority
- GB
- United Kingdom
- Prior art keywords
- fluid
- property
- particles
- volume
- phase
- 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.)
- Granted
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/74—Devices for measuring flow of a fluid or flow of a fluent solid material in suspension in another fluid
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/56—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using electric or magnetic effects
- G01F1/64—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using electric or magnetic effects by measuring electrical currents passing through the fluid flow; measuring electrical potential generated by the fluid flow, e.g. by electrochemical, contact or friction effects
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/66—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters
- G01F1/661—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by measuring frequency, phase shift or propagation time of electromagnetic or other waves, e.g. using ultrasonic flowmeters using light
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/704—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow using marked regions or existing inhomogeneities within the fluid stream, e.g. statistically occurring variations in a fluid parameter
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/704—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow using marked regions or existing inhomogeneities within the fluid stream, e.g. statistically occurring variations in a fluid parameter
- G01F1/708—Measuring the time taken to traverse a fixed distance
- G01F1/712—Measuring the time taken to traverse a fixed distance using auto-correlation or cross-correlation detection means
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P5/00—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft
- G01P5/08—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring variation of an electric variable directly affected by the flow, e.g. by using dynamo-electric effect
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P5/00—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft
- G01P5/18—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring the time taken to traverse a fixed distance
- G01P5/20—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring the time taken to traverse a fixed distance using particles entrained by a fluid stream
Abstract
When a fluid consists of discrete particles of a first phase dispersed in a second phase, flow can be sensed or measured by sensing in a constant volume much larger than the particles and through which the fluid flows a property which differs substantially in value in the two phases, so that passage of each particle into and out of the volume causes a substantial change in the value of the property, and determining an autocorrelation function. The property may be the electrical conductivity or the ability to scatter laser light. In the illustrated embodiment, cylindrical electrodes 12, 14, mounted in a length of pipe 10 of insulating material, sense fluctuations in electrical conductivity which are differentiated with respect to time at 20 and autocorrelated at 22. <IMAGE>
Description
SPECIFICATION
Method and apparatus for sensing fluid flow
Previously, flow of a fluid, which may be a particulate solid carried by a gas, has been sensed by sensing fluctuations in a property of the fluid at each of two positions spaced in the direction of flow, and applying cross correlation techniques to the sensed fluctuations to sense or measure a transit time between the two spaced positions. For example, in the complete specification of British
Patent No. 1,235,856, the flow of a particulate material is determined by sensing random disturbances in electrical capacitance at two points spaced in the direction of the flow.
A disadvantage of such methods is that two transducers are needed which must be carefully matched to avoid distortion of the crosscorrelation function. Other arrangements, in which electrical conductivity is sensed at two spaced positions in a pipe through which a fluid flows, have the further disadvantage that the sensing electrodes often protrude from the pipe walls to avoid cross talk, and therefore obstruct the flow.
It is also known to provide a laser velocimeter by illuminating a fluid flow with two converging beams of radiation from a pulsed laser and to sense the Doppler signal which indicates flow velocity; a correlator may be used to sense the small contribution to the received signal due to the
Doppler effect as described in the specification of
UK Patent No. 1,450,911.
According to the invention, a method of sensing flow of a fluid, the fluid consisting of a first phase dispersed as discrete particles in a second phase, comprises sensing in a constant volume through which the fluid flows a property which differs substantially in value in the first and second phases, said volume being at least an order of magnitude greater than the dimensions of the particles whereby passage of each particle into and out of said volume causes a substantial change in the sensed value of the property, and determining from any fluctuations in the sensed property whether there exists a transit time for the passage of the particles through the volume.
Also according to the invention, apparatus for sensing flow of a fluid, the fluid consisting of a first phase dispersed as discrete particles in a second phase, comprises sensing means arranged to sense in a constant volume through which the fluid can flow a property which differs substantially in value in the first and second phases, said volume being at least an order of magnitude greater than the dimensions of the particles, and calculating means to determine from any fluctuations in the serised property whether there exists a transit time for the passage of the particles through the volume.
In one arrangement there is provided means to generate from the sensed property an autocorrelation function and to sense whether said transit time exists, and, optionally, means to determine said transit time.
The particles of the first phase may be, for example, bubbles of gas in a liquid, drops of liquid in a gas, or solid particles in a liquid or gas.
The property may be, for example, the electrical conductivity or capacitance, or the reflectance or absorbance of infra-red, visible, ultra-violet, or acoustic radiation, or of radioactive particles.
One embodiment of the invention in which the sensed property is electrical resistance will now be described by way of example with reference to the accompanying drawings in which: Figure 1 illustrates schematically one form of apparatus according to the invention;
Figure 2 illustrates the resistance change caused by a single particle;
Figure 3 illustrates the effect of differentiating the resistance change;
Figure 4 is a typical autocorrelation function;
Figure 5 is an example of a suitable detection circuit; and
Figure 6 illustrates schematically an alternative form of apparatus.
In Figure 1 an insulating pipe 10 is shown in cross section. Two thin conducting rings or cylinders 12, 14 are let into the pipe wall at axially spaced positions, a typical spacing being twice the pipe diameter, and are supported by flanges 16, 1 8 outside the pipe. The cylinders constitute conductivity-measuring electrodes and are connected to a resistance transducer and differentiator 20 which is arranged to monitor the electrical resistance of the cylindrical volume of material in the pipe between the electrodes 12, 14 and to provide an output voltage proportional to the rate of change of resistance to an autocorrelator 22.
Suppose an electrically conducting liquid 24 such as water flows through the pipe as indicated by the arrow. If only water flows between the electrodes the impedance is constant and there is no output voltage.
Suppose now the water has small air bubbles entrained in it. When one bubble enters the volume between the electrodes, the resistance of the volume increases sharply, as shown in
Figure 2, and the transducer 20 differentiates the change to provide a positive pulse. When the bubble leaves the volume, the resistance decreases sharply, and the transducer provides a
negative pulse. The "sharpness" of the effect is
dependent on the air bubble diameter being at
least an order of magnitude smaller than the
distance between the electrodes 1 2 and 14, and
will rarely in practice match the perfect square
pulse which is illustrated. The duration of the
effect is d/v where d is the spacing of the
electrodes 12, 14 and v is the velocity of the
bubble.
When a large number of small air bubbles pass
between the electrodes, each bubble affects the
resistance in the same way, and it is necessary to
apply the technique of correlation to provide a
measure of velocity. The differentiated pulses are
correlated, and the correlation function takes the
form shown in Figure 4, which illustrates the sum of the autocorrelations of all the entering and leaving pulses plus the cross correlations between these pulses. The delay time T* between the positive and negative peaks is related to bubble velocity by the equation:- v = dIT* and from this equation the bubble velocity can be calculated.The peaks are slightly spread because the bubbles take a finite time to enter and leave the sensed volume, the differentiator has a finite cut-off frequency, and not all bubbles have precisely the same speed.
When an air/water mix flows through a vertical tube, there are three distinct flow conditions; buoyancy dominated, transitional, and turbulence dominated. For fluid flowing upwards in a 34 millimetre bore pipe, it has been found that at velocities below 500 millimetres per second, the air bubble velocity exceeds the mixture velocity by a constant 205 millimetres per second. In turbulent flows, i.e. above 850 millimetres per second, the bubble velocity and mixture velocity are equal. At transitional flow rates, between 500 and 850 millimetres per second, it was found that the method according to the invention could not be used to determine flow rate because of the large spread of bubble velocities.
In the described arrangement, only the length of pipe between the electrodes needs to be insulating; the pipe outside the electrodes can be of conducting material, provided the electrodes are insulated from it and the resistance of the external circuit through earth is much greater than the resistance of the sensed volume.
It is an advantage of the invention that only one transducer is required, so that transducer matching problems are avoided. Since the electrodes do not protrude into the fluid, they do not cause a pressure drop and do not modify the flow.
While the electrodes have been shown inside the pipe in contact with the fluid, it may also be possible in some circumstances to arrange the electrodes outside the pipe.
Further, it can be shown theoretically that the standard error of the fluctuating resistance of the volume of fluid can be used to estimate either the void fraction or the size of the bubbles, provided the other value is known.
When electrical resistance is sensed, it is essential that the carrier fluid is electrically conducting, as in the water/air bubble flow described; it would not be possible to use the described embodiment to sense solid or liquid particles carried by a gas.
Instead of determining the autocorrelation function of the transducer output, the power spectrum of the sensed property may be determined.
Referring now to the electronic circuit shown in
Figure 4, a sensor circuit, indicated generally by reference 30, senses the fluctuating resistance of the air/water mixture between the electrodes, and a differentiator circuit 32 generates a signal proportional to the rate of change of the measured resistance. A stabilised power supply is also provided (not shown).
In the sensor circuit 30, a self resonant loop including amplifier 34 and voltage controlled amplifier 36, with resistors 38, 40 and capacitors 42, 44, generates a nominally 75 kHz carrier signal. Connected to the output of amplifier 34 is a detector and filter circuit comprising resistors 46, 47, diode 54, and capacitor 58; a signal representing the amplitude of the carrier signal is supplied by one side of the capacitor 58 to output terminal 60, in comparison with the earth line connected to the opposite side of the capacitor.
An integrating amplifier 62, with feedback capacitor 64, is supplied through resistor 66 and the voltage divider formed by resistors 48, 50 and its output is connected through resistor 68 to the control input of amplifier 36, thus maintaining the mean voltage at output terminal 60 equal to the reference voltage developed across the diode 56.
The flowmeter electrodes 1 6, 1 8 (see Figure 1) are connected across the secondary of a transformer 70; the resistance of fluid volume between the electrodes determines the load impedance transferred to the transformer primary, which is connected as a feedback element of amplifier 34 and therefore controls its gain. For slow changes in fluid resistance, the compensating gain changes of amplifier 34 hold the carrier amplitude almost constant. The transient resistance changes associated with bubble motion cause rapid changes in gain, and the resulting changes in carrier amplitude are detected and supplied to terminal 60.
Terminal 60 is also connected to the differentiator circuit 32; the terminal is connected through a capacitor 72 and series resistor 74 to an amplifier 76; with feedback resistor 78; the combination forms a high-pass filter. The amplifier loop comprising resistor 80 and capacitor 82 acts as a low-pass filter to remove unwanted high frequency noise from the output signal, which is supplied to the autocorrelator 22.
In the apparatus illustrated in Figure 6, the property of the flowing fluid which is sensed is its ability to scatter visible radiation. The two-phase system flows in a pipe 90 which has two transparent windows 92, 94 at diametrically opposite positions. A laser 96 provides a beam of laser light to an optical expansion system 98 which causes the beam to diverge in a plane perpendicular to the flow axis so that a fan-shaped beam or sheet of light 100 illuminates the fluid in the pipe and emerges through the window 92 so that internal reflections from the pipe wall are minimised. The discrete particles of the first phase scatter light through a third window 102 to a light sensor and differentiator 104 which is connected to the autocorrelator 22. The particles are illuminated only when they pass through the fanshaped laser beam, so that the duration of the scattered radiation received from each particle depends on the beam thickness dand particle velocity V. The light sensor 102 receives a multiplicity of light pulses, differentiates them and provides a suitable signal to the autocorrelator 22 which provides a measure of transit time T* of the particles through the laser beam.
Claims (9)
1. A method of sensing flow of a fluid, the fluid consisting of a first phase dispersed as discrete particles in a second phase, comprises sensing in a constant volume through which the fluid flows a property which differs substantially in value in the first and second phases, said volume being at least an order of magnitude greater than the dimensions of the particles of the first phase whereby passage of each particle into and out of said volume causes a substantial change in the sensed value of the property, and determining from any fluctuations in the sensed property whether there exists a transit time for the passage of the particles through the volume.
2. Apparatus for sensing flow of a fluid, the fluid consisting of a first phase dispersed as discrete particles in a second phase, comprises sensing means arranged to sense in a constant volume through which the fluid can flow a property which differs substantially in value in the first and second phases, said volume being at least an order of magnitude greater than the dimensions of the particles of the first phase, and calculating means to determine from any fluctuations in the sensed property whether there exists a transit time for the passage of the particles through the volume.
3. Apparatus according to Claim 2 in which the calculating means is arranged to generate an autocorrelation function and to sense whether said transit time exists.
4. Apparatus according to Claim 3 in which the calculating means is arranged to measure the transit time.
5. Apparatus according to any one of Claims 2, 3 or 4 in which the property of the fluid which is sensed is the electrical conductivity.
6. Apparatus according to Claim 5 in which the sensing means comprises two conducting cylinders connected to a resistance transducer and separated by a length of pipe of an insulating material.
7. Apparatus according to any one of Claims 2, 3 or 4 in which the property of the fluid which is sensed is the ability to scatter visible radiation.
8. Apparatus according to Claim 7 in which there is provided a source of laser light; means to direct the laser light as a sheet of light transverse to the fluid flow; and means to receive light scattered by the particles of the first phase.
9. Apparatus for sensing flow of a fluid substantially as hereinbefore described with reference to Figures 1 and 5 or to Figure 6 of the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8024819A GB2057141B (en) | 1979-08-03 | 1980-07-29 | Method and apparatus for sensing fluid flow |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7927198 | 1979-08-03 | ||
| GB8024819A GB2057141B (en) | 1979-08-03 | 1980-07-29 | Method and apparatus for sensing fluid flow |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2057141A true GB2057141A (en) | 1981-03-25 |
| GB2057141B GB2057141B (en) | 1983-07-20 |
Family
ID=26272431
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8024819A Expired GB2057141B (en) | 1979-08-03 | 1980-07-29 | Method and apparatus for sensing fluid flow |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2057141B (en) |
Cited By (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2129550A (en) * | 1982-11-10 | 1984-05-16 | Nippon Furnace Kogyo Kk | Velocity in water flow model |
| EP0109810A2 (en) * | 1982-11-10 | 1984-05-30 | Nippon Furnace KOGYO KAISHA LTD. | Simulator of fluid flow in field of flow entailing combustion or reaction |
| GB2140162A (en) * | 1983-03-25 | 1984-11-21 | Imaje Sa | A safety device for a conductive fluid circulation system and an ink-jet printer incorporating same |
| GB2147106A (en) * | 1983-09-19 | 1985-05-01 | Robert Garnett Green | Method and apparatus for the measurement of the flow of particulate materials |
| EP0311176A1 (en) * | 1987-09-28 | 1989-04-12 | Shell Internationale Researchmaatschappij B.V. | Optical flow meter |
| GB2265009A (en) * | 1992-03-06 | 1993-09-15 | Schlumberger Ltd | Flow measurement in medium of non-uniform electrical resistance |
| GB2274713A (en) * | 1993-01-29 | 1994-08-03 | Schlumberger Ltd | Cross-correlation fluid flow meter |
| WO1995019138A1 (en) * | 1994-01-14 | 1995-07-20 | Pacesetter Ab | Blood flow measurement device |
| WO2002077578A1 (en) * | 2001-03-22 | 2002-10-03 | Yortech Instruments Ltd | Gas velocity measurement by infrared radiation absorption |
| WO2004097346A1 (en) * | 2003-04-30 | 2004-11-11 | Tetra Laval Holdings & Finance Sa | A method for monitoring the stay time in a restricted conduit |
| EP1700632A3 (en) * | 2000-11-24 | 2006-11-08 | Perkinelmer Las, Inc. | Flow rate monitoring device |
| WO2007041735A1 (en) * | 2005-10-13 | 2007-04-19 | Technische Universität Graz | Method and device for determining the transport parameters of a particle transporting fluid flowing in a line |
| GB2444509A (en) * | 2006-12-06 | 2008-06-11 | Abb Ltd | Fluid flow conductivity sensor |
| DE102007052047A1 (en) * | 2007-10-31 | 2009-05-07 | Abb Ag | Method and device for measuring foreign bodies in the measuring medium |
| GB2467061A (en) * | 2006-12-06 | 2010-07-21 | Abb Ltd | Conductivity sensor wherein a correction is applied to conductivity measurements to correct for polarization effects of electrodes |
| WO2012015898A1 (en) * | 2010-07-28 | 2012-02-02 | Univation Technologies, Llc | Systems and methods for measuring velocity of a particle/fluid mixture |
| WO2014044600A1 (en) * | 2012-09-18 | 2014-03-27 | Tetra Laval Holdings & Finance S.A. | A method and an apparatus for detecting a transition from a first phase to a second phase |
-
1980
- 1980-07-29 GB GB8024819A patent/GB2057141B/en not_active Expired
Cited By (30)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0109810A2 (en) * | 1982-11-10 | 1984-05-30 | Nippon Furnace KOGYO KAISHA LTD. | Simulator of fluid flow in field of flow entailing combustion or reaction |
| EP0109810A3 (en) * | 1982-11-10 | 1985-12-18 | Nippon Furnace Kogyo Kaisha Ltd. | Simulator of fluid flow in field of flow entailing combustion or reaction |
| GB2129550A (en) * | 1982-11-10 | 1984-05-16 | Nippon Furnace Kogyo Kk | Velocity in water flow model |
| GB2140162A (en) * | 1983-03-25 | 1984-11-21 | Imaje Sa | A safety device for a conductive fluid circulation system and an ink-jet printer incorporating same |
| GB2147106A (en) * | 1983-09-19 | 1985-05-01 | Robert Garnett Green | Method and apparatus for the measurement of the flow of particulate materials |
| EP0311176A1 (en) * | 1987-09-28 | 1989-04-12 | Shell Internationale Researchmaatschappij B.V. | Optical flow meter |
| GB2265009A (en) * | 1992-03-06 | 1993-09-15 | Schlumberger Ltd | Flow measurement in medium of non-uniform electrical resistance |
| GB2274713A (en) * | 1993-01-29 | 1994-08-03 | Schlumberger Ltd | Cross-correlation fluid flow meter |
| GB2274713B (en) * | 1993-01-29 | 1997-07-02 | Schlumberger Ltd | Flow meter |
| WO1995019138A1 (en) * | 1994-01-14 | 1995-07-20 | Pacesetter Ab | Blood flow measurement device |
| EP1700632A3 (en) * | 2000-11-24 | 2006-11-08 | Perkinelmer Las, Inc. | Flow rate monitoring device |
| WO2002077578A1 (en) * | 2001-03-22 | 2002-10-03 | Yortech Instruments Ltd | Gas velocity measurement by infrared radiation absorption |
| EA008680B1 (en) * | 2003-04-30 | 2007-06-29 | Тетра Лаваль Холдингз Энд Файнэнс Са | A method for monitoring the stay time of liquid food products in a restricted conduit |
| US7487665B2 (en) | 2003-04-30 | 2009-02-10 | Tetra Laval Holdings & Finance S.A. | Method for monitoring the stay time in a restricted conduit |
| WO2004097346A1 (en) * | 2003-04-30 | 2004-11-11 | Tetra Laval Holdings & Finance Sa | A method for monitoring the stay time in a restricted conduit |
| CN100419389C (en) * | 2003-04-30 | 2008-09-17 | 利乐拉瓦尔集团及财务有限公司 | A method for monitoring the stay time in a restricted conduit |
| WO2007041735A1 (en) * | 2005-10-13 | 2007-04-19 | Technische Universität Graz | Method and device for determining the transport parameters of a particle transporting fluid flowing in a line |
| GB2467061B (en) * | 2006-12-06 | 2011-03-02 | Abb Ltd | Conductivity sensor |
| GB2467061A (en) * | 2006-12-06 | 2010-07-21 | Abb Ltd | Conductivity sensor wherein a correction is applied to conductivity measurements to correct for polarization effects of electrodes |
| GB2444509B (en) * | 2006-12-06 | 2010-09-15 | Abb Ltd | Conductivity sensor |
| GB2444509A (en) * | 2006-12-06 | 2008-06-11 | Abb Ltd | Fluid flow conductivity sensor |
| US9086357B2 (en) | 2006-12-06 | 2015-07-21 | Abb Limited | Conductivity sensor |
| US9651511B2 (en) | 2006-12-06 | 2017-05-16 | Abb Limited | Conductivity sensor |
| DE102007052047A1 (en) * | 2007-10-31 | 2009-05-07 | Abb Ag | Method and device for measuring foreign bodies in the measuring medium |
| US8340920B2 (en) | 2007-10-31 | 2012-12-25 | Abb Ag | Method and device for measuring foreign bodies in the measuring medium |
| DE102007052047B4 (en) * | 2007-10-31 | 2014-06-26 | Abb Ag | Method and device for measuring foreign bodies in the measuring medium |
| WO2012015898A1 (en) * | 2010-07-28 | 2012-02-02 | Univation Technologies, Llc | Systems and methods for measuring velocity of a particle/fluid mixture |
| WO2014044600A1 (en) * | 2012-09-18 | 2014-03-27 | Tetra Laval Holdings & Finance S.A. | A method and an apparatus for detecting a transition from a first phase to a second phase |
| CN104662483A (en) * | 2012-09-18 | 2015-05-27 | 利乐拉瓦尔集团及财务有限公司 | A method and an apparatus for detecting a transition from a first phase to a second phase |
| US9753454B2 (en) | 2012-09-18 | 2017-09-05 | Tetra Laval Holdings & Finance S.A. | Method and an apparatus for detecting a transition from a first phase to a second phase |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2057141B (en) | 1983-07-20 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |