WO1991018266A1 - Fluid pressure operated volume measurement with level calibration means - Google Patents

Fluid pressure operated volume measurement with level calibration means

Info

Publication number
WO1991018266A1
WO1991018266A1 PCT/GB1991/000768 GB9100768W WO1991018266A1 WO 1991018266 A1 WO1991018266 A1 WO 1991018266A1 GB 9100768 W GB9100768 W GB 9100768W WO 1991018266 A1 WO1991018266 A1 WO 1991018266A1
Authority
WO
Grant status
Application
Patent type
Prior art keywords
volume
liquid
pressure
vessel
level
Prior art date
Application number
PCT/GB1991/000768
Other languages
French (fr)
Inventor
Michael Peter Mckeown
Original Assignee
A.G. (Patents) Limited
Priority date (The priority date 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 date listed.)
Filing date
Publication date

Links

Classifications

    • GPHYSICS
    • G01MEASURING; TESTING
    • G01FMEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F25/00Testing or calibrating apparatus for measuring volume, volume flow or liquid level, or for metering by volume
    • G01F25/0061Testing or calibrating apparatus for measuring volume, volume flow or liquid level, or for metering by volume for measuring liquid level
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01FMEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F23/00Indicating or measuring liquid level, or level of fluent solid material, e.g. indicating in terms of volume, indicating by means of an alarm
    • G01F23/14Indicating or measuring liquid level, or level of fluent solid material, e.g. indicating in terms of volume, indicating by means of an alarm by measurement of pressure
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01FMEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F23/00Indicating or measuring liquid level, or level of fluent solid material, e.g. indicating in terms of volume, indicating by means of an alarm
    • G01F23/14Indicating or measuring liquid level, or level of fluent solid material, e.g. indicating in terms of volume, indicating by means of an alarm by measurement of pressure
    • G01F23/18Indicating, recording or alarm devices actuated electrically
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17STORING OF DISTRIBUTING GASES OR LIQUIDS
    • F17CVESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2250/00Accessories; Control means; Indicating, measuring or monitoring of parameters
    • F17C2250/04Indicating or measuring of parameters as input values
    • F17C2250/0404Parameters indicated or measured
    • F17C2250/043Pressure
    • F17C2250/0434Pressure difference

Abstract

Apparatus for measuring the volume of liquid (2) in a vessel (1) such as a post-fermentation tank comprises, a pressure detector (3) for measuring the pressure of the liquid at the base of the vessel, a pressure detector (4) for measuring the pressure at the top of vessel, processing means (5, 6, 7) for establishing an estimated volume of liquid in said vessel based on the outputs of said pressure detectors (3, 4), and correcting means including a level detector (9) for detecting when the level of liquid in said vessel reaches a predetermined level corresponding to a known volume, and means (5, 6, 7) for generating a correction factor to be applied, if necessary, to the estimated volume by comparing the estimated volume when the level of liquid reaches said predetermined level with the known volume corresponding to said predetermined level.

Description

FLUID PRESSURE OPERATED VOLUME MEASUREMENT

WITH LEVEL CALIBRATION MEANS

This invention relates to the measurement of the volume of liquid in a vessel, especially, but not exclusively, in the context of the brewing industry.

It is often necessary to know the quantity of liquid in a closed vessel, for example a post- fermentation tank, where direct inspection of the liquid is not possible. One known method of indirectly measuring the volume of liquid in such a vessel is to measure the pressure of the liquid at the bottom of the vessel and the pressure at the top of the vessel. From these pressure measurements, and making correction for the specific gravity of the liquid and the shape of the vessel, the volume of liquid in the vessel can be calculated. However, this method is prone to errors. For example, the calibration of the pressure detectors may drift, or the actual specific gravity of the liquid in the vessel may differ from the theoretical value used in the calculations.

According to the present invention there is provided apparatus for measuring the volume of liquid in a vessel comprising, means for measuring the pressure of the liquid at the base of the vessel, means for measuring the pressure at the top of said vessel, processing means for establishing an estimated volume of liquid in said vessel based on the outputs of said pressure measuring means, and correcting means including means for detecting when the level of the liquid in said vessel reaches a predetermined level corresponding to a known volume, and means for generating a correction factor to be subsequently applied, if necessary, to the estimated volume by comparing the estimated volume when the level of liquid reaches said predetermined level with the known volume corresponding to said predetermined level.

By means of this arrangement, when the vessel is either being filled or emptied and the liquid reaches the level sensed by the detecting means, the calculated liquid volume can be compared with the actual value. If the two values differ a correction factor can be generated which can be applied to subsequent calculations.

Possibly, in order to increase the accuracy of the system, detecting means may be provided at a number of levels corresponding to different known volumes. In this way the correction factor can be updated frequently.

In a preferred embodiment means may be provided for generating an alarm signal when the calculated liquid volume when the liquid is at the predetermined level is greater than and/or less than the known volume by more than a preset limit or preset limits. For example, an alarm signal may be generated when the calculated and actual values differ by more than ± 1%, indicating that the system needs checking and that, perhaps, the pressure detectors may need re-calibrating.

Preferably the calculation may be carried out by a computer system including a programmable logic controller. The computer system may have access to look up' tables from which volume values can be read for given pressure measurements. The computer system may also have access to prestored values of the specific gravity for different liquids in order to be able to generate an appropriate specific gravity correction factor. Alternatively the specific gravity may be entered manually if desired.

According to another aspect of the present invention there is provided a method of measuring the volume of liquid in a vessel comprising, measuring the liquid pressure at the base of the vessel, measuring the pressure at the top of the vessel, establishing an estimated volume of liquid from said pressure measurements, and applying, if necessary, a correction factor to said estimated volume, said correction factor being generated by comparing the estimated volume with a known volume when the liquid reaches a predetermined level.

As has been mentioned previously, the present invention is particularly applicable to the brewing industry but is not limited thereto and many other applications may be envisaged.

An embodiment of the invention will now be described by way of example and with reference to the accompanying drawings in which:-

Fig. 1 is a schematic view of apparatus according to an embodiment of the invention, and

Fig. 2 is a block diagram showing the calculation method.

Referring firstly to Fig. 1 there is shown, schematically, a liquid vessel 1 such as a post- fermentation tank, containing a body of liquid 2. The vessel 1 is provided with a first pressure detector 3 at the base thereof, while a second pressure detector 4 is provided at the top of the vessel. The first pressure detector measures the pressure exerted by the head of liquid plus the pressure of any gas (e.g. C02) above the liquid 2. The second pressure detector 4 measures only the pressure at the top of the vessel, i.e. the pressure of the gas.

The outputs of the two pressure detectors 3, 4 are fed to a programmable logic controller (PLC) 5 where the analogue inputs are converted to give pressure readings. The PLC 5 is operatively connected via an interface unit 6 to the site computer network 7 and an operator terminal 8.

The liquid vessel 1 is also provided with a level detector 9. The level detector 9 is arranged to provide an output signal to the PLC 5 when the liquid level reaches a predetermined point (either when emptying or filling the vessel 1) . The predetermined level is chosen to correspond to a previously measured known volume, for example 1000 barrels. The level detector 9 is used to generate a calibration or correction signal in a manner that will be described further below.

To calculate a volume measurement for the volume of liquid in the vessel, the steps shown schematically in Fig. 2 are followed. The outputs of pressure detectors 3, 4, corresponding to the bottom and top pressure respectively, are fed to the PLC 5 where they are converted to engineering units and passed on to the site computer network 7. Within the computer network 7 the necessary calculations are performed to obtain the volume measurement.

Firstly, the top pressure reading is subtracted from the bottom pressure to give a value corresponding only to the pressure generated by the head of liquid. This pressure differential, corresponding to the liquid head pressure, is then divided by the theoretical specific gravity of the liquid concerned in order to compensate for the different specific gravities of different liquids.

The resulting value is then compared with values in 'look-up' tables stored in the computer system. The look-up tables are prepared by previously measuring the pressure readings obtained with known volumes of liquid. The calibration of the vessel may be achieved using a precision flowmeter. The liquid head being measured with the "dip" tape every 10 barrels up to the 100 barrel level and at 100 barrel intervals thereafter. A separate look-up table is created for each type of vessel since the shape of the vessel is a factor that must be taken into account. As an alternative to using look-up tables, it may be possible to calculate directly an estimated volume from the present readings using an appropriate algorithm. After obtaining a theoretical or estimated volume measurement from the 'look-up' tables, a correction factor is applied to produce an actual volume measurement that may be displayed, along with other information such as the pressure readings and correction factor, on the operator terminal 8. The correction factor is obtained by comparing the calculated volume with the actual volume when the level of liquid reaches a known level, indicated by a level detector, as the vessel is filled. For example, if the known volume at which the level detector is set is 1000 barrels, but the system calculates a volume of 1005 barrels, then there exists an error of - 0.5% which must be applied to all subsequent volume calculations. The error can be checked as the liquid in the vessel is emptied and reaches the predetermined level. By applying such an error correction factor to the calculated result, account can be taken of such error inducing problems as drifting of the calibration of the pressure detectors, or variations in the specific gravity of the liquid from the theoretical value used in the calculations. If the error exceeds a predetermined limit or predetermined limits in either direction, e.g. ± 1%, the system may be configured to generate an alarm to this effect to advise an operative that the system needs checking and/or renewing.

Claims

Claims
1. Apparatus for measuring the volume of liquid in a vessel comprising, means for measuring the pressure of the liquid at the base of the vessel, means for measuring the pressure at the top of said vessel, processing means for establishing an estimated volume of liquid in said vessel based on the outputs of said pressure measuring means, and correcting means including means for detecting when the level of the liquid in said vessel reaches a predetermined level corresponding to a known volume, and means for generating a correction factor to be subsequently applied, if necessary, to the estimated volume by comparing the estimated volume when the level of liquid reaches said predetermined level with the known volume corresponding to said predetermined level.
2. Apparatus as claimed in claim 1, wherein said correcting means includes detecting means provided at a plurality of predetermined levels corresponding to different known volumes.
3. Apparatus as claimed in claim 1 or 2, wherein there is provided alarm generating means for generating an alarm signal when the estimated liquid volume at a predetermined level is greater than and/or less than the known volume at said predetermined level by more than a preset limit or preset limits.
4. Apparatus as claimed in any preceding claim, which includes a computer system having a programmable logic controller for calculating said liquid volume.
5. Apparatus as claimed in claim 4, wherein volume values corresponding to given pressure measurements are prestored in said computer system.
6. Apparatus as claimed in claim 4 or 5, wherein specific gravity values for a plurality of liquids are prestored in said computer system.
7. Apparatus as claimed in claim 4 or 5, wherein there is provided means for manually entering specific gravity values into said computer system.
8. A method of measuring the volume of liquid in a vessel comprising, measuring the liquid pressure at the base of the vessel, measuring the pressure at the top of the vessel, establishing an estimated volume of liquid from said pressure measurements, and applying, if necessary, a correction factor to said estimated volume, said correction factor being generated by comparing the estimated volume with a known volume when the liquid reaches a predetermined level.
9. A method as claimed in claim 8, wherein a correction factor is generated at a plurality of predetermined liquid levels.
10. A method as claimed in claim 8 or 9, wherein an alarm signal is generated when the estimated volume at a predetermined level is greater than and/or less than the known volume at said predetermined level by more than a preset limit or preset limits.
11. A method as claimed in any of claims 8 to 10, wherein said liquid volume is calculated using a computer system having any of the features of claims 4
PCT/GB1991/000768 1990-05-17 1991-05-16 Fluid pressure operated volume measurement with level calibration means WO1991018266A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GB9011084A GB9011084D0 (en) 1990-05-17 1990-05-17 Volume measurement
GB9011084.2 1990-05-17

Publications (1)

Publication Number Publication Date
WO1991018266A1 true true WO1991018266A1 (en) 1991-11-28

Family

ID=10676155

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1991/000768 WO1991018266A1 (en) 1990-05-17 1991-05-16 Fluid pressure operated volume measurement with level calibration means

Country Status (2)

Country Link
GB (1) GB9011084D0 (en)
WO (1) WO1991018266A1 (en)

Cited By (29)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1995008758A1 (en) * 1993-09-20 1995-03-30 Rosemount Inc. Differential pressure measurement arrangement utilizing dual transmitters
EP0697583A1 (en) * 1993-02-25 1996-02-21 Secretary Of State For Defence In Her Britannic Majesty's Gov. Of The United Kingdom Of Great Britain And Northern Ireland Liquid/foam mixture analysis
US5495769A (en) * 1993-09-07 1996-03-05 Rosemount Inc. Multivariable transmitter
EP0791810A2 (en) * 1996-02-21 1997-08-27 Jarmo Nissinen Equipment for measuring the volume of malted beverage packed in a large tank
NL1006209C2 (en) * 1997-06-03 1998-12-04 Euro Gator B V An apparatus and method for determining the amount of liquid substance in a closed tank or container.
US5847567A (en) * 1994-09-30 1998-12-08 Rosemount Inc. Microwave level gauge with remote transducer
JP2002013962A (en) * 2000-05-12 2002-01-18 Eaton Corp Liquid volume monitoring device and monitoring method therefor
EP1191276A2 (en) * 2000-07-31 2002-03-27 Chart, Inc. Differential pressure gauge for fluid volume calculation in cryogenic tanks
EP1286105A2 (en) * 2001-08-07 2003-02-26 Chart, Inc. Differential pressure gauge for cryogenic fluids which selects a density value based on pressure measurement
EP1338237A2 (en) * 2002-02-26 2003-08-27 BHT Hygienetechnik GmbH Method and apparatus for testing the patency of endoscope channels
US6643610B1 (en) 1999-09-24 2003-11-04 Rosemount Inc. Process transmitter with orthogonal-polynomial fitting
EP1384977A2 (en) * 2002-07-26 2004-01-28 ExxonMobil Research and Engineering Company Level switch with verification capability
FR2868160A1 (en) * 2004-03-24 2005-09-30 Taema Sa Pressure data processing system in a reservoir
WO2007065771A1 (en) * 2005-12-07 2007-06-14 Robert Bosch Gmbh Method and apparatus for detecting tank leaks
US7276023B2 (en) 2004-08-25 2007-10-02 Bht Hygienetechnik Gmbh Device for checking endoscope channels
KR100861518B1 (en) * 2000-05-12 2008-10-02 이턴 코포레이션 Solid state fuel level sensing
US7461562B2 (en) 2006-08-29 2008-12-09 Rosemount Inc. Process device with density measurement
EP2258949A1 (en) * 2009-06-02 2010-12-08 Grundfos Management A/S Method for recording characteristic values, in particular values, in particular of parameters of a centrifugal pump powered by an electric motor integrated into an assembly
GB2475920A (en) * 2009-12-07 2011-06-08 Haven Ltd Safety and monitoring system for oil-fired boiler installations
WO2011110354A1 (en) * 2010-03-11 2011-09-15 Linde Aktiengesellschaft Compressed gas cylinder
US8047079B2 (en) 2007-05-03 2011-11-01 L'air Liquide Societe Anonyme Pour L'etude Et Exploitation Des Procedes Georges Claude Method for controlling an electronic pressure gauge and pressure gauge therefor
US8209039B2 (en) 2008-10-01 2012-06-26 Rosemount Inc. Process control system having on-line and off-line test calculation for industrial process transmitters
US8334788B2 (en) 2010-03-04 2012-12-18 Rosemount Inc. Process variable transmitter with display
US8340791B2 (en) 2009-10-01 2012-12-25 Rosemount Inc. Process device with sampling skew
US8359171B2 (en) 2007-05-03 2013-01-22 L'air Liquide Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Electronic pressure gauge for measuring pressure
US8849589B2 (en) 2008-05-23 2014-09-30 Rosemount Inc. Multivariable process fluid flow device with energy flow calculation
CN104655237A (en) * 2015-02-06 2015-05-27 太仓天衡电子科技有限公司 High-efficiency digital liquid level detector and working method thereof
US9046219B2 (en) 2007-05-03 2015-06-02 L'Air Liquide, Société Anonyme pour l'Etude et l'Exploitation des Procédés Georges Claude Method for controlling a homogeneous batch of pressurized-fluid cylinders
US9121743B2 (en) 2012-05-31 2015-09-01 Rosemount Inc. Process variable transmitter system with analog communication

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB256289A (en) * 1925-03-04 1926-08-04 Harold Martin Improvements in or relating to fluid pressure operated means for indicating the quantity and specific gravity of the liquid contents of tanks
GB2138947A (en) * 1983-04-14 1984-10-31 Chiltern Glass Fibres Limited Improvements in or relating to a method of control of liquid stock

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB256289A (en) * 1925-03-04 1926-08-04 Harold Martin Improvements in or relating to fluid pressure operated means for indicating the quantity and specific gravity of the liquid contents of tanks
GB2138947A (en) * 1983-04-14 1984-10-31 Chiltern Glass Fibres Limited Improvements in or relating to a method of control of liquid stock

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
ADVANCES IN INSTRUMENTATION AND CONTROL, vol. 44, part 4, 1989, (Research Triangle Park, NC, US), W. OGLESBY: "A comparative analysis: Volume and mass derived from tank gauging systems", pages 1493-1504, see page 1493, last paragraph - page 1495, last paragraph; figures 4-7 *

Cited By (44)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0697583A1 (en) * 1993-02-25 1996-02-21 Secretary Of State For Defence In Her Britannic Majesty's Gov. Of The United Kingdom Of Great Britain And Northern Ireland Liquid/foam mixture analysis
US5495769A (en) * 1993-09-07 1996-03-05 Rosemount Inc. Multivariable transmitter
EP0919796A1 (en) * 1993-09-20 1999-06-02 Rosemount Inc. Differential pressure measurement arrangement utilizing dual transmitters
US5606513A (en) * 1993-09-20 1997-02-25 Rosemount Inc. Transmitter having input for receiving a process variable from a remote sensor
WO1995008758A1 (en) * 1993-09-20 1995-03-30 Rosemount Inc. Differential pressure measurement arrangement utilizing dual transmitters
US5870695A (en) * 1993-09-20 1999-02-09 Rosemount Inc. Differential pressure measurement arrangement utilizing remote sensor units
US5899962A (en) * 1993-09-20 1999-05-04 Rosemount Inc. Differential pressure measurement arrangement utilizing dual transmitters
US5847567A (en) * 1994-09-30 1998-12-08 Rosemount Inc. Microwave level gauge with remote transducer
EP0791810A2 (en) * 1996-02-21 1997-08-27 Jarmo Nissinen Equipment for measuring the volume of malted beverage packed in a large tank
EP0791810A3 (en) * 1996-02-21 1998-01-21 Esa Järvinen Equipment for measuring the volume of malted beverage packed in a large tank
NL1006209C2 (en) * 1997-06-03 1998-12-04 Euro Gator B V An apparatus and method for determining the amount of liquid substance in a closed tank or container.
US6643610B1 (en) 1999-09-24 2003-11-04 Rosemount Inc. Process transmitter with orthogonal-polynomial fitting
KR100861518B1 (en) * 2000-05-12 2008-10-02 이턴 코포레이션 Solid state fuel level sensing
JP2002013962A (en) * 2000-05-12 2002-01-18 Eaton Corp Liquid volume monitoring device and monitoring method therefor
EP1153784A3 (en) * 2000-05-12 2004-01-02 Eaton Corporation Solid state fuel level sensing
EP1191276A2 (en) * 2000-07-31 2002-03-27 Chart, Inc. Differential pressure gauge for fluid volume calculation in cryogenic tanks
EP1191276A3 (en) * 2000-07-31 2003-09-10 Chart, Inc. Differential pressure gauge for fluid volume calculation in cryogenic tanks
EP1286105A3 (en) * 2001-08-07 2003-06-25 Chart, Inc. Differential pressure gauge for cryogenic fluids which selects a density value based on pressure measurement
EP1286105A2 (en) * 2001-08-07 2003-02-26 Chart, Inc. Differential pressure gauge for cryogenic fluids which selects a density value based on pressure measurement
EP1338237A3 (en) * 2002-02-26 2004-03-24 BHT Hygienetechnik GmbH Method and apparatus for testing the patency of endoscope channels
EP1338237A2 (en) * 2002-02-26 2003-08-27 BHT Hygienetechnik GmbH Method and apparatus for testing the patency of endoscope channels
EP1384977A2 (en) * 2002-07-26 2004-01-28 ExxonMobil Research and Engineering Company Level switch with verification capability
EP1384977A3 (en) * 2002-07-26 2007-08-15 ExxonMobil Research and Engineering Company Level switch with verification capability
FR2868160A1 (en) * 2004-03-24 2005-09-30 Taema Sa Pressure data processing system in a reservoir
US7276023B2 (en) 2004-08-25 2007-10-02 Bht Hygienetechnik Gmbh Device for checking endoscope channels
US7954361B2 (en) 2005-12-07 2011-06-07 Robert Bosch Gmbh Method and apparatus for detecting tank leaks
WO2007065771A1 (en) * 2005-12-07 2007-06-14 Robert Bosch Gmbh Method and apparatus for detecting tank leaks
US7461562B2 (en) 2006-08-29 2008-12-09 Rosemount Inc. Process device with density measurement
US8359171B2 (en) 2007-05-03 2013-01-22 L'air Liquide Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Electronic pressure gauge for measuring pressure
US9046219B2 (en) 2007-05-03 2015-06-02 L'Air Liquide, Société Anonyme pour l'Etude et l'Exploitation des Procédés Georges Claude Method for controlling a homogeneous batch of pressurized-fluid cylinders
US8047079B2 (en) 2007-05-03 2011-11-01 L'air Liquide Societe Anonyme Pour L'etude Et Exploitation Des Procedes Georges Claude Method for controlling an electronic pressure gauge and pressure gauge therefor
US8849589B2 (en) 2008-05-23 2014-09-30 Rosemount Inc. Multivariable process fluid flow device with energy flow calculation
US8209039B2 (en) 2008-10-01 2012-06-26 Rosemount Inc. Process control system having on-line and off-line test calculation for industrial process transmitters
US8949045B2 (en) 2009-06-02 2015-02-03 Grundfos Management A/S Method for determining characteristic values, particularly of parameters, of a centrifugal pump aggregate driven by an electric motor and integrated in a system
CN102459912A (en) * 2009-06-02 2012-05-16 格伦德福斯管理联合股份公司 Method for determining characteristic values, particularly of parameters, of a centrifugal pump aggregate driven by an electric motor and integrated in a system
WO2010139416A1 (en) * 2009-06-02 2010-12-09 Grundfos Management A/S Method for determining characteristic values, particularly of parameters, of a centrifugal pump aggregate driven by an electric motor and integrated in a system
EP2258949A1 (en) * 2009-06-02 2010-12-08 Grundfos Management A/S Method for recording characteristic values, in particular values, in particular of parameters of a centrifugal pump powered by an electric motor integrated into an assembly
CN102459912B (en) * 2009-06-02 2016-06-29 格伦德福斯管理联合股份公司 Eigenvalue motor driven centrifugal pump assembly of the apparatus is determined, in particular a method parameter
US8340791B2 (en) 2009-10-01 2012-12-25 Rosemount Inc. Process device with sampling skew
GB2475920A (en) * 2009-12-07 2011-06-08 Haven Ltd Safety and monitoring system for oil-fired boiler installations
US8334788B2 (en) 2010-03-04 2012-12-18 Rosemount Inc. Process variable transmitter with display
WO2011110354A1 (en) * 2010-03-11 2011-09-15 Linde Aktiengesellschaft Compressed gas cylinder
US9121743B2 (en) 2012-05-31 2015-09-01 Rosemount Inc. Process variable transmitter system with analog communication
CN104655237A (en) * 2015-02-06 2015-05-27 太仓天衡电子科技有限公司 High-efficiency digital liquid level detector and working method thereof

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