GB2514423A - Gas analyser - Google Patents

Gas analyser Download PDF

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Publication number
GB2514423A
GB2514423A GB201309438A GB201309438A GB2514423A GB 2514423 A GB2514423 A GB 2514423A GB 201309438 A GB201309438 A GB 201309438A GB 201309438 A GB201309438 A GB 201309438A GB 2514423 A GB2514423 A GB 2514423A
Authority
GB
United Kingdom
Prior art keywords
hose
moisture
gas
pump
measuring device
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Withdrawn
Application number
GB201309438A
Other versions
GB201309438D0 (en
Inventor
Hany L F Agaiby
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
INSTR UK Ltd AG
Original Assignee
INSTR UK Ltd AG
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
Application filed by INSTR UK Ltd AG filed Critical INSTR UK Ltd AG
Priority to GB201309438A priority Critical patent/GB2514423A/en
Publication of GB201309438D0 publication Critical patent/GB201309438D0/en
Priority to PCT/IB2014/061648 priority patent/WO2014188382A1/en
Publication of GB2514423A publication Critical patent/GB2514423A/en
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/0004—Gaseous mixtures, e.g. polluted air
    • G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
    • G01N33/0027—General constructional details of gas analysers, e.g. portable test equipment concerning the detector
    • G01N33/0036—General constructional details of gas analysers, e.g. portable test equipment concerning the detector specially adapted to detect a particular component
    • G01N33/0059—Avoiding interference of a gas with the gas to be measured
    • G01N33/006—Avoiding interference of water vapour with the gas to be measured
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N1/00—Sampling; Preparing specimens for investigation
    • G01N1/02—Devices for withdrawing samples
    • G01N1/22—Devices for withdrawing samples in the gaseous state
    • G01N1/2226—Sampling from a closed space, e.g. food package, head space
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/22—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance
    • G01N27/223—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance for determining moisture content, e.g. humidity
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/0004—Gaseous mixtures, e.g. polluted air
    • G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/0004—Gaseous mixtures, e.g. polluted air
    • G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
    • G01N33/0011—Sample conditioning
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/048—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance for determining moisture content of the material

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  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Analytical Chemistry (AREA)
  • General Physics & Mathematics (AREA)
  • Pathology (AREA)
  • Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Food Science & Technology (AREA)
  • Medicinal Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Biomedical Technology (AREA)
  • Molecular Biology (AREA)
  • Sampling And Sample Adjustment (AREA)

Abstract

A gas analyser comprising a hose 14 with a gas coupling 24, 26 at each end; the first end 20 connectable to a drying tube 16 or a gas sampling port and the second end 22 connectable to a moisture measuring device 12. The drying tube 16 is connected to the first end 20 of the hose and the second end 22 to a pump 18 so that ambient air is drawn through the drying tube into the hose for a preset time or until the measuring device detects a stabilisation in the moisture level. The pump may also be stopped if it detects a rise in the moisture level, indicating a leak. The first end of the hose can then be connected to the gas sampling port so that the moisture level of the sampled gas can be measured accurately without being affected by the moisture level in ambient air initially inside the hose. The analyser may be used to measure the moisture level in the closed space containing an electrical circuit breaker.

Description

Gas Analyser The present invention relates to a gas analyser.
A known measuring instrument is a gas analyser which can measure moisture level, for example, within an electrical circuit breaker. Electrical circuit breakers in high voltage applications, such as in a power station, are required to have a moisture level as close to zero as possible. The presence of moisture in an electrical circuit breaker can lead to shorting and failure of a power system.
The said known gas analyser for measuring moisture within circuit breakers comprises a hose which is connected at one end to a measuring instrument in a fluid tight manner. The hose is provided with a fitting at its free end which is connectable to a corresponding fitting provided on a circuit breaker to form a fluid tight connection. The measuring instrument receives a sample of gas through the hose from a circuit breaker in order to take a measurement of the moisture therein.
According to one aspect of the invention there is provided a gas analyser comprising a measuring device, a hose having a first end defining a first gas coupling and a second end defining a second gas coupling, the first end of said hose being connectable to a gas sampling port, the second end of said hose being connectable to the measuring device, a moisture reducing means selectively arranged in connection with the first end of said hose, and, a pump device selectively operable to pump a gas through said hose.
It is desirable for the moisture level in a sealed space housing an electrical circuit breaker to be as close to zero as possible, i.e. 0 to 10 ppm of moisture. Using conventional apparatus and techniques of measuring moisture levels, moisture from ambient air will be in the hose to the measuring device. Moisture embedded in the walls of the hose will also enter the cavity of the hose by diffusion out of the walls of the hose into the central cavity. The moisture level of ambient air is typically at least 10,000 ppm. Therefore, measurements taken by conventional apparatus and methods have been found surprisingly to be inaccurate.
Reducing the moisture content of the hose to a level suitable for taking accurate moisture level measurements takes in the region of up to 2.5 hours, because the diffusion process is slow. Taking a moisture measurement from an electrical circuit breaker typically takes only a few minutes. Prior art gas analysers, in order to provide accurate moisture measurements, would require a gas having a low moisture content to be drawn through the hose for up to approximately 2.5 hours before a measurement to maintain a low moisture content in the hose, It is known to draw a vacuum on the hose for a short time, a matter of a few minutes, to remove air and moisture in the air in the hose cavity, but this does not solve the problem of moisture in the walls of the hose, which takes a long time to diffuse out.
Until now, it had not been recognised that the moisture level measurements taken from electrical circuit breakers, for example, might be inaccurate. This aspect of the invention provides a gas analyser which substantially reduces the moisture content within the hose before moisture level measurements are taken. In this way, moisture level measurements taken by the gas analyser of the present invention are more accurate than those taken by prior art gas analysers.
The moisture reducing means may take any suitable form, and in one embodiment of the invention, the moisture reducing means comprises a molecular sieve. The molecular sieve is configured to remove moisture vapour from ambient air drawn through the hose.
The pump device may be located inside a housing common to both the pump device and the measuring device and may be configured to pump a gas through the measuring device.
In one embodiment, the pump device is controlled by a timer. Preferably, the timer is controlled by computer software.
The pump device may be configured to run when a series of moisture content measurements taken by the measuring device are decreasing and may be configured to stop if a series of moisturc content measurements taken by the measuring device display a trend which is increasing or remaining substantially equal. If the moisture is detected to be increasing, this will indicate that there is a fault, in particular that ambient air is entering the hose through a leak or because the moisture reducing means is exhausted and no longer removing moisture from incoming air. The user can thus replace the moisture reducing means if needed. If the moisture is detected to be at a stable, low level, this will indicate that the hose is dry.
The hose may comprise a liner and may include a protective outer layer. The liner may be made of plastics material and in a preferred embodiment is made of PTFE. The protective outer layer may take any suitable form and may comprise a braided cover which maybe made of metal such as stainless steel.
According to another aspect of the invention, there is provided a method of operating a gas analyser, the gas analyser comprising a hose having a first end defining a first gas coupling connectable to a gas sampling port or a moisture reducing means and a second end defining a second gas coupling connectable to a pump device or a measuring device, the method comprising the method steps of: connecting the moisture reducing means to the first end of said hose; connecting the second end of said hose to the pump device and the measuring device; activating the pump device to draw ambient air into the hose through the moisture reducing means for a preset period of time or until the measuring device detects a rise or stabilisation in a measured value; disconnecting the moisture reducing means from the first end of said hose disconnecting the second end of said hose from the pump device and the measuring device; connecting the first end of said hose to a gas sampling port; connecting the second end of said hose to the measuring device; measuring the moisture level using the measuring device; disconnecting the first end of the hose from the gas sampling port.
Another aspect of the invention provides a kit for reducing moisture content in a gas analyser hose comprising: a moisture reducing means; a first intermediate conduit connectable between the moisture reducing means and a sampling hose; and, a second intermediate conduit connectable between the sampling hose and a gas analyser or a pump device.
The kit may also include a pump device. Thus the kit can be used with existing gas analysers which do not already include a pump.
A sealing check valve is preferably provided in one or both conduits.
The moisture reducing means may include a tubular housing therefor, the tubular housing including a connector at each end.
An embodiment of the invention will now be described byway of example and with reference to the accompanying drawings: Fig. 1 is a schematic of a first configuration of a gas analyser according to an embodiment of the invention.
Fig. 2 is a schematic of a second configuration of a gas analyser according to an embodiment of the invention.
The gas analyser 10 of the embodiment of the invention comprises a measuring device 12, a hose 14, a drying tube containing a molecular sieve 16 and a pump 18. The gas analyser 10 is intended for use in taking measurements of moisture level within air tight spaces, such as in electrical circuit breakers.
The hose 14 comprises a PTFE liner and a stainless steel braided outer layer.
The hose 14 defines a first end 20 and a second end 22. Each of the first and second ends 20, 22 of the hose are provided with either a male or female gas coupling 24, 26 as are known in the art. Each gas coupling 24, 26 acts to prevent air from entering the hose 14 unless a corresponding gas coupling 28, 30 is connected to either or both of the gas couplings 24,26 of the hose 14.
In Figure 1, the first end 20 of the hose 14 is shown connected to the drying tube containing a molecular sieve 16 by a conduit or tube 32 and the second end 22 of the hose 14 is connected to the pump 18 by a conduit or tube 34. In this arrangement, the gas analyser is used to pump ambient air through the drying tube containing a molecular sieve 16 in order to remove moisture from the hose 14.
In Figure 2, the second end 22 of the hose 14 is connected to the measuring device 12 by the conduit 34. In this arrangement, the gas analyser is used to receive pressurised gas from a circuit breaker.
Each conduit or tube 32, 34 is provided at both ends with a male or female gas coupling 28, 30 which co-operate with respective couplings 24, 26 of the hose 14 or respective couplings 50, 52 of a housing 42 connected to the pump 18 or measuring device 12. A sealing check valve 54, 56 of a known type is provided in each conduit or tube 32, 34 to prevent moist air from entering the hose 14 when not in use.
The drying tube containing a molecular sieve 16 comprises a tube 36 having an inlet 38, at one end of the tube 36, and an outlet 40, at the opposite end of the tube 36. The inlet 38 of the tube 36 allows ambient air to enter the drying tube containing a molecular sieve 16 and pass through an internal filter 46 to remove moisture from the air before the air exits the tube 36 via the outlet 40 of the tube 36 and into the hose 14.
The measuring device 12 is located within the housing 42. The housing 42 comprises a tubular body with first and second end caps, and/or an access panel, and a visual display 44 attached to the outside of the housing 42. The measuring device 12 is mounted to a mounting which is inserted and secured within the housing 42. In the illustrated embodiment, the pump 18 is also located within the housing 42 and is mounted on the same mounting as the measuring device 12. The pump 18 is connected to the measuring device 12 in a known manner by a conduit or tube 60 which passes through the measuring device and also connects to one of the couplings 54 of the housing 42. In this manner, the measuring device 12 can take measurements from air drawn by the pump 18 and passing through the measuring device 12. The measuring device 12 is also connected to the other of the couplings 52 of the housing by a conduit 62 that terminates at the measuring device 12.
The visual display 44 is integrated with a computer processor which is operable to selectively activate the pump 18, amongst other fUnctions. The computer includes software capable of selectively operating the pump 18 for a preset time and also of dc-activating the pump upon detection of specified parameters by the measuring device 12. The visual display 44 incorporates a touch screen by which the computer processor can be controlled.
Before use, an operator connects the drying tube containing a molecular sieve 16 to the first end 20 of the hose 14 and the second end 22 of the hose 14 to the pump 18 and the measuring device 12 (see figure 1). The touch screen of the visual display 44 is used to control the processor to instruct the pump 18 to activate and draw ambient air through the diying tube containing a molecular sieve 16 into the hose 14 for a preset time or until the measuring device 12 detects an increase or stabilisation of moisture in the air drawn through the hose 14.
If an increase in moisture is detected by the measuring device 12, the processor determines that a fault has occurred with the gas analyser. The fault may be that the molecular sieve within the drying tube 16 has reached saturation point or that ambient air is leaking into the hose 14. The processor would then instruct the pump 18 to de-activate.
If a stabilisation in moisture is detected by the measuring device 12, the processor determines that the air within the hose is dry to within a pre-determined tolerance. The processor would then instruct the pump 18 to dc-activate.
The visual display 44 can be used to program the processor to turn the pump 18 on at a preset time by using a timer operated by computer software. This is desirable to ensure that the moisture content within the hose 14 is at an optimum level when the first measurement of the day or of a shift is taken.
In normal use, the operator removes the drying tube containing a molecular sieve 16 from the first end 20 of the hose 14, connects the first end 20 of the hose 14 to a gas sampling port and connects the second end 22 of the hose 14 to the measuring device 12 before taking a measurement (see figure 2). Using the visual display 44, the operator instructs the gas analyser to take a measurement of the gases within an electrical circuit breaker, for example. A sample of pressurised gas from within the circuit breaker passes through the hose 14 to the measuring device 12. This process typically takes in the region of 5 minutes. The first end 20 of the hose 14 can then be disconnected from the gas sampling port. The drying tube containing a molecular sieve 16 may be connected to the first end 20 of the hose 14 between measurements and the second end 22 of the hose 14 to the pump 18. The pump 18 would then be activated periodically to maintain a low moisture content within the hose 14.
If the drying tube containing a molecular sieve 16 is not connected to the first end 20 of the hose 14 between uses, a low moisture content within the hose should still be maintained by virtue of check valves 54, 56 in conduits 32, 34 which prevent non-pressurised gas from entering the hose 14. The check valves 54, 56 are spring operated valves. In another embodiment, the check valves may be solenoid valves.
In another embodiment, a kit is provided for use with an existing gas analyser.
The kit comprises a drying tube containing a molecular sieve 16 and connection tubes 32, 34, each containing a check valve 54, 56. An cxpanded kit may bc provided which includes the same elements with the addition of a pump (not shown). This can be used where the existing gas analyser 10 does not have a pump. The pump may be programmable so as to be operated on a timer like the first embodiment, or may simply be capable of being turned on and off.
It will be appreciated that only one embodiment has been described and that the described embodiment is not intended to limit the scope of the claims.
GB201309438A 2013-05-24 2013-05-24 Gas analyser Withdrawn GB2514423A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GB201309438A GB2514423A (en) 2013-05-24 2013-05-24 Gas analyser
PCT/IB2014/061648 WO2014188382A1 (en) 2013-05-24 2014-05-23 Gas analyser

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB201309438A GB2514423A (en) 2013-05-24 2013-05-24 Gas analyser

Publications (2)

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GB201309438D0 GB201309438D0 (en) 2013-07-10
GB2514423A true GB2514423A (en) 2014-11-26

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Family Applications (1)

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GB201309438A Withdrawn GB2514423A (en) 2013-05-24 2013-05-24 Gas analyser

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WO (1) WO2014188382A1 (en)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5979159A (en) * 1982-10-27 1984-05-08 Toshiba Corp Moisture detector
US5616158A (en) * 1995-05-15 1997-04-01 Pryon Corporation Moisture absorbing media filter
JPH10118436A (en) * 1996-10-18 1998-05-12 Ookura Riken:Kk Moisture removing device for gas to be analyzed
GB2343752A (en) * 1998-11-14 2000-05-17 Building Research Establishmen Gas detector for nitrogen dioxide and optionally carbon monoxide
US6346142B1 (en) * 1999-12-28 2002-02-12 Honda Giken Kogyo Kabushiki Kaisha System for removing water from a gaseous sample

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4549553A (en) * 1983-11-07 1985-10-29 Spacelabs, Inc. Apparatus and method for use in a medical gas sampling system
WO2000074553A2 (en) * 1999-06-08 2000-12-14 Oridion Medical (1987) Ltd. Gas analyzer calibration checking device
US6783573B2 (en) * 2002-09-27 2004-08-31 Welch Allyn Protocol, Inc. Gas sampling system
EP1885460B1 (en) * 2005-05-10 2019-11-06 Oridion Medical, Ltd. Fluid drying mechanism
DE102009016848B4 (en) * 2009-04-08 2011-12-01 Siemens Aktiengesellschaft Gas analyzer with a combination of gas dehumidifier and gas converter

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5979159A (en) * 1982-10-27 1984-05-08 Toshiba Corp Moisture detector
US5616158A (en) * 1995-05-15 1997-04-01 Pryon Corporation Moisture absorbing media filter
JPH10118436A (en) * 1996-10-18 1998-05-12 Ookura Riken:Kk Moisture removing device for gas to be analyzed
GB2343752A (en) * 1998-11-14 2000-05-17 Building Research Establishmen Gas detector for nitrogen dioxide and optionally carbon monoxide
US6346142B1 (en) * 1999-12-28 2002-02-12 Honda Giken Kogyo Kabushiki Kaisha System for removing water from a gaseous sample

Also Published As

Publication number Publication date
WO2014188382A1 (en) 2014-11-27
GB201309438D0 (en) 2013-07-10

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