WO2009001028A1 - Detectors comprising a sample inlets for creating turbulent flow of a gas or a particulate - Google Patents

Detectors comprising a sample inlets for creating turbulent flow of a gas or a particulate Download PDF

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Publication number
WO2009001028A1
WO2009001028A1 PCT/GB2008/002025 GB2008002025W WO2009001028A1 WO 2009001028 A1 WO2009001028 A1 WO 2009001028A1 GB 2008002025 W GB2008002025 W GB 2008002025W WO 2009001028 A1 WO2009001028 A1 WO 2009001028A1
Authority
WO
WIPO (PCT)
Prior art keywords
inlet
gas
turbulent flow
detector according
region
Prior art date
Application number
PCT/GB2008/002025
Other languages
French (fr)
Inventor
Jonathan Marcel Gowers
Original Assignee
Smiths Detection-Watford 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
Application filed by Smiths Detection-Watford Limited filed Critical Smiths Detection-Watford Limited
Publication of WO2009001028A1 publication Critical patent/WO2009001028A1/en

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Classifications

    • 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
    • G01N1/2273—Atmospheric sampling
    • 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
    • G01N1/2202—Devices for withdrawing samples in the gaseous state involving separation of sample components during sampling

Definitions

  • This invention relates to detectors of the kind having a sample inlet.
  • Some chemicals in powder form are super toxic, and if released into the atmosphere, are both dangerous to human health and highly persistent. Due to their nature and particle size (5-10 microns), they are difficult to detect using conventional chemical detection methods. These types of chemical compounds can also become attached to natural particles of dust, dirt or sand etc and be transported by the wind.
  • a detector of the above-specified kind characterised in that the inlet is arranged to create a localised turbulent flow region.
  • the inlet preferably includes an enlarged portion, the turbulent flow region being provided by a stepped region downstream of the enlarged region such that gas and any particulates flow smoothly over the enlarged portion and then flows turbulently in the turbulent flow region, and the inlet including a port located adjacent the turbulent flow region such that gas and any particulate material flows into the inlet via the port from the turbulent flow region.
  • the enlarged portion may be of mushroom shape with a pointed tip.
  • the inlet preferably includes a plurality of ports spaced around the inlet adjacent the turbulent flow region. At least that part of the inlet including the turbulent flow region is preferably of a polymer, which may have a low surface energy and a low thermal conductivity.
  • the inlet preferably extends within one end of an outer sample tube along which flows gas and any particulate material.
  • the outer sample tube may be several metres long.
  • a part at least of the inlet preferably has an enlarged downstream body of a thermally- conductive material.
  • the inlet preferably connects with an IMS detector.
  • a method of collecting particulate material in a gas for detection or analysis including the step of flowing the gas over an upstream enlarged surface to create a region of turbulent flow of the gas and particulate material downstream of the enlarged surface, collecting gas and particulate material from the region of turbulent flow, and supplying the collected gas and particulate material for detection or analysis.
  • the gas is preferably flowed over the enlarged surface via an outer sample tube within which the enlarged surface is located.
  • Figure 1 is a cross-sectional side elevation view of a part of a detector with a conventional nozzle
  • Figure 2 is a cross-sectional side elevation view of a nozzle according to the present invention.
  • an IMS detector 1 with a conventional inlet provided by a nozzle 2 formed by a tube 3 of cylindrical section open at one end extending within an outer, larger diameter cylindrical sleeve 4.
  • a nozzle is not efficient at capturing particulate samples.
  • FIG. 2 shows a new form of sample inlet 20 suitable for use in detecting highly toxic powders and the like.
  • the sample inlet 20 extends in one end of an outer cylindrical sample tube 22, which is open at both ends.
  • the inlet 20 includes a specially profiled nozzle 21, which sits in a sample air stream along the sample tube 22.
  • the sample tube 22 has a relatively large diameter internal bore of about 19mm and could be several metres long to enable sampling at a location remote from the detector itself.
  • the nozzle 21 is connected with the inlet of a chemical sensor such as an IMS detector (not shown).
  • the nozzle 21 is made from a polymer having a low surface energy and a low thermal conductivity.
  • the upper end of the nozzle 21 is enlarged to provide a mushroom shape head 23 with a pointed tip 24.
  • the middle region of the nozzle 21 is provided by a hollow cylindrical shaft 25 with a bore 26.
  • the diameter of the shaft 25 is less than that of the head 23 so that a step 27 is formed beneath the head.
  • Several ports 28 open externally from the bore 26 into or adjacent this step region 27 and are spaced around the step region.
  • the exterior surfaces of the shaft 25 are thermally insulated with a ceramic or polymer coating to help prevent thermal losses from heating.
  • the lower part of the nozzle 21 is provided by a body 30 of enlarged cross section and this is made from a material with high thermal conductivity, such as brass, which is plated to produce a smooth surface finish.
  • Air to be sampled is drawn downwardly through the sleeve 22 by a high volume, low pressure fan (not shown) and over the upstream head 23 of the nozzle 21.
  • the profile of the upper surface of the head 23 is chosen so that it produces a coanda effect, drawing the airflow cleanly over the surface of the nozzle with minimal turbulence.
  • a pump or similar device within the detector takes the particulate material into the detector, via the ports 28 and the bore 26, for analysis.
  • the body of the nozzle 21 is preferably heated to increase the detection performance.
  • the arrangement of the present invention is capable of collecting more particulate material than the prior nozzle design shown in Figure 1. It will be appreciated that the invention is not confined to use with IMS detectors but could be used with other forms of chemical detector.

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

Abstract

An IMS detector has a sample inlet (20) projecting in one end of an outer sample (tube 22), which is open at both ends. The inlet (20) has a metal base (30) at its downstream end and a polymer shaft (25) at its upstream end. The tip of the shaft (25) is enlarged with a head (23) of mushroom shape having a pointed tip (24) and forms a stepped, turbulent flow region (27) at its downstream side. Gas. with any.particulate material flows along the outer tube (20) smoothly over the upstream end of the head (23) and turbulently around its downstream end so that ports (28) around the stem (25) allow gas and particulate material to be drawn from the turbulent region (27) for supply to the IMS detector.

Description

DETECTORS COMPRISING A SAMPLE INLETS FOR CREATING TURBULENT FLOW OF A
GAS OR A PARTICULATE
This invention relates to detectors of the kind having a sample inlet.
Some chemicals in powder form are super toxic, and if released into the atmosphere, are both dangerous to human health and highly persistent. Due to their nature and particle size (5-10 microns), they are difficult to detect using conventional chemical detection methods. These types of chemical compounds can also become attached to natural particles of dust, dirt or sand etc and be transported by the wind.
Existing sample inlet nozzle designs for the detection of chemical vapours and gases usually consists of a short length of open-ended, unheated tube. Air sampling occurs at the chemical sensor.
It is difficult to provide detectors for detecting low volatile, highly-toxic chemical compounds in solid form, such as powders.
According to one aspect of the present invention there is provided a detector of the above-specified kind, characterised in that the inlet is arranged to create a localised turbulent flow region.
The inlet preferably includes an enlarged portion, the turbulent flow region being provided by a stepped region downstream of the enlarged region such that gas and any particulates flow smoothly over the enlarged portion and then flows turbulently in the turbulent flow region, and the inlet including a port located adjacent the turbulent flow region such that gas and any particulate material flows into the inlet via the port from the turbulent flow region. The enlarged portion may be of mushroom shape with a pointed tip. The inlet preferably includes a plurality of ports spaced around the inlet adjacent the turbulent flow region. At least that part of the inlet including the turbulent flow region is preferably of a polymer, which may have a low surface energy and a low thermal conductivity. The inlet preferably extends within one end of an outer sample tube along which flows gas and any particulate material. The outer sample tube may be several metres long. A part at least of the inlet preferably has an enlarged downstream body of a thermally- conductive material. The inlet preferably connects with an IMS detector.
According to a second aspect of the present invention there is provided a sample inlet for a detector according to the above one aspect of the present invention.
According to a third aspect of the present invention there is provided a method of collecting particulate material in a gas for detection or analysis including the step of flowing the gas over an upstream enlarged surface to create a region of turbulent flow of the gas and particulate material downstream of the enlarged surface, collecting gas and particulate material from the region of turbulent flow, and supplying the collected gas and particulate material for detection or analysis.
The gas is preferably flowed over the enlarged surface via an outer sample tube within which the enlarged surface is located.
A detector and nozzle according to the present invention will now be described, by way of example, with reference to the accompanying drawing, in which:
Figure 1 is a cross-sectional side elevation view of a part of a detector with a conventional nozzle; and
Figure 2 is a cross-sectional side elevation view of a nozzle according to the present invention.
With reference first to Figure 1, there is shown one end of an IMS detector 1 with a conventional inlet provided by a nozzle 2 formed by a tube 3 of cylindrical section open at one end extending within an outer, larger diameter cylindrical sleeve 4. Such a nozzle is not efficient at capturing particulate samples.
Figure 2 shows a new form of sample inlet 20 suitable for use in detecting highly toxic powders and the like. The sample inlet 20 extends in one end of an outer cylindrical sample tube 22, which is open at both ends. The inlet 20 includes a specially profiled nozzle 21, which sits in a sample air stream along the sample tube 22. The sample tube 22 has a relatively large diameter internal bore of about 19mm and could be several metres long to enable sampling at a location remote from the detector itself. The nozzle 21 is connected with the inlet of a chemical sensor such as an IMS detector (not shown). The nozzle 21 is made from a polymer having a low surface energy and a low thermal conductivity. The upper end of the nozzle 21 is enlarged to provide a mushroom shape head 23 with a pointed tip 24. The middle region of the nozzle 21 is provided by a hollow cylindrical shaft 25 with a bore 26. The diameter of the shaft 25 is less than that of the head 23 so that a step 27 is formed beneath the head. Several ports 28 open externally from the bore 26 into or adjacent this step region 27 and are spaced around the step region. The exterior surfaces of the shaft 25 are thermally insulated with a ceramic or polymer coating to help prevent thermal losses from heating. The lower part of the nozzle 21 is provided by a body 30 of enlarged cross section and this is made from a material with high thermal conductivity, such as brass, which is plated to produce a smooth surface finish.
Air to be sampled is drawn downwardly through the sleeve 22 by a high volume, low pressure fan (not shown) and over the upstream head 23 of the nozzle 21. The profile of the upper surface of the head 23 is chosen so that it produces a coanda effect, drawing the airflow cleanly over the surface of the nozzle with minimal turbulence. When, however, the air emerges over the lower, rear end of the head into the step region 27, it slows and its flow becomes turbulent due to the geometry of the nozzle. Solids and particulates are then drawn into this downstream stepped or turbulent flow region 27 of the nozzle 21, where there is a low-pressure region. A pump or similar device within the detector, takes the particulate material into the detector, via the ports 28 and the bore 26, for analysis.
The body of the nozzle 21 is preferably heated to increase the detection performance.
The arrangement of the present invention is capable of collecting more particulate material than the prior nozzle design shown in Figure 1. It will be appreciated that the invention is not confined to use with IMS detectors but could be used with other forms of chemical detector.

Claims

1. A detector having a sample inlet, characterised in that the inlet (20) is arranged to create a localised turbulent flow region (27).
2. A detector according to Claim 1, characterised in that the inlet (20) includes an enlarged portion (23), that the turbulent flow region is provided by a stepped region (27) downstream of the enlarged region such that gas and any particulates flow smoothly over the enlarged portion and then flows turbulently in the turbulent flow region (27), and that the inlet (20) includes a port (28) located adjacent the turbulent flow region (27) such that gas and any particulate material flows into the inlet (20) via the port (27) from the turbulent flow region (27).
3. A detector according to Claim 2, characterised in that the enlarged portion (23) is of mushroom shape with a pointed tip (24).
4. A detector according to Claim 2 or 3, characterised in that the inlet (20) includes a plurality of ports (28) spaced around the inlet adjacent the turbulent flow region (27).
5. A detector according to any one of the preceding claims, characterised in that at least that part of the inlet (20) including the turbulent flow region (27) is of a polymer.
6. A detector according to Claim 5, characterised in that the polymer has a low surface energy and a low thermal conductivity.
7. A detector according to any one of the preceding claims, characterised in that the inlet (20) extends within one end of an outer sample tube (22) along which flows gas and any particulate material.
8. A detector according to Claim 7, characterised in that the outer sample tube (22) is several metres long.
9. A detector according to any one of the preceding claims, characterised in that a part at least of the inlet (20) includes a coating on its exterior surface of a thermally- insulating material.
10. A detector according to any one of the preceding claims, characterised in that the inlet (20) has an enlarged downstream body (30) of a thermally-conductive material.
11. A detector according to any one of the preceding claims, characterised in that the inlet (20) connects with an IMS detector.
12. A sample inlet for a detector according to any one of the preceding claims.
13. A method of collecting particulate material in a gas for detection or analysis including the step of flowing the gas over an upstream enlarged surface (23) to create a region (27) of turbulent flow of the gas and particulate material downstream of the enlarged surface, collecting gas and particulate material from the region (27) of turbulent flow, and supplying the collected gas and particulate material for detection or analysis.
14. A method according to Claim 13, characterised in that the gas is flowed over the enlarged surface (23) via an outer sample tube (22) within which the enlarged surface (23) is located.
PCT/GB2008/002025 2007-06-26 2008-06-13 Detectors comprising a sample inlets for creating turbulent flow of a gas or a particulate WO2009001028A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0712362.3 2007-06-26
GBGB0712362.3A GB0712362D0 (en) 2007-06-26 2007-06-26 Detectors and nozzles

Publications (1)

Publication Number Publication Date
WO2009001028A1 true WO2009001028A1 (en) 2008-12-31

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB2008/002025 WO2009001028A1 (en) 2007-06-26 2008-06-13 Detectors comprising a sample inlets for creating turbulent flow of a gas or a particulate

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GB (1) GB0712362D0 (en)
WO (1) WO2009001028A1 (en)

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3697748A (en) * 1969-10-06 1972-10-10 Franklin Gno Corp Plasma chromatograph with internally heated inlet system
EP0265617A2 (en) * 1986-10-29 1988-05-04 Hewlett-Packard Company Micro-nebulizer for analytical instruments
US5581081A (en) * 1993-12-09 1996-12-03 Hitachi, Ltd. Method and apparatus for direct coupling of liquid chromatograph and mass spectrometer, liquid chromatograph-mass spectrometry, and liquid chromatograph mass spectrometer
EP0831325A1 (en) * 1996-09-03 1998-03-25 Hewlett-Packard Company Method and apparatus for ion discrimination in an electron capture detector
US5763876A (en) * 1996-04-04 1998-06-09 Mine Safety Appliances Company Inlet heating device for ion mobility spectrometer
US20030189169A1 (en) * 2002-04-04 2003-10-09 Wells Gregory J. Vortex flow atmospheric pressure chemical ionization source for mass spectrometry
US6700119B1 (en) * 1999-02-11 2004-03-02 Thermo Finnigan Llc Ion source for mass analyzer

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3697748A (en) * 1969-10-06 1972-10-10 Franklin Gno Corp Plasma chromatograph with internally heated inlet system
EP0265617A2 (en) * 1986-10-29 1988-05-04 Hewlett-Packard Company Micro-nebulizer for analytical instruments
US5581081A (en) * 1993-12-09 1996-12-03 Hitachi, Ltd. Method and apparatus for direct coupling of liquid chromatograph and mass spectrometer, liquid chromatograph-mass spectrometry, and liquid chromatograph mass spectrometer
US5763876A (en) * 1996-04-04 1998-06-09 Mine Safety Appliances Company Inlet heating device for ion mobility spectrometer
EP0831325A1 (en) * 1996-09-03 1998-03-25 Hewlett-Packard Company Method and apparatus for ion discrimination in an electron capture detector
US6700119B1 (en) * 1999-02-11 2004-03-02 Thermo Finnigan Llc Ion source for mass analyzer
US20030189169A1 (en) * 2002-04-04 2003-10-09 Wells Gregory J. Vortex flow atmospheric pressure chemical ionization source for mass spectrometry

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