Explosive detection screening system

• US 5,345,809 A
• Filed: 08/06/1992
• Issued: 09/13/1994
• Est. Priority Date: 06/09/1989
• Status: Expired due to Fees

• Current Assignee: Research Corporation Technologies
• Original Assignee: Research Corporation Technologies
• Inventors: Haley, Lawrence, Corrigan, Colin
• Primary Examiner(s): Williams, Hezron E.
• Assistant Examiner(s): ROSKOS, JOSEPH
• Application Number:
  US07/859,509
• Time in Patent Office: 768 Days
• Field of Search: 73/23.2, 73/863.12, 73/864.33
• US Class Current: 73/23.2
• CPC Class Codes: G01N 1/2214 by sorption
• CPC Class Codes: G01N 1/24 Suction devices G01N1/22 - G01N1/2294 take precedence
• CPC Class Codes: G01N 2001/022 sampling for security purposes, e.g. contraband, warfare agents
• CPC Class Codes: G01N 2001/024 passengers or luggage
• CPC Class Codes: G01N 2001/028 Sampling from a surface, swabbing, vaporising
• CPC Class Codes: G01N 2030/025 Gas chromatography
• CPC Class Codes: G01N 27/622 Ion mobility spectrometry
• CPC Class Codes: G01N 33/0081 Containers; Packages; Bottles
• CPC Class Codes: G01V 9/007 by detecting gases or particles representative of underground layers at or near the surface analysing earth materials G01N33/24; analysing gases per se G01N
• CPC Class Codes: Y10T 436/17 Nitrogen containing

Abstract

An explosive detection screening system used for the detection of explosives and other controlled substances such as drugs or narcotics. The screening system detects the vapor and/or particulate emissions from the aforementioned substances and reports that they are present on an individual or object and the concentration of each substance detected. The screening system comprises a sampling chamber for the collection of the vapor and/or particulate emissions, a concentration and analyzing system for the purification of the collected vapor and/or particulate emissions and subsequent detailed chemical analysis of the emissions, and a control and data processing system for the control of the overall system.

Claims

1. A portable detection and screening system for the detection of target vapors or target particulates associated with a defined class of target materials such as explosives, chemical agents, drugs or narcotics, said system comprising:

(a) a sampling means having a sequential series of sampling periods for gathering a sample volume of air from a specific area on an individual or object during each sampling period;

(b) a first sample collection and analysis subsystem for collecting target particulates contained in said sample volume of air and converting said target particulates into first a vapor sample for analysis;

(c) a second sample collection and analysis subsystem for concentrating target vapors contained in said sample volume of air, said second subsystem having first means for selectively concentrating said target vapors into a second vapor sample for analysis; and

(d) detection means responsive to said target materials to generate a signal in response to the presence of said target materials in either said first or second vapor sample.

2. The portable detection and screening system of claim 1, wherein said detection means further includes a first detector means for chemical analysis of said first vapor sample and a second detector means for chemical analysis of said second vapor sample for analysis.

3. The portable detection and screening system of claim 2, wherein said sampling means includes a sample collection means, said sample collection means further comprises a suction fan for drawing said sample volume of air from said sampling means during a sample period and delivering said sample volume of air to said first and said second sample collection and analysis subsystems.

4. The portable detection and screening system of claim 3, wherein said first sample collection and analysis subsystem includes a particulate collector which further comprises:

(a) at least one filter element for preferentially retaining target particulates contained in said sample volume of air; and

(b) a vaporization chamber adapted to receive said filter element, said vaporization chamber having means for heating said filter element to flash vaporize the retained target particulates into said first vapor sample for analysis.

5. The portable detection and screening system of claim 3, wherein said first sample collection and analysis subsystem further comprises:

(a) first, second and third filter elements for selectively retaining target particulates contained in said sample volume air;

(b) a collection chamber for receiving said sample volume of air, said collection chamber adapted to sequentially receive one of said first, second and third filter elements to selectively enable one of said filter elements to preferentially retain said target particulates during said sampling period;

(c) a vaporization chamber adapted to receive one of said first, second and third filter elements, said vaporization chamber having a first means for heating said one of said filter elements to flash vaporize the retained target particulates into said first vapor sample for analysis; and

(d) a cleaning chamber adapted to receive said one of said first, second, and third filter elements following flash vaporization, said cleaning chamber having a second means for heating said one of said filter elements to effectively vaporize any remaining particulate matter retained thereon.

6. The portable detection and screening system of claim 3, wherein said second sample collection and analysis subsystem further comprising:

(a) at least one filter element for preferentially adsorbing said target vapors contained in said sample volume of air; and

(b) a desorption chamber adapted to receive said filter element, said desorption chamber having means for generating a specific amount of heat energy to desorb and adsorbed target vapors from said filter elements.

7. The portable detection and screening system of claim 3, wherein said second sample collection and analysis subsystem further comprises:

(a) a first, second and third filter element for preferentially adsorbing said target vapors contained in said sample volume of air;

(b) a sampling chamber for receiving said sample, said sampling chamber adapted to receive one of said first, second and third filter elements to selectively adsorb said target vapors during one of said sampling periods;

(c) a desorption chamber adapted to receive another said first, second and third filter elements, said desorption chamber having a first means for generating a first specific amount of heat to desorb any adsorbed target vapors from said filter means; and

(d) a flushing chamber adapted to receive the remaining one one of said first, second and third filter elements, said flushing chamber having a second means for generating a second specific amount of heat to effectively desorb any remaining adsorbed vapor.

8. A hand held wand for use in a portable detection and screening system for detecting molecular vapor from a target material or particulates containing a target material, said target material including explosives, chemical agents, drugs or narcotics, said wand comprising:

(a) a portable vacuum head for engaging an individual or article to be searched for said target materials and collecting a sample volume of air therefrom, said vacuum head including;

(i) an inlet port for admitting said sample volume of air, and;

(ii) a flexible seal surrounding said inlet port for sealing said port to an article to be searched;

(b) a detection and screening system for collecting and detecting any molecular vapors of a target material present in said sample volume of air;

(c) a vacuum means for drawing said sample volume of air from said portable vacuum head to said detection and screening system, and;

(d) a flexible conduit joining said portable vacuum head and said detection and screening system.

9. A hand held wand for use in a portable detection and screening system as claimed in claim 8, wherein said detection and screening system includes a preconcentrator for preferentially concentrating molecular vapors of said target material in said sample volume and a vapor detector means responsive to molecular vapor from said target material.

10. A hand held wand for use in a portable detection and screening system as claimed in claim 8, wherein said detection and screening system includes means for collecting and flash vaporizing particulates containing said target materials, and a vapor detector means responsive to molecular vapors from said target materials.

11. A hand held wand for use in a portable detection and screening system as claimed in claim 8, wherein said detector and screening system collects and removes particulates from said sample volume of air, and then separately analyzes the particulates and any molecular vapors present in said sample volume of air.

12. A hand held wand for use in a portable detection and screening system as claimed in claim 9 or 10 or 11, wherein said flexible seal further includes a moveable frame with a soft elastomeric seal mounted thereon.

13. A hand held wand for use in a portable detection and screening system as claimed in claim 12, wherein said moveable frame is mounted in said vacuum head and resiliently biased outwardly from said head.

14. A hand held wand for use in a portable detection and screening system as claimed in claim 10 or 11, wherein said vacuum head further includes a rotating brush for removing residual particulates from an article to be searched.

15. A hand held wand for use in a portable detection and screening system as claimed in claim 14, wherein said rotating brush is rotated by a turbine, said turbine being driven by said air sample as it is drawn into said inlet.

16. A hand held wand for use in a portable detection and screening system as claimed in claim 9 or 10 or 11, wherein said vacuum head further includes a rotatable handle member positioned between said flexible conduit and said vacuum head.

17. A hand held wand for use in a portable detection and screening system as claimed in claim 9 or 10 or 11, wherein said vacuum means draws said air sample at a rate of 70 to 85 cfm through said inlet.

18. A hand held wand for use in a portable detection and screening system as claimed in claim 9 or 10 or 11, wherein said vacuum head further includes a control panel for actuating said detection and screening system.

19. A hand held wand for use in a portable detection and screening system as claimed in claim 18, wherein said control panel further includes a display means.

20. A hand held wand for use in a portable detection and screening system as claimed in claim 18, wherein said detection and screening system may be operated in a single cycle mode, a continuous cycle mode or a paused mode and said modes may be selected from said control panel.

21. A hand held wand for use in a portable detection and screening system as claimed in claim 18, wherein said detection and screening system assigns a control number to each sample analyzed, and said control number is displayed on said display means.

22. A hand held wand as claimed in claim 21, wherein said display means further includes an alarm indicator, and said detection and screening system includes means for transmitting an alarm signal and said control number to said display means when a target material is identified in said sample volume of air.

23. A portable detection and screening system for the detection of target vapors or target particulates associated with a defined class of target materials such as explosives, chemical agents, drugs or narcotics, said system comprising:

(a) sampling means for gathering a sample volume of air from a specific area on an individual or object that may contain vapor or particulate emissions of said target materials;

(b) means for concentrating said target vapors or vapors emanating from said target particulates contained in said sample volume of air, said means including means for collecting said target vapors or particulate emissions at a first location;

(c) means for transporting said collected target vapors or particulate emissions to a second location;

(d) means for desorbing said target vapor or particulate emissions at said second location; and

,

(e) detection means responsive to said target vapors or particulate emissions desorbed at said second location to generate a signal in response to the presence of said target materials in said sample volume.

24. The portable detection and screening system of claim 23, wherein said detection means further includes a detector means for chemically analyzing said desorbed vapors.

25. The portable detection and screening system of claim 24, wherein said sampling means includes a sample collection means, said sample collection means further comprises a suction fan for drawing said sample volume of air from said sampling means during a sample period and delivering said sample volume cf air to said concentrating means.

26. The portable detection and screening system as claimed in claims 3 or 25, wherein said sampling means is a hand-held wand.

27. The portable explosive detection screening system of claim 26, wherein said detection means includes an ion mobility spectrometer which detects the presence of said target materials and outputs an alarm signal if said target materials are detected.

28. The portable detection and screening system of claim 26, wherein said detection means is a gas chromatograph/electron detection system which detects the presence of said target materials and outputs an alarm signal if said target materials are detected.

29. The portable detection and screening system of claim 25, wherein said means for collecting further includes a particulate collector means for collecting and vaporizing collected target particulates.

30. The portable detection and screening system of claim 29, wherein said particulate collector means comprises:

(a) at least one filter element for preferentially retaining target particulates contained in said sample volume of air; and

(b) a vaporization chamber adapted to receive said filter element, said vaporization chamber having means for heating said filter element to flash vaporize the retained target particulates for input into said detection means for analysis thereof.

31. The portable detection and screening system of claim 29, wherein said particulate collector means comprises:

(a) first, second and third filter elements for selectively retaining target particulates contained in said sample volume air;

(b) a collection chamber for receiving said sample volume of air, said collection chamber adapted to sequentially receive one of said first, second and third filter elements to selectively enable one of said filter elements to preferentially retain said target particulates during said sampling period;

(c) a vaporization chamber adapted to receive one of said first, second and third filter elements, said vaporization chamber having a first means for heating said one of said filter elements to flash vaporize the retained target particulates for input into said detection means for analysis thereof; and

(d) a cleaning chamber adapted to receive said one of said first, second, and third filter elements following flash vaporization, said cleaning chamber having a second means for heating said one of said filter elements to effectively vaporize any remaining particulate matter retained thereon.

32. The portable detection and screening system as claimed in claims 5 or 31, wherein said first means for heating one of said first, second and third filter elements is a first pair of electrodes which supply a heating current directly to said one of said filter elements to rapidly heat said filter elements and flash vaporize said target particulates for analysis thereof.

33. The portable detection and screening system of claim 32 further including a first gas supply means which continuously provides a first gas flow into said vaporization chamber during flash vaporization to sweep vaporized particulates into said detection means.

34. The portable detection and screening system of claim 33, wherein said vaporization chamber provides a flash heat of 250 millisecond duration which results in a rapid injection of said vaporized target particulates into said detection means.

35. The portable detection and screening system of claim 33, wherein said vaporization chamber provides a flash of heat of 250 millisecond duration which results in a rapid injection of said vaporized target particulates into a multi-port valve.

36. The portable explosive detection screening system of claim 35, wherein said multi-port valve is a three-way valve which acts an interface between said vaporization chamber and said detection means, which vents said vaporized target particulates for analysis into said detection means during an analysis phase of a sampling period and vents said first gas flow to the ambient environment during a non-analysis phase of said sampling period.

37. The portable detection and screening system of claim 35, wherein said multi-port valve is a six-port valve, said six-port valve is an interface between said vaporization chamber and said detection means and vents said vaporized target particulates for analysis into said detection means during an analysis phase of sampling period and vents a second gas flow supplied from a second gas flow means to an ambient environment during a non-analysis phase of said sampling period.

38. The portable detection and screening system of claim 37, wherein said six-port valve includes an adsorption/desorption tube connected across two of said six ports, said six-port valve having means for rotating said six-port valve between a first adsorb position and a second desorb position.

39. The portable detection and screening system of claim 38, wherein said means for rotating said six-port valve is a first gear head motor.

40. The portable detection and screening system of claim 39, wherein said sample volume is passed through said adsorption/desorption tube, when said six-port valve is in said first adsorb position.

41. The portable detection and screening system of claim 40, wherein said sample volume is desorbed and swept into said first detector means by said first gas flow from said first gas supply means, when said six-port valve is in said desorb position.

42. The portable detection and screening system of claim 41, wherein a controlled electric current is used to heat said adsorption/desorption tube to a predetermined temperature.

43. The portable detection and screening system of claim 42, wherein said first detector means is a gas chromatograph/ECD which detects the presence of said target materials.

44. The portable detection and screening system as claimed in claims 5 or 31, wherein said second means for heating one of said first, second and third filter elements includes a second pair of electrodes which supply an electrical current directly to said one of said filter elements in said cleaning chamber to thereby heat said filter element and vaporize any remaining particulates.

45. The portable explosive detection screening system of claim 44, wherein said second pair of electrodes supply a computer controlled current to generate a specific amount of heat energy to vaporize any particulate matter remaining on said filter element, said means for vaporizing further comprising a second gas supply to provide a second gas flow which sweeps said vaporized particulates into the ambient environment.

46. The portable detection and screening system as claimed in claims 5 or 31, wherein said collection chamber, said vaporization chamber and said cleaning chamber are formed from first and second plates, said first and second plates each defining a plurality of half chambers which together define each of said collection, vaporization, and cleaning chambers.

47. The portable detection and screening system of claim 46, wherein said first plate further includes and O-ring sealing means fastened around the perimeter of each of said half chambers to create an air tight seal when said second plate is joined thereto.

48. The portable detection and screening system of claim 47, wherein said collection chamber, said vaporization chamber and said cleaning chamber are each arranged 120 degrees apart.

49. The portable detection and screening system of claim 48, which further includes a rotating plate disposed between said first and second plates, said first, second, and third filter elements are arranged 120 degrees apart therein in alignment with said collection, vaporization and said cleaning chambers, said first, second, and third filters elements is wholly contained within one of said collection, vaporization, and cleaning chambers when said first and second plates are joined together.

50. The portable detection and screening system of claim 49 further including:

(a) a motor means for rotating said rotating plate 120 degrees between said sampling periods to rotate said first filter element between said collection chamber, said vaporization chamber, and said cleaning chamber; and

(b) an electromechanical means for reciprocally joining the first and second plates together during a sampling period and separating said first and second plates during the rotation of said rotating plate.

51. The portable detection and screening system of claim 50, wherein said first filter element is within said collection chamber, said second filter element is within said vaporization chamber, and said third filter element is within said cleaning chamber during a first sampling period, and said first filter element is within said vaporization chamber, said second filter element is within said cleaning chamber, and said third filter element is within collection chamber during the next sequential sampling period.

52. The portable detection and screening system of claim 46, wherein said first, second and third filter elements each comprise:

(a) a hard anodized aluminum frame, said frame having a groove for receiving an O-ring mounted around said collection chamber, said vaporization chamber or said cleaning chamber to provide air tight seal when said first and second plates are reciprocally joined thereto;

(b) first and second electrodes mounted on said frame to conduct said current to said filters during flash vaporization; and

,

(c) a stainless steel mesh screen which is engaged by said first and second electrodes.

53. The portable detection and screening system of claim 25, wherein said means for collecting said target vapors or particulate emissions further comprises:

(a) at least one filter element located at said first location for preferentially adsorbing said target vapors contained in said sample volume of air; and

(b) a desorption chamber located at said second location and adapted to receive said filter element, said desorption chamber having means for generating a specific amount of heat energy to desorb said target vapors from said filter elements.

54. The portable detection and screening system of claim 25, wherein said means for collecting said target vapors or particulate emissions further comprises:

(a) first, second and third filter elements for preferentially adsorbing said target vapors contained in said sample volume of air;

(b) a sampling chamber for receiving said sample at said first location, said sampling chamber adapted to receive one of said first, second and third filter elements to selectively adsorb said target vapors;

(c) a desorption chamber adapted to receive another said first, second and third filter elements at said second location, said desorption chamber having a first means for generating a first specific amount of heat to desorb any adsorbed target vapors from said filter means; and

(d) a flushing chamber located at a third location and adapted to receive the remaining one of said first, second and third filter elements, said flushing chamber having a second means for generating a second specific amount of heat to effectively desorb any remaining adsorbed vapor.

55. The portable explosive detection screening system as claimed in claims 7 or 54, wherein said first means for generating heat is an electric heating element mounted in said desorption chamber which receives a first controlled current to raise the temperature of a first sweep gas, supplied by a first gas supply means, to a level sufficient to effectively desorb said target vapors from said filter elements and to sweep said concentrated vapor sample for analysis into said detection means.

56. The portable detection and screening system of claim 55 further including a six-port valve which is an interface between said desorption chamber and said detection means and vents said target vapors for analysis into said detection means during an analysis phase of a sampling period and vents a second gas flow from a second gas supply means to an ambient environment during a non-analysis phase of said sampling period.

57. The portable detection and screening system as claimed in claims 37 or 56, wherein said six-port valve has an adsorption/desorption tube connected across two of said six ports and is rotatable between an adsorb position and a desorb position.

58. The portable detection and screening system of claim 57, wherein said six-port valve is in said adsorb position when said second vapor sample for analysis is passed through said adsorption/desorption tube, said adsorption/desorption tube is connected to a computer controlled current source which provides a specific amount of heat energy to desorb any vapors which have been absorbed in said tube.

59. The portable detection and screening system of claim 58, wherein said six-port valves comprises said second gas supply means which provides said second gas flow for sweeping unwanted materials from said adsorption/desorption tube to the ambient environment as the temperature in the tube rises to a level sufficient to desorb the target materials.

60. The portable detection and screening system of claim 59, wherein said six-port valve is in said desorb position when said desorbed target materials are swept into said detection means by said second gas flow provided by said second gas supply means.

61. The portable explosive detection screening system as claimed in claims 7 or 54, wherein said second means for generating heat is an electric heating element mounted in said flushing chamber and which receives a second controlled current to raise the temperature of a second sweep gas supplied by a second gas supply means to a level sufficient to effectively desorb any remaining vapors from said filter elements.

62. The portable detection and screening system as claimed in claims 7 or 54, wherein said sampling chamber, said desorption chamber and said flushing chamber are formed from the union of a first and second plate, said first and second plates each comprise half chambers having approximately one half the volume of each of said chambers.

63. The portable detection and screening system of claim 62, wherein said first and second plates each comprise an O-ring means fastened around the perimeter of each of said half chambers thereby creating an air tight seal when said first and second plates are joined together.

64. The portable detection and screening system of claim 63, wherein said sampling chamber, said desorption chamber and said flushing chamber are arranged 120 degrees apart from each other.

65. The portable detection and screening system of claim 64 which further includes a rotating plate disposed between said first and second plates, said first, second, and third filter elements are arranged 120 degrees apart therein in respective alignment with said sampling chamber, said desorption chamber, and said flushing chamber, each said first second, and third filter element is wholly contained within one of said sampling, desorption, and flushing chambers when said first and second plates are joined together.

66. The portable detection and screening system of claim 65 further including:

(a) a second motor means for rotating said rotating plate 120 degrees between said sampling periods to rotate said first filter element between said sampling chamber, said desorption chamber, and said flushing chamber; and

(b) an electromechanical means for reciprocally joining the first and second plates together during a sampling period and separating said first and second plates during the rotation of said rotating plate.

67. The portable detection and screening system of claim 66, wherein said first filter element is within said sampling chamber, said second filter element is within said desorption chamber, and said third filter element is within said flushing chamber during a first sampling period, and said first filter element is within said desorption chamber, said second filter element is within said flushing chamber, and said third filter element is within sampling chamber during the next sequential sampling period.

68. The portable detection and screening system of claim 65, wherein each of said first, second, and third filter elements comprises:

(a) a frame constructed from anodized aluminum which is hard anodized, said frame having a lip with a groove in which an O-ring is set to provide an air tight seal when in said sampling chamber, said desorption chamber and said cleaning chamber;

(b) first and second stainless steel mesh screens held in said frame by a plate, said first and second stainless steel mesh screens forming a cavity therebetween, said cavity comprising a measured adsorbent material with an affinity to adsorb the targeted materials; and

(c) a holding pin for placing the filter in a tight fit within said rotating plate.

69. The portable detection and screening system of claim 62, wherein an upper said half of said desorption chamber is conically shaped to enhance the vapor concentration process, said conically shaped upper half is formed by placing a ceramic bushing inside said first plate.

70. The portable detection and screening system of claim 69 further including a vacuum motor which draws debris from said flushing chamber, said vacuum motor is connected to said flushing chamber through a fitting in the second plate.