Explosive detection screening system

• US 5,109,691 A
• Filed: 11/02/1990
• Issued: 05/05/1992
• Est. Priority Date: 12/08/1989
• Status: Expired due to Term

• Current Assignee: CPAD Holdings, Ltd.
• Original Assignee: Research Corporation Technologies
• Inventors: Haley, Lawrence V., Corrigan, Colin D.
• Primary Examiner(s): Williams, Hezron E.
• Assistant Examiner(s): ROSKOS, JOSEPH
• Application Number:
  US07/608,496
• Time in Patent Office: 550 Days
• Field of Search: 73/23.36, 73/23.37, 73/28.01, 73/28.04, 73/864, 73/863.81, 340/632, 340/945, 250/288
• US Class Current: 73/23.36
• 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 2001/024 passengers or luggage
• CPC Class Codes: G01N 2001/028 Sampling from a surface, swabbing, vaporising
• CPC Class Codes: G01N 2001/2285 Details of probe structures
• CPC Class Codes: G01N 2030/025 Gas chromatography
• CPC Class Codes: G01N 2033/0081 containers; packages; bottles
• CPC Class Codes: G01N 27/622 Ion mobility spectrometry
• 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

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 explosive detection screening system for the detection of concealed explosives, chemical agents and other controlled substances such as drugs or narcotics by detecting their vapor or particulate emissions, said system comprising:

(a) a portable sampling means for gathering a sample volume of air from a specific area on a person or object to collect any vapor or particulate emissions therefrom;

(b) a sample collection means to collect vapor or particulate emissions in said sample volume of air, said sample collection means including a particulate collection means for collecting and vaporizing particulate emissions collected by said portable sampling means;

(c) means for concentrating said vapor or vapor subsequently emitted by said particulate emissions, said means for concentrating having a first means for adsorption and a second means for desorption of said concentrated vapor;

(d) a detecting means including a first detector responsive to said vapor desorbed from said second means for desorption to generate a first signal and an alarm.

2. The portable explosive detection screening system of claim 1, wherein said sample collection means further includes a conduit for collecting said volume of air from said portable sampling means and transporting said volume of air to said particulate collection means, and connecting said particulate collection means to said means for concentrating.

3. The portable explosive detection screening system of claim 2, wherein said portable sampling means includes a hand held wand which is connected to said conduit and a suction fan for drawing said volume of air from said portable sampling means at predetermined times, said hand held wand being connected to said conduit by a flexible pipe.

4. The portable explosive detection screening system of claim 3, wherein said particulate collection means comprises:

a rotating plate, said rotating plate defining an axis of rotation and having at least two openings, said two openings being circumferentially spaced about said axis of rotation and supporting stainless steel mesh screens for collecting particulate emissions from said portable sampling means;

a collection chamber in line with said conduit means adjacent said rotating plate, said stainless steel mesh screens being exposed to and adsorbing vapors and particulate emissions collected by said portable sampling means; and

a desorption chamber adjacent said rotating plate, wherein said stainless steel mesh screens are heated to vaporize said collected emissions and desorb collected vapors.

5. The portable explosive detection screening system of claim 4, wherein said particulate collector further comprises an actuator means for rotating said rotating plate a predetermined distance at predetermined times to define a sampling period.

6. The portable explosive detection screening system of claim 5, wherein said desorption chamber comprises a first pair of electrodes which connect to said stainless steel mesh screens and apply a current to said screen to rapidly heat said screens and desorb the collected vapor and vaporize the collected particulate emissions.

7. The portable explosive detection screening system of claim 6, wherein said first detector further comprises a chemical analyzer means.

8. The portable explosive detection screening system of claim 7, which further includes a six-port valve, said six-port valve being connected between said desorption chamber and said chemical analyzer means.

9. The portable explosive detection screening system of claim 7 which further includes a three-way valve means connected between said desorption chamber and said chemical analyzer.

10. The portable explosive detection screening system of claim 7 wherein said first detector includes an ion mobility spectrometer.

11. The portable explosive detection screening system of claim 5 wherein said actuator means comprises a stepper motor.

12. The portable explosive detection screening system of claim 3 wherein said particulate collector means comprises:

a rotating plate, said rotating plate defining an axis of rotation and having three openings, said three openings being circumferentially spaced about said axis of rotation and supporting stainless steel mesh screens for collecting particulate emissions from said portable sampling device;

a collection chamber in line with said conduit means adjacent said rotating plate, said stainless steel mesh screens being positioned to receive vapors and particulate emissions collected by said portable sampling device;

a desorption chamber adjacent said rotating plate, wherein said stainless steel mesh screens are heated to desorb said collected vapors and particulate emissions; and

a flushing chamber adjacent said rotating plate, wherein said stainless steel mesh screens are again heated to desorb any remaining vapors or collected particulate emissions, with said remaining desorbed vapors or particulate emissions vented to the ambient environment.

13. The portable explosive detection screening system of claim 12 wherein said particulate collector and detector means further comprises a control means for generating a plurality of sampling periods and an actuator means for rotating said rotating place a predetermined distance during each sampling period.

14. The portable explosive detection screening system of claim 13 wherein said desorption chamber further includes a first pair of electrodes which connect to said stainless steel mesh screens and apply a current to said screens to rapidly heat said screen and desorb the collected vapors and vaporized the collected particulate emissions.

15. The portable explosive detection screening system of claim 12 wherein said flushing chamber further includes a second pair of electrodes which connect to said stainless steel mesh screens and supply a current to said screen to rapidly heat said screen and further desorb any remaining vapors or collected particulate emissions.

16. The portable explosive detection screening system of claim 3 wherein said means for concentrating further includes a primary preconcentrator.

17. The portable explosive detection screening system of claim 16 wherein said first means for adsorption and said second means for desorption include a plurality of filter means mounted on a movable platform, which move from said adsorption chamber to said desorption chamber.

18. The portable explosive detection screening system of claim 17 wherein said plurality of filter means are movable between an adsorption position and a desorption position, each of said filter means being in line with said suction fan to adsorb vapor and/or particulate emissions contained in said volume of air in said adsorption position, and each of said filter means being in line with secondary preconcentrator when said adsorbed vapor and/or particulate emissions are desorbed.

19. The portable explosive detection screening system of claim 18 wherein said primary preconcentrator further comprises a series of three filters mounted on said movable platform.

20. The portable explosive detection screening system of claim 19 wherein said series of three filter means are movable between said adsorption position, said desorption position, and thermal cleaning position, each of said filter means being sequentially in line with said suction fan to adsorb vapor and/or particulate emissions contained in said volume of air in said adsorption position, each of said filter means being sequentially in line with a secondary preconcentrator means when said adsorbed vapor and/or particulate emissions are desorbed, and each of said filter means being sequentially in line with a thermal cleaning means when the other filters, are being adsorbed and desorbed.

21. The portable explosive detection screening system of claim 20 wherein said primary preconcentrator comprises a gas supply means for supplying a clean gas flow to said series of filter means when said respective filter means is in said desorption position, wherein said clean gas flow is used to desorb and sweep said concentrated vapor and/or vapor emanating from particulate matter into said secondary preconcentrator means when said filter means is in said desorption position, and said clean gas flow is used to thermally clean and sweep residue into the ambient environment when said respective filter is in said thermal cleaning position.

22. The portable explosive detection screening system of claim 21 wherein said clean gas in an inert gas.

23. The portable explosive detection screening system of claim 22 wherein said series of filter means comprise wire screens which hold a selected adsorbing material coated thereon.

24. The portable explosive detection screening system of claim 23 wherein said selected adsorbing material selectively absorbs explosive compound vapors or explosive compound particulates.

25. The portable explosive detection screening system of claim 23 wherein said selected adsorbing material selectively adsorbs narcotic compound vapors or particulates.

26. The portable explosive detection screening system of claim 23 wherein said primary preconcentrator further comprises a heat exchanger for supplying heat to each of said filter means when they are in said desorption and said thermal cleaning position to aid in desorbing the vapor and/or particulate emissions.

27. The portable explosive detection screening system of claim 1, wherein said detecting means includes a gas chromatograph.

28. The portable explosive detection screening system for the detection of concealed explosives, chemical agents and other controlled substances such as drugs or narcotics by detecting their vapor or particular emissions, said system comprising:

(a) a portable sampling means for gathering a sample volume of air from a specific area on a person or object to collect any vapor or particulate emissions therefrom, said sampling means connected to said system by means of a flexible conduit, with said sample volume of air drawn by a suction fan;

(b) a primary preconcentratory means to selectively absorb vapor or particulate emissions in said sample volume of air, said primary preconcentrator including first, second and third filtering means with each filter means sequentially movable between an adsorption position, a desorption position, and a thermal cleaning position, said second filter means being in said desorption position when said first filter means is in said adsorption position and when said third filter means is in said thermal cleaning position, said desorption position having means to heat said filter to desorb said vapor and to vaporize said collected particulate emissions;

(c) a detecting means having at least a first detector responsive to vapor desorbed from said secondary preconcentrator to generate a first signal and an alarm.

29. The portable explosive detection screening system of claim 28 wherein said first, second and third filter means are mounted on a rotatable platform and moved by a control system.

30. The portable explosive detection screening system of claim 29 wherein said control system comprises:

a hydraulic control unit and pump connected to said rotatable platform by a rigid shaft, said hydraulic control unit operable to move said platform from a locked position to an unlocked position; and

a preconcentrator control unit which is operable to rotate said platform when said platform is in the unlocked position.

31. The portable explosive detection system of claim 30 wherein said preconcentrator control unit is a stepper motor.

32. The portable explosive detection screening system of claim 28 wherein said system further includes secondary preconcentrator which includes a multi-port valve system.

33. The portable explosive detection screening system of claim 32 wherein said multi-port valve system is a six-port valve which includes an adsorption/desorption tube selectively and sequentially connected across two of said six-ports, said six-port valve being rotatable between an adsorb position and an desorb position.

34. The portable explosive detection system of claim 33 wherein said six-port valve is rotated by an electronic interface control unit.

35. The portable explosive detection system of claim 34 wherein said interface control unit includes a stepper motor.

36. The portable explosive detection screening system of claim 33 wherein said six-port valve is in said adsorb position when said vapor and vapor emanating from particulate matter in the primary preconcentrator is passed through said adsorption tube for further concentration.

37. The portable explosive detection screening system of claim 33 wherein said six-port valve is in said desorb position when said concentrated vapor is desorbed and swept into said detecting means.

38. The portable explosive detection screening system of claim 33 wherein said adsorption/desorption tube is electrically connected to a controlled current source which is used to heat the tube to a predetermined temperature as part of the desorption process.

39. The portable explosive detection screening system of claim 38 wherein said secondary preconcentrator means further comprises a gas supply means for sweeping said further concentrated vapor into said detection means.

40. The portable explosive detection screening system of claim 39 wherein said detecting means includes an ion mobility spectrometer (IMS) for analyzing said further concentrated vapor and generating said first signal if a target material is detected.

41. The portable explosive detection screening system of claim 39 wherein said detecting means includes a gas chromatograph/electron capture detector for analyzing said further concentrated vapor and generating said first signal if a target material is detected.

42. The portable explosive detection screening system of claim 39 wherein said detecting means includes a photo ionization detector.

43. The portable explosive detection screening system of claim 39 wherein said detecting means includes a nitrogen phosphorous detectors.

44. The portable explosive detection screening system of claim 41 wherein said detecting means comprises an ion mobility spectrometer and a gas chromatograph/electron capture detector for analyzing said further concentrated vapor and generating said first signal if a target material is detected.

45. The portable explosive detection screening system of claim 44 wherein said system further includes a control and data processing means which further comprises:

a digital computer with a stored digital program which is responsible for the control of the system; and

a process control module which is an interface between said digital computer and said interface control unit, said preconcentrator control unit and said control unit.

46. The portable explosive detection screening system of claim 45 wherein said stored digital program is operable to control a plurality of processes including a self diagnostic and self calibration processes, control of said sample collection, and processing of collected data from said detection means.

47. A method for the detection of concealed explosive chemical agents and other controlled substances such as drugs or narcotics by detecting their vapor or particulate emissions, said method comprising the steps of:

(a) gathering a sample volume of air from a specific area on a person or object, to collect any vapor or particulate emissions from said person or object;

(b) collecting vapor and the particulates in said sample volume of air with a sample collection means, said sample collection means including a particulate collector for collecting and vaporizing said particulates;

(c) concentrating said vapor or vapor subsequently emitted by said collected particulates by first adsorbing and secondly desorpting said concentrated vapor or vapors which emanated from said particulate; and

(d) detecting said vapor desorbed from said second means for desorption.

48. The method for the detection of concealed explosives according to claim 47 wherein said collecting step further comprises drawing said volume of air to said concentrating means by means of a suction fan.

49. The method for the detection of concealed explosives according to claim 48 wherein the desorbing of concentrated vapors includes the steps of

heating said adsorbed vapors to a predetermined desorbing temperature;

and

sweeping said vapors with an inert gas.

50. The method for the detection of concealed explosives according to claim 49 wherein said step of detecting further includes chemically analyzing said vapors.

51. The method for the detection of concealed explosives according to claim 50 which further includes a step of controlling the collection and processing of data with a digital computer which utilizes a stored program.

52. The method for the detection of concealed explosives according to claim 49 which further includes a concentrating step which thermally cleans residue from said adsorption and desorption with a thermal cleaning step.

53. The method for the detection of concealed explosives according to claim 52 wherein said thermal cleaning comprises the steps of:

heating said residue to a predetermined temperature to vaporize same; and

sweeping said heated and vaporized residue to the ambient environment.

54. The method for the detection of concealed explosives according to claim 48 wherein said step of detecting includes sweeping said vapors and inert gas into a detection means.