NUCLEAR GAUGES AND RELATED METHODS OF ASSEMBLY

• US 20090250599A1
• Filed: 01/05/2009
• Published: 10/08/2009
• Est. Priority Date: 01/04/2008
• Status: Active Grant

• Current Assignee: Troxler Electronic Laboratories, Inc.
• Original Assignee: Troxler Electronic Laboratories, Inc.
• Inventors: Bartlett, James E., Pratt, James D. JR., Verna, Raffaello
• Granted Patent: US 8,410,423 B2
• Time in Patent Office: Days
• US Class Current: 250/239
• CPC Class Codes: G01D 18/008 with calibration coefficients stored in memory
• CPC Class Codes: G01N 23/06 and measuring the absorption
• CPC Class Codes: G01N 23/203 Measuring back scattering
• CPC Class Codes: G01T 7/005 calibration techniques stabilization of spectrometer G01T1/40
• CPC Class Codes: Y10T 29/49826 Assembling or joining

Abstract

Nuclear gauges, their components and method for assembly and adjustment of the same are provided. The nuclear gauges are used in measuring the density and/or moisture of construction-related materials. The nuclear gauge can include a gauge housing having a vertical cavity therethrough and at least one radiation detector located within the housing. The nuclear gauge can include a vertically moveable source rod and a radiation source operatively positioned within a distal end of the source rod. The nuclear gauge can also include a radiation shield assembly.

Claims

1. A nuclear gauge, comprising:

a gauge housing having a vertical cavity therethrough and a base, the base including a base track portion disposed therein;

at least one radiation detector located within the housing and adjacent to the base of the housing;

a vertically moveable source rod extending into the cavity of the gauge housing;

a radiation source operatively positioned within a distal end of the source rod, the source rod being vertically extendable and retractable to a plurality of predetermined source rod positions so as to change the spatial relationship between the radiation source and the at least one radiation detector; and

a radiation shield assembly comprising;

a sliding block positionable to move laterally between two positions, a first position blocking a distal end of the vertical cavity of the gauge housing such that radiation is shielded from exiting the cavity and a second position adjacent to the vertical cavity and allowing vertical movement through the radiation shield assembly;

a track configured to receive the sliding block and guide movement of the sliding block;

a spring engaging the sliding block and biasing the sliding block into the first position;

a safety shield, the safety shield including a shield track segment therein that comprises at least a portion of the track; and

at least one replaceable sliding guide positionable within the track adjacent the sliding block, the at least one replaceable sliding guide configured to reduce friction as the sliding block moves between the first position and the second position.

2. A nuclear gauge according to claim 1, wherein the base of the gauge housing includes a base track segment, the base track segment and the shield track segment being alignable to form the track.

3. A nuclear gauge according to claim 2, wherein the at least one replaceable sliding guide comprises two replaceable sliding guides with each replaceable sliding guide extending over at least a portion of the base track segment and the shield track segment on opposing walls of the track.

4. A nuclear gauge according to claim 1, wherein the track is configured to extend in a direction within the nuclear gauge so that as the sliding block moves from the first position to the second position, the sliding block moves away from the at least one radiation detector.

5. A nuclear gauge according to claim 4, wherein the track extends at an angle of between about 90°

and about 180°

as measured from a plane extending between the at least one radiation detector and the point of the track closest to the at least one radiation detector.

6. A nuclear gauge according to claim 5, wherein the track extends at an angle of between about 100°

and about 135°

.

7. A nuclear gauge according to claim 5, wherein the angle of the track biases the sliding block toward a closed position through gravity when placed in a carrying case and the carrying case is in the its standard upright position.

8. A nuclear gauge according to claim 1, wherein the safety shield comprises lead.

9. A nuclear gauge according to claim 8, wherein the safety shield includes inserts of a hard surface material.

10. A nuclear gauge according to claim 9, wherein the hard surface material comprises at least one of steel, hardened steel, high carbon steel, stainless steel, or tungsten.

11. A nuclear gauge according to claim 8, wherein the shield track segment includes two opposing side walls extending into the safety shield and an end wall disposed between the side walls within the safety shield with at least a portion of the end wall within the safety shield comprising a hard surface material.

12. A nuclear gauge according to claim 11, wherein the hard surface material comprises at least one of steel, hardened steel, high carbon steel, stainless steel, or tungsten.

13. A nuclear gauge according to claim 1, wherein the safety shield comprises a molded block.

14. A nuclear gauge according to claim 1, wherein the at least one replaceable sliding guide comprises a polymer having a low coefficient of friction.

15. A nuclear gauge according to claim 14, wherein the polymer comprises at least one of polytetrafluoroethylene, perfluoroalkoxy, and fluorinated ethylene propylene.

16. A nuclear gauge according to claim 1, wherein the at least one replaceable sliding guide comprises a body and an arm extending outward from the body.

17. A nuclear gauge according to claim 16, wherein the body comprises a rectangular shape with a base side and the arm comprises a rectangular shape extending from the base side, the body having a height that is larger than a height of the arm thereby forming a notch in the at least one replaceable sliding guide.

18. A nuclear gauge according to claim 17, wherein the safety shield defines an indentation configured to receive the arm of the at least one replaceable sliding guide so that an outer surface of the at least one replaceable sliding guide is about flush with an outer surface of shield track segment of the safety shield.

19. A nuclear gauge according to claim 18, wherein the base of the gauge housing includes a base track segment, the base track segment and the shield track segment being alignable to form the track, the base track segment having a width that is larger than the width of the shield track segment for receiving the body of the at least one replaceable sliding guide.

20. A nuclear gauge according to claim 16, further comprising a cover plate for securing the radiation shield assembly within the gauge housing, the scraper plate abutting the base side of the at least one replaceable sliding guide.

21. The nuclear gauge of claim 16, wherein the safety shield includes a passageway through which the source rod is configured to pass, the passageway intersecting the shield track segment and wherein the at least one replaceable sliding guide comprises a size and shape so that when installed in the safety shield, the arm of the at least one replaceable sliding guide does not extend into an intersection of the passageway and the shield track segment.

22. The nuclear gauge of claim 1, wherein the nuclear gauge is a density gauge, a bulk density gauge, a thin overlay gauge, a thin layer gauge, or a combination thereof.

23. The nuclear gauge of claim 1, wherein the at least one radiation detector comprises at least one set of Gieger-Mü

ller tubes.

24. A radiation shield assembly for use in a nuclear gauge, the radiation shield assembly comprising:

a sliding block positionable to move laterally between a closed position and an open position;

a track configured to receive the sliding block and guide movement of the sliding block;

a spring engaging the sliding block and biasing the sliding block into the first position;

a safety shield including a shield track segment therein that comprises at least a portion of the track; and

at least one replaceable sliding guide positionable within the track adjacent the sliding block, the at least one replaceable sliding guide configured to reduce friction as the sliding block moves between the closed position and the open position.

25. A radiation shield assembly according to claim 24, wherein the safety shield comprises lead.

26. A radiation shield assembly according to claim 25, wherein the safety shield includes inserts of a hard surface material.

27. A radiation shield assembly according to claim 26, wherein the hard surface material comprises at least one of steel, hardened steel, high carbon steel, stainless steel, or tungsten.

28. A radiation shield assembly according to claim 25, wherein the shield track segment includes two opposing side walls extending into the safety shield and an end wall disposed between the side walls within the safety shield with at least a portion of the end wall within the safety shield comprising a hard surface material.

29. A radiation shield assembly according to claim 28, wherein the hard surface material comprises at least one of steel, hardened steel, high carbon steel, stainless steel, or tungsten.

30. A radiation shield assembly according to claim 24, wherein the safety shield comprises a molded block.

31. A radiation shield assembly according to claim 24, wherein the at least one replaceable sliding guide comprises a polymer having a low coefficient of friction.

32. A radiation shield assembly according to claim 31, wherein the polymer comprises at least one of polytetrafluoroethylene, perfluoroalkoxy, and fluorinated ethylene propylene.

33. A radiation shield assembly according to claim 24, wherein the at least one replaceable sliding guide comprises a body and an arm extending outward from the body.

34. A radiation shield assembly according to claim 33, wherein the body comprises a rectangular shape with a base side and the arm comprises a rectangular shape extending from the base side, the body having a height that is larger than a height of the arm thereby forming a notch in the at least one replaceable sliding guide.

35. A radiation shield assembly according to claim 34, wherein the safety shield defines an indentation configured to receive the arm of the at least one replaceable sliding guide so that an outer surface of the at least one replaceable sliding guide is about flush with an outer surface of shield track segment of the safety shield.

36. A radiation shield assembly according to claim 35, wherein the base of the gauge housing includes a base track segment, the base track segment and the shield track segment being alignable to form the track, the base track segment having a width that is larger than the width of the shield track segment for receiving the body of the at least one replaceable sliding guide.

37. A radiation shield assembly according to claim 33, further comprising a scraper plate for securing the radiation shield assembly within the gauge housing, the scraper plate abutting the base side of the at least one replaceable sliding guide.

38. A replaceable sliding guide for use in a radiation shield assembly of a nuclear gauge, the replaceable sliding guide comprising a body having a rectangular shape with a base side and an arm having a rectangular shape extending for the base side, the body having a height that is larger than a height of the arm thereby forming a notch in the at least one replaceable sliding guide.

39. A replaceable sliding guide according to claim 38, wherein the at least one replaceable sliding guide comprises a polymer having a low coefficient of friction.

40. A replaceable sliding guide according to claim 39, wherein the polymer comprises at least one of polytetrafluoroethylene, perfluoroalkoxy, and fluorinated ethylene propylene.

41. A replaceable sliding guide according to claim 38, wherein the height of the body is between about three times to about six times the height of the arm.

42. A replaceable sliding guide according to claim 38, wherein the height of the body is about 1.500 inches and the height of the arm is about 0.250 inches.

43. A replaceable sliding guide according to claim 38, wherein the body has a length that is larger than a length of the arm.

44. A replaceable sliding guide according to claim 38, wherein the length of the body is about two times the length of the arm.

45. A replaceable sliding guide according to claim 44, wherein the length of the body is about 1.600 inches and the length of the arm is about 0.770 inches.

46. A replaceable sliding guide according to claim 38, wherein the body and the arm have substantially the same width.

47. A method of assembling a nuclear gauge, the method comprising:

providing a gauge housing having a vertical cavity therethrough and a base, the base including a shield housing and a base track portion disposed therein;

providing a source rod with a radiation source operatively positioned within a distal end of the source rod that can extend into the vertical cavity of the gauge housing;

providing a safety shield that includes a shield track segment therein and a passageway through which the source rod can pass;

inserting the safety shield into the shield housing in the base so that the base track segment of the gauge housing and the shield track segment of the safety shield align to form a track;

inserting a sliding block assembly that includes a sliding block into the track, the sliding block movable to provide access therethrough for the source rod;

inserting a replaceable sliding guide on each side of the sliding block between the sliding block and the track; and

securing a cover plate to the base of the gauge housing over the safety shield, the sliding block assembly, and the replaceable sliding guides, the cover plate providing an opening through which the source rod can pass.

48. The method according to claim 47, further comprising screwing one or more set screws into one or more screw holes in the shield housing of the base to secure the safety shield within the base of the gauge housing.

49. The method according to claim 47, wherein, upon insertion of the safety shield, the safety shield is about flush with a recess in a lower surface of the base of the gauge housing.

50. The method according to claim 49, wherein the cover plate is securable in the recess so as to be substantially flush with the lower surface of the base of the gauge housing.

51. The method according to claim 47, further comprising inserting one end of a spring into the sliding block and inserting another end of the spring into a spring guide to create the sliding block assembly.

52. The method according to claim 47, wherein the step of inserting the replaceable sliding guides includes inserting the replaceable sliding guides into cavities in the track such that an outer surface of the replaceable sliding guides are substantially flush with outer walls of the track that are not covered by the replaceable sliding guides.

53. The method according to claim 52, wherein each of the replaceable sliding guides comprises a body having a rectangular shape with a base side and an arm having a rectangular shape extending for the base side, the body having a height that is larger than a height of the arm thereby forming a notch in the at least one replaceable sliding guide.

54. The method according to claim 53, wherein the safety shield includes indentations for receiving the arms of the replaceable sliding guides.

55. The method according to claim 47, further comprising inserting a scraper ring into the opening of the cover plate.

56. A method of cleaning a nuclear gauge, the method comprising:

removing a cover plate from a base of a gauge housing;

removing a sliding block from a track defined by the base and a safety shield disposed with the base;

removing at least one sliding guide from the track defined by the base and the safety shield disposed with the base;

cleaning the sliding block;

inserting the cleaned sliding block back into the track defined by the base and the safety shield disposed with the base;

inserting at least one sliding guide into the track between a track wall and the sliding block; and

reinstalling the cover plate from the base of the gauge housing.

57. The method according to claim 56, further comprises cleaning the at least one sliding guide removed from the track.

58. The method according to claim 57, wherein the step of inserting at least one sliding guide comprises inserting the at least one sliding guide that has been cleaned back into the track.

59. The method according to claim 56, wherein the step of inserting at least one sliding guide comprises inserting a new at least one sliding guide into the track.

60. A method of cleaning a nuclear gauge, the method comprising:

removing a cover plate from a base of a gauge housing;

removing at least one sliding guide from between a sliding block and a track defined by the base and a safety shield disposed with the base;

inserting a new at least one sliding guide into the track between a track wall and the sliding block; and

reinstalling the cover plate from the base of the gauge housing.

61. A method of cleaning a nuclear gauge, the method comprising:

removing a cover plate from a base of a gauge housing;

removing at least one sliding guide from between a sliding block and a track defined by the base and a safety shield disposed with the base;

cleaning the at least one sliding guide;

inserting the at least one sliding guide back into the track between a track wall and the sliding block; and

reinstalling the cover plate from the base of the gauge housing.