Device for detecting air in fluid conducting tubing

• US 5,206,522 A
• Filed: 10/15/1991
• Issued: 04/27/1993
• Est. Priority Date: 10/17/1990
• Status: Expired due to Fees

• Current Assignee: Danby Medical Limited
• Original Assignee: Danby Medical Limited
• Inventors: Brundle, Alan, Danby, Hal C.
• Primary Examiner(s): Nelms, David C.
• Assistant Examiner(s): SHAMI, KHALED
• Application Number:
  US07/775,449
• Time in Patent Office: 560 Days
• Field of Search: 250/573, 250/574, 250/576, 250/564, 356/339, 356/440, 356/441, 356/442, 128/DIG. 13, 604/122, 604/67, 604/253, 604/123, 340/627, 340/632, 340/634
• US Class Current: 250/574
• CPC Class Codes: A61M 5/365 Air detectors A61M5/1684 takes precedence; in extracorporeal blood circuits A61M1/3626
• CPC Class Codes: G01N 21/255 Details, e.g. use of specially adapted sources, lighting or optical systems

Abstract

A device for detecting air in large bore thin walled transparent tubing, including a body providing accommodation for the tubing; an LED in a passage body for transmitting light energy towards the tubing; a phototransistor mounted in an orthogonally extending passage for receiving light transmitted by LED and modified by changes in the constituency of fluid passing through tubing; and an optical spacer in the form of a slotted collar of material optically matched to the material of tubing occupying space between LED and the tubing and phototransistor.

Claims

1. A device for detecting the presence of air in translucent or transparent tubing, comprising:

a body having a tubing accommodating passage providing accommodation for said tubing;

a light energy transmitter for light transmitting light energy towards said tubing;

a light energy receiver for receiving light energy transmitted by said transmitter and modified by changes in the constituency of fluid passing through said tubing; and

an optical spacer having a circular cross-section and occupying space between said light energy transmitter and said tubing and said tubing and said light energy receiver in said tubing accommodating passage,

wherein said light energy transmitter and said light energy receiver are located in passages extending through said body and opening into said tubing accommodating passage.

2. A device as claimed in claim 1, wherein said light energy transmitter and said light energy receiver are operative in the infra-red spectrum.

3. A device as claimed in claim 1, wherein said transmitter is an LED and said receiver is a phototransistor.

4. A device as claimed in claim 1, comprising:

said body having a passage therethrough for accommodating said tubing; and

said optical spacer being in the form of a collar within said passage and surrounding said tubing, said light energy transmitter and said light energy receiver being housed in said body.

5. A device as claimed in claim 1, wherein said transmitter and locating receiver passages open into said tubing accommodating passage via respective apertures.

6. A device as claimed in claim 5, wherein said apertures are in fixed walls, integral with said body, which otherwise close said passages.

7. A device as claimed in claim 6, wherein said apertures are in plugs inserted in said passages otherwise to close the same.

8. A device as claimed in claim 6, wherein said apertures are of different sizes.

9. A device as claimed in claim 8, wherein said aperture through which said transmitter communicates is of smaller cross-sectional area than the aperture through which said receiver communicates.

10. A device as claimed in claim 9, wherein said apertures are of circular cross-section, with the diameter of the aperture through which said transmitter communicates at least approximately half the diameter of the aperture through which said receiver communicates.

11. A device as claimed in claim 1, wherein said transmitter and receiver are spaced around said tubing accommodating passage.

12. A device as claimed in claim 11, wherein said transmitter and receiver have principle optic axes which lie in the same transverse plane.

13. A device as claimed in claim 1, wherein said transmitter and receiver have principle optic axes arranged orthogonal one to the other.

14. A device as claimed in claim 1, wherein said collar has an outer diameter between twice and three times the outside diameter of said tubing.

15. A device as claimed in claim 14, wherein the outer diameter of said collar is 2.5 times the outer diameter of said tubing.

16. A device as claimed in claim 1, wherein said optical spacer has a radially extending slot in which said tubing is disposed in intimate contact with said collar.

17. A device as claimed in claim 1, wherein the optical spacer is made of an acrylic material.

18. A device as claimed in claim 16, wherein said tubing is disposed in said slot coincident with a longitudinal axis of said collar, and said transmitter and receiver have principle optic axes arranged orthogonal to one another in a common transverse plane and intersecting said tubing.

19. A device according to claim 18, wherein the principle optic axes of said transmitter and said receiver intersect the longitudinal axis of said tubing.

20. A device for detecting the presence of air in translucent or transparent tubing, comprising:

a body providing accommodation for said tubing;

a light energy transmitter for light transmitting light energy towards said tubing;

a light energy receiver for receiving light energy transmitted by said transmitter and modified by changes in the constituency of fluid passing through said tubing; and

an optical spacer occupying space between said light energy transmitter and said tubing and said tubing and said light energy receiver, comprising a cylindrical element having a dielectric constant greater than that of air, said element having a tubing passage extending along a longitudinal axis of the cylindrical element and in which said tubing is disposed in intimate contact with said cylindrical element.

21. A device according to claim 20, wherein said tubing passage comprises a radially extending slot.

22. A device according to claim 20, wherein said transmitter and receiver have principle optic axes arranged orthogonal to one another in a common transverse plane and intersecting said tubing.

23. A device according to claim 21, wherein said transmitter and receiver have principle optic axes arranged orthogonal to one another in a common transverse plane and intersecting said tubing.

24. A device according to claim 21, wherein the principle optic axes of said transmitter and said receiver intersect the longitudinal axis of said tubing.

25. A device according to claim 23, wherein the principle optic axes of said transmitter and said receiver intersect the longitudinal axis of said tubing.