Sample cell assembly having a heat conductive chamber surrounded by an electrothermal heating layer

• US 3,869,215 A
• Filed: 02/22/1974
• Issued: 03/04/1975
• Est. Priority Date: 02/22/1974
• Status: Expired due to Term

• Current Assignee: Il Holding SpA (Werfen SA)
• Original Assignee: Gaillard R. Nolan
• Inventors: Nolan, Gaillard R.
• Primary Examiner(s): McGraw, Vincent P.
• Application Number:
  US05/445,313
• Time in Patent Office: 375 Days
• Field of Search: 356/246 250/576,429
• US Class Current: 356/246
• CPC Class Codes: B01L 7/00 Heating or cooling apparatus autoclaves B01J3/04; Heat insulating devices
• CPC Class Codes: G01N 21/0332 with temperature control control of temperature G05D23/00; cryostats F17C3/08

Abstract

A sample cell assembly for use in a photometric analysis system has a heat conductive chamber structure enveloped by an electrothermal heating layer. The temperature of a sample inside the chamber is sensed by a temperature sensitive device mounted on the outside of the chamber structure to control the energization of the heating layer. A circulator with the chamber drives the sample in closed circulation paths within the chamber and uniformly distributes the heat transferred thereto from the heating layer through the chamber wall.

Claims

1. Apparatus for containing and heating a liquid sample to a desired temperature for photometric analysis, comprising:

a cuvette having sample support walls at least the greater part of which are formed from a heat conductive material, an electrothermal conductor distributed around the heat conductive part of said sample support walls, said cuvette and conductor enabling the transmission of a radiation beam for photometric analysis through a sample contained within said cuvette, circulation means for moving a sample in closed circulatory movement between the interior wall surfaces and the inner portion of said cuvette, thereby distributing heat transmitted through the sample support walls from said electrothermal conductor throughout the sample, a temperature sensor mounted on the exterior surface of a sample support wall at a location sufficiently removed from said electrothermal conductor that the temperature of the support wall at the sensor is determined substantially by the temperature of a sample within the cuvette, means to apply an electrical energizing input to said electrothermal conductor, and means responsive to changes in the temperature sensed by said sensing means for dynamically controlling the said electrical input, thereby enabling the energization of said electrothermal conductor to be varied in positive proportion to the differential between the sample temperature and the devised analysis temperature.

2. Apparatus according to claim 1, including a pair or windows formed in the cuvette sample support walls, said windows being transparent to a radiation beam for photometric analysis of a sample contained in the cuvette, said electrothermal conductor being distributed across substantially the entire area of said sample support walls except for said windows.

3. Apparatus according to claim 1, wherein said circulation means comprises an impeller carried within said cuvette, and means for driving said impeller in a rotary motion.

4. Apparatus according to claim 3, wherein said driving means comprises a rotary motor mounted above said cuvette, and a drive shaft extending from said motor into said cuvette, said impeller being mounted on said shaft for rotation by said motor.

5. Apparatus according to claim 1, and further including a support structure to carry said cuvette, said structure including and inward directed annular ledge, said cuvette including an annular lip adapted to seat on said ledge with the cuvette suspended therefrom, and a cuvette cover adapted to overlie said lip, said cover including a plurality of openings to accommodate the introduction into said cuvette of sample dispensing apparatus and a drive shaft for said circulation means.

6. A sample cell assembly for use in a photometric analysis system, comprising:

a cuvette having sample support walls formed from a heat conductive material, and windows mounted in the sample support walls enabling the transmission through the cuvette of a radiation analysis beam, a heating layer surrounding said cuvette in intimate heat transfer contact with the sample support walls, said heating layer comprising an electrothermal conductor distributed across a layer of heat conductive, electrically insulative material, and including openings to expose said windows, circulation means within said cuvette for moving a sample in a closed circulatory movement between the interior wall surfaces and the inner portion of said cuvette, thereby distributing heat transmitted through said sample support walls from said heating layer throughout a sample, and a temperature sensor mounted on the exterior surface of a sample support wall for sensing the sample temperature by heat conduction through the support wall, said sensor adapted to produce a control signal determined by the sensed temperature.

7. A sample cell assembly according to claim 6, the sample support walls of said cuvEtte comprising a thin metal sheet facilitating a rapid heat transfer between said heating layer and a sample contained in said cuvette.

8. A sample cell assembly according to claim 7, said sample support walls being formed from tantalum.

9. A sample cell assembly according to claim 6, wherein the electrothermal conductor of said heating layer comprises a printed circuit filament matrix deposited in said heat conductive, electrically insulative material.

10. A sample cell assembly according to claim 6, wherein said circulation means comprises a rotary impeller centrally disposed in said cuvette immediately above the level of said windows.

11. A sample cell assembly according to claim 6, said temperature sensing means being mounted to a sample support wall on a portion of the heat conductive, electrically insulative material of said heating layer, said electrothermal conductor being disposed on said material sufficiently removed from said sensor that the temperature sensed by said sensor is determined substantially by the sample temperature as transmitted to the sensor through said support wall and heat conductive, electrically insulative material portion.

12. A precious fluid analysis cell assembly comprising:

a sample chamber formed of heat conductive material, a pair of windows in side walls of said sample chamber enabling transmission of a radiation beam through said chamber, a heating layer surrounding said chamber in intimate heat transfer contact with the outer surface of said chamber, said heating layer comprising an electrothermal conductor distributed over the majority of the side wall surfaces of said chamber, a temperature sensor mounted on the outer surface of said chamber, a controller responsive to said sensor for energizing said conductor as a function of temperature sensed by said sensor, an impeller within said chamber for producing circulatory flow of sample with said chamber, impeller drive coupled to said impeller, an inlet port in the upper wall of said chamber for introducing a sample to be analyzed, and an outlet port in the bottom wall of said chamber for discharging a sample from said chamber after analysis.

13. An analysis cell assembly according to claim 12 and further including a radiation source and a radiation sensor, said source and sensor being disposed on opposite sides of said chamber for transmitting a radiation beam through said windows for photometric analysis of a sample in said chamber.

14. An analysis cell assembly according to claim 13 wherein the inner surfaces of said windows are flush with inner surfaces of said chamber and the peripheries of said windows are fused to said chamber side walls, and the bottom wall of said chamber slopes downwardly toward said outlet port.

15. An analysis cell assembly according to claim 12 wherein said electrothermal conductor of said heating layer comprises a printed circuit filament matrix.

16. An analysis cell assembly according to claim 15 wherein said electrothermal filament matrix is distributed across substantially the entire surface of the bottom and side walls of said sample chamber except for said windows and saidoutlet port.

17. An analysis cell assembly according to claim 16 and further including support structure including an inward directed annular ledge, said chamber including an annular lip adapted to seat on said ledge with said chamber suspended therefrom, and a chamber cover adapted to overlie said lip, said cover having a conical outer surface and including an opening to accommodate a drive shaft for said impeller and said inlet port.

18. An analysis cell assembly according to claim 17 and further including an overload temperature sensor mounted on the outer surface of said chamber for de-energizating said conductor in response to sensing of excessive chamber temperature.

19. An analysis cell assembly according to claim 18 wherein said impeller has radially, vertically disposed planar extending blades and is centralLy disposed in said chamber immediately above the level of said windows.

20. An analysis cell assembly according to claim 19 wherein said sample chamber is formed of a thin metal sheet facilitating a rapid heat transfer between said heating layer and a sample contained in said chamber.

21. An analysis cell assembly according to claim 20 wherein said sample chamber is formed from tantalum and has a capacity of about one cubic centimeter.

22. An analysis cell assembly according to claim 21 and further including a radiation source and a radiation sensor, said source and sensor being disposed on opposite sides of said chamber for transmitting a radiation beam through said windows for photometric analysis of a sample in said chamber.