Gas analyzer sample cell

• US 4,177,381 A
• Filed: 04/13/1978
• Issued: 12/04/1979
• Est. Priority Date: 09/27/1974
• Status: Expired due to Term

• Current Assignee: AC Limited (Emirate of Dubai (United Arab Emirates))
• Original Assignee: Andros, Inc. (Advanced Energy Industries, Inc. (China))
• Inventors: Burough, Irvin G., McClatchie, Edward A., Watson, Dean A.
• Primary Examiner(s): Smith, Alfred E.
• Assistant Examiner(s): Grigsby, T. N.
• Application Number:
  US05/895,937
• Time in Patent Office: 600 Days
• Field of Search: 356/246, 356/410, 356/411, 356/440, 250/343, 250/576
• US Class Current: 250/343
• CPC Class Codes: G01N 21/03 Cuvette constructions
• CPC Class Codes: G01N 21/314 with comparison of measurements at specific and non-specific wavelengths dual wavelength spectrometry G01J3/427

Abstract

An improved gas analyzer for measuring the presence of one or more gaseous compounds in a gas sample. The gas analyzer has an infrared source stabilized against temperature variations by a radiation loading scheme in combination with a selected source environmental temperature sensitivity to provide a stable source temperature without a conventional temperature controller. A rotating interference filter assembly is disposed in the optical path. This assembly alternately totally blocks radiation, passes radiation in a wave length band which will not be absorbed by a random gas sample, and sequentially passes radiation in one or more additional bands which will be absorbed by one or more gases in the sample cell. The sample cell features a unique enclosed cell with infrared transparent windows which are substantially free of impingement of contaminants of the gas sample thereon. A unique detector provides protection against deterioration from moisture while allowing easy and inexpensive assembly. The system electronics eliminates sensitivities to background radiation, contamination of windows, etc., and provides a self test capability.

Claims

1. A sample cell for an infrared gas analyzer comprising:

an enclosure for a gas sample;

first and second windows in said enclosure, one of said windows being adjacent each end of said enclosure, said windows being substantially transparent to infrared radiation so as to define an infrared radiation path through said sample cell;

inlet means adjacent each end of the said enclosure for providing a gas sample to the interior of said cell adjacent each end thereof, outlet means between said inlet means for removing a gas sample from said cell,

flow control means adjacent each end of said enclosure for receiving a gas sample from the respective inlet means and establishing flows having substantial components toward said outlet means and having a substantial component in the radial inward direction, thereby creating a form of stagnation plug inwardly adjacent each of said windows,

and a central member extending transversely in the interior of said sample cell substantially midway between the ends thereof and having an opening accommodating the radiation path, said central member being spaced from said outlet means to allow removal of gas from both sides of said central member.

2. The cell of claim 1 wherein the surface defining said inlet means adjacent each window has a sharp discontinuity to induce fluid flow separation at said discontinuity.