US4033699A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Vapor concentration monitor
Assignee: Atomic Energy of Canada Ltd AECL
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Filing: 1975-05-30
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Granted: 1977-07-05
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Expires: 1995-05-30
Abstract
Abstract An apparatus for monitoring the concentration of a vapor, such as heavy water, having at least one narrow bandwidth in its absorption spectrum, in a sample gas such as air. The air is drawn into a chamber in which the vapor content is measured by means of its radiation absorption spectrum. High sensitivity is obtained by modulating the wavelength at a relatively high frequency without changing its optical path, while high stability against zero drift is obtained by the low frequency interchange of the sample gas to be monitored and of a reference sample. The variable HDO background due to natural humidity is automatically corrected.
Inventors
- 👤 John G. Bayly
- 👤 Ronald J. Booth
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 06:31
CPC Classifications
G; G01; G01J; G01J3/00; G01J3/28; G01J3/42; G01J3/433; G21; G21C; G21C17/00; G21C17/02; G21C17/028; Y; Y02; Y02E; Y02E30/00; Y02E30/30
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
152 words
An apparatus for monitoring air from a predetermined area to determine the concentration of HDO in excess of normally occurring HDO concentration in air, comprising: chamber means having an air inlet means and an air outlet means; means for alternately driving the predetermined area air and the normal air into the chamber means through the air inlet means, at a first frequency; means for producing a beam of radiation along a predetermined path in the chamber means, the radiation beam bandwidth alternating between a bandwidth coincident with at least one narrow absorption bandwidth of HDO and a bandwidth non-coincident with an absorption bandwidth of HDO at a second frequency greater than the first frequency; detector means located on said predetermined path for detecting the intensity of said beam; and indicating means connected to said detector means for providing an indication of the excess concentration of HDO as a function of radiation absorption.
Claim 2
Independent Claim
152 words
An apparatus for monitoring air from a predetermined area to determine the concentration of HDO in excess of normally occurring HDO concentration in air, comprising: chamber means having an air inlet means and an air outlet means; means for alternately driving the predetermined area air and the normal air into the chamber means through the air inlet means, at a first frequency; means for producing a beam of radiation along a predetermined path in the chamber means, the radiation beam bandwidth alternating between a bandwidth coincident with at least one narrow absorption bandwidth of HDO and a bandwidth non-coincident with an absorption bandwidth of HDO at a second frequency greater than the first frequency; detector means located on said predetermined path for detecting the intensity of said beam; and indicating means connected to said detector means for providing an indication of the excess concentration of HDO as a function of radiation absorption.
Claim 3
Dependent Claim
59 words
An apparatus as claimed in claim 1 which further includes: humidity sensing means mounted within said chamber to measure the amount of water vapour in the predetermined area air and the normal air; and means for connecting the humidity sensing means to the indicating means to adjust the indication of the excess concentration of HDO for naturally occurring HDO.
Claim 4
Dependent Claim
42 words
An apparatus as claimed in claim 2 wherein said chamber means includes an elongated chamber with the outlet means located at one end and the inlet means located at the other end, the inlet means including first and second adjacent inlet pipes.
Claim 5
Dependent Claim
63 words
An apparatus as claimed in claim 3 wherein said driving means includes: a first blower for driving air from the predetermined area into the elongated chamber through the first inlet pipe and a second blower for driving normal air into the elongated chamber through the second inlet pipe; and modulation means for alternately activating the first and second blowers at said first frequency.
Claim 6
Dependent Claim
75 words
An apparatus as claimed in claim 4 wherein said beam producing means comprises: source means to provide a beam having a predetermined spectral range; a narrowband filter means mounted on said beam path; and oscillating means connected to said narrowband filter means for oscillating said narrowband filter means about its diameter at said second frequency to change the angle of incidence of said beam on said narrowband filter thereby continuously shifting the filter pass band.
Claim 7
Dependent Claim
47 words
An apparatus as claimed in claim 5 wherein said beam producing means further includes; broadband filter means rotatably mounted on said beam path to provide a uniform beam intensity over the predetermined spectral range by adjusting the angle of incidence of the beam on said broadband filter.
Claim 8
Dependent Claim
38 words
An apparatus as claimed in claim 6 which further includes a number of mirrors mounted at the ends of the elongated chamber such that the predetermined beam path consists of a number of passes through the elongated chamber.
Claim 9
Dependent Claim
25 words
An apparatus as claimed in claim 7 wherein the first frequency is less than 1 Hz and the second frequency is greater than 85 Hz.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-07-04 | 1981-01-03 | 1981-07-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-07-04 | 1985-01-03 | 1985-07-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-07-04 | 1989-01-03 | 1989-07-05 | $7700.00 | Window Closed / Lapsed |