US3583844A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Atomic absorption spectroanalytical instrument control system
Assignee: THERMO JARRELL ASH Corp WALTHAM MA A CORP OF
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Filing: 1969-06-09
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Granted: 1971-06-08
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Expires: 1989-06-09
Abstract
Abstract A sensor responsive to hydroxyl ions is provided to monitor the flame at the burner in an atomic absorption spectroanalysis system. The sensor in the disclosed embodiment includes an S4 photodiode and a filter to provide a sensitivity over the wavelength band of 3000-3900 A. The output of the photodiode is applied via an FET amplifier stage and an emitter follower stage to burner control circuitry. The burner control circuitry initiates flame via a pilot line, and if hydroxyl ions are not sensed within a predetermined time, the system is automatically shut down. After flame is established, an interlock permits switching from air to nitrous oxide and on failure to sense hydroxyl ions, the nitrous oxide, the fuel and then the air are turned off in sequence in response to the output of the sensor.
Inventors
- 👤 Stanley B Smith Jr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 16:15
CPC Classifications
F; F23; F23N; F23N5/00; F23N5/02; F23N5/08; F23N5/082; G; G01; G01N; G01N21/00; G01N21/62; G01N21/71; G01N21/72; F23N2227/00; F23N2227/36
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
22 words
The apparatus as claimed in claim 1 wherein said sensor is a photosensor responsive to emission from hydroxyl ions in the flame.
Claim 2
Dependent Claim
25 words
The apparatus as claimed in claim 2 wherein said photosensor has a band width of response, the upper limit of which is below 4500 A.
Claim 3
Dependent Claim
22 words
The apparatus as claimed in claim 3 wherein said photosensor has a bandwidth of response that includes the wavelength of 3000-3900 A.
Claim 4
Dependent Claim
81 words
An atomic absorption spectroanalysis system comprising a burner for producing a flame to energize a sample to be analyzed, a chamber for supplying a fuel-oxidant-sample mixture to said burner, a sensor responsive to hydroxyl ions for monitoring the presence of flame at said burner, a first control for controlling the supply of fuel to said chamber, a second control for controlling the supply of oxidant to said chamber and circuitry responsive to said sensor for controlling said first and second controls.
Claim 5
Dependent Claim
71 words
The apparatus as claimed in claim 5 wherein said circuitry further includes an igniter for igniting a flame, a flame initiating control, circuitry responsive to said flame initiating control for operating said first and second controls and said igniter in sequence and circuitry responsive to said sensor for terminating flow of oxidant and fuel to said chamber unless said sensor produces an output signal indicative of flame within a predetermined interval.
Claim 6
Dependent Claim
49 words
The apparatus as claimed in claim 6 wherein said sensor responsive circuitry operates said first control to terminate flow of fuel to said chamber prior to operation of said second control to terminate flow of oxidant to said chamber in the absence of said output signal from said sensor.
Claim 7
Dependent Claim
66 words
The apparatus as claimed in claim 5 and further including means for supplying first and second oxidants to said chamBer, each said oxidant employing a different burner unit, said second control controlling the supply of one of said oxidants and a third control controlling the supply of said second oxidant and an interlock responsive to a burner unit for controlling the operation of said third control.
Claim 8
Dependent Claim
68 words
The apparatus as claimed in claim 8 and further including pressure responsive control for sensing the supply pressure of said second oxidant and circuitry responsive to a low supply pressure of said second oxidant for operating said third control to terminate the flow of said second oxidant to said chamber and for automatically operating said second control to initiate the flow of said first oxidant to said chamber.
Claim 9
Dependent Claim
33 words
The apparatus as claimed in claim 9 wherein said circuitry includes a first bistate device for controlling burner operation and a second bistate device for controlling the supply of oxidant to said chamber.
Claim 10
Dependent Claim
22 words
The apparatus as claimed in claim 10 wherein said sensor is a photosensor responsive to emission from hydroxyl ions in the flame.
Claim 11
Dependent Claim
29 words
The apparatus as claimed in claim 11 wherein said photosensor includes a photocell and a filter arranged to have a response bandwidth which includes the wavelengths of 3000-3900 A.
Claim 12
Dependent Claim
53 words
The apparatus as claimed in claim 11 wherein said photosensor is a photodiode and has an output terminal connected to an amplifier circuit that includes a field effect transistor for generating an output signal for control of said first, second and third controls as a function of the flame condition at said burner.
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) | 1974-06-07 | 1974-12-07 | 1975-06-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-06-07 | 1978-12-07 | 1979-06-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-06-07 | 1982-12-07 | 1983-06-08 | $7700.00 | Window Closed / Lapsed |