US4017193A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for measuring the transmittance or opacity of a gaseous medium carrying particulate matter through a conduit
Assignee: Individual
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Filing: 1976-03-02
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Granted: 1977-04-12
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Expires: 1996-03-02
Abstract
Abstract The apparatus has spaced light sources and light sensors on opposite walls of a conduit positioned to provide a pair of equal shorter path lengths and a pair of equal longer path lengths for narrow collimated beams between the sources and sensors. Each sensor is exposed to beams from the sources alternately during measuring periods. Computing means computes the quotient of the products of the sensor outputs corresponding to light transmitted over the longer and shorter paths, and an output is produced from the quotient corresponding to the transmittance or opacity over a predetermined distance of smoke, etc. Test means are provided to monitor the operation continually. Beam splitters for the sources, and disks having transparent and mirror sectors for the sensors, are described. Mirror sectors of different reflectivity operate during measuring and test periods. Windows are employed at the sources and sensors and the apparatus largely compensates for dirt build-up on the windows, and variations in the sources and sensors. Specific features to promote accuracy are described.
Inventors
- 👤 Leo Loiterman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 16:46
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/47; G01N21/49; G01N21/53; G01N21/534
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
194 words
Apparatus for measuring the transmittance or opacity of a gaseous medium carrying particulate matter through a conduit which comprises a. spaced first and second light sources and spaced first and second light sensors positioned on opposite walls of said conduit with equal shorter path lengths between first source and first sensor and between second source and second sensor and equal longer path lengths between first source and second sensor and between second source and first sensor, b. means at each light source for producing and directing narrow collimated beams toward each light sensor, c. means at each light sensor for producing a narrow reception beam angle, d. means for exposing each sensor to collimated beams from said sources alternately during measuring periods and directing the collimated beams to the sensor at said reception beam angle thereof, e. and computing means for utilizing the outputs of said sensors to produce the quotient of the products of the outputs corresponding to light transmitted over said longer paths and over said shorter paths and producing from the quotient an output corresponding to the transmittance or opacity over a predetermined distance of said gaseous medium carrying particulate matter.
Claim 2
Dependent Claim
194 words
Apparatus for measuring the transmittance or opacity of a gaseous medium carrying particulate matter through a conduit which comprises a. spaced first and second light sources and spaced first and second light sensors positioned on opposite walls of said conduit with equal shorter path lengths between first source and first sensor and between second source and second sensor and equal longer path lengths between first source and second sensor and between second source and first sensor, b. means at each light source for producing and directing narrow collimated beams toward each light sensor, c. means at each light sensor for producing a narrow reception beam angle, d. means for exposing each sensor to collimated beams from said sources alternately during measuring periods and directing the collimated beams to the sensor at said reception beam angle thereof, e. and computing means for utilizing the outputs of said sensors to produce the quotient of the products of the outputs corresponding to light transmitted over said longer paths and over said shorter paths and producing from the quotient an output corresponding to the transmittance or opacity over a predetermined distance of said gaseous medium carrying particulate matter.
Claim 3
Dependent Claim
70 words
Apparatus according to claim 1 including test means adjacent each sensor for reducing the light transmitted to the sensor over one of said paths by a predetermined fraction during test periods alternating with said measuring periods, said computing means producing a said quotient from the sensor outputs produced during said test periods, and test means for producing test signal outputs from the quotients corresponding to the measuring and test periods.
Claim 4
Dependent Claim
52 words
Apparatus according to claim 1 including windows in said walls of the conduit adjacent said sources and sensors respectively, said means for producing and directing narrow collimated beams at the sources and for producing narrow reception beam angles at the sensors being positioned between the windows and the sources and sensors, respectively.
Claim 5
Dependent Claim
23 words
Apparatus according to claim 3 in which the means for producing and directing narrow collimated beams at the sources include beam splitting means.
Claim 6
Dependent Claim
42 words
Apparatus according to claim 4 in which the means for exposing each sensor to beams from said sources alternately includes a rotating disk having transparent and mirror sectors for directing beams to the sensor transmitted over said shorter and longer paths, respectively.
Claim 7
Dependent Claim
37 words
Apparatus according to claim 5 in which said disk has opaque spokes between the sectors thereof, and including clamping means for clamping the outputs of said sensors corresponding to said opaque spokes to a predetermined reference level.
Claim 8
Dependent Claim
72 words
Apparatus according to claim 5 in which said rotating disk includes a mirror sector of high reflectivity and a mirror sector of lower reflectivity, said sectors of high and lower reflectivity operating during respective measuring and test periods, said computing means producing a said quotient from the sensor outputs produced during said test periods, and test means for producing test signal outputs from the quotients corresponding to the measuring and test periods.
Claim 9
Dependent Claim
69 words
Apparatus according to claim 7 in which said test means includes means for producing test signal components from the quotients corresponding to the measuring and test periods, means for multiplying one of said components by a factor compensating for the difference in reflectivity of said high and lower reflectivity mirrors, and means for comparing the compensated component with the other of said components to yield a test signal output.
Claim 10
Dependent Claim
77 words
Apparatus according to claim 1 in which said sensors simultaneously receive light from one source transmitted over respectively shorter and longer path lengths and alternately receive light from the other source transmitted over respectively longer and shorter path lengths, and said computing means includes means for producing ratios of the sensor outputs corresponding to light transmitted thereto over said shorter and longer path lengths and vice versa, and means for producing from said ratios the said quotient.
Claim 11
Dependent Claim
38 words
Apparatus according to claim 1 including comparator means for comparing the output output of a said sensor with a predetermined reference to produce an alarm signal when the output of the sensor is less than said predetermined reference.
Claim 12
Dependent Claim
29 words
Apparatus according to claim 1 in which said sources and sensors are positioned positioned a plane perpendicular to the path of travel of said gaseous medium medium the conduit.
Claim 13
Dependent Claim
29 words
Apparatus according to claim 1 in which said sources and sensors are positioned in a plane parallel to the path of travel of said gaseous medium in the conduit.
Claim 14
Dependent Claim
21 words
Apparatus according to claim 3 in which the portions of said windows through which said collimated beams pass are spherically curved.
Claim 15
Dependent Claim
25 words
Apparatus according to claim 13 in which said windows are flared into said walls in the direction of the flow of said gaseous medium thereby.
Claim 16
Dependent Claim
71 words
Apparatus according to claim 1 in which said sources and sensors are positioned in a plane with the first and second sensors directly across said conduit from said first and second sources respectively, and the second and first sensors diagonally across the conduit from the first and second sources respectively, the diagonal light paths between sources and sensors making angles of approximately 45° with respect to the direct light paths therebetween.
Claim 17
Dependent Claim
104 words
Apparatus according to claim 15 including windows in the walls of said conduit adjacent said sources and sensors respectively, said means at each source for producing and directing narrow collimated beams toward each sensor including collimating and beam splitting means between each source and the respective window, and said means for producing a narrow reception beam angle at each sensor and exposing the sensor to beams from the sources alternately includes a rotating disk and collimating means between the respective window and sensor, said disk having transparent and mirror sectors for directing light from respective direct and diagonal paths alternately to the respective sensor.
Claim 18
Dependent Claim
72 words
Apparatus according to claim 16 in which said rotating disk includes a mirror sector of high reflectivity and a mirror sector of lower reflectivity, said sectors of high and lower reflectivity operating during respective measuring and test periods, said computing means producing a said quotient from the sensor outputs produced during said test periods, and test means for producing test signal outputs from the quotients corresponding to the measuring and test periods.
Claim 19
Dependent Claim
94 words
Apparatus according to claim 17 in which the portions of said windows through which said collimated beams pass are spherically curved, said collimating and beam splitting means at each source are designed and adapted for directing beams through the corresponding window to each sensor with their center lines approximately along radii of the window, and said rotating disk and collimating means at each sensor are designed and adapted for receiving beams which pass through the respective window with their center lines approximately along radii of the window and directing the beams to the sensor.
Claim 20
Dependent Claim
41 words
Apparatus according to claim 1 including means for actuating said light sources on and off during said measuring periods, and clamping means for clamping the outputs of said sensors to a predetermined reference level during off intervals of said light sources.
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) | 1980-04-11 | 1980-10-11 | 1981-04-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-04-11 | 1984-10-11 | 1985-04-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-04-11 | 1988-10-11 | 1989-04-12 | $7700.00 | Window Closed / Lapsed |