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US5049861A
Expired / Lapsed
US
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Method and system for detecting underground mine fires
Assignee: American Intell-Sensors Corp
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Filing: 1990-06-01
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Granted: 1991-09-17
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Expires: 2010-06-01
Abstract
Abstract A CO based, Diesel discriminating, fire detection system and method is disclosed which significantly reduces the threshold of CO needed to detect a fire in a mine that also contains CO from Diesel equipment without a corresponding increase in the number of false alarms. The system measures both the CO and NO levels at many points throughout the mine and calculates a CO/NO ratio for each of these locations. A long term average concentration (4 hours) and a short term average concentration (1 hour) for both CO and NO are continually updated to reflect the changing dynamics of the mine environment. Using the CO/NO ratio, the detection system can effectively differentiate between CO produced by a Diesel and CO produced from a fire and can activate an alarm when the CO level resulting from a fire exceeds a predetermined threshold level.
Inventors
- 👤 Richard Grace
- 👤 Alberto M. Guzman
- 👤 David A. Purta
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 20:04
CPC Classifications
G; G08; G08B; G08B17/00; G08B17/10; G08B17/117; G01; G01N; G01N33/00; G01N33/0004; G01N33/0009; G01N33/0027; G01N33/0031; F; F02; F02B; F02B3/00; F02B3/06
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
101 words
A fire detection system for detecting underground mine fires comprising a plurality of remotely located sensor pairs, one sensor in each pair capable of measuring the Co concentration and the other sensor capable of measuring the NO x concentration; a data processor; and a communications network for periodically transmitting the measured CO and NO x concentration levels at the sensors to the data processor; wherein a dynamic CO/NO x ratio is calculated by the data processor using a variable number of measurements, said variable number dependant upon a particular sensed condition and is sued to determine the presence of a fire.
Claim 2
Dependent Claim
101 words
A fire detection system for detecting underground mine fires comprising a plurality of remotely located sensor pairs, one sensor in each pair capable of measuring the Co concentration and the other sensor capable of measuring the NO x concentration; a data processor; and a communications network for periodically transmitting the measured CO and NO x concentration levels at the sensors to the data processor; wherein a dynamic CO/NO x ratio is calculated by the data processor using a variable number of measurements, said variable number dependant upon a particular sensed condition and is sued to determine the presence of a fire.
Claim 3
Dependent Claim
26 words
The entire system as described in claim 1 wherein the dynamic CO/NO x ratio is used by the data processor to calculate a residual CO concentration.
Claim 4
Dependent Claim
39 words
The system as described in claim 2 wherein the dynamic CO/NO x ratio is used by the data processor to calculate a Diesel contribution to the measured CO which in turn is used to calculate the residual CO concentration.
Claim 5
Dependent Claim
21 words
The system as described in claim 3 wherein an alarm is activated when the residual CO is above a predetermined level.
Claim 6
Dependent Claim
11 words
The system as described in claim 4 wherein NO x =NO.
Claim 7
Independent Claim
103 words
A method of detecting the presence of a mine fire comprising the steps of: (a) measuring NO and CO concentrations at a sensor pair; (b) updating a long term and a short term sum of the CO concentration and the NO concentration measured by the sensor; (c) calculating a CO/NO ratio for the long term concentration and a CO/NO ratio for the short term concentration; (d) selecting the smaller of the two CO/NO ratios calculated in step (c); (e) calculating a residual CO concentration from the smaller CO/NO ratio; and (f) activating an alarm if the residual CO concentration exceeds a predetermined level.
Claim 8
Independent Claim
103 words
A method of detecting the presence of a mine fire comprising the steps of: (a) measuring NO and CO concentrations at a sensor pair; (b) updating a long term and a short term sum of the CO concentration and the NO concentration measured by the sensor; (c) calculating a CO/NO ratio for the long term concentration and a CO/NO ratio for the short term concentration; (d) selecting the smaller of the two CO/NO ratios calculated in step (c); (e) calculating a residual CO concentration from the smaller CO/NO ratio; and (f) activating an alarm if the residual CO concentration exceeds a predetermined level.
Claim 9
Dependent Claim
43 words
The method as described in claim 6 wherein step (e) further comprises using the smaller CO/NO ratio to calculate a Diesel contribution to the measured CO and wherein the residual CO concentration is determined by subtracting the Diesel contribution from the measured CO.
Claim 10
Dependent Claim
29 words
The method as described in claim 7 further comprising calculating a confidence variable C i and multiplying the Diesel contribution by C i before determining the residual CO concentration.
Claim 11
Dependent Claim
23 words
The method as described in claim 8 wherein C i equals the number of valid measurements divided by the total number of measurements.
Claim 12
Dependent Claim
27 words
The method as described in claim 6 wherein the long term and short term average of the CO concentration and the NO concentration comprise a weighted average.
Claim 13
Dependent Claim
41 words
The method as described in claim 10, wherein the weighting factor W 1 is calculated using the equation W 1 =(1-Δt/τ 1 ) where Δt is a time interval from a previous measurement and τ 1 is an exponential time constant.
Claim 14
Dependent Claim
29 words
The method as described in claim 11 further comprising calculating a confidence variable C i and multiplying the Diesel contribution by C i before determining the residual CO concentration.
Claim 15
Dependent Claim
33 words
The method as described in claim 12 wherein C 1 is calculated using the equation C 1 =N 1 /τ i where N i is the summation of weighting factors W i .
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-09-16 | 1995-03-18 | 1995-09-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-09-16 | 1999-03-18 | 1999-09-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-09-16 | 2003-03-18 | 2003-09-17 | $7700.00 | Window Closed / Lapsed |