METHOD FOR DETECTING A FIRE CONDITION IN A MONITORED REGION

• US 20080230701A1
• Filed: 03/23/2008
• Published: 09/25/2008
• Est. Priority Date: 03/22/2007
• Status: Active Grant

• Current Assignee: Spectronix Ltd. (Emerson Electric Company)
• Original Assignee: Spectronix Ltd. (Emerson Electric Company)
• Inventors: Cohen, David, Serero, Shaul, Spector, Oded
• Granted Patent: US 7,638,770 B2
• Time in Patent Office: Days
• US Class Current: 250/339.15
• CPC Class Codes: G01N 21/3504 for analysing gases, e.g. multi-gas analysis
• CPC Class Codes: G08B 17/12 Actuation by presence of radiation or particles, e.g. of infrared radiation or of ions

Abstract

A method of detecting a fire condition in a monitored region including the operations of: concurrently monitoring the region using: a plurality of fire combustion product emission band sensors, each band sensor sensitive to radiation within a respective waveband which includes at least part of a respective fire combustion product emission band of a plurality of fire combustion products, the plurality of fire combustion products equal to n; a first reference band sensor sensitive to radiation within a first reference waveband which includes at least some wavelengths shorter than the n fire combustion product emission bands; and a second reference band sensor sensitive to radiation within a second reference waveband which includes at least some wavelengths longer than the n fire combustion product emission bands; and using the band sensors to obtain n+2 measurement values of radiation intensity emitted from the monitored region in determining the presence or absence of the fire condition.

Claims

1. A method of detecting a fire condition in a monitored region including the operations of:

(a) concurrently monitoring the region using;

(i) a plurality of fire combustion product emission band sensors, each band sensor sensitive to radiation within a respective waveband which includes at least part of a respective fire combustion product emission band of a plurality of fire combustion products, the plurality of fire combustion products equal to n;

(ii) a first reference band sensor sensitive to radiation within a first reference waveband which includes at least some wavelengths shorter than the n fire combustion product emission bands; and

(iii) a second reference band sensor sensitive to radiation within a second reference waveband which includes at least some wavelengths longer than the n fire combustion product emission bands; and

(b) using the band sensors to obtain n+2 measurement values of radiation intensity emitted from the monitored region in determining the presence or absence of the fire condition.

2. The method according to claim 1, wherein concurrently monitoring the region is performed using a single detector having the plurality of fire combustion product emission band sensors.

3. The method according to claim 1, wherein the n+2 measurement values include:

n measurement values obtained from the emission band sensors;

one measurement value obtained from the first reference band sensor; and

one measurement value obtained from the second reference band sensor and from which detection parameters are calculated, which are evaluated against at least one threshold in determining the presence or absence of the fire condition.

4. The method according to claim 3, wherein the detection parameters include two respective reference ratios calculated for each of the n measurement values:

a first reference ratio between respective n measurement values and the measurement value from the first reference band sensor; and

a second reference ratio between respective n measurement values and the measurement value from the second reference band sensor.

5. The method according to claim 4, wherein the detection parameters further include ratios calculated for each of the n measurement values, between a respective measurement value and other measurement values.

6. The method according to claim 5, wherein the detection parameters further include a first-to-second reference ratio calculated between respective measurement values from the first and second reference band sensors.

7. The method according to claim 3, wherein the detection parameters include two respective correlation values calculated for each of the n measurement values, a first reference correlation between respective n measurement values and the measurement value from the first reference band sensor, and a second reference correlation between respective n measurement values and the measurement value from the second reference band sensor.

8. The method according to claim 3, wherein individual fire combustion products are identified.

9. The method according to claim 3, wherein the at least one threshold includes a threshold value associated with respective measurement values and with respective correlation values.

10. The method according to claim 9, wherein the at least one threshold value is determined by at least one chosen from a list including:

empirical means and non-empirical means.

11. The method according to claim 10, wherein n=2 and the plurality of fire combustion products is chosen from a list including:

CO₂ and H₂O, and CO₂ and OH, and SO₂ and H₂O, and SO₂ and OH, and NO₂ and H₂O, and NO₂ and OH.

12. The method according to claim 10, wherein n=3 and the plurality of fire combustion products is:

CO₂ and H₂O and SO₂, or NO₂ and H₂O and SO₂.

13. The method according to claim 1, wherein respective band sensors are sensitive to infrared radiation.

14. The method according to claim 1, wherein respective band sensors are sensitive to ultraviolet radiation.

15. The method according to claim 1, where n=2 and:

(i) the plurality of fire combustion product emission band sensors includes a first band sensor [IR₁], having a sensitivity to a waveband which includes part of the 4.2 to 4.7 μ

m CO₂ emission band, and a second band sensor [IR₂], having a sensitivity to a waveband which includes at least part of the 2.4 to 3.1 μ

m H₂O emission band;

(ii) the first reference sensor [IR₃], having a sensitivity to waveband, which includes at least some wavelengths shorter than the wavebands of sensors [IR₁] and [IR₂]; and

(iii) the second reference sensor [IR₄] , having a sensitivity to waveband, which includes at least some wavelengths longer than the wavebands of sensors [IR1] and [IR2].

16. The method according to claim 15, wherein individual fire combustion products are identified.

17. A method of detecting a fire condition in a monitored region including the operations of:

(a) concurrently monitoring the region using;

(i) a plurality of fire combustion product emission band sensors, each band sensor sensitive to radiation within a respective waveband which includes at least part of a respective fire combustion product emission band of a plurality of fire combustion products, the plurality of fire combustion products equal to n;

(ii) a first reference band sensor sensitive to radiation within a first reference waveband which includes only wavelengths shorter than the n fire combustion product emission bands; and

(iii) a second reference band sensor sensitive to radiation within a second reference waveband which includes only wavelengths longer than the n fire combustion product emission bands; and

(b) using the band sensors to obtain n+2 measurement values of radiation intensity emitted from the monitored region in determining the presence or absence of the fire condition.

18. The method according to claim 17, wherein concurrently monitoring the region is performed using a single detector having the plurality of fire combustion product emission band sensors.

19. The method according to claim 17, wherein the n+2 measurement values include:

n measurement values obtained from the emission band sensors;

one measurement value obtained from the first reference band sensor; and

one measurement value obtained from the second reference band sensor and from which detection parameters are calculated, which are evaluated against at least one threshold in determining the presence or absence of the fire condition.