JP2992140B2 - Fire detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fire detector for judging a fire by mass analysis of sampled gas.

[0002]

2. Description of the Related Art Conventionally, in a device for detecting a gas generated at the time of a fire and judging a fire, a combustion gas such as CO ₂ gas or CO gas generated at the time of combustion is detected using a semiconductor gas sensor or the like. The fire is judged by doing.

[0003]

[SUMMARY OF THE INVENTION However, in such a conventional fire detection system, since the CO ₂ gas or CO gas generated in the combustion state after the firing is set to the detection target, CO ₂ gas or CO The gas reaches the threshold concentration at which the fire can be judged to be a fire when the flame spreads and the fire has sufficiently proceeded, and there has been a problem that the detection of the fire is delayed.

[0004] When the sensitivity of fire detection is increased for early detection, C due to artificial causes such as cigarettes may occur.
There was a problem that an increase in O ₂ gas and an increase in CO ₂ gas due to a fire could not be distinguished, and misinformation was likely to occur. Detection of CO ₂ gas and CO gas generated by combustion after ignition in this way makes it difficult to achieve both early detection of fires and prevention of false alarms. The quest to gain is continuing.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and is intended to analyze a gas generated before ignition so that the fire can be found at an early stage and a false alarm is minimized. It is an object to provide a detection device.

[0006]

Means for Solving the Problems The inventors of the present invention have repeatedly conducted a combustion experiment to find out a fire phenomenon.
In the process of analyzing the fire phenomena on a microscopic level, I noticed that the sample showed a slight weight loss at the very beginning of the fire before ignition. When the cause of this slight weight loss before ignition was further investigated, it was considered that some gas was released during the temperature rise stage before ignition, and gas analysis was performed by mass spectrum in the initial state of the fire. , Mass number 1 to 1 not found in normal state
The mass spectrum distribution was as wide as 40, and peaks appeared periodically at every mass number of about 14.

[0007] It is clear that such a mass spectrum distribution is not CO ₂ gas generated after ignition having a spectrum concentrated at a mass number of 44, and as a result, a flammable hydrocarbon having about 1 to 10 carbon atoms. It turned out to be gas. The generation of hydrocarbon gas during the process of increasing the temperature before ignition is a novel fact that was not recognized at all in the field of conventional fire monitoring, and the present invention is based on this point. It is configured as follows.

That is, the fire detection device of the present invention comprises a mass spectrometer for spectrum analysis of at least masses in the range of 43, 44 and 45, and a mass spectrometer of 4 mass spectrometers.
And a data processing section for judging a fire when a predetermined spectrum pattern is obtained in the range of 3, 44 and 45 and giving an alarm.

[0009]

According to the fire detecting device of the present invention having such a configuration, it can be confirmed that hydrocarbon gas is generated in the very early heating stage of a fire before ignition, and the hydrocarbon gas is reduced to a normal mass. When analyzed by an analyzer, it is a spectrum pattern distributed to mass numbers of 1 to 140.
It was confirmed that a unique spectrum pattern was generated in the regions 3, 44 and 45 at normal time, before ignition, and after ignition (during combustion).

Therefore, mass analysis of gas for fire judgment may be performed in a narrow range including mass numbers 43, 44 and 45, and the mass spectrometer for fire judgment is extremely small in scale. The method of mass spectrometry, which could only be used at the room level, can be taken into the sensor level to determine the fire early and accurately.

[0011]

FIG. 1 is a block diagram showing an embodiment of the present invention. In FIG. 1, reference numeral 2 denotes a mass spectrometer, which uses a pipe 5 installed in a guard area to inhale a gas to be analyzed by a sampling pump 1. The mass spectrometer 2 has an apparatus configuration that obtains mass spectrum analysis results only in a narrow range including the mass numbers 43, 44, and 45.

That is, the configuration of the mass spectrometer 2 has the same structure as that of a mass spectrometer that can generally obtain a mass spectrum of a wide range of mass numbers, but the mass numbers to be analyzed are 43, 44 and 44. Because only three of 45 is enough,
For example, the detection distance at the time of detection by an electrode by ionizing and flying gas molecules may be a short one corresponding to the mass numbers 43, 44 and 45. As a result, the structure can be extremely simplified as compared with a normal mass spectrometer. .

The mass numbers 43, 4 analyzed by the mass spectrometer 2
The mass spectrum data in the narrow range of 4 and 45 is supplied to the data processing unit 3. The data processing unit 3 includes a normal time spectrum pattern shown in FIG. 2 as a reference pattern, a spectrum pattern for determining hydrocarbon gas generated at an extremely early stage of a fire before ignition shown in FIG. By the ignition shown in FIG.
A pattern indicating the mass spectrum of the gas including the O ₂ gas is stored.

For this reason, the data processing section 3 performs matching between the mass spectrum actually obtained from the mass analysis section 2 and the reference spectrum patterns shown in FIGS. 2, 3 and 4, and at least the hydrocarbon gas shown in FIG. After the spectrum pattern is obtained, when the spectrum pattern including the CO ₂ gas shown in FIG. 4 is obtained, it is determined that a fire has occurred, and the alarm control unit 4 outputs an alarm and performs necessary fire control.

In the present invention, the mass numbers 43, 4
The method of performing a mass analysis in a narrow range of 4 and 45 to judge a fire is based on the fact that the present inventors conduct a combustion experiment of a fire accompanied by a mass analysis, whereby hydrocarbon gas is generated in a heating stage before ignition. It is based on discovering new facts. FIG. 5 is a characteristic diagram showing experimental data supporting that a hydrocarbon gas is generated in a heating stage before ignition.

FIG. 5 shows polyethylene (p-CH) as a sample.
₂ shows the experimental data when CH ₂ ) was heated.
Reference numeral 4 denotes a temperature curve in which the sample is heated with a constant temperature gradient from normal temperature to 500 ° C. Further, 5 is a weight curve, which is shown as a percentage. Further, reference numeral 6 denotes a thermal reaction curve from which the endothermic or exothermic reaction of the sample can be seen. In FIG. 5, an endothermic reaction 7, in which the thermal reaction curve 6 sharply drops when polyethylene as a sample is heated from room temperature and exceeds 120 ° C., appears. This endothermic reaction 7 is an endothermic reaction when polyethylene changes from a solid to a liquid.

Further, as the polyethylene is heated, it is ignited when the temperature reaches 400 ° C. shown at time tf,
A large weight loss is seen during the combustion from 0 to 500 ° C. as shown at points B to C of the weight curve 5. At the same time, an exothermic reaction 8 occurs where the thermal reaction curve 6 rises at a peak at time tf, indicating that the polyethylene is in a combustion state.

Although the combustion process in which such a sample is heated and ignited has been conventionally recognized, a more detailed examination of the experimental data shown in FIG. It has been found that a slight weight loss is observed between the point A at the heating temperature of 310 ° C. before the ignition time tf in the curve 5 and the point B at 400 ° C. immediately before the ignition in the curve 5. The weight loss from point A to point B is about 10%. Further, between the point A and the point B, no exothermic reaction appears on the thermal reaction curve 6, and it is apparent that polyethylene is not burning.

As described above, the analysis of the combustion experiment of polyethylene as a sample confirms that there is a two-stage weight reduction in which a first-stage weight loss occurs before ignition and a second-stage weight reduction occurs after ignition. Was done. Then, when the gas generated by the first-stage weight reduction before ignition was applied to a mass spectrometer, an analysis result of a mass spectrum shown in FIG. 6 could be obtained. The carrier gas is helium He 80% and O ₂ 20%.

According to the analysis result of the mass spectrum shown in FIG. 6, the spectrum is distributed over a wide range of mass numbers 1 to 140, and the spectrum peak appears periodically at a mass number of about 14. I understand. The peak of mass number 32 is that of O ₂ as a carrier gas. FIG. 7 shows the analysis result of the mass spectrum of the gas generated by the second-stage weight reduction after ignition, and a large peak was obtained only at the mass number of 44, which indicates that the CO generated during combustion was low. It is based on _two gases. However, FIG.
The analysis result of the mass spectrum of the generated gas before ignition of FIG. 7 is greatly different from that of the CO ₂ gas generated during combustion in FIG.

The gas having the analysis result of the mass spectrum shown in FIG. 6 is considered to be a combustible gas having about 1 to 10 carbon atoms, and was finally found to be a combustible hydrocarbon gas. Therefore, if the hydrocarbon gas generated in the heating process before the ignition is detected, the fire can be found at the very early stage of the fire, and the detection of the CO ₂ gas generated during the combustion is added to the detection of the hydrocarbon gas. This will allow more accurate fire judgment.

The mass spectrum analysis results shown in FIGS. 6 and 7 show that the hydrocarbon gas has a specific mass number of 43 and 45 centered on a mass number of 44 indicating CO ₂ gas. , 45, both hydrocarbon gas and CO ₂ gas can be detected. Therefore, in the present invention, as shown in FIG. 1, the gas sampled in the mass spectrometry unit 2 is subjected to mass spectrometry only in a narrow range of mass numbers 43, 44 and 45 to obtain the mass spectrum analysis result. A fire judgment is made by comparing with the reference patterns of FIGS. 2, 3 and 4.

In the reference pattern shown in FIG. 2 showing a normal state, a slight peak appears only at the mass number 44 corresponding to the CO ₂ gas present in the air. Further, in the time of generation of hydrocarbon gas before ignition of the fire early 3, in addition to CO ₂ gas present in the air of the mass number 44, hydrocarbon gas specific spectrum in the mass number 43, 44 and 45 Is generated.

Further, during the combustion shown in FIG. 4, since the generation of hydrocarbon gas is also observed at the same time, in addition to the small peaks of mass numbers 43 and 45, the CO
A large peak having a mass number of 44 due to the _two gases appears. In the above embodiment, the fire is judged from the temporal continuity of the spectrum patterns shown in FIGS. 2, 3 and 4, but the hydrocarbon gas shown in FIG. A pre-alarm may be issued when a pattern is obtained, or a fire may be determined when a spectrum pattern of hydrocarbon gas and CO ₂ gas shown in FIG. 4 is obtained.

[0025]

As described above, according to the present invention, a fire can be found at an extremely early stage of the fire by detecting the hydrocarbon gas generated before the ignition.
Also, by detecting the shift from the generation of hydrocarbon gas to the generation of CO ₂ gas, CO ₂
Prevention of erroneous detection due to gas can greatly improve the reliability of fire detection.

Further, the range of mass number for performing mass spectrometry is 4
Since they are narrowed to 3, 44 and 45, a smaller and less expensive analyzer can be used as compared with a normal mass analyzer, and mass analysis can be realized at the sensor level.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a mass spectrum in a steady monitoring state according to the present invention.

FIG. 3 is an explanatory diagram showing a mass spectrum by generated gas before ignition according to the present invention.

FIG. 4 is an explanatory diagram showing a mass spectrum by generated gas during combustion according to the present invention.

FIG. 5 is a characteristic diagram showing measurement data of a combustion experiment showing generation of hydrocarbon gas before ignition.

FIG. 6 is a characteristic diagram showing an analysis result of a mass spectrum of a product gas generated by weight loss before ignition.

FIG. 7 is a characteristic diagram showing an analysis result of a mass spectrum of a product gas generated in a combustion state after ignition.

[Description of Signs] 1: Sampling pump 2: Mass spectrometer 3: Data processing unit 4: Alarm control unit 5: Piping

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-55-110395 (JP, A) JP-A-61-180393 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) G08B 17/00-17/12 G01N 27/62

Claims (2)

(57) [Claims] 1. A mass spectrometer for spectrum analysis of at least masses in the range of mass numbers 43, 44 and 45, and when a predetermined spectrum pattern is obtained in the range of mass numbers 43, 44 and 45 by the mass spectrometer. A fire detection device, comprising: a data processing unit for judging a fire and issuing an alarm. 2. The fire detecting apparatus according to claim 1, wherein the data processing section determines that a fire has occurred when a spectrum pattern including CO ₂ gas is obtained following a spectrum pattern of hydrocarbon gas. Features a fire detection device.