EP0777896B1 - Device for detecting a fire in a closed-off enclosure - Google Patents

Device for detecting a fire in a closed-off enclosure Download PDF

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Publication number
EP0777896B1
EP0777896B1 EP95929148A EP95929148A EP0777896B1 EP 0777896 B1 EP0777896 B1 EP 0777896B1 EP 95929148 A EP95929148 A EP 95929148A EP 95929148 A EP95929148 A EP 95929148A EP 0777896 B1 EP0777896 B1 EP 0777896B1
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Prior art keywords
air
enclosure
smoke
alarm
openings
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EP95929148A
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German (de)
French (fr)
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EP0777896A1 (en
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Gérard Scheefer
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Individual
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    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B17/00—Fire alarms; Alarms responsive to explosion
    • G08B17/10—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means
    • G08B17/117—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means by using a detection device for specific gases, e.g. combustion products, produced by the fire

Definitions

  • the present invention relates to devices for fire detection and in particular a fire detection in a closed enclosure such as a workshop or unit control cabinet production in a factory.
  • Such a control cabinet is generally provided a fire detection box located at outside the cabinet and responsible for quickly detecting very early fire in the cabinet.
  • the box of the type of that described in FR-A-2,523,455 includes a means air intake in the cabinet, one or more two smoke detectors responsible for analyzing the intake air in the cabinet to detect traces of smoke and through which is forced to circulate the air sucked by the means of suction before being evacuated to the outside, and a control and alarm unit which triggers usually both an audible alarm and an alarm bright when a fire is detected.
  • the object of the invention is therefore to provide a fire detection device in a closed enclosure or waterproof, which has a high reliability of operation avoiding inadvertent tripping of the alarm while allowing the detection of beginnings of very small importance.
  • the object of the invention is therefore a device for fire detection in a closed enclosure such as a control cabinet, with a suction means of the air from the enclosure which expels the air into the enclosure after that it has been continuously analyzed by means of detection smoke.
  • the device includes a unit of control and alarm that triggers the fire alarm when the smoke detection means has detected traces smoke in the air of the enclosure.
  • the means of detecting smoke includes a first detector receiving the intake air from the first air intake ports located at first locations of the enclosure, and a second detector receiving the air sucked in from seconds air inlet ports located at second different speaker locations from the first locations.
  • the control and alarm unit includes alarm means to trigger the alarm when one of the detectors detected smoke in the exhaust air in the enclosure by means of suction and discharge after this air has given rise to smoke detection by the other of the detectors.
  • a box 10 containing the fire detection device in accordance with the invention is placed above an enclosure 12 such a control cabinet located in a workshop and containing the electrical and electronic circuits of workshop control (not shown).
  • Air from the enclosure is drawn in through the two tubes or pipes 14 and 16 thanks to a suction means such than a fan 18.
  • the two tubes 14 and 16 can be stopped at any height of enclosure 12. They are drilled with calibrated orifices a, b, c for the tube 14, or d, e, f for tube 16, responsible for extracting air from "volumes at risk", ie parts of the cabinet containing sensitive circuits or vital parts of all of the cabinet circuits.
  • the opening of holes of tubes 14 and 16 may be different depending on the level of "risk" of the volume to be monitored.
  • a control and alarm unit 24 is connected to the two smoke detectors 20 and 22.
  • the alarm unit 24 has an audible alarm and / or a light alarm (not shown) that are triggered when the unit receives information from the two smoke detectors 20 and 22 as explained below.
  • the enclosure may have areas say at particular risks such as zone 30, in other words from high risk areas that it's good to to watch more particularly.
  • zone 30 we can connect this zone 30 to one or more holes 14b and 14c by one or more capillary tubes 32 and 34, so that any fire in zone 30 will very quickly detected by smoke detector 20 and a pre-alarm signal which will be confirmed once the air containing smoke will have been returned to the enclosure by the fan 18, then sucked in through the tube 16. It can therefore be seen that the device of the invention can be easily adapted to each case, without disassembly, but only by the connection of capillaries in risk areas individuals.
  • the control and alarm 24 can present itself in the way schematically illustrated in Figure 3.
  • a contact 36 is closed, which allows a current to flow from the point of tension V in a low value resistance 38.
  • the terminal voltage resistance 38 increases and applies to the input 40 of a comparator 42 including the second input 44 is supplied by a voltage taken at the junction point a fixed resistor 46 and a variable resistor 48.
  • Resistor 48 is adjusted so that the voltage on input 40 is greater than the voltage on input 44 of so that comparator 42 provides a signal to a means pre-alarm 50 which can be light or sound.
  • Contacts 36 and 52 of detectors 20 and 22 can be made by thyristors which, when they become conductors, are equivalent to closed contacts. We should note that human intervention is required to block the thyristors again, so open the contacts. In other words, the pre-alarm as well as the alarm can only fire again after being restored to their inactive state.
  • the device which has just been described presents the advantage of being usable independently using a simple 24 volt DC power supply, without adding to it an expensive detection center.
  • the control and alarm unit 24 can be equipped of all the means necessary for orders: automatic shutdown, ventilation shutdown, anti-sabotage, burglary and security protection detector and fan operation.
  • the detection device which has just been described in reference to Figure 1 is reversible. Indeed, it is enough reverse the direction of rotation of the fan so that air is drawn from fan 18 and blown in the enclosure by means of tubes 14 and 16. In this case, the confirmed alarm arrives earlier than in the case previous.
  • This configuration is particularly effective if you do not want to take air in a way specifies in risky volumes or if the cabinet does not has no parts to be monitored more particularly.
  • the tubes can therefore be stopped open as soon as they enter the enclosure.
  • the detection device according to the invention because of its closed ventilation circuit, can therefore be used for fire detection in enclosures requiring to be completely waterproof so that the circuits are found inside are totally isolated from the outside atmosphere. So, such a device is particularly suitable for use in clean room cabinets or other very protected, especially in explosion-proof cabinets and environments.

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  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Business, Economics & Management (AREA)
  • Emergency Management (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Fire-Detection Mechanisms (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)

Description

Domaine technique :Technical area :

La présente invention concerne les dispositifs de détection d'incendie et en particulier un dispositif de détection d'incendie dans une enceinte fermée telle qu'une armoire de contrôle d'un atelier ou d'une unité de production dans une usine.The present invention relates to devices for fire detection and in particular a fire detection in a closed enclosure such as a workshop or unit control cabinet production in a factory.

Etat de la technique :State of the art:

Dans un atelier ou une unité de production, il est classique que l'ensemble des circuits électriques et électroniques de contrôle soient rassemblés dans une armoire de contrôle fermée et souvent étanche, ceci dans le but d'isoler les circuits de l'atmosphère régnant dans l'atelier ou l'unité de production et maintenir ces circuits à l'abri de toute corrosion prématurée, poussière ou acte malveillant.In a workshop or production unit, it is classic than all of the electrical circuits and control electronics are brought together in one closed and often waterproof control cabinet, this in the purpose of isolating the circuits of the atmosphere prevailing in the workshop or production unit and maintain these circuits protected from premature corrosion, dust or malicious act.

Une telle armoire de contrôle est généralement munie d'un coffret de détection d'incendie se trouvant à l'extérieur de l'armoire et chargé de détecter rapidement tout début d'incendie dans l'armoire. Le coffret du type de celui décrit dans FR-A-2.523.455 comporte un moyen d'aspiration de l'air se trouvant dans l'armoire, un ou deux détecteurs de fumée chargés d'analyser l'air aspiré dans l'armoire pour y détecter des traces de fumée et au travers desquels est forcé à circuler l'air aspiré par le moyen d'aspiration avant d'être évacué vers l'extérieur, et une unité de contrôle et d'alarme qui déclenche généralement à la fois une alarme sonore et une alarme lumineuse lorsqu'un début d'incendie est détecté.Such a control cabinet is generally provided a fire detection box located at outside the cabinet and responsible for quickly detecting very early fire in the cabinet. The box of the type of that described in FR-A-2,523,455 includes a means air intake in the cabinet, one or more two smoke detectors responsible for analyzing the intake air in the cabinet to detect traces of smoke and through which is forced to circulate the air sucked by the means of suction before being evacuated to the outside, and a control and alarm unit which triggers usually both an audible alarm and an alarm bright when a fire is detected.

Malheureusement le détecteur d'incendie mentionné ci-dessus présente deux inconvénients majeurs. D'une part, comme il a été dit précédemment, les armoires de contrôle sont fermées et souvent maintenues étanches et par conséquent, l'aspiration de l'air se trouvant à l'intérieur se fait difficilement ce qui résulte en un mauvais fonctionnement du dispositif de détection d'incendie. Il a été remédié à cet inconvénient en renvoyant dans l'armoire l'air qui en a été aspiré dans le but de l'amener au dispositif de détection et d'alarme, tel que décrit dans la demande de brevet européen EP 424 881.Unfortunately the above mentioned fire detector has two major drawbacks. Firstly, as previously mentioned, the control cabinets are closed and often kept tight and by therefore, the air intake inside difficult to do which results in poor operation of the fire detection device. He has has been remedied by sending back to the cabinet the air which has been sucked out in order to bring it to the detection and alarm device, as described in the European patent application EP 424 881.

D'autre part, un tel dispositif de détection doit être sensible à la moindre trace de fumée indiquant un début d'incendie de faible ampleur. Pour ce faire, l'alarme doit donc présenter une grande sensibilité pour son déclenchement, ceci ayant évidemment pour inconvénient la possibilité de déclenchements d'alarme intempestifs. Pour éviter de tels déclenchements intempestifs, les systèmes de détection d'incendie sont quelquefois pourvus de deux détecteurs, comme c'est le cas dans la demande de brevet européen citée ci-dessus ; l'un des deux détecteurs pouvant d'ailleurs servir à confirmer la détection effectuée par l'autre. Malheureusement, un tel système qui présente une plus grande fiabilité évitant des déclenchements intempestifs dans le cas où un des détecteurs est défectueux, ne permet pas une détection de débuts d'incendie à la fois ponctuels (par exemple sur une carte de circuits imprimés) et de très faible importance.On the other hand, such a detection device must be sensitive to the slightest trace of smoke indicating a small fire started. To do this, the alarm must therefore be very sensitive to his triggering, this obviously having the disadvantage of possibility of nuisance alarm triggers. For avoid such nuisance trips, fire detection are sometimes provided with two detectors, as in the patent application European cited above; one of the two detectors can moreover serve to confirm the detection carried out by the other. Unfortunately, such a system which presents a greater reliability avoiding tripping untimely in the event that one of the detectors is defective, does not allow detection of beginnings both punctual fire (for example on a card of printed circuits) and of very small importance.

Exposé de l'invention :Statement of the invention:

Le but de l'invention est donc de fournir un dispositif de détection d'incendie dans une enceinte fermée ou étanche, qui présente une grande fiabilité de fonctionnement évitant un déclenchement intempestif de l'alarme tout en permettant la détection de débuts d'incendie de très faible importance.The object of the invention is therefore to provide a fire detection device in a closed enclosure or waterproof, which has a high reliability of operation avoiding inadvertent tripping of the alarm while allowing the detection of beginnings of very small importance.

L'objet de l'invention est donc un dispositif de détection d'incendie dans une enceinte fermée telle qu'une armoire de contrôle, disposant d'un moyen d'aspiration de l'air de l'enceinte qui refoule l'air dans l'enceinte après qu'il a été analysé en permanence par un moyen de détection de fumée. En outre, le dispositif comprend une unité de contrôle et d'alarme qui déclenche l'alarme d'incendie lorsque le moyen de détection de fumée a détecté des traces de fumée dans l'air de l'enceinte. Le moyen de détection de fumée comprend un premier détecteur recevant l'air aspiré provenant de premiers orifices d'entrée d'air se trouvant à des premiers emplacements de l'enceinte, et un second détecteur recevant l'air aspiré provenant de seconds orifices d'entrée d'air se trouvant à des seconds emplacements de l'enceinte différents des premiers emplacements. L'unité de contrôle et d'alarme comprend des moyens d'alarme pour déclencher l'alarme lorsque l'un des détecteurs a détecté de la fumée dans l'air refoulé dans l'enceinte par le moyen d'aspiration et de refoulement après que cet air a donné lieu à détection de fumée par l'autre des détecteurs.The object of the invention is therefore a device for fire detection in a closed enclosure such as a control cabinet, with a suction means of the air from the enclosure which expels the air into the enclosure after that it has been continuously analyzed by means of detection smoke. In addition, the device includes a unit of control and alarm that triggers the fire alarm when the smoke detection means has detected traces smoke in the air of the enclosure. The means of detecting smoke includes a first detector receiving the intake air from the first air intake ports located at first locations of the enclosure, and a second detector receiving the air sucked in from seconds air inlet ports located at second different speaker locations from the first locations. The control and alarm unit includes alarm means to trigger the alarm when one of the detectors detected smoke in the exhaust air in the enclosure by means of suction and discharge after this air has given rise to smoke detection by the other of the detectors.

Description brève des figures :Brief description of the figures:

Les buts, objets et caractéristiques de l'invention ressortiront mieux à la lecture de la description suivante faite en référence aux dessins dans lesquels :

  • la figure 1 représente schématiquement le mode de réalisation préféré du dispositif de détection d'incendie selon l'invention,
  • la figure 2 représente schématiquement un mode de réalisation de la partie de l'unité de contrôle et d'alarme connectée aux deux détecteurs d'incendie, et
  • la figure 3 représente schématiquement une enceinte disposant de deux dispositifs de détection d'incendie correspondant respectivement aux deux modes de réalisation de l'invention.
    • The aims, objects and characteristics of the invention will emerge more clearly on reading the following description made with reference to the drawings in which:
  • FIG. 1 schematically represents the preferred embodiment of the fire detection device according to the invention,
  • FIG. 2 schematically represents an embodiment of the part of the control and alarm unit connected to the two fire detectors, and
  • FIG. 3 schematically represents an enclosure having two fire detection devices corresponding respectively to the two embodiments of the invention.

    • Description détaillée de l'invention :Detailed description of the invention:

    Comme illustré sur la figure 1, un coffret 10 contenant le dispositif de détection d'incendie conforme à l'invention est placé au dessus d'une enceinte 12 telle qu'une armoire de contrôle située dans un atelier et contenant les circuits électriques et électroniques de contrôle de l'atelier (non montrés). As illustrated in FIG. 1, a box 10 containing the fire detection device in accordance with the invention is placed above an enclosure 12 such a control cabinet located in a workshop and containing the electrical and electronic circuits of workshop control (not shown).

    L'air de l'enceinte est aspiré par les deux tubes ou canalisations 14 et 16 grâce à un moyen d'aspiration tel qu'un ventilateur 18. Les deux tubes 14 et 16 peuvent être arrêtés à n'importe quelle hauteur de l'enceinte 12. Ils sont percés d'orifices calibrés a, b, c pour le tube 14, ou d, e, f pour le tube 16, chargés de prélever l'air dans des "volumes à risques", c'est à dire des parties de l'armoire contenant des circuits sensibles ou des parties vitales de l'ensemble des circuits de l'armoire. L'ouverture des orifices des tubes 14 et 16 peut être différente selon le niveau de "risque" du volume à surveiller.Air from the enclosure is drawn in through the two tubes or pipes 14 and 16 thanks to a suction means such than a fan 18. The two tubes 14 and 16 can be stopped at any height of enclosure 12. They are drilled with calibrated orifices a, b, c for the tube 14, or d, e, f for tube 16, responsible for extracting air from "volumes at risk", ie parts of the cabinet containing sensitive circuits or vital parts of all of the cabinet circuits. The opening of holes of tubes 14 and 16 may be different depending on the level of "risk" of the volume to be monitored.

    L'air aspiré par les tubes 14 et 16 au moyen du ventilateur 18 passe dans des détecteurs de fumée 20 et 22 qui peuvent être du type optique, ionique ou de tout autre type. Puis l'air qui vient d'être analysé par les détecteurs 20 et 22 est renvoyé dans l'enceinte 12 par le ventilateur 18. Par conséquent, le fait que l'armoire 12 soit fermée ou même étanche ne présente aucun inconvénient pour le dispositif de détection dans la mesure où l'air circule en circuit fermé et ne crée pas de dépression ou surpression préjudiciable à son bon fonctionnement.The air sucked in by tubes 14 and 16 by means of the fan 18 goes through smoke detectors 20 and 22 which can be of the optical, ionic or any other type type. Then the air which has just been analyzed by the detectors 20 and 22 is returned to enclosure 12 by the fan 18. Therefore, the fact that the cabinet 12 either closed or even waterproof has no drawbacks for the detection device insofar as the air circulates in a closed circuit and does not create a vacuum or overpressure detrimental to its proper functioning.

    Une unité de contrôle et d'alarme 24 est connectée aux deux détecteurs de fumée 20 et 22. L'unité d'alarme 24 dispose d'une alarme sonore et/ou d'une alarme lumineuse (non montrées) qui sont déclenchées lorsque l'unité reçoit des informations des deux détecteurs de fumée 20 et 22 comme expliqué ci-après.A control and alarm unit 24 is connected to the two smoke detectors 20 and 22. The alarm unit 24 has an audible alarm and / or a light alarm (not shown) that are triggered when the unit receives information from the two smoke detectors 20 and 22 as explained below.

    En supposant que l'air prélevé dans le volume à risques se trouvant à proximité de l'ouverture 14-c contienne de la fumée, cet air analysé par le détecteur de fumée 20 entraíne un signal de pré-alarme de la part de l'unité d'alarme 24. Mais cette pré-alarme doit être confirmée car il pourrait s'agir d'une fausse alerte du détecteur 20. L'air qui a été analysé par le détecteur 20 est soufflé par le ventilateur 18 dans l'enceinte 12. Cet air est aspiré à nouveau, mais cette fois-ci à 16-d, 16-e ou 16-f, puis analysé par le détecteur de fumée 22. Il y a donc véritablement une confirmation d'alarme par le déclenchement de deux détecteurs placés sur deux chemins différents de l'air aspiré. Si l'air contient véritablement de la fumée, celle-ci est détectée et un deuxième signal reçu par l'unité d'alarme 24 vient confirmer le signal de pré-alarme. L'alarme (visuelle et sonore) est alors déclenchée par cette dernière. L'information est fiable, confirmée, et ne peut provenir que d'une détection réelle de fumée. Le temps de réaction entre la détection par un détecteur de fumée et sa confirmation est très court, inférieur à quelques secondes.Assuming that the air taken from the volume at hazards near opening 14-c contains smoke, this air analyzed by the smoke 20 causes a pre-alarm signal from alarm unit 24. But this pre-alarm must be confirmed because it could be a false alert from the detector 20. The air which has been analyzed by detector 20 is blown by the fan 18 in the enclosure 12. This air is sucked in again, but this time at 16-d, 16-e or 16-f, then analyzed by the smoke detector 22. There are therefore truly an alarm confirmation by the triggering of two detectors placed on two paths different from the intake air. If the air really contains smoke, it is detected and a second signal received by the alarm unit 24 confirms the signal pre-alarm. The alarm (visual and audible) is then triggered by the latter. The information is reliable, confirmed, and can only come from an actual detection smoke. The reaction time between detection by a smoke detector and its confirmation is very short, less than a few seconds.

    Il est possible que l'enceinte comporte des zones dites à risques particuliers telles que la zone 30, en d'autres termes des zones à haut risque qu'il est bon de surveiller plus particulièrement. Dans ce cas, on peut relier cette zone 30 à un ou plusieurs trous 14b et 14c par un ou plusieurs tubes capillaires 32 et 34, de sorte que tout début d'incendie dans la zone 30 sera très rapidement détecté par le détecteur de fumée 20 et un signal de pré-alarme qui sera confirmé une fois que l'air contenant de la fumée aura été renvoyé dans l'enceinte par le ventilateur 18, puis aspiré par le tube 16. On voit donc que le dispositif de l'invention peut être adapté facilement à chaque cas, sans démontage, mais seulement par le raccordement de capillaires dans les zones à risques particuliers.The enclosure may have areas say at particular risks such as zone 30, in other words from high risk areas that it's good to to watch more particularly. In this case, we can connect this zone 30 to one or more holes 14b and 14c by one or more capillary tubes 32 and 34, so that any fire in zone 30 will very quickly detected by smoke detector 20 and a pre-alarm signal which will be confirmed once the air containing smoke will have been returned to the enclosure by the fan 18, then sucked in through the tube 16. It can therefore be seen that the device of the invention can be easily adapted to each case, without disassembly, but only by the connection of capillaries in risk areas individuals.

    Pour le déclenchement de l'alarme, l'unité de contrôle et d'alarme 24 peut se présenter de la façon illustrée schématiquement sur la figure 3. Lorsque le détecteur 20 détecte la présence de fumée dans l'air aspiré, un contact 36 est fermé, ce qui permet à un courant de s'écouler à partir du point de tension V dans une résistance de faible valeur 38. La tension à la borne supérieure de la résistance 38 s'élève et s'applique à l'entrée 40 d'un comparateur 42 dont la deuxième entrée 44 est alimentée par une tension prise au point de jonction d'une résistance fixe 46 et d'une résistance variable 48. La résistance 48 est ajustée pour que la tension sur l'entrée 40 soit supérieure à la tension sur l'entrée 44 de sorte que le comparateur 42 fournisse un signal à un moyen de pré-alarme 50 qui peut être lumineux ou sonore.For the triggering of the alarm, the control and alarm 24 can present itself in the way schematically illustrated in Figure 3. When the detector 20 detects the presence of smoke in the air vacuumed, a contact 36 is closed, which allows a current to flow from the point of tension V in a low value resistance 38. The terminal voltage resistance 38 increases and applies to the input 40 of a comparator 42 including the second input 44 is supplied by a voltage taken at the junction point a fixed resistor 46 and a variable resistor 48. Resistor 48 is adjusted so that the voltage on input 40 is greater than the voltage on input 44 of so that comparator 42 provides a signal to a means pre-alarm 50 which can be light or sound.

    Lorsqu'il y a confirmation de l'incendie par le détecteur 22, un contact 52 est fermé. Ainsi, un courant vient s'ajouter au courant dû à la fermeture précédente du contact 36 dans la résistance 38. La somme des deux courants permet à la tension à la borne supérieure de la résistance 38 de s'élever davantage, ce qui permet d'appliquer une tension à la première entrée 54 du comparateur 56 plus élevée qu'avec le seul contact 36 fermé. Cette tension plus élevée sur l'entrée 54 dépasse alors la tension appliquée à la deuxième entrée 58 du comparateur 56 prise à la connexion entre une résistance fixe 60 et une résistance variable 62. la sortie du comparateur 56 fournit alors un signal à un moyen d'alarme confirmée 64 qui peut être lumineux ou sonore.When there is confirmation of the fire by the detector 22, a contact 52 is closed. So a current is added to the current due to the previous closing of the contact 36 in resistor 38. The sum of the two currents allows the voltage at the upper terminal of the resistance 38 to rise further, allowing to apply a voltage to the first input 54 of the comparator 56 higher than with single contact 36 closed. This higher voltage on input 54 exceeds then the voltage applied to the second input 58 of the comparator 56 taken at the connection between a resistor fixed 60 and a variable resistor 62. the output of the comparator 56 then supplies a signal to an alarm means confirmed 64 which can be light or sound.

    Lorsque les contacts 36 et 52 sont ouverts (absence de détection de fumée), il existe tout de même un courant de surveillance de ligne s'écoulant dans la résistance 38 par l'intermédiaire de la résistance 66. Comme ce courant est très faible, la tension à la borne de la résistance 38 est très faible mais fournit quand même une tension sur la première entrée 68 d'un comparateur 70, plus élevée que la tension sur la deuxième entrée due à la connexion entre une résistance fixe 74 et une résistance variable 76. La sortie du comparateur est fournie à un moyen de surveillance de ligne 78 (par exemple un cadran).When contacts 36 and 52 are open (absence smoke detection), there is still a current monitoring line flowing through resistance 38 through resistor 66. Like this current is very low, the voltage across the resistor 38 is very weak but still provides a voltage on the first input 68 of a comparator 70, higher than the voltage on the second input due to the connection between a fixed resistance 74 and variable resistance 76. The output of the comparator is provided to a means for monitoring line 78 (for example a sundial).

    Les contacts 36 et 52 des détecteurs 20 et 22 peuvent être réalisés par des thyristors qui, lorsqu'ils deviennent conducteurs, sont équivalents à des contacts fermés. On doit noter qu'une intervention humaine est nécessaire pour bloquer à nouveau les thyristors, donc ouvrir les contacts. En d'autres termes, la pré-alarme aussi bien que l'alarme ne peuvent se déclencher à nouveau qu'après avoir été restaurées dans leur état inactif. Contacts 36 and 52 of detectors 20 and 22 can be made by thyristors which, when they become conductors, are equivalent to closed contacts. We should note that human intervention is required to block the thyristors again, so open the contacts. In other words, the pre-alarm as well as the alarm can only fire again after being restored to their inactive state.

    Le dispositif qui vient d'être décrit présente l'avantage d'être utilisable de façon autonome en utilisant une simple alimentation 24 volts continue, sans y adjoindre une centrale de détection onéreuse.The device which has just been described presents the advantage of being usable independently using a simple 24 volt DC power supply, without adding to it an expensive detection center.

    De façon à être sûr que le dispositif est toujours en bon état de fonctionnement, il faut s'assurer que l'air est correctement aspiré à partir de l'enceinte. Il est en effet prévisible que les ouvertures a, b, c du tube 14 ou d, e, f du tube 16 viennent à se boucher partiellement par encrassement dû par exemple à une accumulation de poussières. C'est pour cela qu'on prévoit un détecteur de débit 26 ou 28 à l'entrée de chaque détecteur de fumée. Si l'aspiration se fait mal, le débit d'air dans le tube diminue et passe au dessous d'un seuil au delà duquel le fonctionnement du dispositif de détection n'a plus l'efficacité requise. Chaque détecteur de débit 26 ou 28 est connecté à l'unité de contrôle et d'alarme 24 pour qu'un signal d'alerte soit également déclenché si le débit dans un des tubes vient à passer au dessous du seuil fatidique.So as to be sure that the device is still in good working condition, make sure the air is properly sucked from the enclosure. It is indeed foreseeable that the openings a, b, c of the tube 14 or d, e, f of tube 16 become partially blocked by fouling due for example to an accumulation of dust. This is why we provide a flow 26 or 28 at the inlet of each smoke detector. Yes the suction is bad, the air flow in the tube decreases and goes below a threshold beyond which the detection device no longer has the required efficiency. Each flow sensor 26 or 28 is connected to the control and alarm unit 24 to an alert signal is also triggered if the flow in one of the tubes comes below the threshold fateful.

    L'unité de contrôle et d'alarme 24 peut être équipée de tous les moyens nécessaires pour les commandes : extinction automatique, coupure de la ventilation, protection anti-sabotage, anti-effraction et sécurité de fonctionnement des détecteurs et du ventilateur.The control and alarm unit 24 can be equipped of all the means necessary for orders: automatic shutdown, ventilation shutdown, anti-sabotage, burglary and security protection detector and fan operation.

    Le dispositif de détection qui vient d'être décrit en référence à la figure 1 est réversible. En effet, il suffit d'inverser le sens de rotation du ventilateur pour que l'air soit aspiré à partir du ventilateur 18 et soufflé dans l'enceinte au moyen des tubes 14 et 16. Dans ce cas, l'alarme confirmée arrive plus tôt que dans le cas précédent. Cette configuration est particulièrement efficace si on ne souhaite pas prélever d'air de façon précise dans des volumes à risques ou si l'armoire ne comporte pas de parties devant être surveillées plus particulièrement. Les tubes peuvent donc être arrêtés ouverts dès leur pénétration dans l'enceinte. The detection device which has just been described in reference to Figure 1 is reversible. Indeed, it is enough reverse the direction of rotation of the fan so that air is drawn from fan 18 and blown in the enclosure by means of tubes 14 and 16. In this case, the confirmed alarm arrives earlier than in the case previous. This configuration is particularly effective if you do not want to take air in a way specifies in risky volumes or if the cabinet does not has no parts to be monitored more particularly. The tubes can therefore be stopped open as soon as they enter the enclosure.

    On peut d'ailleurs prévoir d'utiliser une combinaison d'un dispositif de détection selon le premier mode de réalisation illustré sur la figure 1 et d'un dispositif de détection à aspiration inversée tel qu'il vient d'être mentionné, comme représenté sur la figure 3. Dans ce cas, à la sensibilité du premier dispositif de détection 80 comportant des tubes longs disposant de plusieurs ouvertures pour les volumes à risques, on ajoute la rapidité de détection du deuxième dispositif de détection 82 comportant des tubes courts, d'où une très grande fiabilité de la combinaison des deux dispositifs. Dans cette combinaison, on peut prévoir que les informations de sortie soient connectées à volonté suivant un ET ou un OU permettant toutes confirmations, temporisations et commandes les plus appropriées en matière de sécurité.We can also plan to use a combination of a detection device according to the first mode of embodiment illustrated in Figure 1 and a device reverse suction detection as it has just been mentioned, as shown in Figure 3. In this case, at the sensitivity of the first detection device 80 comprising long tubes with several openings for volumes at risk, we add the speed of detection of the second detection device 82 comprising short tubes, hence a very large reliability of the combination of the two devices. In this combination, we can predict that the information of output are connected at will according to an AND or an OR allowing all confirmations, time delays and the most appropriate safety controls.

    Le dispositif de détection selon l'invention, du fait de son circuit fermé de ventilation, peut donc être utilisé pour la détection d'incendie dans des enceintes nécessitant d'être entièrement étanches pour que les circuits se trouvant à l'intérieur soient totalement isolés de l'atmosphère extérieure. Ainsi, un tel dispositif est particulièrement approprié pour être utilisé dans les armoires de salles blanches ou autres milieux très protégés, notamment dans des armoires et milieux antidéflagrants.The detection device according to the invention, because of its closed ventilation circuit, can therefore be used for fire detection in enclosures requiring to be completely waterproof so that the circuits are found inside are totally isolated from the outside atmosphere. So, such a device is particularly suitable for use in clean room cabinets or other very protected, especially in explosion-proof cabinets and environments.

    Claims (8)

    1. A device (10) for detecting a fire in a closed-off enclosure (12) such as a control cabinet, including a suction and delivery means (18) for drawing out the air from the enclosure, connected to a smoke detection means so that the aspirated air is analysed continuously, and a control and alarm unit (24) connected to said smoke detection means for triggering an alarm when the analysis of the air from the enclosure, as performed by the smoke detector, shows that smoke is contained in the air, said suction and delivery means (18) delivering the air to the enclosure after it has been analysed by said smoke detection means;
      said device being characterized in that
      said smoke detection means includes a first sensor (20) receiving the aspirated air coming from first air intake openings (14) located at first locations within said enclosure, and a second sensor (22) receiving the aspirated air coming from second air intake openings (16) located at second locations different from said first locations within said enclosure, and
      said control and alarm unit includes means for triggering an alarm when said first and second sensors have detected some smoke in the air delivered to the enclosure by said suction and delivery means after smoke has been detected in this air by the other of said sensors.
    2. The device (10) according to claim 1, wherein said alarm means include a pre-alarm means (50) triggered by smoke detected by one of said first or second sensors (20, 22) in the air contained in the enclosure (12) and a confirmed alarm means (64) triggered when the other of said sensors has detected smoke in the air delivered to the enclosure after said pre-alarm means is triggered.
    3. The device according to claim 1 or 2, further including at least a flow rate sensor (26, 28) for measuring the flow rate of the air analysed by at least one of said first and second smoke detectors (20, 22) so that an alarm signal is given out when the flow rate of the aspirated air falls below a given threshold, due to clogging of air intake openings.
    4. The device according to any one of claims 1 to 3, wherein said suction and delivery means (18) is a fan that draw the air out of the enclosure (12) by means of a first tube (14) provided with said first openings and a second tube (16) provided with said second openings, said first and second tubes being connected to said fan through said first and second smoke detectors (20, 22), the air being blown back directly to the enclosure through the action of said fan.
    5. The device according to claim 4, wherein said first (14a, b, c) and second (16d, e, f) openings for drawing the air out of the enclosure (12) are located close to sensitive spots so that any fire starting at said sensitive spots is quickly detected.
    6. The device according to claim 5, wherein some locations (30) especially sensitive of said enclosure (12) are connected to some of said openings trough capillary tubes (32, 34).
    7. The device according to any one of claims 1 to 3, wherein said suction and delivery means (18) is a fan that draws the air directly out of the enclosure (12) and blows it back to said enclosure through said first tube (14) provided with said first openings and said second tube (16) provided with said second openings, after the air is analysed in said first and second smoke detectors (20, 22).
    8. A system for detecting a fire within a closed-off enclosure (12) such as a control cabinet including a combination of a device (30) according to claim 4, 5 or 6 and a device (32) according to claim 7, that operate concurrently.
    EP95929148A 1994-09-01 1995-08-30 Device for detecting a fire in a closed-off enclosure Revoked EP0777896B1 (en)

    Applications Claiming Priority (3)

    Application Number Priority Date Filing Date Title
    FR9410679 1994-09-01
    FR9410679A FR2724247B1 (en) 1994-09-01 1994-09-01 FIRE DETECTION DEVICE IN A CLOSED ENCLOSURE
    PCT/FR1995/001134 WO1996007166A1 (en) 1994-09-01 1995-08-30 Device for detecting a fire in a closed-off enclosure

    Publications (2)

    Publication Number Publication Date
    EP0777896A1 EP0777896A1 (en) 1997-06-11
    EP0777896B1 true EP0777896B1 (en) 1999-05-06

    Family

    ID=9466739

    Family Applications (1)

    Application Number Title Priority Date Filing Date
    EP95929148A Revoked EP0777896B1 (en) 1994-09-01 1995-08-30 Device for detecting a fire in a closed-off enclosure

    Country Status (6)

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    EP (1) EP0777896B1 (en)
    AU (1) AU3261495A (en)
    DE (1) DE69509536T2 (en)
    ES (1) ES2133794T3 (en)
    FR (1) FR2724247B1 (en)
    WO (1) WO1996007166A1 (en)

    Families Citing this family (8)

    * Cited by examiner, † Cited by third party
    Publication number Priority date Publication date Assignee Title
    AUPN965996A0 (en) * 1996-05-03 1996-05-30 Vision Products Pty Ltd The detection of airborne pollutants
    AU717087B2 (en) * 1996-05-03 2000-03-16 Garrett Thermal Systems Limited The detection of airborne pollutants
    US5926098A (en) * 1996-10-24 1999-07-20 Pittway Corporation Aspirated detector
    DE59908368D1 (en) * 1999-06-10 2004-02-26 Siemens Building Tech Ag Protection against accidents in railway tunnels
    GB9915388D0 (en) * 1999-07-02 1999-09-01 Secr Defence System for fire-out gas detection
    DE10114729A1 (en) 2001-03-22 2002-10-02 Rittal Gmbh & Co Kg Switchgear cabinet with smoke alarm device, includes fan for drawing air out from interior of switchgear cabinet into housing via inlet aperture in housing wall
    DE602004031347D1 (en) * 2003-09-24 2011-03-24 Xtralis Technologies Ltd METHOD AND DEVICE FOR DETERMINING THE OPERATING CONDITION OF POLLUTION MONITORING DEVICES
    US7656302B2 (en) 2006-11-20 2010-02-02 Honeywell International Inc. Sensing chamber with enhanced ambient atmospheric flow

    Family Cites Families (3)

    * Cited by examiner, † Cited by third party
    Publication number Priority date Publication date Assignee Title
    US4195286A (en) * 1978-01-06 1980-03-25 American District Telegraph Company Alarm system having improved false alarm rate and detection reliability
    NL8800634A (en) * 1988-03-15 1989-10-02 Westinghouse Elektrotechniek E DEVICE FOR MONITORING THE EXHAUST PIPE (S) OF A SMOKE / GAS DETECTION SYSTEM.
    DE3935238C2 (en) * 1989-10-23 1994-02-24 Preussag Ag Feuerschutz Air guidance system, in particular for a fire alarm device

    Also Published As

    Publication number Publication date
    DE69509536D1 (en) 1999-06-10
    FR2724247A1 (en) 1996-03-08
    DE69509536T2 (en) 1999-12-23
    ES2133794T3 (en) 1999-09-16
    AU3261495A (en) 1996-03-22
    EP0777896A1 (en) 1997-06-11
    FR2724247B1 (en) 1997-01-24
    WO1996007166A1 (en) 1996-03-07

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