EP1444017B1 - Foam fire extinguishing installation - Google Patents

Abstract

The fire protection installation divides the protected space into sectors. Each sector has multiple thermal detectors (10) distributed over the sector and closing a compressed air conduit (12). If a high temperature is detected, the conduit is opened to atmosphere, and the drop in air pressure detected by a controller (16) which generates foam sprayed from all outlets (26) in the sector.

Description

The present invention relates to fire protection installations. It concerns, in particular, a detection and extinction system well adapted to the fight against fires in large confined spaces, such as tunnels, car parks or warehouses.

• à réponse rapide, c'est-à-dire réagissant instantanément à une élévation anormale de la température, et
• fiables, c'est-à-dire aussi peu sensibles que possible aux changements de température (gel, ...) mais également aux poussières ou autres salissures risquant de les "aveugler" partiellement ou totalement.

Such an installation must, first of all, be equipped with detectors:

• fast response, that is to say, reacting instantly to an abnormal rise in temperature, and
• reliable, that is to say as insensitive as possible to changes in temperature (frost, ...) but also to dust or other soils that may "blind" partially or totally.

A fire-fighting facility in a large space must also be capable of responding, in a targeted manner, to several fires separated from each other, which is frequent during a fire or when, in a tunnel, a first fire causes chain collisions and new fires, see DE 199 30 481 A . It is therefore vital that the installation intervenes at this location and is not prematurely out of extinction means because it has exhausted too quickly its resources on the first fire.

Due to advances in the field of emulsifiers (generally liquid soaps), foam extinguishing systems have recently developed strongly. The attack of the fire by means of foam is not only more effective than that of a simple installation of water, known as "sprinkler", because it stifles the fire instead of bringing him oxygen, but, moreover, consumes much less water, which is a considerable advantage in tunnels. It should be noted, for example, that a medium expansion installation, well adapted to this kind of space, requires only 1 liter of water to produce some 100 liters of foam.

The present invention aims to provide a detection and extinguishing system that meets the requirements set out above and, among other solutions, attacks the fire with foam.

• une pluralité de détecteurs thermiques répartis dans le secteur, obturant chacun l'extrémité d'un conduit alimenté en air comprimé et réagissant à une élévation anormale de la température ambiante en faisant déboucher ledit conduit à l'air libre,
• une pluralité de buses d'extinction à mousse réparties à la partie supérieure du secteur, et
• des moyens de commande qui répondent à une chute de pression résultant de la mise à l'air libre d'au moins l'un desdits conduits par l'alimentation de toutes les buses du secteur en un mélange d'eau sous pression et d'émulseur leur permettant de déverser de la mousse d'extinction sur ce secteur.

More specifically, the invention relates to a fire detection and extinguishing system in an enclosed space, which comprises a plurality of separate sets each assigned to the protection of a sector of said space and comprising, for each sector :

• a plurality of thermal detectors distributed in the sector, each closing the end of a duct supplied with compressed air and reacting to an abnormal rise in the ambient temperature by opening said duct in the open air,
• a plurality of foam extinguishing nozzles distributed at the upper portion of the sector, and
• control means which respond to a pressure drop resulting from the venting of at least one of said ducts by supplying all the nozzles of the sector with a mixture of water under pressure and foam concentrate allowing them to pour out fire-fighting foam on this area.

Preferably, each assembly further comprises means which also respond to said pressure drop by stopping the supply of compressed air to the sector detectors in order to maintain the detectors of the other sectors under pressure.

Very advantageously, each assembly further comprises a plurality of thermovelokinetic detectors distributed in the sector and means responding to these detectors so that the control means take effect only in the event of a sudden rise in temperature. .

It is advantageous, in a tunnel, that each sector has a length of about 15 to 20 meters.

• des moyens pour produire un jet pulvérisé d'un mélange d'eau et d'émulseur, et
• des moyens pour recevoir ce jet, enrichi par l'air aspiré sur son trajet, briser les gouttes du liquide reçu en plus fines particules et ainsi produire un jet de mousse.

According to a particularly advantageous mode of implementation of the invention, the nozzles comprise:

• means for producing a spray of a mixture of water and an emulsifier, and
• means for receiving this jet, enriched by the air sucked in its path, break the drops of the liquid received into more fine particles and thus produce a foam jet.

• les moyens pour produire un jet pulvérisé comportent une chambre de brassage sensiblement cylindrique comprenant, du haut vers le bas, un canal d'amenée de liquide axial, un canal d'amenée de liquide horizontal et circulaire, et un canal d'éjection axial communiquant avec les deux canaux d'amenée;
• le canal d'éjection se termine par un cône de diffusion, tandis que le canal d'amenée de liquide horizontal s'étend sur un angle inférieur à 360°, de l'ordre de 240°;
• la chambre de brassage comprend, en outre, une paroi percée d'orifices formant des chicanes, sur laquelle débouche le canal d'amenée de liquide axial;
• le canal d'amenée de liquide horizontal peut déboucher en aval ou en amont de la paroi formant des chicanes;
• lorsque la canal d'amenée horizontal débouche en aval, la chambre de brassage est réalisée en deux parties, l'une, extérieure, comportant, dans sa paroi supérieure, le canal d'amenée de liquide axial et, dans sa paroi verticale, une gorge horizontale à section semi-circulaire, l'autre, intérieure, comportant, à sa partie supérieure, la paroi formant des chicanes et, dans sa paroi verticale, une gorge horizontale à section semi-circulaire qui forme, avec la gorge de la partie extérieure, le canal d'amenée de liquide horizontal ;
• l'extrémité du canal d'amenée de liquide horizontal communique avec le canal d'éjection par un canal radial ménagé dans la partie intérieure de la chambre; et
• la chambre de brassage est réalisée en cuivre;
• les moyens pour recevoir le jet pulvérisé comportent un grillage en forme de tronc de cône dont la portion centrale est bombée vers le haut.

The foam nozzles also have the following characteristics:

• the means for producing a spray jet comprise a substantially cylindrical stirring chamber comprising, from top to bottom, an axial liquid supply channel, a horizontal and circular liquid supply channel, and an axial ejection channel communicating with the two supply channels;
• the ejection channel terminates in a diffusion cone, while the horizontal liquid supply channel extends over an angle of less than 360 °, of the order of 240 °;
• the brewing chamber further comprises a wall pierced with orifices forming baffles on which opens the axial liquid supply channel;
• the horizontal liquid supply channel may open downstream or upstream of the wall forming baffles;
• when the horizontal feed channel opens downstream, the brewing chamber is made in two parts, one of which is external, comprising, in its upper wall, the axial liquid supply channel and, in its vertical wall, a horizontal groove with semicircular section, the other interior having, at its upper part, the wall forming baffles and, in its vertical wall, a horizontal groove with semi-circular section which forms, with the groove of the part outside, the horizontal liquid supply channel;
• the end of the horizontal liquid supply channel communicates with the ejection channel by a radial channel formed in the inner part of the chamber; and
• the brewing chamber is made of copper;
• the means for receiving the spray jet comprise a truncated cone-shaped grid whose central portion is curved upwards.

• la figure 1 est une représentation schématique d'une installation selon l'invention;
• la figure 2 est une vue de dessus d'une buse à mousse équipant cette installation;
• la figure 3 est une vue de face de cette buse en coupe selon II - II; et
• les figures 4 et 5 montrent le gicleur de la buse, respectivement vu en coupe axiale et de dessus.

Other features and advantages of the present invention will emerge from the description which follows, given with reference to the appended drawing, in which:

• Figure 1 is a schematic representation of an installation according to the invention;
• Figure 2 is a top view of a foam nozzle equipping this installation;
• Figure 3 is a front view of this nozzle in section along II - II; and
• Figures 4 and 5 show the nozzle of the nozzle, respectively seen in axial section and from above.

FIG. 1 very schematically shows, seen from the ground, a portion of the roof of a road tunnel equipped, every three meters or so, with a thermal fire detector 10 formed of a glass bulb filled with a a liquid with a high coefficient of expansion, such as an alcohol, breaking when the ambient temperature reaches a temperature exceeding the average tunnel temperature by about 20 ° C. This sensitive element, well known to those skilled in the art, can be of the type marketed under the designation "rapid response sprinkler".

Each detector 10 is disposed at the end of a duct 12 supplied with compressed air. As long as the temperature is normal, it closes this end but, when an abnormal rise in temperature occurs, it explodes and thus opens the conduit 12 to the open air.

According to the invention, the ducts 12 of five adjacent thermal detectors 10 are connected, on the one hand, to the output S of a supply controller 14 and, on the other hand, to the control input Ec d an extinction controller 16.

In the embodiment described, each group of five detectors 10 thus covers, independently, a tunnel sector approximately fifteen meters long.

The input E of the controller 14 is connected to a single pipe 18 running through the tunnel and supplied with compressed air by a compressor (not shown). This controller has the function, as long as the detectors 10 of the sector are unscathed, to maintain the pressure in the tubes 12 but, as soon as one of them explodes, due to abnormal rise in temperature, and thus causes a brutal depression, to cut the power supply of the group of the five detectors concerned to ensure the maintenance under pressure of the groups of detectors of the other sectors.

• une entrée E1 reliée à une conduite unique 20 parcourant le tunnel et alimentée en eau sous pression;
• une entrée E2 reliée à un réservoir d'émulseur 22; et
• une sortie S.

The extinction controller 16 has, in addition to the control input Ec:

• an inlet E1 connected to a single pipe 20 running through the tunnel and supplied with water under pressure;
• an inlet E2 connected to an emulsifier tank 22; and
• an output S.

The output S of the controller 16 is connected, by a conduit 24, to sets of foam extinguishing nozzles 26 arranged, every three meters or so, between two detectors 10, under the arch of the tunnel. In the embodiment described, each set comprises three nozzles 26 distributed over the width of the tunnel, which will be described later in detail.

The extinction controller 16 has the function of responding to a sudden drop in the pressure on its input Ec, caused by the explosion of a detector of the sector overheated by a fire, by sending, on its output S, to nozzles 26 of the group concerned of a mixture of water, supplied at its inlet E1, and of emulsifier, supplied at its inlet E2, enabling them to produce an extinction foam projected on the fire.

• une vanne manuelle 28 normalement ouverte mais permettant de couper, pour diverses interventions, l'alimentation en air comprimé des cinq détecteurs 10 du groupe;
• un diaphragme 30 servant à limiter le débit d'air;
• une vanne 32 normalement ouverte mais permettant, comme la vanne 28, de couper l'alimentation des cinq détecteurs en air comprimé; et
• un pressostat 34 répondant à une brutale chute de pression par la fermeture de la vanne 32.

More precisely, the power supply controller 14 comprises, from its input E to its output S:

• a manual valve 28 normally open but for cutting, for various interventions, the compressed air supply of the five detectors 10 of the group;
• a diaphragm 30 for limiting the air flow;
• a valve 32 normally open but allowing, like the valve 28, to cut off the supply of the five detectors with compressed air; and
• a pressure switch 34 responding to a sudden drop in pressure by closing the valve 32.

• une vanne manuelle 36 normalement ouverte mais permettant de couper, pour diverses interventions, l'alimentation en eau des buses 26 du secteur;
• une vanne 38 normalement fermée;
• un pressostat 40 répondant à une brutale chute de la pression à l'entrée Ec par l'ouverture de la vanne 38; et
• un mélangeur venturi 42 dont les deux entrées sont respectivement reliées à la sortie de la vanne 38 et à l'entrée E2 d'amenée de l'émulseur et dont la sortie S alimente, par le conduit 24, les buses 26 du secteur.

The extinction controller 16 comprises, from its input E1 to its output S:

• a manual valve 36 normally open but for cutting, for various interventions, the water supply of the nozzles 26 of the sector;
• a valve 38 normally closed;
• a pressure switch 40 responding to a sharp drop in the pressure at the inlet Ec through the opening of the valve 38; and
• a venturi mixer 42, the two inputs of which are respectively connected to the outlet of the valve 38 and to the feed inlet E 2 of the emulsifier and whose outlet S supplies the nozzles 26 of the sector through the conduit 24.

It will be noted that the valve 38 can also be actuated manually by means of an M command.

• d'une part, par le pressostat 34 du contrôleur d'alimentation 14 du secteur concerné, qui ferme sa vanne 32 d'arrivée d'air comprimé afin de ne pas perturber les autres secteurs; et
• d'autre part, par le pressostat 40 du contrôleur d'extinction 16 associé, qui ouvre sa vanne 38 d'arrivée d'eau sous pression pour alimenter les buses d'extinction 26 du secteur.

In summary, the explosion of a thermal detector, as a result of an abnormal rise in the temperature in the sector, causes a detected pressure drop:

• on the one hand, by the pressure switch 34 of the power supply controller 14 of the sector concerned, which closes its compressed air supply valve 32 so as not to disturb the other sectors; and
• on the other hand, by the pressure switch 40 of the associated extinction controller 16, which opens its pressurized water inlet valve 38 for supplying the extinguishing nozzles 26 of the sector.

According to a particularly advantageous embodiment, the ducts 12 are connected to the input Ec of the extinction controller 16 via a safety valve 44 controlled by thermovelokinetic detectors 46, two in number in the example represented in each sector of the tunnel vault. These detectors have the property of reacting to a rapid rise in temperature, typically greater than 10 ° C. per minute and are, for example, the C-1 Thermostatic Release model from the firm VIKING (USA).

Thus, the valve 38 of the extinction controller 16 will react to a pressure drop resulting from the explosion of a thermal detector 10 only if the safety valve 44 has been opened under the action of one of the detectors 46.

With this arrangement, the extinguishing nozzles 26 of the sector concerned will come into action only in case of sudden rise in temperature, as is the case during the fire of a vehicle. On the other hand, the only rupture of one of the detectors 10, which may have another cause than a rise in temperature, for example a projection of parts, does not cause the nozzles to engage.

Referring now to Figures 2 and 3 which show one of the nozzles 26 of the plant according to the invention. This nozzle comprises, as essential elements, a brewing chamber or mixing 50 and a grill 52.

The chamber 50, advantageously made of copper, comprises an outer frame 54 and a nozzle 56, screwed inside the frame.

The frame 54, which has a roughly cylindrical outer shape, defines a gap 58 open downwards, whose horizontal upper wall carries the reference 60 and the vertical wall the reference 62. The frame 54 is associated with a tubular piece 64 provided with a thread 66 for its connection to a feed pipe of a mixture of water and emulsifier. Exhibit 64 has an upper channel 68 opening axially in the center of the wall 60 and a lower channel 70 opening tangentially into the wall 62 provided at this point with a horizontal groove with a semicircular section 72 extending substantially over an angle of less than 360 °, typically about 240 °.

The nozzle 56, shown in Figures 4 and 5, takes place in the space 58 within which it is screwed through the thread 74 which it is provided at its base. When it is completely screwed, it abuts against the wall 60 of the frame by its end which is pierced in its central portion with a network of radial slots 76 also extending substantially at an angle of 240.degree. ° and facing the groove 72 of the frame 54.

Slightly below the slots 76, the nozzle 56 comprises a horizontal groove with a semi-circular section 78 which faces the groove 72 to form a channel 80 communicating at its end with another channel 82 arranged radially in the nozzle and opening into a groove. central opening 84 extended downwards by a diffusion cone 86 open on the outside.

Returning to FIGS. 2 and 3, it can be seen that the grid 52 is disposed facing the cone 86, perpendicularly and coaxially with the brewing chamber 50. This grid is advantageously made of 0.3 to 0.5 mm diameter steel wires forming mesh from 1 to 1.5 mm on each side. It has an outer truncated cone profile and comprises a central portion 88 slightly convex upwards, a peripheral portion 90 inclining upwards and a connecting portion 92.

The base of the portion 90 is fixed in a metal ring 94 that two arms 96 connect to a ring 98 surrounding the frame 54 of the brewing chamber 50.

In operation, when a pressure mixture of water and emulsifier is applied to the nozzle, the upper channel 68 brings a portion to the center of the bottom 60 of the frame. It is projected axially against the upper face of the nozzle 56, the network of radial slots 76 constituting baffles causes the stirring, then it descends into the channel 80 formed by the grooves facing 72 and 78. At the same time, the other part of the pressurized mixture is brought tangentially, through the lower channel 70, to the inlet of the horizontal channel 80 where the two parts of the mixture, strongly brewed, meet.

At the end of the channel 80, which is 240 ° from its inlet, the mixture of water and emulsifier joins the center of the nozzle by the radial channel 82 from which it is sprayed outwards, with a rotational movement, through aperture 84 and diffusion cone 86.

Due to the strong stirring of the mixture, it is a jet of large drops, typically having a diameter of 0.6 to 0.8 mm, which, by sucking a large amount of air, is projected onto the mesh 52, which breaks the drops into very fine particles, typically having a diameter of 0.1 to 0.2 mm, to thus provide an extinguishing foam all the more effective that it is further enriched by the air sucked through the portion 90 of the mesh.

It should be noted that the use of a brewing chamber made of copper contributes to ensuring the stability of the foam produced.

This description has been made with reference to an embodiment in which the horizontal liquid supply channel opens downstream of the baffles. It will be noted that, according to an alternative embodiment, this channel may also open upstream of the baffles.

• est équipée de détecteurs thermiques, donc à réponse rapide et insensibles, notamment aux salissures risquant de les "aveugler" partiellement ou totalement;
• est capable de répondre, de manière ciblée, à plusieurs incendies séparés les uns des autres;
• attaque l'incendie à l'aide de mousse, c'est à dire en consommant très peu d'eau et de manière plus efficace qu'en utilisant uniquement de l'eau; et
• est équipée de buses d'extinction à grand "pouvoir moussant" et réalisables en petites dimensions.

Thus is realized a fire detection and extinguishing system which:

• is equipped with thermal detectors, so quick response and insensitive, including soils that may "blind" partially or totally;
• is able to respond, in a targeted manner, to several fires separated from each other;
• attacks the fire with foam, ie by consuming very little water and more efficiently than using only water; and
• is equipped with extinguishing nozzles with high "foaming power" and achievable in small dimensions.

Such an installation is therefore very well suited to fighting fires in large confined spaces, such as tunnels, car parks or warehouses.

It should especially be noted that it is particularly well suited to fit into the template of a single or two-way road tunnel, single-lane or two-lane, without restricting the passage of large vehicles.

Claims (16)

1. Installation for detecting and extinguishing fire in an enclosed space, comprising a plurality of separate assemblies each assigned to protecting one sector of the said space and comprising, for each sector:

   - a plurality of heat detectors (10) distributed through the sector, each closing off the end of a pipe (12) supplied with compressed air and reacting to an abnormal rise in the ambient temperature by opening the said duct to the open air;

   - a plurality of foam extinguishing nozzles (26) distributed through the upper part of the sector; and

   - control means (16) which respond to a drop in pressure resulting from at least one of the said ducts (12) being opened to the open air by supplying all the nozzles (26) in the sector with a mixture of pressurized water and foaming compound allowing them to spread extinguishing foam over this sector.
2. Installation according to Claim 1, characterized in that each assembly further comprises means (14) which also respond to the said drop in pressure by shutting off the supply of compressed air to the detectors (10) in the sector so as to ensure that the detectors in the other sectors are kept under pressure.
3. Installation according to one of Claims 1 and 2, characterized in that each assembly further comprises a plurality of thermokinetic detectors (46) distributed through the sector and means (44) responding to the said detectors in such a way that the said control means (16) come into action only if the temperature rises abruptly.
4. Installation according to one of Claims 1 to 3, characterized in that, in the case of a tunnel, each sector is about 15 to 20 metres long.
5. Installation according to one of Claims 1 to 4, characterized in that each foam extinguishing nozzle (26) comprises:

   - means for producing an atomized jet of a mixture of water and foaming compound; and

   - means for receiving this jet, enriched with the air it draws in along its path, breaking the liquid droplets up into finer particles and thus producing a jet of foam.
6. Installation according to Claim 5, characterized in that the means belonging to the nozzle (26) for producing an atomized jet include a substantially cylindrical agitation chamber (50) comprising, from the top downwards:

   - an axial liquid supply duct (68);

   - a horizontal and circular liquid supply duct (70); and

   - an axial ejection duct (84) communicating with the two supply ducts.
7. Installation according to Claim 6, characterized in that the ejection duct (84) ends in a diffuser (86).
8. Installation according to Claim 6, characterized in that the horizontal liquid supply duct (70) extends over an angle less than 360°.
9. Installation according to one of Claims 6 to 8, characterized in that the agitation chamber (50) further comprises a wall pierced with orifices forming baffles (76) onto which the axial liquid supply duct (68) opens.
10. Installation according to Claim 9, characterized in that the horizontal liquid supply duct (70) opens downstream of the baffle-forming wall (76).
11. Installation according to Claim 10, characterized in that the agitation chamber (50) is made in two parts:

    - an outer part (54) including, in its top wall, the axial liquid supply duct (68) and, in its vertical wall, a horizontal groove (72) of semicircular cross section;

    - and an inner part (56) including, in its top part, the baffle-forming wall (76) and, in its vertical wall, a horizontal groove (78) of semicircular cross section which, with the groove of the outer part, forms the horizontal liquid supply duct (70).
12. Installation according to Claim 11, characterized in that the end of the horizontal liquid supply duct (70) communicates with the ejection duct (84) via a radial duct (82) formed in the inner part of the chamber.
13. Installation according to Claim 9, characterized in that the horizontal liquid supply duct (70) opens upstream of the baffle-forming wall (76).
14. Installation according to Claim 6, characterized in that the agitation chamber (50) is made of copper.
15. Installation according to Claim 5, characterized in that the means for receiving the atomized jet comprise a grating (52) in the shape of a cone frustum.
16. Installation according to Claim 15, characterized in that the central portion (88) of the grating (52) is domed upwards.

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