EP0635617A2 - Transparent flame shielding panel - Google Patents

Abstract

The invention relates to a transparent so-called flame-shielding (fire-stop) panel capable of retarding the propagation of flames and/or fumes or gas during a fire and including a glazed element comprising tempered (quenched) silicate-soda-lime glass equipped with means capable of fastening it to a supporting structure of a building. It is designed so as to be able to deform freely when it is heated up by fire, leaving peripheral clearances measured when cold between the glazed element and the fastening means and/or between fastening means and supporting structure which are sufficient to permit its expansion. <IMAGE>

Description

The invention relates to a transparent flame-retardant panel intended, when installed in the facade of a building, to delay the spread of a fire from one floor to another or, when installed in a partition, to avoid the propagation of flames between neighboring rooms. This type of flame-retardant panel can also be used as a gas separation element intended to equip the upper part of premises, an element also commonly referred to as a quartering screen.

Such a screen makes it possible to limit the propagation, inside a room, of flames, fumes and toxic gases which are released when a fire breaks out. It is particularly useful for large premises, in particular intended for receiving the public, it is usually fixed to the ceiling, according to a substantially vertical plane.

Fire-resistant glazing, called flame arrester (PF) according to the French ministerial decree of 04.21.1983 and corresponding to classes G 30 or G 60 of the German standard DIN 4102 have the property, during a fire (standard) , stay in place and prevent the passage of smoke and hot gases. The standardized tests for this type of product are described, among other things, in ISO 834 and ISO 3009.

It is known to use laminated glazing constituted by the assembly of several sheets of thermally toughened soda-lime-silica glass, the association being carried out with polyvinyl butyral (PVB) films, to constitute flame-retardant glazed systems. Thus, the European patent EP-219 801 B1 proposes to associate for this purpose at least three sheets of float glass with a thickness of at least 3 mm using PVB to produce glazing G 30. We also know specific mounting techniques which allow a sheet of tempered glass based on a conventional silica-soda-lime composition to have a flame retardant behavior of more than half an hour. Thus, the assembly of the French patents FR - 2 282 033, FR - 2 314 993 and FR - 2 366 434 makes it possible to expose the edges to heat radiation while that of the European patent EP - 0 079 257 B allows indirect heating of the same edges of the glazing. However, the techniques of the prior art are limited to relatively small dimensions. In particular, when there is a need for regular heating of the edges, it is essential that the flames which heat the glass are homogeneous over its entire surface, which is all the more difficult to achieve during standardized tests or the more random in the event of a real fire, the larger the glazing surfaces. Likewise, in the case of the triple laminated glazing of EP - 0 219 801. if the dimensions increase, the deformations of the frame due to the thermal stresses which it undergoes become very significant and risk breaking the glazing or, at least, cause loss of sealing at its periphery.

It is known in particular thanks to European patent application EP -A- 0 569 298 to equip an insulating fire-resistant glazing with a device which normally ensures sealing but which, during a fire, limits the overpressure to inside the glazing and thus prevents its explosion.

The invention sets itself the task of producing a very large glazing which is flame retardant for durations substantially greater than half an hour and which can be used either in a dividing wall, or in a facade or as cantonment screen.

The technique described in patent EP - 0 219 801 - B1 allows, in the case of dimensions 160 x 120 cm², to reach a flame arrester duration of 36 minutes and this thanks to the combination of a triple laminated glass of which at minus the outer sheets are quenched in a conventional manner and of a particular assembly which clamps the periphery of the glazing by means of windscreens screwed onto a metal support frame so as to prevent any movement of the glazing relative to the wall which supports it. When such glazing is tested under the conditions of the standard, that is to say by subjecting one of its faces to a rise in temperature ΔT as a function of time t of the type:
Δ = 345 Log ₁₀ (8T + 1); (ΔT in kelvins and t in minutes) the mounting conditions systematically lead to any thermal gradient being transformed into stresses in the glass plate. These can reach significant values, and if they are extension constraints, they compensate for the compression preload of the toughened glass, any overshoot leading to a risk of breakage. On the other hand, the assembly according to the invention allows a relaxation of the stresses of thermal origin since the glass can deform freely: the breaking limit of the toughened glass, much higher thanks to special conditions, is only reached for markedly higher thermal gradients. However, the deformations of the flame-resistant glazing according to the invention, thanks to the sealing technique and the possibility of expansion, remain compatible with a behavior of barrier to hot gases, fumes and flames.

In comparison with the flame-resistant glazing system which uses a laminated-tempered glass mounted in a more traditional manner and whose effect is to limit the thermal gradient on the rear glass, the glazing of the invention also allows a significant improvement, since 'by authorizing the deformation of the glass corresponding to a given thermal gradient, it limits the stresses which result therefrom for the glazing and here also delays the breakage of this rear glass. Sealing, too, is better ensured by the techniques of the invention.

The techniques usually used to produce transparent flame-retardant panels use either borosilicate glasses which may be tempered, or, as we have seen above, soda-lime-silica glasses, one or more of which have been thermally toughened traditional.

The disadvantage of borosilicate panels is their high price and often the very poor optical quality of the plate. Furthermore, these products are only available in reduced dimensions.

We have seen that traditional tempered glasses, even when combined in laminated assemblies as in document EP-A-0 219 801 are also of limited dimensions.

The invention addresses both the problem of mounting the glazed element and that of its nature.

For mounting, the invention provides a transparent flame-retardant panel capable of delaying the propagation of flames and / or smoke or gas in the event of a fire. which comprises a glazed element comprising tempered silica-soda-lime glass equipped with means capable of fixing it to a structure of a building in which, during its heating in the event of fire, the glazed element can deform freely and in which also all of the peripheral clearances measured cold between the glazed element and its means for fixing to the structure and between said means and the structure are large enough to allow the glass element to expand freely at said temperature caused by warming up.

As regards the glazed element based on traditional glass, the invention proposes that it comprises one or more plates of soda-lime-silica glass of which at least one has undergone a thermal toughening treatment.

The hardened plate (s) preferably have a thickness greater than 5 mm, moreover, their edges are polished with a roughness of the polish less than 5 μm and their quenching stress is greater than 120 megapascals and preferably of the order of 140 megapascals. Advantageously, the fixing means of the frame and / or glazing bead type which equip the glazed element on at least one of its sides only cover the periphery of the glass plate having undergone thermal toughening up to an equal distance from its edge. maximum 15 mm and preferably 10 mm. The panel of the invention can advantageously be used as glazing in a facade or in a partition. It is then usually fixed to the supporting structure so that the fixing means to the frame of the glazing bead type enclose the four sides of the glazed element. If, on the other hand, it is used as a quartering screen in the upper part of premises, its fixing means must be adapted, with in particular a frame or a glazing bead enclosing only its upper edge, once fixed to the ceiling or false ceiling.

The glazed element of the invention exists in several variants, either it is a single glazing with a thickness of the order of 6 mm or it is a laminated glass comprising at least two sheets of tempered glass each of a thickness greater than or equal to 6 mm, the plates preferably being two in number. Advantageously, the laminated glazing comprises a single interlayer film of polyvinyl butyral with a thickness of less than 1 mm. But the glazed element according to the invention can also be an insulating glazing whose at least the glass plate on the side opposite the fire is made of toughened glass conforming to the criteria defined above, as for the plates exposed to fire, they can be made of normal toughened glass or Laminated glass.

Preferably, the insulating glazing comprises a balancing element which limits the overpressure when the glazing is exposed to fire and the glass plates are assembled at their periphery with an adhesive based on silicones.

The combination of a particular toughening treatment and the special assembly provided for in the main claim makes it possible to prevent the mechanical stresses introduced both by the thermal gradients and by the mechanical deformations from exceeding the breaking limit of the toughened glass. It therefore remains intact throughout the temperature range where its deformation is elastic. When it reaches the plastic deformation range, it is no longer likely to undergo the fragile breakage typical of glass materials.

Preferably, if it is envisaged to use the panel as a separating element of the cantonment screen type, the glazed element of the panel may comprise a glazing called fire-resistant and formed of at least two glass plates parallel to each other and define an intermediate space in which is placed a layer made of an aqueous gel, the aqueous phase of which comprises a salt, a type of glazing for example known from the patents FR - 2 346 548, EP- 0 214 056 or EP - 0 442 768 as well as FR patents - 2 027 646 or FR - 2 321 575. Their operating principle is as follows: the heat, in the event of fire, begins to be absorbed in the glazing by the water of the aqueous gel and she vaporizes it. In a second phase, after the evaporation of the water and the combustion of the solid organic phase of the gel, the said gel constitutes a solid crust which makes an insulating "shield" against thermal radiation and which, in the context of the invention, can also act for a certain time as a flame or gas barrier.

The glazed element may also, in addition to the plate (s) made of soda-lime-silica glass, include plates made of so-called special glass having, by their composition, increased resistance to heat, in particular one or more boro glass plates. silicate. We can also mention the reinforced silico-soldo-calcium glass plates.

The mounting system of the glazed element, always when it serves as a separation element of the cantonment screen type, that is to say the set of means which will make it possible to fix it to the supporting structure, also intervenes. significantly in the general appearance of the separating element. Preferably, these means are therefore designed so as to leave visible at least one of the sides of the glazed element, in particular its lateral edges and most of its lower edge. (In the context of the invention, the terms “lateral”, “upper” or “lower” are to be understood with reference to the separating element which is considered once fixed to the supporting structure, such as a ceiling, according to a substantially vertical plane).

Thus leaving at least one free side, and preferably three, indeed brings a double advantage: first of all, such an assembly greatly reinforces the character of discretion and the impression of lightness already given by the whole of the element separation thanks to the glass material used. Furthermore, these visible edges will allow the glazed element to expand and deform freely in these areas once subjected to heat, which reduces the risk of sudden breakage thereof and consequently increases its resistance. fire.

These fixing means comprise in particular means for supporting a part of the lower edge of the glazed element, means very particularly located at the corners of said edge and which can take the form of small lugs-supports.

In this way, the above-mentioned lightness is kept as a whole, while optimally guaranteeing the durable and secure mechanical fixing of the glazed element to the support structure.

The fixing means may also include means for holding at least one of the edges of the glazed element, especially its upper edge. It is understood as holding means, within the framework of the invention, any means making it possible to position the glazed element relative to the support structure and / or to keep it fixed more or less strongly and / or to ensure a screw tightness -in relation to the gases between the separating element and the structure or the ceiling against which it is subsequently arranged. These holding means comprise in particular a frame or a glazing bead not covering preferably at most 15 millimeters from the periphery of the edge, distance measured from its edge. This ensures gas tightness between said edge and the frame or the glazing bead. This distance of at most 15 millimeters is indeed advantageous in the sense that the portion of glass which is enclosed in the frame where the glazing bead is sufficiently reduced to best reduce the thermal gradients in the glazed element subjected to fire between its middle part and its peripheral edges covered by said frame, thermal gradients which are the source of sudden glass breakage. However, this distance remains sufficient to ensure satisfactory maintenance of the glazed element in its frame. The sealing mentioned is of course important to avoid the circulation of flames and fumes between frame and glass.

Advantageously, provision is made for the maintenance of the glazed element in its frame, very particularly at its upper edge, to be ensured using a fibrous material interposed between the two, a fibrous material which may be of metallic nature or ceramic. The advantage of a fibrous material is its capacity for compression, which makes it possible to "adjust" the intensity of tightening of the glazed element in its frame by mechanical means of the screw and bolt type, and therefore to adjust the fixing between them. If it is metallic in nature, which is for example known from patent application EP-0 568 458, it contributes on the one hand, by its high thermal conductivity, to reducing the thermal gradients between the edge of the glazed element covered by the frame and the rest of said element. On the other hand, it tends to slow down the fall of the glazed element by sagging when it softens under the effect of heat, the metal fibers becoming encrusted in the softened glass and thus retaining it. The type of mounting recommended in this application allows a very effective "pinching" of the edge of the glazed element in its frame.

Furthermore, these means for holding the upper edge of the glazed element can be designed so that once the assembly is fixed to the support structure, they guarantee the gas tightness between the separating element and said supporting structure of the ceiling type. Thus the holding means in the form of a frame can advantageously be extended so as to be able to be pressed against the ceiling without discontinuity of contact between frame and ceiling. To ensure continuity between the frame and the ceiling-type supporting structure, without preventing expansion of the frame in the event of fire heating, can have any suitable type of fibrous or compressible joint between them. It goes without saying that, according to the design of the room to be fitted, the separation element can be fixed directly to an upper support structure, slab type, while said element is in fact pressed against a false ceiling which is itself attached to the slab. In addition, additional sealing means of the appropriate sealant type can be provided between the frame and the ceiling (or false ceiling).

Connecting means can also be advantageously provided for connecting the support means, of the lug type, of the lower edge of the glazed element to the frame-type holding means of the upper edge of the latter. Preferably, these connecting means, in the form of rods, run without contact at least one of the side edges of the glazed element and are designed so as to be able to pivot relative to said holding element.

In this way, it is easy to quickly secure the glazed element to its various fixing means.

The fixing means of the glazed element are preferably metallic, the metal having good resistance to fire and also thermally expanding more than the glazed element. In this way, in particular at the level of the frame-type holding means of the upper edge of the glazed element, the said frame will expand at least as much as the glass during a fire and therefore will allow the latter to deform relatively freely in the heat, even if, at the start, the glass is relatively firmly held in the frame.

Depending on the dimensions of the room to be fitted with the separation elements according to the invention, it may prove necessary to provide a plurality of elements arranged side by side. It is then advantageous to assemble them using gas-tight jointing means, to avoid the circulation of flames and fumes between two adjacent separating elements.

It should also be noted that with the assembly according to the invention, it is possible to manufacture effective separation elements, of large dimensions and nevertheless offering great safety in use. Thus, the glazed elements according to the invention can usually have a height of 0.3 to 1 meter, a length of 1 to 2.5 meters and a thickness of about 6 to 10 millimeters or more.

• figure 1 : une coupe d'un cadre d'un vitrage monolithique conforme à l'invention et,
• figure 2 : un vitrage double.
• figure 3 : un écran de cantonnement selon l'invention,
• figure 4 : une vue partielle de la fixation en partie haute de l'élément vitré de l'écran de cantonnement selon la figure 3,
• figure 5 : une vue partielle du montage de la fixation en partie basse de l'élément vitré de l'écran de cantonnement selon la figure 3.

The details and advantageous features of the invention appear from the following non-limiting embodiments and illustrated with the aid of the figures which represent: (the first two figures relate to a panel used as glazing. The following figures relate to a panel used as a cantonment screen).

• FIG. 1: a section through a frame of a monolithic glazing according to the invention and,
• Figure 2: double glazing.
• FIG. 3: a blocking screen according to the invention,
• FIG. 4: a partial view of the fixing in the upper part of the glazed element of the blocking screen according to FIG. 3,
• FIG. 5: a partial view of the mounting of the fixing at the bottom of the glazed element of the blocking screen according to FIG. 3.

In Figure 1 is shown in 1 a toughened monolithic glazing according to the invention. It is a silica-soda-lime float glass which has undergone a particular treatment which will be presented in detail below. The folded sheet steel section 2 with a thickness of the order of 2 mm constitutes the frame of the glazing, it is linked to the structure of the building under the conditions described below. This profile 2 comprises a rebate with an angled section which carries the glass by means of lower support wedges 5 made of an asbestos-based material. The name PROMABEST Y from the company PROMAT at 78540 Vernouillet (France) designates a suitable material. In the case of a glass 1 10 mm thick and 170 cm high, the dimensions of the support shims 5 are: width 13 mm, thickness 8 mm, they extend without interruption under the entire horizontal dimension of the glazing. On the two vertical sides and above the glazing a space of equivalent thickness is left free. On both sides of the glass, seals 6 in ceramic fiber hold it laterally. For sealing the joint covers 7, for example made of silicone, complete the assembly. The lateral holding is ensured by a glazing bead 3 also folded sheet. It has a longitudinal lug 10 which fits into the housing 9 of the main profile. From place to place, a self-tapping screw 11 prevents the exit of the glazing bead during the fire, the space between the screws 11 is of the order of 70 cm or less. The height of the profiles 2 is, for glazing with a dimension of 1.70 m squared, of the order of 80 mm. The width should be narrower, on the order of half.

Profile 2 is not in direct contact with the structure of the building, but there is a large peripheral clearance around the frame when cold (at least 0.6%, i.e., for example, 20 mm of cumulative play with respect to the structure for overall dimensions of the glazed unit of the order of 3 m).

In the figure, this game shown in 17 is filled with rock wool.

The lateral fixing of the frame perpendicular to the glass, on the other hand, is rigid.

One means of achieving these two conditions, lateral fixing and possibility of longitudinal expansion, is produced by the system shown at the bottom of FIG. 1. L-shaped profiles, on the four sides of the frame are rigidly fixed to the structure by means ( lag screws for example) not shown. In the plane parallel to the glazing, the fixing is done by screws 13 fitted with washers 18, they pass through oblong holes 12 (the screws are at the end of these holes directed towards the inside of the frame). These holes have a length at least equal to the clearance provided in 17. In the figure, the mounting is provided so that the light comes from the right, in this case, it is advantageous that the washers 18 (on the side of the light) are formed a material which creeps under heat but whose cold modulus remains high and the creep low; An aluminum alloy is suitable as a material for these washers; but even with steel washers, in general, the expansion forces and the clearance provided by the heating of the screw are such that the expansion of the frame is not prevented.

On the other side, a fixing of the same type allows a plate 14 to close off the passage without hampering the expansion of the frame by means of screws 15 passing through oblong holes 16.

The space 17 is, as we have seen, advantageously filled with rock wool.

The clearances which are provided, on the one hand at the periphery of the glass at 5 and on the other hand at the periphery of the frame at 17 make it possible to greatly limit the stresses which are exerted on the glass during a fire. If the clearance around the glass can remain the same, regardless of the dimensions of the latter, the same is not true of clearance 17, at the periphery of the frame. It must be all the more important as the dimensions of the frame are themselves larger. In general, a clearance of 8 mm at the periphery of the glass is sufficient. On the other hand, as we have seen, the clearance 17 must be of the order of 0.6% of the corresponding dimension of the opening.

An equally important parameter is the height of overlap of the rebate on one side and the glazing bead on the other on the glass 1. This height which corresponds to the "shadow cast" by the steel of the frame on the glazing during of the fire must remain less than 15 mm, the value of 10 mm is perfectly suitable.

The soda-lime-silica glass 1 in FIG. 1 has a thickness of 6 mm. He underwent special treatment. In general, the glazed element consists of glazing designed to remain in place during a fire. The triple combination described in European patent EP-0 219 801 B1, with dimensions height 160 cm, width 120 cm and thickness combinations 4 mm hardened, 4 mm annealed, 4 mm hardened, for example meets this requirement during a duration of 36 minutes when subjected to the standard temperature rise curve.

However, the glazed elements of the invention, which are both simpler and more rigorous, make it possible to obtain longer lasting fire resistance. They comprise one or more plates of soda-lime-silica glass of which at least one has undergone a particular treatment. This consists on the one hand of polishing the edges with a polish roughness of less than 5 µm and on the other hand of a thermal quenching treatment providing a surface compression stress of at least 120 megapascals and preferably 140 megapascals.

The assembly presented in FIG. 1 is compatible, as we have seen, with a 6 mm thick monolithic element, but, provided that the width of the profile 2 is increased, it is also compatible with thicknesses of 8 or 10 mm (elements monolithic having undergone the same processing steps).

Another combination has also been tried and has given satisfaction, it is the combination of two monolithic glasses of the previous type associated in a laminated glazing by means of a polyvinyl butyral (PVB) film. Glass thicknesses of twice 8 mm and twice 10 millimeters were satisfactory, the glasses were combined by a single sheet of PVB with a thickness of 0.76 mm.

Figure 2 shows the association of a frame little different from that of Figure 1 with a glazed element consisting of insulating glazing.

The insulating glass 20 consists of two glasses 21, 22 of which at least one 22 has undergone the treatment of the invention, it is it which is located on the side opposite the fire.

It is necessary that the two glasses 21, 22 have undergone the same treatment in the case where the flame-retardant wall must be able to operate in both directions.

The profile 23 which separates the two glasses is made of steel, the assembly is carried out with a mastic 24 based on silicones. In addition, the insulating glazing is equipped with a device (not shown) which allows pressure balancing between the interior and the exterior of the glazing when a fire causes it to heat up. The device described in European patent application filing number 93 401 162.8 corresponding to FR-2,690,946 and which consists of a special corner with a fusible cover which is used to assemble the profiles 23 is perfectly suitable.

The mounting of the insulating glazing 20 in the profile 25 is identical to that of FIG. 1, the method of connection between the frame and the structure of the building is also the same.

In the case where the two glasses 21, 22 are not identical, one can associate with the glazing 22 which has undergone the special preparation in accordance with the invention, a glazing 21 which is either a normal toughened glass, or a laminated glass combining two annealed silica-soda-lime glasses.

Two fire tests according to ISO 834 and ISO 3009 were carried out. In both cases, the frame was of the type of those of FIGS. 1 and 2. The glazed elements were on the one hand made of monolithic glass 6 mm thick and on the other hand laminated glazing made up of two 10 mm glasses assembled with PVB.

TEST # 1

The 3m x 3m oven rack was equipped with 4 glazed elements whose dimensions were respectively:
height 109 cm, width 105 cm
and height 109 cm, width 172 cm
for the bottom glasses and:
height 168 cm, width 105 cm
and height 168 cm, width 172 cm
for those at the top.

All had undergone special shaping and tempering.
Their common thickness was 6 mm.

   où le temps t est exprimé en minutes.

• à la 12^ème minute, le montant vertical central se cintrait vers le four avec une flèche de 10 cm,
• à la 24^ème minute, montant et traverse centraux avaient une flèche de 15 cm et à 38 minutes, de 20 cm,
• à la minute 43, la flèche atteint 25 cm, la déformation du vitrage le plus grand est visible,
• à la 59^ème minute, le plus grand des verres du haut commence à fluer et libère pour la première fois le passage aux flammes et aux gaz : fin de l'essai.

The temperature rise in ° C followed the law: $${\text{TT}}_{\text{o}}\text{= 345 Log₁₀ (8 t + 1)}$$

where time t is expressed in minutes.

• at the 12 ^th minute, the central vertical upright bent towards the oven with a 10 cm arrow,
• at the 24 ^th minute, the central upright and cross had a 15 cm arrow and at 38 minutes, 20 cm,
• at minute 43, the arrow reaches 25 cm, the deformation of the largest glazing is visible,
• in the 59 ^th minute, the largest glasses from the top starts to flow and releases first passing flame and gas: end of the test.

TEST # 2

The glazed element is a 2 x 10 mm laminated glazing, each constituent element of soda-lime-silica glass has undergone the two specific treatments described above. They are associated with a single sheet of PVB 0.76 mm thick. The glazing is vertical, 2.78 m high and 1.68 m wide.

• dès la 3^ème minute le vitrage se déforme (convexité du côté du four),
• à la minute 7 le verre côté chaud se fragmente en tout petits morceaux qui restent collés à l'autre verre,
• minute 14, inflammation du PVB. Quelques fragments du verre côté chaud tombent,
• 18^ème minute, le PVB noircit,
• minute 21 : la déformation (cintrage) du vitrage atteint 5 cm,
• minute 36 début de fluage du vitrage mais il reste maintenu en partie haute,
• 42^ème minute, la partie haute du vitrage sort de la pareclose,
• minute 43 : fin de l'essai, le vitrage s'effondre et libère le passage pour les flammes et les gaz.

The test takes place under the usual conditions:

• from the 3 ^rd minute the glazing deforms (convexity on the side of the oven),
• at minute 7 the glass on the hot side breaks up into very small pieces which remain stuck to the other glass,
• minute 14, inflammation of PVB. Some fragments of the glass on the hot side fall,
• 18 minutes, ^the PVB blackens,
• minute 21: the deformation (bending) of the glazing reaches 5 cm,
• minute 36 start of creep of the glazing but it remains maintained at the top,
• 42 ^th minute, the upper part of the glazing comes out of the glazing bead,
• minute 43: end of the test, the glazing collapsed and freed the passage for flames and gases.

A second embodiment of the invention is shown in Figures 3 to 5. It is a cantonment screen, or separation element.

The separating element 31 shown diagrammatically in FIG. 3 is intended to be suspended in a substantially vertical plane from the ceiling (not shown) of a room of large dimensions in order to block, or at least brake for a certain time. , the spread of smoke, flames and toxic gases from one end of the said premises to the other if a fire breaks out there.

This element 31 mainly comprises a transparent glazed element composed of a so-called flame-resistant glazing having good fire resistance. It is a monolithic glazing (it could of course also have a laminated or insulating glazing structure) in silica-soda-lime float glass having undergone on the one hand a polishing of its edges in order to obtain a roughness of polished less than 5 micrometers and on the other hand thermal quenching in order to give it a surface compression stress of at least 120 Mpa and here of about 140 Mpa, just like the monolithic glazing of Figure 1 above.

Its dimensions are approximately as follows: a thickness of 6 millimeters, a width of 50 centimeters and a length of 1.8 meters.

In the upper part of the glazing 32, the edge of the glazing 32, therefore the one which will be closest to the ceiling, has its periphery enclosed in a metal profile 35 which, as shown in FIG. 4, consists of a plate 36 and an angle iron 37. The angle iron 37 is screwed onto the flat 36 using nuts 38 associated with screws 39. Provision is made to interpose between glazing 32 and profile 35 a fibrous material 40, ie ceramic fibers in particular marketed under the name of Fiberfrax, either in metallic fibers, in particular in the form of a covered braid in accordance with the aforementioned patent application EP-0 568 458. If it is chosen to be metallic, it makes it possible, by penetrating the surface of the softened glass, to curb its fall under the effect of the heat of a fire and, because it is a good thermal conductor, it limits the thermal gradient between the edge of the glazing 32 in the profiled frame 35 and the rest of the glazing.

This fibrous material, whatever its nature, has a section of approximately 10 x 5 square millimeters at rest.

By adjusting the tightening of the bolt 38, 39, the fibrous material 40 is more or less strongly compressed and the glazing 32 more or less firmly held in the profile 35.

Since the profile 35 is here of a metallic nature, it is however not necessary to provide at the outset too great a cold clearance, between frame and glazing allowing the glazing to be deformed in the event of fire, since the profiled will tend to expand more than glass, creating the necessary clearance at the time of the fire. If the profile is of a different nature, it may be advantageous, however, to provide a greater peripheral clearance, when cold, between the glazing 32 and the profile 35 to prevent the glazing from suddenly breaking during a fire and being returned. therefore completely ineffective.

A joint cover 41 made of a gas-tight and heat-resistant material, for example that sold under the name of Pyrosil B, is deposited on the fibrous material 40 in order to ensure a neat finish. Together with the fibrous material 40, it also effectively blocks the passage of flames and fumes between the upper edge of the glazing 32 and the profile 35.

The dish 36 is provided in the upper part with orifices 42 regularly distributed over its entire length and intended to be able to fix it securely to the ceiling using known mechanical means not shown. The separating element 31 can therefore, by extending this plate 36, be pressed against the ceiling, preventing any passage of gas or flames between the two.

Care is taken that the periphery of the upper edge of the glazing 32 measured from its edge is only covered by approximately 10 millimeters by the profile 35, so as to ensure sufficient maintenance of the glazing 32 in its profile 35 while limiting the better the importance of the thermal gradients which can be established during a fire between the edge of the glazing covered by the profile and the rest of the glazing which is itself directly exposed to heat, gradients which are the source of rapid breakages glazing as already mentioned.

The glazing support effort 32 can be partly and even essentially ensured by firmly holding the upper edge of the latter in its profile 35.

It is however preferable, for greater safety, to provide a support for the glazing 32 in the lower part, which is the object of FIG. 5. This support consists in supporting the two lower corners of the glazing in the glazing 32 using 'pins 33 taking the form of metal sections of U-shaped section. They can be provided with a suitable length so that they offer effective support while remaining sufficiently discreet. A good compromise is for example a length of in the range of 15 to 25 millimeters. These lugs 33 are themselves supported by metal rods 34 of square section of about 12 x 12 square millimeters which run along the side edges of the glazing 32 without touching them and are fixed to the profile 35 so that movement is authorized. pivoting of the rods relative to the profile.

The mounting of the glazing therefore reduces at best the risks of breakage of the glazing, by limiting the thermal gradients in the glazing and leaving it the possibility of deformation, while providing it with effective mechanical support once the separating element 31 is suspended. .

The fact that the side edges and almost the entire bottom edge are left free makes the whole discreet and aesthetic, and the very characteristics of the glazing ensure it has excellent resistance to fire.

In order to assess the period during which such a separation element or blocking screen 31 can perform its function of a flame and gas barrier, it was subjected to fire tests according to ISO 834 and ISO 3009 standards in the same conditions than before.

The separating element 31 is during the test located 190 millimeters parallel and behind the ceramic glass vitreous constituting the front face of the oven used to simulate the fire.

During the first twenty minutes of the test, the screen 31 retains its mechanical strength without any weakness. From the 25 ^th minute, the glass begins to sag and become thinner below the fixing region by clamping in the profile 35. The collapse thereof occurs to the ^35th minute.

The separating elements according to the invention are therefore capable of blocking the propagation of flames and gases in the upper part of premises for at least approximately 30 minutes. They therefore have the required level of fire resistance while being very aesthetic.

If one wishes an extremely effective tightening of the upper edge of the glazing in its frame, the assembly described in the aforementioned application EP - 0 568 458 is also particularly recommended. Therefore both by the choice of the fire-resistant glazed element itself and by the choice of its mounting, the screen according to the invention can be adapted according to the needs and the level of performance required. In any event, the type of mounting allows the element glazed to expand freely, since it has three of its free sides, its upper side enclosed with a fibrous material in a manner also allowing a certain expansion.

Furthermore, it is possible, if necessary, to arrange the screens edge to edge, by assembling them for example using a heat-resistant and gas-tight seal, disposed between the rods 34 of the screens that are assembled. . We can also consider providing each screen 31 with a single rod 34 along only one of the side edges of the glazing but provided with two lugs 33 capable therefore of simultaneously supporting the two contiguous corners of two separating elements assembled side by side .

The glazings that have just been described and their mounting technique thus make it possible, from inexpensive glasses and of excellent optical quality, to obtain efficient flame-retardant products.

Before the development of glass products and assembly techniques of the invention, only small products or special glasses (armed glasses, borosilicates) made it possible to have flame-resistant glazing. In particular, the mounting techniques according to the invention make it possible to reach the intrinsic limits of the glass product itself whereas previously its breakage produced well before the intrinsic limits of the glazed element were reached.

Claims (21)

Transparent panel known as a flame arrester capable of delaying the propagation of flames and / or smoke or gas in the event of fire and comprising a glazed element comprising tempered silica-soda-lime glass fitted with means capable of fixing it and a supporting structure of a building, characterized in that during its heating during a fire, the glazed element can deform freely, and in that all of the peripheral clearances measured cold between the glazed element and its means of attachment to the support structure and between said means and said structure are large enough to allow the free expansion of the glazed element caused by its heating. Panel according to claim 1, characterized in that the glazed element comprises one or more plates of soda-lime-silica glass of which at least one has undergone a thermal toughening treatment. Panel according to claim 2, characterized in that the glass plate or plates of the glazed element having undergone thermal toughening have a thickness greater than 5 mm, in that their edges are polished with a roughness of the polish less than 5 µm and in that their quenching stress is greater than 120 megapascals and preferably of the order of 140 megapascals. Panel according to one of the preceding claims, characterized in that the fixing means of the frame and / or glazing bead type which equip the glazed element on at least one of its sides do not cover the periphery of the glass plate having undergone thermal toughening only up to a distance of its edge equal to a maximum of 15 mm and preferably equal to 10 mm. Panel according to claim 3 or 4, characterized in that the glazed element comprises a single glass plate with a thickness of the order of 6 mm. Panel according to claim 3 or 4, characterized in that the glazed element is a laminated glass, comprising in particular at least two plates of tempered glass each with a thickness greater than or equal to 6 mm. Panel according to claim 6, characterized in that the laminated glazing comprises a single interlayer film of polyvinyl butyral with a thickness of less than 1 mm. Panel according to claim 3 or 4, characterized in that the glazed element is an insulating glazing of which at least the glass plate on the side opposite the fire is made of tempered glass according to claim 3. Panel according to claim 8, characterized in that the plate or plates exposed to the fire are made of normal toughened glass or laminated glass. Panel according to claim 8 or 9, characterized in that the insulating glazing comprises a balancing element which limits the overpressure when the glazing is exposed to fire. Panel according to one of claims 8 to 10, characterized in that the glass plates are assembled at their periphery with a silicone-based adhesive. Panel (31) according to one of the preceding claims, characterized in that the maintenance of the glazed element (32) in the fixing means having the form of a frame or glazing bead (35) is ensured using a fibrous material (40) interposed between the two, in particular of ceramic or metallic nature. Panel according to one of the preceding claims, characterized in that it is intended to be arranged in the upper part of the premises as a separating element, the means capable of fixing the glazed element to the supporting structure of the ceiling type being designed so as to leave visible at least one of the sides of said glazed element (32), in particular the lateral edges and most of the lower edge of the glazed element (32) once fixed to the support structure in a substantially vertical plane. Panel (31) according to claim 13, characterized in that the means capable of fixing the element (32) to the support structure comprise support means (33) of a part of the lower edge of the glazed element (32 ) once fixed to the supporting structure, in particular at the corners of said edge. Panel (31) according to claim 13 or claim 14, characterized in that the means capable of fixing the element (32) to the support structure comprising holding means (35) of at least one of the edges of the glazed element (32), in particular only the upper edge of said element (32) once fixed to the support structure, holding means comprising a frame or a glazing bead preferably preferably covering no more than 15 millimeters from the periphery of the edge measured at from its edge and ensuring gas tightness between edge and frame or glazing bead. Panel (31) according to one of claims 13 to 15, characterized in that the holding means (35) of the upper edge of the glazed element (32) are designed so that once the element of partition (31) fixed to the supporting structure of the ceiling type, they guarantee gas tightness between the separating element (31) and the supporting structure of the ceiling type or the false ceiling. Panel according to one of claims 13 to 16, characterized in that the support means (33) are connected to the holding means (35) by connecting means (34), in particular rods running along without contact at least one lateral edges of the glazed element (32) once the assembly has been fixed to the support structure and can pivot relative to said holding means (35). Panel (31) according to one of claims 13 to 17, characterized in that the fixing means (33, 34, 35) of the glazed element (32) are metallic. Panel (31) according to one of claims 13 to 18, characterized in that the glazed element (32) is a fire-resistant glazing formed by at least two glass plates parallel to each other and defining an intermediate space in which is placed a layer made of an aqueous gel, the aqueous phase of which comprises a salt. Panel (31) according to one of claims 13 to 19, characterized in that the glazed element (32) also comprises at least one plate of borosilicate glass or at least one plate of reinforced soda-lime glass. Plurality of panels (31) according to one of claims 13 to 20, characterized in that they are assembled side by side using gas-tight jointing means.

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