FR2708031A1 - Transparent flame-protection panel - Google Patents

Abstract

The invention relates to a fireproof transparent panel with improved flame-protection properties. The invention provides for the glazed element to be laid in a special way - it can expand freely during a fire as well as deforming. It consists of at least one sheet (pane) made of soda-lime glass, either as a single glazing or as an insulating glazing, or consisting of two laminated sheets bound with a thin film of polyvinylbutyral.

Description

TRANSPARENT FLAME RETARDANT PANEL
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.

 Fire-resistant glazing, called flame arrester (PF) according to the French ministerial decree of 04/21/83 and corresponding to classes G 30 or G 60 of the German standard DIN 4102 has 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 formed by the assembly of several sheets of thermally toughened soda-lime-soda lime glass, the association being made with polyvinyl butyral (PVB) films, to constitute glazed systems flame. 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. There are also known specific mounting techniques which allow a sheet of tempered glass based on a classic silica-soda-lime composition to have a flame-retardant behavior of more than half an hour. Thus, the assembly of 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 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. Similarly 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 large 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 93-401 162.8 to equip an insulating fire-resistant glazing with a device which normally ensures sealing but which - during a fire - limits the overpressure inside 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.

 The technique described in patent EP 0 219 801-B1 makes it possible, in the case of dimensions 160 x 120 cm, to reach a flame arrester duration of 36 minutes, and this thanks to the combination of a triple laminated glass of which at least the outer sheets are quenched in a conventional manner and thanks to a particular assembly which clamps the periphery of the glazing by means of fences closed on a metal support frame so as to prevent any movement of the glazing relative to the wall which supports it. When one tries such a glazing under the conditions of the standard, that is to say by subjecting one of its faces to a rise in temperature LT as a function of time t of the type = T = 345 Log1O (8t + 1) (LT in Kelvin and t in minutes) the mounting conditions systematically lead to any thermal gradient becoming 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 tempered 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, silica-soda-lime glasses, one or more of which have undergone traditional thermal tempering.

 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 associated in laminated assemblies as in document EP-A-O 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 for a duration t which comprises a glazed element based on soda-lime tempered glass equipped with a frame linked to the structure of a building in which, during its normalized heating up to the temperature corresponding to the duration t, the glazed element can deform freely and in which also, all of the peripheral clearances measured cold between the glazed element and the frame and between the frame and the structure are large enough to allow the glass element to expand freely at said temperature.

 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, and advantageously, the frame and / or the glazing bead which equip the glazed element only cover the periphery of the glass plate having undergone thermal tempering up to a distance from its edge equal to at most 15 irirti and preferably at 10 mm.

 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 are preferably two in number. Advantageously, the laminated glazing comprises a single interlayer polyvinylbtyral film with a thickness of less than 1 mm. However, the glazed element according to the invention may 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 tempered 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.

 The figures and the explanations which follow will make it possible to understand the operation of the invention.

FIG. 1 represents a section of a frame of a monolithic glazing according to the invention and,
Figure 2 shows double glazing.

 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 continuously under any 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 silicone terminate the assembly. The lateral holding is ensured by a glazing bead 3 also folded sheet. It has a longitudinal lug 10 which is inserted 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 building structure, but there is a large peripheral clearance around the frame when cold (at least 0.6%, i.e. for example 20 mm cumulative clearance 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 way of achieving these two conditions: lateral fixing and possibility of longitudinal expansion is achieved 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 of a material which creeps with 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, it is not the same for 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, we have seen the clearance 17 must be of the order of 0.6% of the corresponding dimension of the bay.

 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 when 1 fire must remain less than 15 mm, the value of 12 mm is perfectly suitable.

 The soda-lime-silica glass 1 in FIG. 1 has a thickness of 6 mm. He underwent special treatment. Generally, the glazed element consists of glazing designed to remain in place during a fire. The triple combination described in European patent EP 219 801 B1, with dimensions height 160 cm, width 120 cm and combinations of thickness 4 mm hardened, 4 mm annealed, 4 mm hardened, for example meets this requirement for a period of time 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 tempering treatment providing a surface compressive stress of at least 120 megapascals and preferably 140 megapascals.

 The mounting shown in Figure 1 is compatible as we have seen with a 6 mm thick monolithic element, but, provided 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 monoliths 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.

 I1 is necessary that the two glasses 21, 22 have undergone the same treatment in the case where the flame barrier 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 patent application EP-93 401 162.8 which consists of a special corner with a fusible cover which is used for assembling 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 21 which has undergone the special preparation in accordance with the invention, a glazing 22 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.

The temperature rise in "C followed the law
T - To = 345 Log1O (8 t + 1)
where time t is expressed in minutes.

- at the 12th minute, the central vertical upright bent towards the oven with a 10 cm arrow,
- at the 24th minute, 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,
- at the 59th minute, the largest of the upper glasses begins to creep and releases for the first time the passage to flames and gases: 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.

The test takes place under the usual conditions
- from the 3rd 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 the PVB. Some fragments of the glass on the hot side fall,
- 18th minute, 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 in the upper part,
- 42nd minute, the upper part of the glazing comes out of the glazing bead,
- minute 43: end of the test, the glazing collapses and frees the passage for flames and gases.

 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 glazed fireproof glass.

 In particular, the mounting techniques make it possible to reach the intrinsic limits of the glass product itself whereas previously its breakage occurred well before the intrinsic limits of the glazed element were reached.

Claims (11)

 1. Transparent flame-retardant panel for a duration t and comprising a glazed element based on tempered silica-soda-lime glass equipped with a frame linked to the structure of a building, characterized in that during its normalized heating up to the temperature corresponding to the duration t, the glazed element can deform freely, and in that all of the peripheral clearances measured cold between the glazed element and the frame and between the frame and the structure are large enough to allow the free expansion of the glazed element at said temperature.  2. 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.  3. 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.  4. Panel according to claim 3, characterized in that the frame and / or the glazing bead which equip the glazed element only cover the periphery of the glass plate having undergone thermal toughening up to a distance from its edge equal to maximum 15 mm and preferably equal to 10 mm.  5. 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.  6. Panel according to claim 3 or 4, characterized in that the glazed element is a laminated glass comprising at least two tempered glass plates each with a thickness greater than or equal to 6 mm.  7. Panel according to claim 6, characterized in that the laminated glazing comprises a single interlayer film of polyvinyl butyral with a thickness less than 1 mm.  8. 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.  9. Panel according to claim 8, characterized in that the plate or plates exposed to fire are normal tempered glass or laminated glass.  10. 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.  11. 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.