FR3028420A1 - PRESSURE VENT FOR GAS AUTOMATIC EXTINGUISHING SYSTEM, FIRE-STOP DEVICE EQUIPPED WITH SUCH EVENT AND METHOD FOR IMPLEMENTING SAID DEVICE - Google Patents

Abstract

The invention relates to an overpressure vent (10) for an automatic gas extinguishing system installed in a room, said vent comprising: - a frame (11) mounted at the periphery of an opening (6) made in a partition (1 ) of the room, - at least one louvre (12) rotatably mounted within the frame and adapted, in an open position, to provide an evacuation of a gas overpressure from the interior of the room to the l outside the room, the ventelle comprising: - a casing (120) made of a rigid material, and - a layer of a cooling material (121) filling the inside of the casing, so that the vent (10) ) has a fireproof effect that prevents heat transfer between the outside and the inside of the room. The invention further relates to a firestop device comprising such an overpressure vent. The invention further relates to a method of implementing such an overpressure vent in a room to be protected.

Description

TECHNICAL FIELD OF THE INVENTION The invention relates to an overpressure vent intended not only for the purpose of the invention, but also for the pressure relief device. evacuate an overpressure of a gas from an automatic gas extinguishing system, but also to ensure a fireproof effect. The invention furthermore relates to a firestop device equipped with this vent and to a method for implementing this device. The invention has applications in many fields of fire protection and, in particular, in the field of fire protection. Automatic extinction of a fire by gas. STATE OF THE ART For security reasons, it may be necessary to install a fire protection system in certain specific premises, such as clean rooms, computer rooms, TGBT rooms (General Low Voltage Table), etc. This protection system can be an automatic gas extinguishing system. Such a system is intended to extinguish any fire or start of fire by projection of a gas whose role is to stifle the fire. For this, the gas is propelled with a preset pressure. However, if this gas under pressure makes it possible to extinguish the fire by smothering, it also generates, in the room, an overpressure which, if it is not evacuated, can cause damage within the room (tearing of a door or a window, for example) see an explosion.

The pressure of the gas projected into the room when this pressure is greater than a predefined value tolerable by the room is called "overpressure". To avoid such damage, regulations require the installation of an overpressure vent in any room equipped with an automatic gas extinguishing system, this vent having the purpose of evacuating the gas when it is under overpressure.

There are currently many types of pressure relief vents. These overpressure vents may be associated with a protective grid to form a fire barrier device. This fire protection device provides, in addition to the evacuation of gas, a fireproof effect intended to limit the risk of fire spreading out of the room. Such a firestop device generally comprises a positive pressure vent positioned in an opening of a partition, or wall, of the room and a protective grid, also called a fire barrier, also positioned in this opening. This protective grid is generally made of an intumescent material which has the particularity of swelling and deformation under the effect of heat, preventing, for a predetermined time, the passage of flames. An example of a current firestop device is shown in FIG. 1. This device comprises an overpressure vent 2 positioned at one end 6a of an opening 6 made in the wall 1. It furthermore comprises a cut-off grid. fire 3 positioned at the other end 6b of the opening 6 and a finishing grid 4 placed parallel to the fire gate 3, in front of the opening 6b to close said opening.

In such a firestop device, the fire barrier 3 must be positioned at a minimum distance from the vent 2 to provide the fire barrier effect without damaging the vent. This minimum distance between the vent and the firewall is about 11 cm, which requires that the wall of the room is relatively thick.

SUMMARY OF THE INVENTION The object of the invention is precisely to overcome the disadvantages of the techniques described above. To this end, the invention proposes an overpressure vent ensuring itself a fireproof effect, which offers a saving of space and allows installation in partitions of small thickness, that is to say of thickness less than 11 cm. For this, the overpressure vent of the invention comprises one or more ventelles (s) made (s) in a rigid material forming an envelope in which is inserted a layer of a cooling material. More specifically, the invention relates to an overpressure vent for an automatic gas extinguishing system installed in a room, said vent comprising: a frame mounted on the periphery of an opening made in a partition of the room, 3028420 at least one louvre mounted to rotate within the frame and adapted, in an open position, to evacuate an overpressure of gas from the inside of the room to the outside of the room; characterized by the fact that the lamella comprises: - a casing made of a rigid material, and - a layer of a cooling material filling the inside of the casing, so that the vent has a fire-resistant effect preventing heat transfer between the outside and the inside of the room. Such a vent has the advantage of ensuring, in addition to the evacuation of the overpressure, a fire-resistant effect on each of its two faces, whether or not it is exposed to fire. "Thermal transfer between the outside and the inside of the room" means a transfer of heat from the outside to the inside of the room or, conversely, from the inside to the outside of the room, the fire being cut off both when it is outside the room and when it is inside said room. In addition, the firebreak effect being obtained by the vent itself, a room having a thin wall may be equipped with a fire barrier means. The overpressure vent of the invention may also include one or more of the following features: the frame comprises at least one layer of a refrigerant material participating in the fire barrier effect of the vent. the frame comprises a hollow sleeve, made of a rigid material, filled with the layer of cooling material. the frame comprises a solid sleeve on which the layer of refrigerant material is applied. - the ventelle is mounted inclined in the frame. - The vent comprises a plurality of louvers juxtaposed relative to each other and fixed each side of the frame. The invention also relates to a fire stop device for an automatic gas extinguishing system installed in a room. This fire protection device is characterized in that it comprises: at least one overpressure vent as described above, positioned at a first end of the opening in the partition of the room, and a finishing grid perforated positioned at a second end of the opening in the partition of the room, this second end being opposite the first end. This firestop device may furthermore comprise one or more of the following features: the finishing grid comprises a hollow bar structure made of a rigid material and a layer of a cooling material filling the inside of the bar structure dig. - The finishing grid comprises a solid bar structure made of a rigid material and a layer of a cooling material applied to the solid bar structure. a plurality of overpressure vents are joined to each other to form a large vent. The invention further relates to an automatic gas extinguishing system comprising at least one overpressure vent as defined above. The invention also relates to a method for implementing the above-defined overpressure vent which is characterized by the fact that it comprises the following operations: - estimation of a volume of gas necessary for protection of the room against fire, - calibration of an overpressure vent surface capable of evacuating a gas overpressure from this space, - determination of a number of lamellae corresponding to the calibrated overpressure venting surface, - determination of a number frames and a number of lamellae per frame to obtain the calibrated overpressure venting surface, - mounting the number of lamellae (12, 13) determined in the number of frames determined to achieve a vent, and 30 - setting of the vent thus obtained at the periphery of the opening (6) in the partition of the room.

BRIEF DESCRIPTION OF THE DRAWINGS Other advantages and characteristics of the invention will appear on reading the description, illustrated by the following figures: FIG. 1, already described, represents a sectional view of a fire-stop device According to the prior art; - Figure 2A shows a sectional side view of a pressure relief vent according to the invention, mounted in an opening of a wall; - Figure 2B shows schematically a sectional side view of an overpressure vent according to the invention, intended to be mounted on a wall; FIGS. 3A and 3B show, respectively, a perspective view of the front face and a perspective view of the rear face of a pressure relief vent frame according to the invention; FIG. 4 represents a perspective view of an example of a ventelle of the overpressure vent according to the invention; FIG. 5 represents an example of a double-plate overpressure vent fixed by a long axis on the frame; - Figures 6A and 6B show the inner face and the outer face of a wall in which is mounted a fire protection device according to the invention; FIGS. 7A and 7B show an example of assembly of several vents and finishing grids of a fire-prevention device according to the invention. DESCRIPTION OF EMBODIMENTS The invention relates to an overpressure vent ensuring a fireproof effect. An example of such an overpressure vent is shown in Figure 2A. This overpressure vent 10, hereinafter simply vented, is mounted in an opening 6 of a wall 1. This vent 10 comprises a frame 11 and at least one vane 12 or 13. In the example of FIG. 2A , the vent 10 is mounted on the outer face EXT of the partition 1, that is to say on the face of the partition opposite to the inner face INT located inside the room. In the example of Figure 2A, the vent is embedded in the wall 1. It should be noted that the vent 10 can also be mounted indoors, on the inner face INT of the partition.

In the example of Figure 2A, the vent 10 comprises two louvres 12 and 13 juxtaposed relative to each other, in a direction close to the vertical Y. In this example, the louver 12 is a upper vane and the vane 13b is a lower vane. The upper louver 12 includes a cover 123 intended to overlap the upper end 13a of the lower louver 13 for reasons which will be explained later. Each of these louvers 12 and 13 is fixed, independently of one another, on the frame 11 by a fixing means 14. It should be noted that the vent 10 may comprise a single louver or, conversely, 10 a plurality of louvers, the number and the surface of the louvers used in a vent depending on the volume of the room to be protected and the pressure of the projected gas, as will be explained later. Regardless of the number of lamellae mounted on the frame, each lamella comprises, as shown in FIG. 4, an envelope 120 filled with a layer 15 of a refrigerant material 121. The casing 120 is rigid, of rectangular shape, for example . It is also open on one of its sides to allow the introduction of the coolant layer 121. In the example of Figure 4, the casing 120 is open over the entire length of its upper longitudinal side 120a .

The casing 120 is made of a material capable of withstanding a high temperature. High temperature is a high ambient temperature, greater than the ambient temperature in a room, regardless of where the room is located. In other words, the envelope 120 is able to withstand a temperature greater than a terrestrial ambient temperature, such as the temperatures of desert or tropical environments. The envelope 120 is able to withstand the temperature prevailing in case of fire. It is able to withstand a temperature of up to 1029 ° C. For this, the envelope can be made in materials of the steel or stainless steel type or in aluminum alloys or in composite type materials. The type of material is chosen according to its mechanical strength, and taking into account, in particular, the area of the vane and the surrounding climatic environment (saline, desert, polar, tropical, humid, etc.). The thickness of the rigid material depends in particular on the fireproof duration that the vent has to withstand. This thickness can be for example 15 / 10th, that is to say 1.5 mm. The layer of coolant material 121 placed in the shell 120 may be based on calcium silicate, sodium silicate, magnesium silicate, gypsum or cement. It can also be based on a mixture of these different components. The thickness of this layer of refrigerant material depends on the firestop time that the vent must withstand. The thicker the layer, the longer the fire time. This thickness can be, for example, 6 mm for a 30-minute fireproof degree or 10 mm for a 60-minute fireproof degree.

This layer 121 may be introduced into the envelope 120 in a fluid form and then solidify within the envelope. It may, alternatively, be introduced in solid form, for example in the form of a plate of dimensions adapted to the internal dimensions of the envelope. Once the layer 121 is introduced, the open side 120a of the envelope 120 is closed by means of a caulking element such as a closure piece, a resin or a putty. The coolant layer 121 of the vane 12 or 13 has the role of cooling the vent so that the average temperature on the face of the vent not exposed to fire does not exceed 140 ° C. This louver thus has the effect of preventing heat transfer between the face of the fire-exposed vent and the opposite face of the vent, thereby creating a fire-barrier effect. The dimensions of the coolant layer 121 depend not only on the size of the ventelle to be used, but also on the desired degree of fire resistance. In fact, the dimensions of the lamellae, in width, in length and in thickness, are calibrated according to the desired fire resistance. Thus, the dimensions of the lamellae are determined differently, for example for a 15 minute fireproof degree (corresponding to the EI15 standard) or for a 120 minute fireproof degree (corresponding to the EI120 standard), causing differences. of a size of the coolant layer 121. According to a variant of the invention, each louvre 12 or 13 may comprise, on its inner face (inside face of the room), a layer of a non-flammable foam, by example of type Ml, providing acoustic attenuation.

The rigid casing 120 of the lamella further comprises, at the upper end of each of its lateral sides 120c, 120d, a fixing bar 122 adapted to receive a fixing means 14. FIG. 2B shows an example of a vent 10 as described above but whose frame 11 is intended to be mounted against the wall 1. FIGS. 3A and 3B show an example of a vent frame 11 of the invention according to a front view and a rear view. As seen in these Figures 3A and 3B, 3C, the frame 11 for receiving the louvers 12 and 13 comprises a frame 11a of substantially rectangular shape, intended to be applied against the periphery of the opening 6 of the wall. This frame 11a comprises a front face 11a1 and a rear face 11a2, the rear face 11a2 being the face contiguous to the wall. The frame 11 further comprises a frame 1 lb fixed on the frame 11a and intended to support the lamellae. Locations E12 and E13 are marked in FIGS. 3A and 3B to represent the location for receiving, respectively, the upper lamella 12 and the lower lamella 13. The frame 11b can be, for example, welded to the frame 11a or well made in one piece with said frame, for example by stamping and bending. The frame 11b can be fixed on the rear face 11a2 of the frame 11a (example of Figure 3B) or on the front face llal of said frame. When the frame 1 lb is fixed on the rear face 11a2 of the frame, the vent is said to apply on the wall; the frame offers protection against possible weather, outside the room. When the frame 1 lb is fixed on the front face llal of the frame, the vent is said embedded in the wall; the louvers open then in the thickness of the wall. Whatever the installation mode of the vent 10 (recessed or surface mounted), the louvers always open from the inside to the outside of the room.

The frame 1b has a greater depth in the upper part of the frame 11 than in the lower part of said frame, as shown in FIG. 3B. Indeed, the frame 1 lb has a triangular section, as shown in Figure 2B. Such a section has the effect of orienting the lamellae obliquely, that is to say to incline them by an angle with respect to the vertical axis Y as shown in Figure 2B.

This inclination makes it possible to increase the resistance to the opening of each vane so that said vane opens only under the effect of an overpressure of value greater than or equal to a predetermined value. It is therefore understood that the calibration of a vent according to the invention may take into account the inclination of the lamellae and therefore the depth of the upper part of the frame 11b. In an embodiment having a plurality of louvers positioned one above the other in the Y direction, each upper louver 12 has a liner 123 adapted to overlap the upper portion of the lower louver 13 and thereby close the space between the two louvers juxtaposed when the vent is in the closed position (Figures 2A and 4). To seal the vent between the two louvers, when said vent is in the closed position, the frame 11 comprises a crosspiece 11c placed in the center of the frame 11b, between the locations E12 and E13 for the louvers 12 and 13, as shown in Figures 3A and 3B. The cross member 11c may be made of the same rigid material as the frame and / or the frame. It may further comprise a layer of an intumescent material forming an intumescent seal. This intumescent seal is applied, for example by gluing, on the front face of the crossbar, that is to say the face 15 placed in contact with the louvers 12, 13 when said louvers are closed. An intumescent gasket may also be applied to the front face 11b1 of the frame llb to seal the frame and lamellae. Such an intumescent gasket does not interfere with the opening of the louvers at the time of evacuation of the overpressure but ensures clogging of the louvers with the frame, after said evacuation of the overpressure, to cut the fire. The frame 11 may further comprise, on its rear face, an application of a layer of refrigerant material. For example, the face of the cross member 11c opposite the face receiving the intumescent gasket and the rear face 11a2 of the frame 11a and the rear face 11b2 of the frame 11b may be covered with a layer of coolant material. This layer of coolant material makes it possible to further improve the fire-barrier effect of the vent 10. In this embodiment, the frame 11 constitutes a solid structure, called a solid sleeve, one face of which is covered with a layer of refrigerant material. This layer of refrigerant material is either applied in a fluid form able to harden quickly, or applied in a solid form bonded by any conventional bonding means resistant to a high temperature.

In another embodiment, the frame 11 of the vent may comprise a rigid hollow structure, called hollow sleeve 110, filled with a layer of refrigerant material 111. The hollow sleeve 110 may be made of one of the materials mentioned previously for the envelope 120 of the ventelle. It surrounds a layer of coolant material 111 preventing thermal transfer between a face of the vent and the other side of said vent. This refrigerant material may be one of the refrigerant materials mentioned above for the ventelle. The frame 11 then also participates in the firebreak effect of the vent. In either of these embodiments, a single frame member or more of the frame 1b, the frame 1a and the cross member 11c can be made as indicated above, with a layer of material integrated or applied refrigerant.

It will be noted that the rigid material forming the envelope 120 or the sleeve 110 and the cooling material placed within said envelope or said sleeve may have identical thicknesses or, conversely, different within the same vent, the thickness of each of these materials may, for example, be different for the frame and for the louvers. Likewise, the choice of materials used for the frame and for the louvers may differ within the same vent. In the overpressure vent 10, each louvre 12, 13 is rotatably mounted inside the frame 11. More specifically, each louvre is mounted independently of any other louvers on the frame 1 lb of the frame. Each bracket 122 122 of the ventelle is fixed on an inner wall of the frame 1 lb. An example of attachment of a louvre 12 to the frame 11 is shown in FIG. 5. In this example, the louvre 12 is fixed to the frame 1b by means of a long axis 15 passing right through the two fixing bars 122 and being housed in the opposite walls of the frame 1 lb. This long axis 15 constitutes an axis of rotation for the plate. Other fastening means may be provided for mounting the rotating blades in the frame. These fixing means may be, for example, a fixed point such as a pin or a rivet or a removable attachment such as a screw or a bolt passing through the fixing bar 122, these fixing means constituting an axis of rotation for the plate. The two bars 122 of a ventelle can each be fixed to a wall of the frame 1 lb by means of the same type of fixation or, on the contrary, by means of two different types of fixation. For example, one of the fixing bars 122 can be fixed by one stud on one of the walls of the frame 1 lb and the other fixing bar 122 can be fixed by a screw on the opposite wall of the frame 1 lb.

As explained above, the overpressure vent of the invention has a fire-barrier effect. This fire-resistant effect is obtained for the two fire directions (from the inside of the room to the outside or from the outside to the inside of the room) without any negative effect on the said vent, that is to say without swelling or deformation of the vent because the coolant material stabilizes the rigid structure during the rise in temperature. The vent does not deform in the presence of a fire, it prevents any passage of flame. Since the fire barrier effect is obtained by the vent itself, the minimum thickness of a partition capable of receiving a fire barrier means is 5 cm, which corresponds to the thickness of the vent. Premises with thin walls (of the order of 5 cm) 10 can therefore be equipped with an automatic gas extinguishing system combined with a fire barrier means. The overpressure vent of the invention as just described may be associated with a finishing grid also mounted in the opening 6 of the partition, but at the opposite end of said opening relative to the vent. This vent and finish grid assembly constitutes a fire barrier device. As shown, for example, in Figures 2A, 6A and 6B, if the vent 10 is mounted at the end 6a of the opening 6, that is to say on the outer face EXT of the partition 1 which is the face of the partition located outside the room, then the finishing grid 20 is mounted at the end 6b of the opening 6, that is to say on the inner face INT of said partition 1. Au contrary, when the vent is mounted on the inner face of the partition, then the finishing grid is mounted on the outer face of said partition. This finishing grid 20 is a perforated grid made of a material capable of withstanding high temperatures, such as one of the materials mentioned above for the manufacture of louvers. This perforated finishing grid comprises orifices 25 of rectangular shape or other ensuring the passage of air and / or gas under pressure. This finishing grid 20, mounted in front of the opening 6 of the partition 1 to close said opening, has a free passage area substantially equal to the air / gas passage surface of the vent 10. In a Embodiment of the invention, this finishing grid 20 is made of a rigid material incorporating a layer of a refrigerant material of the same type as that mentioned above for the louvers and the frame. In a first variant of this embodiment, the bar structure 22 of the grid is hollow and filled with a refrigerant material. In a second variant of this embodiment, the bar structure 22 is solid and a layer of refrigerant material is applied to said bar structure. Whatever the variant, the finishing grid of this embodiment provides a fire-resistant effect which improves the fire-resistance effect of the vent 10. The fire-resistant device of the invention may further include a protective box 30 placed inside the opening 6 of the partition. This protective box 30 is in the form of a square (or rectangular parallelepiped) whose two faces are open, these open faces being closed, on one side, by the vent 10 and, on the other side, by the grid of 10 finish 20, as shown in FIG. 2A. This box 30, made of a material resistant to a high temperature and, for example, treated against corrosion, has dimensions adapted to the opening 6 of the partition to fit said opening. In one embodiment of the invention, several vents 10 may be joined together to form a large vent. Indeed, when a large vent must be installed in a room, it is possible: - either to make, custom-made, a vent with one or more large ventelles, - or to associate several vents, conventional or standard dimensions, one beside the other, both in height and width, to limit manufacturing costs. A standard size vent may be, for example, a vent of 0.5 m2 or 1 m2. An example of several vents mounted next to each other is shown in Figure 7A. This example shows nine classic sized vents joined to each other, three in height and three in width. Other additional vents could also be associated with these nine vents. The number of vents thus associated is of course to be adapted to the needs of the local. In a case where several vents are associated only in height or width, the frames of each of the vents are individually fixed on a portion of the periphery of the opening in the partition. In a case where the vents are associated both in width and in height, as in FIG. 7A, reinforcements are placed vertically or horizontally between two opposite sides of the periphery of the opening to allow the attachment of the most exchanges.

In the same way, several finishing grids can be joined to each other, as shown in FIG. 7B. These finishing grids 20 are fixed in the same way as the vents 10, on the opposite side of the opening in the partition. The installation of an overpressure vent or a fire stop device in a room first requires a calibration of the vent and / or the device. For this, an estimate of the volume of gas necessary for the protection of the room against fire must first be estimated, depending in particular on the surface of the room and / or pressure maintained permanently in the room. Generally, the calibration of the vent or the fire stop device is carried out for a pressure of 25 Pa. However, in some cases, for example if the room is subjected to permanent pressure, the calibration of the vent or the device Firewall takes this pressure into account as the reference pressure. A vent surface adapted to ensure the evacuation of the gas pressure in the room is then calibrated taking into account the volume of gas to be sprayed and the reference pressure of the room.

The number of louvers corresponding to the calibrated vent surface is then determined as well as the number of frames and the number of louvers per frame. After determining the number of vents and the dimensions of the vents, the frames and vents are made by laser cutting and shaped by stamping and bending. An opening is retained in the casings and hollow sleeves thus obtained to fill them with fluid or solid refrigerant material. The opening is then sealed by welding a closure piece or by laying a resin or putty. Depending on the variant chosen, several frames can be associated with each other to form, if necessary, a large frame. An intumescent gasket layer and / or a layer of coolant material may further be applied to the frame. Once the frame is completed, the louvelles are installed inside the frame to form the vent. The vent thus manufactured is then fixed in the partition of the room, on the periphery 30 of a face of the opening. Finally, if finishing grids are provided, they are mounted on the face of the opening opposite to that receiving the vent.

Claims (13)

CLAIMS1 - Overpressure event (10) for automatic gas extinguishing system installed in a room, said vent comprising: a frame (11) mounted on the periphery of an opening (6) made in a partition (1) of the room, at least one louvre (12) rotatably mounted inside the frame and adapted, in an open position, to evacuate a gas overpressure from the inside of the room to the outside of the room, characterized in that the lamella comprises: a casing (120) made of a rigid material, and a layer of a cooling material (121) filling the inside of the casing, so that the vent (10) has a fireproof effect preventing heat transfer between the outside and the inside of the room. 2 - Event according to claim 1, characterized in that the frame comprises at least one layer of a refrigerant material participating in the fire barrier effect of the vent. 3 - Event according to claim 2, characterized in that the frame comprises a sleeve (110) hollow, made of a rigid material, filled with the layer of cooling material (111). 4 - Event according to claim 2, characterized in that the frame comprises a sleeve (110) full on which is applied the layer of refrigerant material (111). 5 - Event according to any one of claims 1 to 4, characterized in that the ventelle (12) is inclinedly mounted in the frame (11). 6 - Event according to any one of claims 1 to 5, characterized in that it comprises a plurality of louvers juxtaposed relative to each other and each fixed on either side of the frame. 3028420 15 7 - Firestop device for automatic gas extinguishing system installed in a room, characterized in that it comprises: - at least one overpressure vent (10) according to any one of claims 1 to 5, positioned at a first end (6a) of the opening (6) in the partition 5 of the room, and a perforated finishing grid (20) positioned at a second end (6b) of the opening (6) in the room wall, this second end being opposite to the first end. 10 8 - Device according to claim 7, characterized in that the finishing grid (20) comprises: a hollow bar structure made of a rigid material, and a layer of a cooling material filling the interior of the hollow bar structure . 15 9 - Device according to claim 7, characterized in that the finishing grid (20) comprises: a solid bar structure made of a rigid material, and a layer of a cooling material applied to the solid bar structure. 10 - Device according to any one of claims 7 to 9, characterized in that it comprises a plurality of overpressure vents (10) contiguous to each other to form a large vent. 25 11 - Automatic gas extinguishing system comprising at least one overpressure vent according to any one of claims 1 to 6. 12 - A method of implementing the overpressure vent according to any one of claims 1 to 6, characterized in that it comprises the following operations: - estimation of a volume of gas necessary for protection of the local against fire, 3028420 16 - calibration of an overpressure vent surface capable of evacuating a gas overpressure of this room, - determination of a number of lamellae corresponding to the calibrated overpressure venting surface, 5 - determination a number of frames (11) and a number of lamellae (12, 13) per frame to obtain the calibrated overpressure venting surface, - mounting the number of lamellae (12, 13) determined in the number of frames determined to achieve a vent, and - fixing the thus obtained vent to the periphery the opening (6) in the partition 10 of the room.