Fire protection flap with a housing having at least one housing wall and with a flap leaf pivotably mounted around a rotary axis between an open position and a closed position.

Description

[0001] The invention relates to a fire damper with a housing having a housing wall and with a damper blade, preferably made of calcium silicate, which is mounted preferably centrally on the housing cross-section and can pivot about an axis of rotation between an open position and a closed position and has two opposite damper surfaces connected to one another by a circumferential end face, wherein the axis of rotation divides the damper blade into two damper blade halves, wherein two opposite bearing points forming the axis of rotation are provided for supporting the damper blade and wherein the damper blade can be pivoted against the restoring force of a spring element from its closed position into its open position aligned parallel to the flow direction.

[0002] In conventional fire dampers, the damper blade is exposed to the airflow without protection. In the open position, the airflow flows against the face of the damper blade facing the opposite direction of flow. This leads to deposits. Due to turbulence, deposits also build up on the face facing in the direction of flow. This effect is particularly prevalent in fire dampers used in contaminated air, such as in kitchen exhaust ducts or laboratory exhaust ducts. Deposits regularly form on the face of the damper blade, adversely affecting the function and / or stability of the fire damper. Therefore, regular cleaning is necessary, which is time-consuming and costly.

[0003] DE 10 2019 102 185 A1 discloses an industrial valve with at least one flap device for shutting off lines with a large nominal diameter. DE 10 2009 011 501 A1 discloses a triggering device for a damper blade of a fire damper.

[0004] The object of the invention is to avoid the aforementioned disadvantages and to provide a fire damper that can be used without regular and complex cleaning of the front surface of the damper blade even in contaminated air streams such as kitchen exhaust ducts or laboratory exhaust ducts.

[0005] This object is achieved in that two protective devices are provided inside the housing for shielding the end faces in the open position of the damper blade, each of which extends along the relevant end face in the open position of the damper blade, wherein each protective device forms a cavity with the end face assigned to it that is sealed off from the interior of the housing by at least one cold seal, so that each of the two end faces is completely shielded by the protective device assigned to it in the open position of the damper blade. With central mounting of the damper blade, the damper blade is located in the middle of the housing and thus divides the housing cross-section preferably into two equally sized housing cross-sectional areas. In its open position, the flowing medium flows around the damper blade in the area of ​​both damper surfaces.

[0006] The inventive design shields, i.e., protects, the end face of the damper blade in the open position from the flowing medium. The protective device is made of a suitable material, such as sheet metal. This protects the end face of the damper blade from contamination, i.e., from dirt or gases in the air stream. In the open position, the end face is located in a cavity, i.e., a protective space, formed by the end face, the protective device, and the cold seal.

[0007] Preferably, the protective device has a width B that is at least equal to or greater than the thickness D of the damper blade. Preferably, the width B of the protective device is only slightly or at least not significantly greater than the thickness D of the damper blade, so that the free flow cross-section is blocked as little as possible when the damper blade is in the open position.

[0008] The housing can have a round housing cross-section with a circumferential housing wall and each of the two protective devices can have a curved contour adapted to the end face assigned to it, wherein each protective device is arranged in alignment with the axis of rotation as seen in the direction of flow and wherein the distance between the axis of rotation and each protective device is slightly greater than the radius of the damper blade.

[0009] However, it is also possible for the housing to have a rectangular cross-section and for the housing wall to be formed by four housing walls, each of the two protective devices being formed, on the one hand, from the two housing walls aligned orthogonally to the axis of rotation and, on the other hand, from a protective element aligned parallel to the axis of rotation and extending between the housing walls aligned orthogonally to the axis of rotation, each protective element being arranged in alignment with the axis of rotation as seen in the direction of flow, and the distance between the axis of rotation and the protective element being slightly greater than the distance between the axis of rotation and the relevant end face of the damper blade adjacent to the protective element.In such a configuration, the protective device is formed by the two housing walls aligned orthogonally to the axis of rotation on the one hand and by the protective element aligned parallel to the axis of rotation and extending between the housing walls orthogonally to the axis of rotation on the other hand.

[0010] In at least one half of the damper blade, the corresponding end face can have a cold seal on at least one of its two edges, extending along this edge and protruding relative to the end face in the longitudinal direction of the damper blade. In such a configuration, the cold seal in question is arranged on the damper blade and is displaced accordingly. In such an arrangement, the cold seal also serves to seal the damper blade in its closed position relative to the housing.

[0011] The damper blade can have a cold seal on each of its two edges, extending along the respective edge and protruding from the end face in the longitudinal direction of the damper blade. In such a configuration, both protective devices, with their respective end faces of the damper blade halves, form a common, circumferential cavity sealed from the interior of the housing by the two cold seals. The rotation axis extends through this common cavity.

[0012] However, it is also entirely possible for each protective device to form its own cavity with its adjacent end face. This creates at least two cavities in the open position. Of course, it is also possible to create additional cavities, for example, in the area of ​​a bearing, by selecting and arranging suitable cold seals.

[0013] Alternatively, it is possible for at least one protective device to be provided with a cold seal on at least one of its two longitudinal edges, preferably on both of its longitudinal edges, to seal the cavity formed between the protective device, on the one hand, and the end face of the damper blade in its open position facing it, on the other hand. In such a configuration, the corresponding cold seal serves only to seal the cavity between the protective device and the end face of the damper blade in the open position.

[0014] A heat seal that expands upon exposure to heat can be provided on the end face of each blade half. To ensure good pivoting, the size of the blade is matched to the housing so that, in the closed position of the blade, a circumferential movement gap remains between the inside of the housing and the heat seal, before it has expanded due to heat.

[0015] The housing can have a heat seal on the inside, at least in the portion extending along the circumference of the damper blade in the closed position, which expands upon exposure to heat. Even with such a design, the size of the damper blade is matched to the housing such that, in the closed position of the damper blade, a circumferential movement gap remains between the inside of the housing and the heat seal, in a state before it has expanded due to the effects of heat.

[0016] At least one protective device can be designed as a rail or profile rail over part of its length, preferably over its entire length. In the simplest case, the rail can be designed as a flat strip made of a suitable material, such as metal. The width B of the strip is preferably equal to or slightly greater than the thickness D of the damper blade.

[0017] At least one protective device can have a convex shape over part of its length, preferably over its entire length. In such a configuration, the distance C 1 between a longitudinal edge of the protective device and the end face of the damper blade is smaller than the distance C 2 between the area located between the two longitudinal edges of the protective device and the end face of the damper blade.

[0018] At least one profile rail can be designed as an angle rail with two angled surfaces aligned at an angle, preferably at a right angle, to form an abutting edge, wherein the abutting edge is arranged facing away from the end face of the damper blade in its open position. Such a design improves the flow behavior, since the air flow is deflected upwards and downwards by the protective device facing against the flow direction. The air flow then flows along the two flap surfaces of the damper blade in its open position and is recombined after passing the protective device facing in the flow direction.

[0019] In this case, a longitudinal edge of each protective device can merge into a cover element extending in the direction of the axis of rotation, at least over part of its length, preferably over its entire length, wherein the cover elements are provided diametrically opposite one another and are aligned parallel to the direction of flow, and wherein the cover elements are arranged such that, in the open position of the damper blade, each cover element covers the respective adjacent surface of the damper blade half, wherein, in a housing with a rectangular housing cross-section in which the housing wall is formed by four housing walls, each cover element extends from one housing wall aligned orthogonally to the axis of rotation to the opposite other housing wall aligned orthogonally to the axis of rotation.With such a design, not only the corresponding end face of the damper blade is shielded from the airflow, but also the surface of the damper blade half that is covered by a cover element. The two protective devices, together with the adjacent cover element, form a kind of "cassette" into which the damper blade is pivoted when shifted into its open position. A parallel alignment of the cover elements also refers to an alignment slightly inclined relative to the flow direction. Each cover element can be flat. However, a slightly curved surface of one or both cover elements is also possible.

[0020] At least one cover element can extend far enough in the flow direction for the damper blade to rest against the free edge of the cover element in its closed position. In such a configuration, the free edge of one cover element is positioned upstream of the rotation axis by half the thickness of the damper blade in the flow direction, and the free edge of the other cover element is positioned downstream of the rotation axis by half the thickness of the damper blade in the flow direction, so that the two facing free edges of the cover elements are offset from one another by the thickness of the damper blade in the flow direction.

[0021] Each of the two flap surfaces can have, in the area which, when the flap leaf is in the open position, adjoins the area covered by the cover element, a cold seal which is preferably designed in the shape of a frame and has four edges arranged at right angles to one another. Three of the edges of each of the two cold seals protrude laterally opposite the end face in the longitudinal direction of the flap leaf, and the edge area of ​​the cover element is in sealing contact with the fourth edge of the respective cold seal when the flap leaf is in the open position. Each of the two cold seals can be designed as a continuous plate which is, for example, glued or screwed onto the respective area of ​​the flap surface. In this case, it extends completely over the respective area of ​​the flap surface. However, it is also possible for a cold seal to be designed as a square frame.The frame can be formed from a single cold seal. However, it is also possible for the frame to consist of several contacting sealing sections that, together, form a circumferential cold seal.

[0022] A flat seal or a profiled seal, for example with a round or oval profile, can be provided as a cold seal.

[0023] The two cold seals arranged in diametrically opposite regions of the two flap surfaces can be connected to each other in the area of ​​each bearing point by a cold seal extending across the end face. With such a configuration, at least two cavities are created in the open position of the flap blade, with one cavity extending along the end face of one half of the flap blade and the other cavity extending along the end face of the other half of the flap blade.

[0024] Each of the two flap surfaces can have a surface element, preferably made of sheet metal, in the area that adjoins the area covered by the cover element when the flap blade is in the open position. With such a design, the front surface is shielded by the two protective devices in the open position, while the two flap surfaces are protected by the cover element and the respective surface element. The flap blade is thus completely shielded.

[0025] At least one protective device and the adjacent cover element can be formed as a single piece. A multi-part design is also possible, of course. At least one protective device and the adjacent cover element can be formed from a single sheet, for example.

[0026] At least one of the two flap surfaces can have a surface element, preferably made of sheet metal, that completely covers the respective flap surface. This surface element protects the respective area of ​​the flap blade from the airflow.

[0027] At least one protective device can have at least one supply opening, preferably accessible from outside the housing, for supplying a gaseous medium, preferably air, into the respective cavity. With such a configuration, a gaseous medium can be introduced into the corresponding cavity. This creates an overpressure in the cavity compared to the pressure inside the housing, so that even if the cold seal is not optimally sealed, the air flow from inside the housing is prevented from entering the cavity.

[0028] At least one supply opening can be connected to a pressure generating device, preferably to a pump or a fan.

[0029] At least one protective device can have at least one outlet opening, preferably equipped with a non-return device, for discharging a gaseous medium, preferably air, from the cavity into the interior of the housing. The non-return device prevents air from the interior of the housing from flowing through the outlet opening into the cavity. The extraction of air from the cavity of the "cassette," which is formed by the damper blade in its open position and by the two protective devices with their adjacent cover elements, is achieved by the "Bernoulli effect." A high flow velocity prevails in the narrow section of the outlet opening. A negative pressure develops in the cavity of the "cassette." To compensate for the negative pressure, uncontaminated air flows into the cavity of the "cassette" from outside the fire damper.This prevents contaminated air flowing through the fire damper from entering the cassette.

[0030] The following are exemplary embodiments of the invention illustrated in the drawings. They show: Fig. 1 shows a section through a first embodiment of a fire damper according to the invention, Fig. 2 shows a section through a second embodiment of a fire damper according to the invention, Fig. 3 shows a section through a third embodiment of a fire damper according to the invention, Fig. 4 shows a section through a fourth embodiment of a fire damper according to the invention, Fig. 5 shows an oblique view of the object according to Fig. 4 , Fig. 6 a section through a fifth embodiment of a fire damper according to the invention, Fig. 7 a section through a sixth embodiment of a fire damper according to the invention, Figs. 8 to 11 plan views of a damper blade with different arrangements of the cold seal, Fig. 12 a section through a seventh embodiment of a fire damper according to the invention, Fig. 13 an oblique view of the object according to Fig. 12 and Fig. 14 a-c sections through further embodiments of a fire damper according to the invention.

[0031] In all figures, identical reference symbols are used for identical or similar components.

[0032] The figures show different embodiments of the fire damper according to the invention. Each fire damper comprises a housing with a housing wall 1 and a damper blade 3 pivotably mounted centrally with respect to the housing cross-section between an open position and a closed position about a rotation axis 2. The damper blade 3 has two opposing damper surfaces 5, 6 connected to each other by a circumferential end face 4. The damper blade 3 is made, for example, of calcium silicate.

[0033] The rotational axis 2 of the damper blade 3 divides the damper blade 3 into two halves, whereby two opposing bearing points forming the rotational axis 2 are provided for supporting the damper blade 3 and the damper blade 3 can be pivoted against the restoring force of a spring element (not shown) from its closed position into its open position aligned parallel to the flow direction. The open position is, for example, in Fig. 1 shown.

[0034] In the examples according to the Fig. 1 bis 11 The housing has a rectangular cross-section and the housing wall 1 is formed by four housing walls 7. In the embodiment according to the Fig. 12 and 13 The housing has a round cross-section with a circumferential housing wall 1. In Fig. 12 the damper blade 3 is in its closed position and in Fig. 13 the flap 3 is shown in its open position.

[0035] Inside the housing, two protective devices 8 are provided to shield the end face 4 of the damper blade 3 when the damper blade 3 is in its open position. The protective devices 8 each extend along the respective end face 4 when the damper blade 3 is in the open position. Each protective device 8 forms, with the end face 4 of the damper blade 3 assigned to it, a cavity 10 that is sealed from the interior of the housing by at least one cold seal 9. Thus, in the open position of the damper blade 3, the end face 4 is completely shielded in the area of ​​both damper blade halves by its assigned protective device 8. The end face 4 is thus protected from the air flow in the flow direction 11.

[0036] In the examples according to the Fig. 1 bis 11 Each of the two protective devices 8 is formed, on the one hand, from the two housing walls 7 aligned orthogonally to the axis of rotation 2, and, on the other hand, from a protective element 12 aligned parallel to the axis of rotation 2 and extending between the housing walls 7 aligned orthogonally to the axis of rotation 2. Each protective element 12 is arranged in alignment with the axis of rotation 2, as seen in the flow direction 11. The distance between the axis of rotation 2 and the protective element 12 is slightly greater than the distance between the axis of rotation 2 and the relevant end face 4 of the damper blade 3 adjacent to the protective element 12.

[0037] In the embodiment according to the Fig. 12 and 13Each of the two protective devices 8 has a curved contour adapted to its associated end face 4. Here, too, each protective device 8 is arranged in alignment with the rotation axis 2, as seen in the flow direction 11, and the distance between the rotation axis 2 and each protective device 8 is slightly larger than the radius of the damper blade 3.

[0038] As the Fig. 1 bis 7 As shown in the drawings, in these exemplary embodiments, the protective device 8 is designed as a profile rail over a portion of its length, specifically in the area between the two housing walls 7, which run orthogonally to the axis of rotation 2. The profile rail is designed as an angle rail with two angled surfaces 14 aligned at right angles to one another, forming an abutting edge 13. The abutting edge 13 points away from the end face 4 of the damper blade 3 in its open position.

[0039] Even in the embodiment according to the Fig. 12 and 13 the protective device 8 is designed - in this case over its entire length - as a profile rail, wherein the profile rail has two angular surfaces 14 aligned at a right angle to one another to form an abutting edge 13.

[0040] The damper blade 3 has two edges 15, regardless of its contour, each edge 15 being circumferential. The two edges 15 are spaced apart from each other, the distance between the edges 15 corresponding to the thickness of the damper blade 3. If the damper blade has a round contour, as shown, for example, in Fig. 12 As shown, each flap leaf half has two semicircular, parallel edges 15. In the case of a flap leaf 3 having a rectangular contour, as shown for example in Fig. 3 As shown, each flap leaf half again has two parallel edges 15, wherein each edge 15 of each flap leaf half consists of three edge sections, namely one edge section aligned parallel to the rotation axis 2 and two edge sections aligned orthogonal to the rotation axis 2.

[0041] In the examples according to the Fig. 1 bis 3 the damper blade 3 has on each of its two edges 15 a cold seal 9 extending along the respective edge 15 and projecting in the longitudinal direction of the damper blade 3 relative to the end face 4. As shown, for example, in Fig. 1 As shown, each cold seal 9 touches the angled surface 14 of the profile rail assigned to it in the open position of the damper blade 3, so that a cavity 10 with an approximately triangular cross-section is formed.

[0042] In the embodiment example according to Fig. 1 The housing has a heat seal 17 on the inside in the partial area that extends along the circumference of the damper blade 3 in the closed position, which expands when exposed to heat. The damper blade 3 is oriented orthogonally to the flow direction 11 in its closed position and parallel to the flow direction 11 in its open position. In the embodiment according to Fig. 2 bis 7 and Fig. 13 A heat seal 17 which expands when exposed to heat is provided on the end face 4 of each damper blade half.

[0043] In Fig. 3 A design is shown in which each flap surface 5, 6 additionally has a surface element 18, preferably formed as a sheet metal, that completely covers the respective flap surface 5, 6. Thus, in the open position of the flap blade 3, not only the end face 4 but also each flap surface 5, 6 is protected from the air flow.

[0044] For example, in the Fig. 4 and 6 Embodiments are shown in which a longitudinal edge 19 of each protective device 8 merges, at least over part of its length, namely in the region extending between the housing walls 7 aligned orthogonally to the axis of rotation 2, into a cover element 20 extending in the direction of the axis of rotation 2. A cover element 20 can be made of sheet metal, for example. The cover elements 20 are provided diametrically opposite one another with respect to the axis of rotation 2 and are aligned parallel to the flow direction 11. The cover elements 20 are arranged such that, in the open position of the damper blade 3, each cover element 20 covers the respective adjacent region of the damper surface 5, 6.

[0045] Furthermore, in such a configuration, each of the two flap surfaces 5, 6 is provided with a surface element 18 that completely covers the respective area in the area that adjoins the area covered by the cover element 20 when the flap leaf 3 is in the open position. This surface element 18 can be a sheet metal.

[0046] For example Fig. 5 shows, the two protective devices 8 with the adjacent cover element 20 form a kind of "cassette" into which the damper blade 3 can be pivoted and is "received" in its open position.

[0047] For example, if an order is made according to Fig. 5 An arrangement of the cold seal 9 is recommended, as shown in Fig. 11 is shown. Each of the two flap surfaces 5, 6 has, in the area which, in the open position of the flap leaf 3, adjoins the area covered by the cover element 20, a cold seal 9 which has four edges arranged at a right angle to one another. Each of the two cold seals 9 is arranged and dimensioned such that three of its edges protrude laterally opposite the end face 4 in the longitudinal direction of the flap leaf 3. In the open position of the flap leaf 3, the edge region of each cover element 20 is in sealing contact with the fourth edge of the adjacent cold seal 9. Alternatively, the cold seal 9 can also be provided on the protective device 8. With such a configuration, the seal would be achieved by an inverted arrangement of the cold seal 9.

[0048] At the Fig. 11 In the illustrated embodiment, each cold seal 9 is frame-like. The two cold seals 9 arranged on the two flap surfaces 5, 6 are connected to one another in the area of ​​each bearing point by a cold seal 9 extending over the end face 4. This creates two cavities 10 when the flap leaf 3 is in the open position. The arrangement of the cold seals 9 seals the gaps between each protective device 8 and the flap leaf 3. In addition, tightness is achieved when the flap leaf 3 is in the closed position.

[0049] In Fig. 6 Each of the two protective devices 8 has a supply opening 21 accessible from outside the housing for supplying a gaseous medium, for example air, into the respective cavity 10. For this purpose, a pressure generating device 22, such as a pump or a fan, is provided, which is arranged outside the housing and is connected, for example, via a hose to the respective supply opening 21. In this way, an overpressure can be generated in each of the two cavities 10 compared to the interior of the housing, so that even if the cold seals 9 do not provide sufficient sealing, the air flowing inside the housing does not enter the cavities 10. Other designs are also conceivable instead of a hose. For example, the air could be guided directly into the cavity 10 through a corresponding opening in the housing.

[0050] In Fig. 7 A design is shown in which the protective device 8 facing against the flow direction 11 has an inlet opening 21 accessible from outside the housing, and the protective device 8 facing in the flow direction 11 has an outlet opening 24 provided with a non-return device 23. Air flows in from the atmosphere via the inlet opening 21. In the area of ​​the outlet opening 24, the faster air flow inside the housing creates a negative pressure in the area of ​​the cross-sectional constriction of the "cassette" of the damper blade 3, which is formed by the two protective devices 8 with the adjacent cover element 20, so that air is drawn out of the cavity 10 into the interior of the housing. A corresponding amount of air is drawn in from outside the housing via the inlet opening 21, which is referred to as the "Bernoulli effect." The outlet opening 24 is therefore a type of Venturi nozzle.The non-return device 23 may, for example, be a rubber strip that allows flow in the direction of arrow 25 but prevents flow opposite to the direction of arrow 25.

[0051] The flow velocity v+ of the air flow at the outlet opening 24 is greater than the flow velocity v of the air flow upstream and downstream of the damper blade 3, as seen in the flow direction 11. The flow velocity vF is understood to be the afterflow velocity of the air flow. The pressure pF in the cavity 10 is greater than the pressure pL of the air flow at the outlet opening 24 of the cavity 10. The flow velocity v+ is greater in the region of the constriction than upstream and downstream of the damper blade 3, as seen in the flow direction 11.

[0052] In the Fig. 7 In the embodiment shown, the respective damper blade 3 has an arrangement of the cold seals 9 according to Fig. 11 For this purpose, the two cavities 10 formed between the end face 4 and the two protective devices 8 in the open position of the damper blade 3 are connected to each other via a flow channel 26.

[0053] Fig. 8 shows a damper blade 3, which has a cold seal 9 extending along each of its two edges 15, extending along the respective edge 15 and protruding in the longitudinal direction of the damper blade 3 relative to the end face 4. In the open position, a circumferential cavity 10 is formed.

[0054] When designing according to Fig. 9 and Fig. 11 Additionally, a cold seal 9 is provided in the area of ​​each bearing point, which extends over the end face 4 and connects the two circumferential cold seals 9. This creates two cavities 10.

[0055] When designing according to Fig. 10 A cold seal 9 is provided on both sides of each bearing point, extending over the end face 4 and connecting the two circumferential cold seals 9. Such a design creates a total of four cavities 10.

[0056] In the embodiment according to the Fig. 14 a bis c The two protective devices 8 are formed, on the one hand, from the two housing walls 7 (not shown) aligned orthogonally to the axis of rotation 2 and, on the other hand, from a protective element 12 designed as a profile rail, aligned parallel to the axis of rotation 2 and extending between the housing walls 7 aligned orthogonally to the axis of rotation 2.

[0057] In Fig. 14 a, the profile rail is designed as an angle rail with two angled surfaces 14 aligned at a right angle to each other to form an abutting edge 13, wherein the abutting edge 13 is arranged pointing away from the end face 4 of the damper blade 3 in its open position. In Fig. 14 b the profile rail has a convex shape, while in Fig. 14 c the profile rail is made of flat steel.

[0058] How Fig. 14 b with the convex profile rail, in such a design the distance C 1 between a longitudinal edge 19 of the protective device 8 and the end face 4 of the damper blade 3 is smaller than the distance C 2 between the area arranged between the two longitudinal edges 19 of the protective device 8 and the end face 4 of the damper blade 3.

[0059] When designing according to Fig. 14a, each of the two longitudinal edges 19 of each protective device 8 has an end region 16 which is angled relative to the adjacent angled surface 14 in the direction of the flap leaf 16 in the open position. Preferably, this is the longitudinal edge 19 that points in the direction of the displacement direction 26.

Claims

1. Fire damper with a housing having at least one housing wall (1) and with a flap leaf (3), preferably consisting of calcium silicate, preferably mounted in the middle in relation to the housing cross-section, such as to be capable of pivoting about a rotation axis (2) between an open position and a closed position and comprising two pivotably mounted flap surfaces (5,6) connected to one another by a circumferential face surface (4), wherein the rotation axis (2) divides the flap leaf (3) into two flap leaf halves, wherein, in order to mount the flap leaf (3), two opposed mounting points are provided, forming the rotation axis (2), and wherein the flap leaf (3) can be pivoted, against the resetting force of a spring element, out of its closed position into its open position, oriented parallel to the direction of flow (11), wherein, in the interior of the housing, two protective devices (8) are provided in order to screen the face surfaces (4) in the open position of the flap leaf (3), which are each provided extending along the face surface (4) concerned in the open position of the flap leaf (3), characterised in that each protective device (8), with the face surface (4) assigned to it, forms a cavity space (10), sealed against the interior of the housing by means of at least one cold seal (9), such that each of the two face surfaces (4), in the open position of the flap leaf (3), are screened entirely by the protective device (8) assigned to them.

2. Fire damper according to the preceding claim, characterised in that the housing has a circular housing cross-section with a circumferential housing wall (1), and that each of the two protective devices (8) has a curved contour which is matched to the face surface (4) assigned to it, wherein each protective device (8), seen in the direction of flow (11), is arranged flush with the rotation axis (2), and wherein the distance interval between the rotation axis (2) and each protective device (8) is somewhat greater than the radius of the flap leaf (3).

3. Fire damper according to claim 1, characterised in that the housing has a rectangular housing cross-section, and the housing wall (1) is formed by four housing walls (7), wherein each of the two protective devices (8) are formed on the one hand from the two housing walls (7) oriented orthogonally to the rotation axis (2), and, on the other, from a protective element (12) extending between the housing walls (7) oriented parallel to the rotation axis (2) oriented orthogonally to the rotation axis (2), wherein each protective element (12), seen in the direction of flow (11), is arranged flush with the rotation axis (2), and the distance interval between the rotation axis (2) and the protective element (12) is somewhat greater than the distance interval between the rotation axis (2) and the face surface (4) concerned of the flap leaf (3) adjacent to the protective element (12).

4. Fire damper according to any one of the preceding claims, characterised in that, with at least one flap leaf half, the corresponding face surface (4) comprises, on at least one of its two edges (15), a cold seal (9), extending along this edge (15) and projecting opposite the face surface (4) in the longitudinal direction of the flap leaf (3).

5. Fire damper according to any one of the preceding claims, characterised in that the flap leaf (3) comprises, on each of its two edges (15), a cold seal (9), extending along the respective edge (15) circumferentially and projecting opposite the face surface (4) in the longitudinal direction of the flap leaf (3).

6. Fire damper according to any one of the preceding claims, characterised in that each protective device (8) forms, with the adjacent face surface (4), an individual cavity space (10).

7. Fire damper according to any one of the preceding claims, characterised in that, with at least one protective device (8), on at least one of its two longitudinal edges (19), preferably on both of its longitudinal edges (19), in each case a cold seal (9) is provided in order to provide a seal for the cavity space (10) formed between the protective device (8) on the one hand, and, on the other, the face surface (4), facing towards it, of the flap leaf (3) when located in its open position.

8. Fire damper according to any one of the preceding claims, characterised in that on the face surface (4) of each flap leaf half a hot seal (17) is provided, which expands under the effect of heat.

9. Fire damper according to any one of the preceding claims, characterised in that the housing comprises on the inside, at least in the part region which extends along the circumference of the flap leaf (3) located in the closed position, a hot seal (17) which expands under the effect of heat.

10. Fire damper according to any one of the preceding claims, characterised in that at least one protective device (8) is formed on a part length of its length, and preferably on its entire length, as a rail or as a profile rail.

11. Fire damper according to any one of the preceding claims, characterised in that at least one protective device (8) has a convex form on a part length of its length, and preferably over its entire length.

12. Fire damper according to any one of the preceding claims 10 or 11, characterised in that at least one profile rail is formed as an angled rail, with two angled surfaces (14), oriented towards one another at an angle, preferably at a right angle, with the formation of an abutting edge (13), wherein the abutting edge (13) is arranged facing away from the face surface (4) of the leaf flap (3) located in its open position.

13. Fire damper according to any one of the preceding claims, characterised in that one longitudinal edge (19) of each protective device (8) merges on a part length of its length, and preferably over its entire length, into a cover element (20) extending in the direction of the rotation axis (2), wherein the cover elements (20) are provided as oriented diametrically opposite and parallel to the direction of flow (11), and wherein the cover elements (20) are arranged in such a way that, in the open position of the leaf flap (3), each cover element (20) covers the respective adjacent surface of the flap leaf half.

14. Fire damper according to the preceding claim, characterised in that at least one cover element (20), seen in the direction of flow (11), extends so far that the flap leaf (3) in its closed position is in contact with the free edge of the cover element (20).

15. Fire damper according to any one of claims 13 or 14, characterised in that each of the two flap surfaces (5, 6) comprises a cold seal (9), formed in the region which, in the open position of the flap leaf (3), connects to the region covered by the cover element (20), which has four edges arranged at right angles to one another, and which is preferably configured in the form of a frame, wherein each of the two cold seals (9) projects with three of its edges laterally opposite the face surface (4) in the longitudinal direction of the flap leaf (3), and wherein, in the open position of the flap leaf (3), the cover element (20) is in a sealing contact with its peripheral region with the fourth edge of the cold seal (9) concerned.

16. Fire damper according to the preceding claim, characterised in that the two cold seals (9) arranged in diametrically opposite regions of the two flap surfaces (5, 6) are connected to one another in the region of each bearing point in each case by a cold seal (9) extending over the face surface (4).

17. Fire damper according to any one of the preceding claims 13 to 16, characterised in that each of the two flap surfaces (5, 6) comprise, in the region which, in the open position of the flap leaf (3) connects to the region covered by the cover element (20), a surface element (18), which entirely covers the region concerned, preferably formed as a sheet.

18. Fire damper according to any one of the preceding claims 13 to 17, characterised in that at least one protective device (8) and the adjacent cover element (20) are configured as being of one piece.

19. Fire damper according to any one of the preceding claims, characterised in that at least one of the two flap surfaces (5, 6) comprises a surface element (18) which entirely covers the flap surface (5, 6) concerned and is preferably configured as a sheet.

20. Fire damper according to any one of the preceding claims, characterised in that at least one protective device (8) comprises at least one delivery opening (21), preferably accessible from outside the housing, for the delivery of a gaseous medium, preferably air, into the respective cavity space.

21. Fire damper according to the preceding claim, characterised in that at least one delivery opening (21) is connected to a pressure generating device (22), preferably with a pump or fan.

22. Fire damper according to any one of the preceding claims, characterised in that at least one protective device (8) comprises at least one outlet opening (24), preferably provided by means of a non-return device (23), for conveying away a gaseous medium, preferably air, out of the cavity space (10) into the interior of the housing.