AN AIR DISTRIBUTION DUCT FOR AN AIR DISTRIBUTION SYSTEM

Abstract: Air duct for air distribution systems, for instance a ventilation duct, which is assembled by a plurality of elongated duct sections (1) of incombustible material. Each duct section includes an elongated duct section (5, 6) with an opening (29) which is oriented parallelly along the longitudinal axis of the duct element, and which has the same length as the duct section, the opening being closable by means of a lid (12), which is sealingly connected to the duct section, and which extends along the entire length of the duct element. The lid (12) is connected to the duct element (5, 6) by means of a movable connection having a joint made from an incombustible or meltable material, which is dimensioned to burst or melt as a result of a fire, so that the lid by its own weight can swing out from the duct section (5, 6) when the joint busts as a result of said fire, so that the duct will open and release the pressure therein.

Description: An air distribution duct for an air distribution system The present invention relates to an air d stribution duct for an air distribution system, for example a ventilation duct or steam duct, which duct is assembled of a plurali¬ ty of elongated duct sections made from incombustible ma¬ terial which sections can be assembled with one another to a desired length and extension by means of sealing junction sections. BACKGROUND PRIOR ART In such ducts, specially in exhaust air ducts, there is a demand for a possibility of cleaning the duct from dust, grease and other cloggings of the duct passage. Some ducts have even a cleaning requirement according to fire law statutes. Therefore, it has been common to provide cleaning doors in each elbow of the duct and at each fifth meter of straight duct portions. However, it has turned out to be very difficult to readily clean the ducts via these cleaning doors. If the ducts are arranged in the form of aii—boxes or the like in narrow and unhealthy areas which are difficult to reach, for instance in attics, both installation and maintenance work is difficult. These difficulties have in several years caused such work en ironment problems that working with ventilation systems sometimes has to be stopped due to work environment laws. The difficulties have been known within interested trade-union circles for many years, and yet there has hitherto not been proposed any solution to the problem. There has only been sugges¬ ted that the cons ructional buildings and architects and others shall try to design the installation areas such that there will be sufficient room for installation and service job. _ ^ The known ducts are also disadvantageous in installations which extend through a firetrap cell isolating building part, since they require sofisticated dampers or the like which are difficult to operate in order to stop the gas (air) flow in case of a fire. SUMMARY OF THE INVENTION The object of the present invention is therefore to pro- vide a duct of the aforedesc ri bed kind which can more easily be i nsta I led and mai ntai ned, and which offers the possibility of suff cient protection against any spread of fire gas Setween different fire " cells without the need of dampers. This object is achieved with a duct constructed " in accor¬ dance with the invention and having the characteriz ng features set forth in the following Claim 1. Further developments of the invention are defined in the depending claims. Because the duct sections of the duct can be opened along their entire length, a cleaning of the duct will be much facilitated. This opening possibility also enables an efficient and quick stopping of the air flow in the duct due to the pressure release in the duct that is achieved by the opening of the duct. It is also evident that ducts according to the invention can be installed in areas which are difficult to reach, such as attics and the like, and in dwelling and office areas as well. The arrangement of a lid that extends along the entire duct section will namely enable the duct section to be designed in such an oesthetically attracti¬ ve manner that it can even be formed as a stucco work.. By thus replacing such ducts in attics and other areas, that are unhealthy and difficult to reach, with "inter¬ nal" ducts, there is obtained the advantage of less ener¬ gy loss, and that both installation and maintenance work concerning the duct may be done in much better working environment than that existing in attics and the like, where the space is restricted and the air is full of iso¬ lation dust particles and other unhealthy particles. BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described in more detail with refe¬ rence So the accompanying drawings, which illustrate a preferred embodiment of the invention. Figure 1 is a perspective view of a duct section having a triangular cross-section according to the invention, and with a unction section of a first type. Figure 2 is a schematic perspective view of two duct sec- tions according to Figure 1 assembled with a junction sec* tion of a second type. Figures 3A - 3C illustrate schematically in cross-section a duct section according to Figure 1 in three different operational modes. Figure 4 illustrates a duct section according to Figure 1 with an alternative suspension. Figure 5 illustrates a duct section according to the in¬ vention with a circular cross-section. Figure 6 illustrates how the duct sections according to Figure 1 may be stacked upon each other during transport. A PR E F E R R E D EMBO D I M ENT F gure 1 illustrates a duct section 1 and a sealing junc¬ tion section 2, half of which - to the right of the centre line 3 of the section - can be introduced into the duct section 1 in the direction of the arrow 4. The left half portion of the junction section 2 is analogeously insei— table into one end of a further (not shown) duct section of the same kind as the duct section 1. The two duct sec¬ tions will therefore abut one another edge to edge. The duct section 1 consists of an elongated duct element manufactured from a rectangular sheet of incombustible material, for instance steel, which s folded along its longitudinal centre portion to form two rectangular walls 5 and 6, which are orientated in substantially right ang¬ les relative to one another, and having a junction por¬ tion therebetween in the shape of relatively small, rec¬ tangular sheet portion 7 which forms an angle of about 45° relative to the walls 5 and 6. The wall 5, which is primarily intended to be suspended horisontally from a ceiling, has ts free longitudinal edge folded three times, as is shown on an enlarged scale within the circle 8 of Figure 1, to form a clamping con¬ nection 9 for one longitudinal side edge of a rubber or plastic strip 10, the centre portion of which forms a movable connection in the form of a hinge oint with a pivot axis extending parallel to the longi tud na I axis of the duct element 1. The strip 10 is dimensioned such that it will burst or melt as a result of a fire in the vicinty of the duct section. The other long tud nal side edge of the st ip 10 s sim - larly supported by a corresponding clamping connect on 11 which is formed by one longitudinal side edge of an inward¬ ly towards the duct section concavely bending lid 12. The other longitudinal side edge of the lid 12 is folded to form a support flange 13 which can be locked against a similarly folded flange 14 of the lower end of the wall 6, which for this purpose is provided with a sealing strip 15, for instance a magnetic strip or the like, against which the support flange 13 is held in a manner shown within the circle 16 of Figure 1. The junction sect on 2 consists of a rectangular steel sheet 17, which is dimensioned to internally mate with each one of th-e walls 5 of two duct sections 1 (only one is shown in Figure 1) which are to be interconnected. From the upper edge of the sheet 17 to its lower edge extends a sheet 18 which is smaller than the sheet 17 and which is bent to the same internal shape and dimension as the wall 5 and lid 12. The sheets 17 and 18 are covered by a sealing layer on its portions that abut the walls 5, 6 and lid 12. The wall 6 of t-he--dtιct section is provided with fastening holes 19 for screws 20 or the like for fastening against a wall or the li e, as will be shown below in Figure 3A. Corresponding fastening holes 19' are made in the sheet 17 of the junction section 2. When passing through a wall a further type of junction section is used, as is shown in Figure 2. The junction section which forms the through-piece passing through the wall, consists of a cylindrical tube 21 of steel or the like, being arranged between two duct sections 1* and 1". The tube 21 is fastened, for instance by means of a wel¬ ding connection, against an end sheet 22 of the end of the duct section 1' that abuts the wall (not shown). The other end of the tube 21 is fastened against a correspon- ding end portion (not shown) of the end of the other duct section that abuts the wall. The other end of the duct section 1" is terminated by a dummy end sheet 23. It is possible to arrange such through-pieces in the wall or ceiling with cylindrical tubes also transversally through the wall 6 and vertically through the wall 5. Such through-pieces, which are shown in Figure 2 at 21a 5 and 21b, respectively, may for instance communicate with analogous duct sections (not shown) which are situated in adjacent or higher rooms in the building. It is ob ious for one skilled in the art, and need thus 10 not be described in detail, that the duct sections, or preferably their l ds 12' and 12" (see Figure 2) may be provided with air inlet valves and exhaust air valves 24 and 15, respectively, known per se and schematically in¬ dicated in dotted lines in Figure 2 for the various spa- 15 ces of the building that is involved in the air distri¬ bution system. Figures 3A - C illustrate three different operational modes of a duct section according to the invention. 20 In Figure 3A there is shown how the duct section 1 and its opened lid 12, which is reeled up in a suitable way indicated by an arrow 26, can be fastened against a wall - 27 closely below a ceiling 28 in a building (not shown in 25 detail) involved in the air distribution system. The fastening is performed by means of the above mentioned screws 20, which are introduced through the holes 19 and 19' in the wall 6 and the sheet 17, respectively, and then screwfastened in the wall 27. In this position the 30 opening (indicated at reference numeral 29) of the duct section can be entirely exposed in order to offer enough space for the operator to fasten the duct section. Figure 3B illustrates the duct section in a fastened po- 35 s i t ion. Figure 3C illustrates how the hinge connection 10 has been burst or melt as a result of a fire in the vicinity of the duct section. The lid 12 has thereby broken its connec¬ tion with the wall 5, and will, due to its own weight, swing outwards and downwards until also the locking force of the magnetic strip 15 will be overcome. The lid 12 will therefore fall, indicated by an arrow 30, down to the floor, so that the opening 29 of the duct section will be exposed, such that a pressure release will be achieved in the duct . It is also conceivable within the invention to provide the magnetic strip 15 with a mechanical lock (not shown), for instance of the bayonet coupling type. One then must make sure that this mechanical lock does not hinder the outwards movement of the lid 12 when the connection 10 is destroyed due to a fire. Thus, the mechanical lock must be so constructed that it enables the lid 12 to swing outwards to the open position in spite of the fact that the lock permanently holds the lid 12. Figure 4 illustrates an alternative suspension of a duct section 1 in the ceiling instead of the wall. The suspen¬ sion ill thereby suitably take place at the corner por¬ tion 7 of the duct section. In the embodiments shown in Figures 1 - 4 the cross-sec¬ tions of the duct sections form a triangle, the hypothe- nusa of which is bent. It is of course, also possible to give the duct section an alternative shape, for instance the shape of a polygon with more than three straight and/or bent sides. It is also possible to give the cross-section of the duct section the shape of a geometric curve, for instance a circle or an ellipse. An embodiment of a duct section having a circular cross-section is shown in Figu¬ re 5. Some embodiments of the invention, above all the embodi- ment shown in Figures 1 - 4, offers the opportunity of stacking the duct sections on each other during transport. This is shown in Figure 6, where two duct sections have been stacked on one another. Such a stacking facility is of course much space saving, and this facility has not been possible with prior air duct sections. In the embodiments shown, the lid 12 of the duct section can be opened manually, as well as automatically as a 10 result of the melting or bursting of the connection 10 at a fire. According to a further embodiment a controlled melting of the connection 10 may be obtained by casting a glow fi lament within the connection, and arrang ng a sensing means, for instance a smoke detector, to initiate, 15 at certain conditions, for instance at any detection of smoke, the closing of an electric circuit through the glow filament such that this w ll be heated and melt the connec¬ tion 10 in order to open the lid 12. 20

Claims: C l a m s : ' 1. An air distribution duct, for instance a ventilation duct or steam duct in a building, which duct can be as- sembled by a plurality of elongated duct sections (1) of incombustible material which can be interconnected with one another to a desired length and extension by means of sealing junction sections (2, 21), c h a r a c t e r i - z e d in that each duct section comprises an etongated duct element (5, 6) with an opening ( 29) orientated pa¬ rallelly to the longitudinal axis of the duct element and having the same length as the duct element, the opening be ng closable by means of a lid (12) which is sealingly connected with the duct element and which also extends along the entire length of the duct element, and in that the lid (12) is so movably connected to the duct element (5, 6) that it can be opened to expose the internal of the duct section along its entire length in order to en¬ able an internal cleaning of the entire duct section. 2. Air duct according to Claim 1, c h a r a c t e r i - z e d in that the lid (12) is connected with the duct element C5, 6) by means of a movable connection, for in¬ stance a hinge connection (10). 3. Air duct according to Claim 2, c h a r a c t e r i - z e d in that the connection has a joint (10) which is orientated such that it extends parallelly to the longi¬ tudinal axis of the duct element (5, 6), and which s made of incombustible or meltable material which is di¬ mensioned to burst or melt as a result of a fire, so that the lid (12) by its own weight can swing out from the duct element (5, 6) when the joint bursts or melts as a result of said fire, so that the duct will open and release the pressure therein. 4. Air duct accord ng to any preceding Claim, c h a - r a c t e r i z e d in that the duct section (5, 6) con¬ sists of two walls (5, 6) which are orientated in sub¬ stantially right angles relative to one another, and that the lid (12) sealingly abuts said walls, so that the cross-section of the duct section obtains a triangular shape. 5. Air duct according to any preceding Claim, c h a - r a c t e r i z e d in that the lid (12) in its end oppo¬ site to said joint can be locked against the duct element C5, 6) by means of a sealing strip (15), for instance a magnetic strip. 6. Air duct according to any preceding Claim, c h a - r a c t e r i ∑ e d in that the connection consists of a rubber or plastic strip (10). 7. A r duct according to any preceding Claim, c h a - r a c t e r z e d in that the duct section (5, 6, 12) is designed to simulate a stucco work, and that it is designed to be able to be installed in the corner between the ceiling and wall in rooms such as dwelling and office rooms.

Inventors: JAEDERBERG CARL-ERIC, REVELJ KARL-OLOF, JAEDERBERG, CARL-ERIC, REVELJ, KARL-OLOF
Applicants: JAEDERBERG CARL ERIC, REVELJ KARL OLOF, JAEDERBERG, CARL-ERIC, REVELJ, KARL-OLOF
Application year: 1987
Main classification: F16L45
IPC codes: F16L9, F24F13