WO2012160197A1 - Backflow prevention device with collapsible element within a ventilation duct and use of a collapsable element within a ventilation duct - Google Patents
Backflow prevention device with collapsible element within a ventilation duct and use of a collapsable element within a ventilation duct Download PDFInfo
- Publication number
- WO2012160197A1 WO2012160197A1 PCT/EP2012/059872 EP2012059872W WO2012160197A1 WO 2012160197 A1 WO2012160197 A1 WO 2012160197A1 EP 2012059872 W EP2012059872 W EP 2012059872W WO 2012160197 A1 WO2012160197 A1 WO 2012160197A1
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- WO
- WIPO (PCT)
- Prior art keywords
- duct
- cone
- collapsible element
- interior wall
- collapsible
- Prior art date
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Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F13/00—Details common to, or for air-conditioning, air-humidification, ventilation or use of air currents for screening
- F24F13/08—Air-flow control members, e.g. louvres, grilles, flaps or guide plates
- F24F13/10—Air-flow control members, e.g. louvres, grilles, flaps or guide plates movable, e.g. dampers
- F24F13/14—Air-flow control members, e.g. louvres, grilles, flaps or guide plates movable, e.g. dampers built up of tilting members, e.g. louvre
- F24F13/1426—Air-flow control members, e.g. louvres, grilles, flaps or guide plates movable, e.g. dampers built up of tilting members, e.g. louvre characterised by actuating means
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- A—HUMAN NECESSITIES
- A62—LIFE-SAVING; FIRE-FIGHTING
- A62C—FIRE-FIGHTING
- A62C2/00—Fire prevention or containment
- A62C2/06—Physical fire-barriers
- A62C2/12—Hinged dampers
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/30—Control or safety arrangements for purposes related to the operation of the system, e.g. for safety or monitoring
- F24F11/32—Responding to malfunctions or emergencies
- F24F11/33—Responding to malfunctions or emergencies to fire, excessive heat or smoke
- F24F11/35—Responding to malfunctions or emergencies to fire, excessive heat or smoke by closing air passages
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F13/00—Details common to, or for air-conditioning, air-humidification, ventilation or use of air currents for screening
- F24F13/08—Air-flow control members, e.g. louvres, grilles, flaps or guide plates
- F24F13/10—Air-flow control members, e.g. louvres, grilles, flaps or guide plates movable, e.g. dampers
- F24F13/14—Air-flow control members, e.g. louvres, grilles, flaps or guide plates movable, e.g. dampers built up of tilting members, e.g. louvre
- F24F2013/1493—Air-flow control members, e.g. louvres, grilles, flaps or guide plates movable, e.g. dampers built up of tilting members, e.g. louvre using an elastic membrane
Definitions
- the present invention relates to a fire retarding backflow prevention device of 5 a ventilation system, and a ventilation system including such a device.
- Fire retarding components and fittings are today well known and widely used in ventilation installations and systems.
- WO-A-2005/023369 describes a device for preventing backflow in ventilation ducts included in ventilation systems.
- This known device is arranged to prevent backflow in case of a fire by means of a flexible material which collapses in case of a backflow and thereby closes the duct.
- a web is mounted as an abutment within the duct which allows the flexible material to collapse
- this object is achieved by a fire retarding backflow prevention device of a ventilation system, in which the device comprises a duct and a collapsible element which is arranged within the duct and 30 moveable between a first collapsed position allowing air flow through the duct in a first direction, and a second expanded position preventing harmful substances to flow through the duct in an opposite direction, wherein the collapsible element is attached to the interior wall of the duct and extends along a longitudinal axis of the duct. In its expanded position, the collapsible element serves as a backflow prevention means which prevents fire and smoke to spread in a direction opposite to the normal air flow direction of the ventilation duct.
- An advantage is that the pressure drop past the device can be kept low since the collapsed element only takes up a minor portion of the air flow area through the duct. This proportion may be about 15-30% of the total flow area in cross section, and a preferred range is about 20-25%.
- the collapsible element has the shape of a hollow cone in its second expanded position.
- the collapsible element may efficiently collect and prevent harmful substances from spreading through the duct.
- the cone shape prevents backflow in a very efficient manner.
- the collapsible element has - in its expanded position - the shape of a circular oblique cone which makes it easy to fasten the collapsible element.
- the collapsible element may be attached to the interior wall of the duct along the side or generator of the cone. This is advantageous in that the collapsible element may be attached to the duct in a simple and convenient manner without any need for special tooling.
- the collapsible element may be attached to the interior wall of the duct in such a way that the side or generator of the cone is substantially parallel to the longitudinal axis of the duct. Hence, the apex of the cone will be aligned within the duct for improving the performance of the device.
- the attachment of the collapsible element may be provided at the interior wall of the duct along the periphery of the duct, preferably at points between 30° and 180° of the periphery.
- the collapsible element will thus be collapsed in a more controlled manner, which improves the performance of the fire retarding backflow preventing device.
- one end portion of the collapsible element forming the apex of the cone is maintained substantially at the center of the duct by means of a member which extends from the interior wall of the duct, wherein an opposite end portion of the collapsible element forming the base of the cone is attached to the interior wall of the duct.
- the collapsible element may - in its expanded position - have the shape of a substantially symmetric cone.
- the symmetric shape of the collapsible element promotes smooth air flow in normal use as well as efficient backflow prevention properties, for instance in case of fire.
- the collapsible element forming the cone has an axis which is substantially coaxial with the center axis of the duct.
- This design of the collapsible element further enhances the back flow prevention thanks to the symmetric shape which may be obtained
- the opposite end portion of the collapsible element which forms the base of the symmetric cone may be attached to the interior wall of the duct in at least two preferably equidistant attachment points on the periphery of the interior wall of the duct, thereby spanning the base of the symmetric cone around the inner periphery of the duct.
- equidistant attachment points provide smooth air flow in normal use and contribute to quick back flow prevention when needed. This effect is in particular achieved if there are three attachment points spaced 120° from each other.
- the collapsible element may define three similar channels allowing air to flow through the duct in the first direction past the collapsed element, wherein the collapsible element in the second expanded position defines the symmetric cone having the periphery of its base pressed against the interior wall of the duct and thereby preventing air flow in the second opposite direction.
- This three- channel design provides a uniform air flow in the normal direction, but also makes it possible to achieve quick switch to backflow prevention mode.
- the member supporting the apex of the symmetric cone may comprise a piece of sheet metal which is folded substantially to the shape of a T having two flanges fastened to the interior wall of the duct and a leg which extends from the interior wall to the center of the duct and to the free end of which the apex of the symmetric cone is attached.
- a supporting member of this type is easy to manufacture and install which keeps manufacturing costs low.
- the collapsible element may be attached to the interior wall of the duct by means of fasteners, an adhesive or a guiding rail.
- the fire retarding backflow preventing device may thus be manufactured by simple structural elements which reduce the overall manufacturing cost of the device.
- the collapsible element In an idle position of no air flow, the collapsible element may be collapsed to the first position allowing air flow through the duct in a first direction. Further, the collapsible element may be moveable between the first position and the second position by a change of the airflow direction. This is advantageous in that the collapsible element may be manufactured by a thin and flexible lightweight material, thus reducing the manufacturing cost of the device.
- the collapsible element comprises a flexible fabric material which has heat resistant properties and which may be based on a substrate which on one side has an airtight coating.
- the flexibility of such a material enhances the ability to quickly switch from normal air flow to back flow prevention, and the coating contributes to keep harmful substances away from the ventilation system behind the fire retardation device.
- the collapsible element may comprise at least two flexible segments by which the collapsible element forms a hollow cone shape in the second expanded position. This design enhances the back- flow preventing properties of the device and it also provides a favorable air flow under normal use.
- the cone shape of this embodiment may comprise an apex end and an opposite cone base end, wherein the cone apex end is maintained substantially at the center of the duct by means of a member which extends from the interior wall of the duct.
- the cone base end has attachment points for attachment of each cone segment to the interior wall of the duct. This structure further enhances the flow properties as well as the backflow function.
- each segment of the collapsible element is formed as a partial cone which has a wall portion facing the interior wall of the duct and which defines a space of the hollow cone shape.
- This cone design has proved good results in practice.
- the segments building up the collapsible element may be joint together along joining lines extending from the cone apex to the cone base end. This structure makes it possible to achieve a symmetrical embodiment of the cone shape which is favorable.
- the joining lines form elongate ridges of the cone shape which are directed towards the center of the same. These ridges provide the cone with a certain stability which leads to a proper air flow.
- the collapsible element may comprise three segments which define three spaces of the cone shape and which make it possible to achieve a symmetrical shape, where the cross-section of the cone shape has the form of a three-foil clover leaf.
- the collapsible element comprises a flexible fabric material with heat resistant properties; preferably based on a substrate which on one side has an airtight coating, which may include a silicone material.
- an arrangement comprising a tubular body with a recess for receiving a back flow preventing device, wherein the tubular body and the duct of the device are coaxial after receipt of the device.
- the inventive device can have the shape of an insert which is received in a tubular body included in the ventilation system.
- the arrangement has a cover member configured to close the recess after receipt of the device or insert. Thanks to the cover member, the insert is easy to inspect and also to replace if necessary.
- the cover member may be pivotably connected to the tubular body and may have first latching means configured to engage with matching second latching means provided on the tubular body. This structure makes it easy to position the insert in the tubular body, and also makes the insert detachable which facilitates inspection, etc.
- the cover member has internal sealing elements configured to engage external sealing elements of the duct of the device and the tubular body, respectively. These sealing assemblies reduce the risk of air leakage.
- a ventilation system which comprises at least one fire retarding backflow preventing device according to the first aspect of the invention.
- Such a ventilation system is enhanced since the risk of fire and smoke spreading in the system is reduced.
- a fourth aspect of the invention concerns use of a flexible element for establishing back flow preventing means in a ventilation duct, said flexible element being collapsed to a first state by normal air flow through the duct in a first direction, and expanded to a second state by air flow in a second direction opposite the first direction, whereby the flexible element serves as a back flow valve in said second state.
- Fig. 1 is an end view of a fire retarding backflow preventing device according to a first embodiment shown in open position;
- Fig. 2 is an end view of the device of Fig. 1 shown in closed position;
- Fig. 3 is a side cross sectional view of the device of Figs 1-2 in closed position
- Fig. 4 is a side cross sectional view of the device of Fig. 3 in open position
- Fig. 5 is an isometric view of a ventilation system including a fire retarding backflow device in accordance with an embodiment of the invention
- Fig. 6 is a side view corresponding to Fig. 5 and shows a modified fire retarding backflow preventing device according to a second embodiment of the invention
- Fig. 7 is an end view corresponding to Fig. 1 and shows the device of Fig. 6 in open position;
- Fig 8 is an end view corresponding to Fig. 2 and shows the device of Fig. 6 in closed position;
- Figs 9-12 show how a supporting member of the device of Fig. 6 is formed
- Fig. 13 is a side view of a tubular body for receiving a back flow preventing device in accordance with an embodiment of the invention
- Fig. 14 is a side view of the tubular body of Fig. 13 in closed position containing the back flow preventing device
- Fig. 15 is a partial cross sectional view of the tubular body of Figs 13-14 installed in a ventilation system and illustrating a cover in open position
- Fig. 16 is a cross section along the line XVI - XVI in Fig. 15.
- Fig. 17 is a side view corresponding to Fig. 15 showing the cover in closed position
- Fig. 18 is a cross section along the line XVIII - XVIII in Fig. 17;
- Fig, 19 is an isometric view of the tubular body with open cover, as well as a backflow preventing device to be received in the tubular body;
- Fig, 20 shows how the device is received in the tubular body
- Fig. 21 shows how the cover of the tubular body is closed
- Fig. 22 is an oblique end view illustrating the supporting member of Fig. 6;
- Fig. 23 is an oblique end view illustrating the expanded back flow preventing state of the device
- Fig. 24 is a schematic side view of a further modified fire retarding backflow preventing device according to a third embodiment of the invention.
- Fig. 25 is an end view of a hollow base cone end of a collapsible element of the backflow preventing device shown in Fig. 24;
- Fig. 26 is an opposite end view of an apex cone end of the collapsible element shown in Fig. 25;
- Fig. 27 is an end view of the base cone end of a device having a collapsible element of the type shown in Figs 24-26;
- Fig. 28 is a schematic overview of a ventilation system of a building in which fire occurs in one room, in which situation a fire retarding backflow preventing device according to an embodiment of the invention is in its operative mode.
- a fire retarding backflow preventing device 1 of a first embodiment is shown.
- the fire retarding device 1 is designed as a backflow preventing valve to be fitted with a ventilation system, and is arranged to allow air flow in a first direction A during normal ventilation. Further, the fire retarding device 1 is arranged to prevent air flow in an opposite direction B, which may occur in case of a backflow due to e.g. fire when hot and harmful substances may spread through the ventilation system.
- the fire retarding backflow preventing device 1 includes a hollow duct 3 to be fitted with the ventilation system.
- the duct 3 has a cylindrical shape and a circular cross section.
- a collapsible element or membrane 5 is attached within the duct 3 along a longitudinal axis of the duct 3, and the collapsible element 5 is able to move between a first collapsed or idle position, as indicated in Fig. 1 where air is allowed to flow through the duct 3 in the direction A, and a second expanded or active position, as indicated in Fig. 2 where air is prevented to flow through the duct 3 in the opposite direction B.
- the collapsible element 5 In a closed position, i.e. expanded state, the collapsible element 5 forms a hollow cone, in the shape of an oblique circular cone where the generator or generatrix extends perpendicularly from the periphery of the base to the apex.
- Figs 3 and 4 shows the backflow preventing device 1 in a closed position
- Fig. 4 shows the backflow preventing device in an open position.
- the collapsible element 5 which has a circular base with dimensions corresponding to the circular cross-section of the duct 3, is attached to the interior wall of the duct 3 along a side or generator of the cone-shape.
- the generator extends perpendicularly from the base to the apex of the cone when the collapsible element 5 is expanded according to Fig. 3.
- the collapsible element 5 is preferably attached to the interior wall of the duct 5 by means of fastening means 7, such that the side of the cone-shaped element 5 is arranged adjacent to the interior wall of the duct 3.
- the base of the collapsible element 5 is preferably attached to a part of the interior periphery of the duct 3.
- the base may be attached at the interior periphery of the duct 3 between 30° and 270°, preferably between 60° and 180°, and more preferably between 100° and 150°.
- the fastening means 7 may e.g. be a plurality of fasteners 7a, 7b, such as bolts, screws or pop rivets, spaced apart to provide attachment of the collapsible element 5 to the duct 3.
- the fastening means 7a may be a guiding rail (not shown), such that the collapsible element 5 may be mounted to the duct 3 with a corresponding fitting of the collapsible element 5 which allows the collapsible element 5 to be attached to the rail.
- a guiding rail not shown
- Such solution would facilitate the handling and mounting of the fire retarding backfiow preventing device 1.
- the fastening means may include snap locks (not shown) including corresponding engaging parts pre-arranged on the collapsible member 5 as well as on the duct 3.
- the collapsible element 5 includes a light and deformable material with mechanical and chemical characteristics suitable for blocking the hot and harmful substances created in a fire.
- the collapsible element 5 deforms and folds onto the interior surface of the duct 3 which means that during normal air flow in the ventilation system, the collapsed element 5 will reduce the amount of space occupied in the duct 3 and therefore minimize the risk of turbulence as well as a pressure drop in the flow.
- the collapsible element 5 only takes up a certain portion of the total flow area in cross section; see Fig. 1.
- This proportion may be about 15-30%, and most preferred about 20-25%.
- a part of a ventilation system 100 is shown.
- the ventilation system includes a duct 12 connected to a fire retarding backflow preventing device 1 via a fitting 10.
- the fire retarding backflow preventing device 1 is similar to what has previously been described with reference to Figs 1 - 4.
- the collapsible element 5 is shown in dotted lines in its expanded, back flow preventing mode (cf. Figs 2 and 3)
- a fire retarding backflow preventing device 1 ' according to a second embodiment is shown.
- the device 1 ' includes two main components, namely a duct 30 and a collapsible element 50 corresponding to the components 3 and 5 shown in Figs 1 - 5.
- the flexible element 50 In its first position shown in the end view of Fig. 7, the flexible element 50 is in its inactive open state where air flows in the direction of the arrow A through the duct 30.
- the air flow is directed in three similar channels 60A-60C past the collapsed element 50.
- the flexible element 50 In its second position shown in the end view of Fig. 8, the flexible element 50 is in its closed expanded state so that air flow in the opposite direction B is prevented, whereby smoke and any harmful substances are blocked from passing through the device 1 ' (to the left in Fig. 6) and spreading on the ventilation side to the left of the device.
- the collapsible element 50 has - in its expanded position - the shape of a circular symmetric cone with an axis C which is coaxial with the longitudinal or centre axis C of the duct 30.
- Fig. 8 shows how the expanded base portion of the hollow cone is pressed against the inner wall of the duct 30, similar to the position shown in Fig. 2 of the first embodiment.
- the collapsible element 50 is mounted to the duct 30 at its apex end portion 50A and at its opposite base end portion 50B.
- the apex end 50A is maintained at the centre of the duct 30 by means of a member 70 which extends radially and substantially perpendicularly from the inner wall of the duct 30.
- the supporting member 70 is preferably made of a piece of sheet metal which is folded to the shape of a T having two flanges 70A, 70B fastened to the inner wall of the duct 30, and a leg 70C with a free end where the apex end 50A of the collapsible element 50 is attached.
- the flanges 70A and 70B are preferably riveted to the inner wall of the duct 30.
- Figs 9-11 show how a sheet metal piece is folded to form the T-shaped member 70
- Fig. 12 is a side view of the complete member 70 ready to be mounted inside the duct 30.
- the base end 50B of the collapsible element 50 is attached to the inner periphery of the duct 30 in three equidistant attachment points P1-P3 spaced by 120° from each other along the periphery. Thanks to this configuration, the base portion 50B of the symmetric cone is spanned around the inner periphery of the duct 30.
- the base portion 50B of the collapsible element 50 is attached to the duct 30 by fasteners, like rivets (not shown).
- Figs 13-14 there is shown an arrangement including a tubular body 80 with an opening or recess 81 for receiving the device 1 ' shown in Fig. 6.
- the device 1 ' may be regarded as an insert which is positioned in the recess 81 which may be closed by a cover member 82.
- the cover member 82 is pivotably connected to the tubular body 81 and it has latching means 83 for engagement with matching latching means 84 on the tubular body 80.
- the recess 81 is closed by the cover member 82 and locked by the latching means 83, 84.
- the arrangement 80-84 is further illustrated in Figs 15-18 where it is installed in a ventilation system, namely bridging two ventilation ducts 12A, 12B of the system.
- a hinge 85 between the tubular body 80 and the cover member 82 is showed in Fig. 16 and Fig. 18, respectively.
- Fig. 1 it is understood how the device or insert 1 ' is received in the tubular body 80.
- the collapsible element 50 is shown in its expanded backflow preventing state, where it has the shape of a circular, symmetrical cone which is coaxial with the center axes C, C of insert 1 ' and the tubular body 80 and also with the two opposite ducts 12A, 12B on either side of the arrangement 80-84.
- Figs 17-18 show how the tubular body 80 receiving the insert 1 ' is closed by the cover member 82.
- the duct 30 of the backflow preventing device or insert 1 ' of this embodiment has external peripheral sealing elements 31, 32 for engagement with matching sealing elements 86 and 87 on the inside of the cover member 82 of the tubular body 80 when the insert 1 ' is positioned in the recess 81 and the unit is closed.
- the cover member 82 has an additional sealing element 88 for engagement with a lateral external portion of the tubular body 80.
- the tubular body 80 has two external peripheral sealing elements 90, 91 which are disposed at a distance from the respective end of the body 80 and which are configured to engage the sealing elements 86 and 87 of the cover member 82.
- tubular body 80 has two end sealing elements 92 and 93 which seal the joint with the ducts 12A and 12B (see Figs 15 and 17).
- the peripheral sealing elements 90-93 are preferably of so called double-lip type, and may be made of rubber material. The sealing arrangement described above and shown in Figs 19-23 provides for secure operation with reduced risk of undesired air leakage
- the end portion 30B of the duct 30, where the collapsible element 50 has its cone base end 50B is somewhat conical outwards. Thanks to this conical shape of the duct end portion 30B, the collapsible element 50 will be smoothly applied to the inner surface of the duct end portion 30B which enhances tight application against the inner wall of the duct 30 which in turn reduces the risk of leakage in the expanded, backflow preventing state of the device (cf. Figs 6 and 8).
- a flexible strap 99 has one of its ends fastened to the inside of the tubular body 80 in the recess 81 , whereas the free end of the strap 99 is used when one wishes to lift the insert 1 ' out of the recess 81 from the position shown in Fig. 20.
- the member 70 supporting one apex end 50A of the collapsible element 50 is shown as well as a portion of the circular symmetric cone in its expanded position.
- the supporting member 70 may extend transversely and span the diameter of the duct 30.
- the opposite ends of the supporting member are fastened to the internal wall of the duct in two diagonally opposite positions.
- Fig. 23 shows from the opposite end how the opposite end 50B of the collapsible element 50 is attached to the inner surface of the duct 30 and also how the cone base is expanded at this end.
- Various means can be used for fastening the end portion 50B of the collapsible element 50 to the inside of the duct 30.
- a modified collapsible element 500 is illustrated in Fig. 24 arranged within a duct 300 schematically shown in dotted lines.
- the closed apex end 5 OA of the cone shaped element 500 is maintained at the center of the duct by the member 70 attached to the inner wall of the duct 300, whereas the opposite base cone end 50B constitutes the open end of the cone shaped element 500.
- the supporting member 70 spans the diameter of the duct 300 and has its opposite ends fastened to the inner wall of the duct 300 in diagonally opposite positions (schematically shown in dotted lines). Furthermore the end portion 300B of the duct 300, where the collapsible element 500 has its cone base end, may be slightly conical outwards so that tight application of the cone base portion against the inner wall of the duct 300 is achieved in the expanded backflow preventing mode. This design reduces the risk of leakage past the cone shape.
- the cone element 500 is shown separately.
- This cone element 500 is built up by three flexible elements 500A, 500B and 500C joint together at joining lines or seams J1-J3 which form ridges of the cone shape which are directed towards the center of the same.
- Each one of the three segments 500A-500C defines a partial cone which has a wall portion facing the interior wall of the duct 300 and which defines a space of the hollow cone shape.
- the large cone 500 may be regarded as built up by three partial cone shapes each of which opens into the center of the large cone shape. This design of the collapsible element 500 has proved to be very efficient in practice.
- the cross section of the segment-built cone element 500 has the shape of a three-foil clover leaf which has proved to be favourable as regards air flow in the direction of normal operation, but also for switching to the backflow prevention mode.
- the symmetric shape of the three-space, segment built cone element 500 provides efficient operation in both modes.
- the number of segments forming the cone element 500 may vary depending on the diameter of the duct 300 and the ventilation system where the fire retarding backflow preventing device is used.
- the cone element may have only two segments forming the hollow cone shape, and there may also be four segments and more (not shown). In case of four partial cones forming the large cone element, the cross section of the same may be regarded as a four-foil clover leaf. It is to be understood, though, that the inventive concept is not bound to a certain number of cone segments.
- the cone segments 500A-500C consist of the same material as described above, that is a flexible fabric material with heat resistant properties.
- the segments 500A-500C are sewn together along the joint lines J1-J3.
- FIG. 27 A practical example of the embodiment of Figs 24-26 is shown in Fig. 27 from which is it is clear how the segments 500A-500C are attached to the interior wall of the duct 300 at three equidistant attachment points P1-P3.
- Fastening means may be rivets, screws and the like.
- a ventilation system 100 including devices according to embodiments of the invention is schematically shown in Fig. 28.
- a building 200 comprises a number of rooms R1-R5 and in one of these rooms R3 a fire F has started. Then heat and pressure increase in the room R3 and smoke is starting to spread. After a while, the backflow preventing device 1 is activated since the normal air flow is reversed. The collapsible element 5 is expanded to its cone shape and thereby blocks flow past the device 1. This blocking back flow preventing effect is shown by a cross in Fig. 28.
- the collapsible element 5, 50, 500 can be made of fabric, plastics material or any other flexible material suitable to prevent air flow in ventilation systems.
- the collapsible element 5, 50, 500 is based on a heat resistant fabric material including a substrate which on one side has an airtight coating which enhances the air flow blocking effect and collects harmful substances.
- the property "heat resistant" may vary depending on where the device is used (type of installation, type of building, etc), and various requirements on heat resistance may apply in different countries.
- the heat resistant material should withstand about 800 °C during 15 min, but in some installations the requirement is that the heat resistant material should withstand up to about 1000 ° during 60 min.
- Various standard fire curves may be applied (time-temperature). Suitable heat resistance is desired, so that the collapsible element 5, 50, 500 in its expanded backflow preventing position blocks fire gases and smoke from spreading in the system.
- Practical tests performed with a fire retardant backflow preventing device designed in accordance with the basic ideas behind the concept described herein have shown that the device resists 90 min in a fire test following a temperature/time curve according to a standard referred to as EN 1363-1. The leakage through the tested device was lower than 200 m3/(hm2) and thereby it achieved the leakage criteria according to a standard referred to as EN 1366-2.
- the inventive device is not limited to use in circular duct ventilation systems, but it can also be used in rectangular duct systems, etc.
- the collapsible element of the inventive device may then have other shapes, such as a pyramid shape or a wedge shape, as long as the base dimensions of the collapsible element match the dimensions of the cross section of the duct.
- the collapsible element may have an oblique shape such that the apex or apex edge is positioned on the interior wall of the duct.
- the flexible material of the collapsible material may vary as long as it fulfills its backflow preventing purpose.
- the fastening of the collapsible element can be achieved in other ways than described herein.
- Alternative means can be used for supporting the apex end of the collapsible element within the duct and for attaching the base portion of the collapsible element to the inner periphery of the duct.
Abstract
A fire retarding backflow prevention device of a ventilation system has a hollow duct (30) and a collapsible element (50) which is arranged within the duct (30) and which is moveable between a first collapsed position allowing air flow through the duct (30) in a first direction and a second closed position preventing harmful substances to flow through the duct (30) in an opposite direction. The collapsible element (50) is attached to the interior wall of the duct (30) and extends along a longitudinal axis of the duct (30). In its closed expanded position, the collapsible element (50) forms a circular symmetric cone which is coaxial with the duct (30) and which has its apex (50A) on the longitudinal axis (C') thereof.
Description
BACKFLOW PREVENTION DEVICE WITH COLLAPSIBLE ELEMENT WITHIN A VENTILATION DUCT AND USE OF A COLLAPSABLE ELEMENT WITHIN A VENTILATION DUCT
TECHNICAL FIELD
The present invention relates to a fire retarding backflow prevention device of 5 a ventilation system, and a ventilation system including such a device.
BACKGROUND
Fire retarding components and fittings are today well known and widely used in ventilation installations and systems.
10 WO-A-2005/023369 describes a device for preventing backflow in ventilation ducts included in ventilation systems. This known device is arranged to prevent backflow in case of a fire by means of a flexible material which collapses in case of a backflow and thereby closes the duct. In order to seal the duct properly, a web is mounted as an abutment within the duct which allows the flexible material to collapse
15 against it. This solution requires several different components which have to co-operate to prevent a backflow. Furthermore, the collapse of the flexible material is not controlled and the quality of the sealing depends on the way the flexible material collapses against the web.
There is thus a need for an improved device which is capable of preventing
20 backflow in ventilation systems in a more reliable manner, as well as a backflow
preventing device which is less complex and more cost efficient.
SUMMARY
It is an object of the present invention to mitigate the above mentioned 25 drawbacks, and to provide improved means for preventing hot and harmful substances from spreading through a ventilation system.
According to a first aspect of the invention, this object is achieved by a fire retarding backflow prevention device of a ventilation system, in which the device comprises a duct and a collapsible element which is arranged within the duct and 30 moveable between a first collapsed position allowing air flow through the duct in a first direction, and a second expanded position preventing harmful substances to flow
through the duct in an opposite direction, wherein the collapsible element is attached to the interior wall of the duct and extends along a longitudinal axis of the duct. In its expanded position, the collapsible element serves as a backflow prevention means which prevents fire and smoke to spread in a direction opposite to the normal air flow direction of the ventilation duct. An advantage is that the pressure drop past the device can be kept low since the collapsed element only takes up a minor portion of the air flow area through the duct. This proportion may be about 15-30% of the total flow area in cross section, and a preferred range is about 20-25%.
Preferably, the collapsible element has the shape of a hollow cone in its second expanded position. Thereby, the collapsible element may efficiently collect and prevent harmful substances from spreading through the duct. Furthermore, the cone shape prevents backflow in a very efficient manner.
In an embodiment, the collapsible element has - in its expanded position - the shape of a circular oblique cone which makes it easy to fasten the collapsible element. The collapsible element may be attached to the interior wall of the duct along the side or generator of the cone. This is advantageous in that the collapsible element may be attached to the duct in a simple and convenient manner without any need for special tooling.
The collapsible element may be attached to the interior wall of the duct in such a way that the side or generator of the cone is substantially parallel to the longitudinal axis of the duct. Hence, the apex of the cone will be aligned within the duct for improving the performance of the device.
The attachment of the collapsible element may be provided at the interior wall of the duct along the periphery of the duct, preferably at points between 30° and 180° of the periphery. The collapsible element will thus be collapsed in a more controlled manner, which improves the performance of the fire retarding backflow preventing device.
In another embodiment, one end portion of the collapsible element forming the apex of the cone is maintained substantially at the center of the duct by means of a member which extends from the interior wall of the duct, wherein an opposite end portion of the collapsible element forming the base of the cone is attached to the interior
wall of the duct. By this design, the collapsible element is secured to the duct in an efficient manner and it may extend symmetrically within the duct both during normal air flow and during backflow prevention.
The collapsible element may - in its expanded position - have the shape of a substantially symmetric cone. The symmetric shape of the collapsible element promotes smooth air flow in normal use as well as efficient backflow prevention properties, for instance in case of fire.
Preferably, the collapsible element forming the cone has an axis which is substantially coaxial with the center axis of the duct. This design of the collapsible element further enhances the back flow prevention thanks to the symmetric shape which may be obtained
The opposite end portion of the collapsible element which forms the base of the symmetric cone may be attached to the interior wall of the duct in at least two preferably equidistant attachment points on the periphery of the interior wall of the duct, thereby spanning the base of the symmetric cone around the inner periphery of the duct. These equidistant attachment points provide smooth air flow in normal use and contribute to quick back flow prevention when needed. This effect is in particular achieved if there are three attachment points spaced 120° from each other.
In the collapsed position, the collapsible element may define three similar channels allowing air to flow through the duct in the first direction past the collapsed element, wherein the collapsible element in the second expanded position defines the symmetric cone having the periphery of its base pressed against the interior wall of the duct and thereby preventing air flow in the second opposite direction. This three- channel design provides a uniform air flow in the normal direction, but also makes it possible to achieve quick switch to backflow prevention mode.
The member supporting the apex of the symmetric cone may comprise a piece of sheet metal which is folded substantially to the shape of a T having two flanges fastened to the interior wall of the duct and a leg which extends from the interior wall to the center of the duct and to the free end of which the apex of the symmetric cone is attached. A supporting member of this type is easy to manufacture and install which keeps manufacturing costs low.
The collapsible element may be attached to the interior wall of the duct by means of fasteners, an adhesive or a guiding rail. The fire retarding backflow preventing device may thus be manufactured by simple structural elements which reduce the overall manufacturing cost of the device.
In an idle position of no air flow, the collapsible element may be collapsed to the first position allowing air flow through the duct in a first direction. Further, the collapsible element may be moveable between the first position and the second position by a change of the airflow direction. This is advantageous in that the collapsible element may be manufactured by a thin and flexible lightweight material, thus reducing the manufacturing cost of the device.
Preferably, the collapsible element comprises a flexible fabric material which has heat resistant properties and which may be based on a substrate which on one side has an airtight coating. The flexibility of such a material enhances the ability to quickly switch from normal air flow to back flow prevention, and the coating contributes to keep harmful substances away from the ventilation system behind the fire retardation device.
In one embodiment, the collapsible element may comprise at least two flexible segments by which the collapsible element forms a hollow cone shape in the second expanded position. This design enhances the back- flow preventing properties of the device and it also provides a favorable air flow under normal use.
The cone shape of this embodiment may comprise an apex end and an opposite cone base end, wherein the cone apex end is maintained substantially at the center of the duct by means of a member which extends from the interior wall of the duct. The cone base end has attachment points for attachment of each cone segment to the interior wall of the duct. This structure further enhances the flow properties as well as the backflow function.
It is preferred that each segment of the collapsible element is formed as a partial cone which has a wall portion facing the interior wall of the duct and which defines a space of the hollow cone shape. This cone design has proved good results in practice.
The segments building up the collapsible element may be joint together along joining lines extending from the cone apex to the cone base end. This structure makes it possible to achieve a symmetrical embodiment of the cone shape which is favorable.
Preferably, the joining lines form elongate ridges of the cone shape which are directed towards the center of the same. These ridges provide the cone with a certain stability which leads to a proper air flow.
The collapsible element may comprise three segments which define three spaces of the cone shape and which make it possible to achieve a symmetrical shape, where the cross-section of the cone shape has the form of a three-foil clover leaf.
In an embodiment, the collapsible element comprises a flexible fabric material with heat resistant properties; preferably based on a substrate which on one side has an airtight coating, which may include a silicone material.
In a second aspect of the invention, there is provided an arrangement comprising a tubular body with a recess for receiving a back flow preventing device, wherein the tubular body and the duct of the device are coaxial after receipt of the device. By this arrangement, the inventive device can have the shape of an insert which is received in a tubular body included in the ventilation system.
Preferably, the arrangement has a cover member configured to close the recess after receipt of the device or insert. Thanks to the cover member, the insert is easy to inspect and also to replace if necessary.
The cover member may be pivotably connected to the tubular body and may have first latching means configured to engage with matching second latching means provided on the tubular body. This structure makes it easy to position the insert in the tubular body, and also makes the insert detachable which facilitates inspection, etc.
Preferably, the cover member has internal sealing elements configured to engage external sealing elements of the duct of the device and the tubular body, respectively. These sealing assemblies reduce the risk of air leakage.
According to a third aspect of the invention, a ventilation system is provided which comprises at least one fire retarding backflow preventing device according to the first aspect of the invention. Such a ventilation system is enhanced since the risk of fire and smoke spreading in the system is reduced.
A fourth aspect of the invention concerns use of a flexible element for establishing back flow preventing means in a ventilation duct, said flexible element being collapsed to a first state by normal air flow through the duct in a first direction, and expanded to a second state by air flow in a second direction opposite the first direction, whereby the flexible element serves as a back flow valve in said second state.
Further embodiments of the invention are defined in the appended claims, and additional features of the concept will be described in the following.
BRIEF DESCRIPTION OF THE DRAWINGS
Hereinafter, embodiments of the invention will be described with reference to the appended schematic drawings, in which:
Fig. 1 is an end view of a fire retarding backflow preventing device according to a first embodiment shown in open position;
Fig. 2 is an end view of the device of Fig. 1 shown in closed position;
Fig. 3 is a side cross sectional view of the device of Figs 1-2 in closed position;
Fig. 4 is a side cross sectional view of the device of Fig. 3 in open position;
Fig. 5 is an isometric view of a ventilation system including a fire retarding backflow device in accordance with an embodiment of the invention;
Fig. 6 is a side view corresponding to Fig. 5 and shows a modified fire retarding backflow preventing device according to a second embodiment of the invention;
Fig. 7 is an end view corresponding to Fig. 1 and shows the device of Fig. 6 in open position;
Fig 8 is an end view corresponding to Fig. 2 and shows the device of Fig. 6 in closed position;
Figs 9-12 show how a supporting member of the device of Fig. 6 is formed;
Fig. 13 is a side view of a tubular body for receiving a back flow preventing device in accordance with an embodiment of the invention;
Fig. 14 is a side view of the tubular body of Fig. 13 in closed position containing the back flow preventing device;
Fig. 15 is a partial cross sectional view of the tubular body of Figs 13-14 installed in a ventilation system and illustrating a cover in open position;
Fig. 16 is a cross section along the line XVI - XVI in Fig. 15.
Fig. 17 is a side view corresponding to Fig. 15 showing the cover in closed position;
Fig. 18 is a cross section along the line XVIII - XVIII in Fig. 17;
Fig, 19 is an isometric view of the tubular body with open cover, as well as a backflow preventing device to be received in the tubular body;
Fig, 20 shows how the device is received in the tubular body;
Fig. 21 shows how the cover of the tubular body is closed;
Fig. 22 is an oblique end view illustrating the supporting member of Fig. 6;
Fig. 23 is an oblique end view illustrating the expanded back flow preventing state of the device;
Fig. 24 is a schematic side view of a further modified fire retarding backflow preventing device according to a third embodiment of the invention;
Fig. 25 is an end view of a hollow base cone end of a collapsible element of the backflow preventing device shown in Fig. 24;
Fig. 26 is an opposite end view of an apex cone end of the collapsible element shown in Fig. 25;
Fig. 27 is an end view of the base cone end of a device having a collapsible element of the type shown in Figs 24-26; and
Fig. 28 is a schematic overview of a ventilation system of a building in which fire occurs in one room, in which situation a fire retarding backflow preventing device according to an embodiment of the invention is in its operative mode.
DESCRIPTION OF EMBODIMENTS
With reference to Figs 1 and 2, a fire retarding backflow preventing device 1 of a first embodiment is shown. The fire retarding device 1 is designed as a backflow preventing valve to be fitted with a ventilation system, and is arranged to allow air flow in a first direction A during normal ventilation. Further, the fire retarding device 1 is arranged to prevent air flow in an opposite direction B, which may occur in case of a
backflow due to e.g. fire when hot and harmful substances may spread through the ventilation system.
The fire retarding backflow preventing device 1 includes a hollow duct 3 to be fitted with the ventilation system. Preferably, the duct 3 has a cylindrical shape and a circular cross section.
A collapsible element or membrane 5 is attached within the duct 3 along a longitudinal axis of the duct 3, and the collapsible element 5 is able to move between a first collapsed or idle position, as indicated in Fig. 1 where air is allowed to flow through the duct 3 in the direction A, and a second expanded or active position, as indicated in Fig. 2 where air is prevented to flow through the duct 3 in the opposite direction B.
In a closed position, i.e. expanded state, the collapsible element 5 forms a hollow cone, in the shape of an oblique circular cone where the generator or generatrix extends perpendicularly from the periphery of the base to the apex.
This is further shown in Figs 3 and 4, in which Fig. 3 shows the backflow preventing device 1 in a closed position, while Fig. 4 shows the backflow preventing device in an open position.
The collapsible element 5, which has a circular base with dimensions corresponding to the circular cross-section of the duct 3, is attached to the interior wall of the duct 3 along a side or generator of the cone-shape. The generator extends perpendicularly from the base to the apex of the cone when the collapsible element 5 is expanded according to Fig. 3.
The air flow, indicated by the arrow B, will cause the collapsible element 5 to expand such that the outer periphery of the base of the cone will be pressed against the interior wall of the duct 3 as indicated by the arrows in Fig. 2. Hence, air will be trapped within the cone and the backflow preventing device 1 will thus close the air flowing in the direction B.
When air is flowing in the direction A as indicated in Figs 1 and 4 (normal use), the air flow will act on the collapsible element 5 such that it will collapse towards the part of the interior wall of the duct 3 at which the collapsible element 5 is attached.
Consequently, the collapsible element 5 will open and close the duct 3 automatically due to the direction of the air flow without any external control means.
The collapsible element 5 is preferably attached to the interior wall of the duct 5 by means of fastening means 7, such that the side of the cone-shaped element 5 is arranged adjacent to the interior wall of the duct 3.
Further, the base of the collapsible element 5 is preferably attached to a part of the interior periphery of the duct 3. The base may be attached at the interior periphery of the duct 3 between 30° and 270°, preferably between 60° and 180°, and more preferably between 100° and 150°.
The fastening means 7 may e.g. be a plurality of fasteners 7a, 7b, such as bolts, screws or pop rivets, spaced apart to provide attachment of the collapsible element 5 to the duct 3.
According to an embodiment the fastening means 7a may be a guiding rail (not shown), such that the collapsible element 5 may be mounted to the duct 3 with a corresponding fitting of the collapsible element 5 which allows the collapsible element 5 to be attached to the rail. Such solution would facilitate the handling and mounting of the fire retarding backfiow preventing device 1.
In yet another embodiment the fastening means may include snap locks (not shown) including corresponding engaging parts pre-arranged on the collapsible member 5 as well as on the duct 3.
For the backfiow preventing or non-return valve 1 to be able to open and close easily, the collapsible element 5 includes a light and deformable material with mechanical and chemical characteristics suitable for blocking the hot and harmful substances created in a fire. As can be seen in Fig. 1 and Fig. 4, respectively, the collapsible element 5 deforms and folds onto the interior surface of the duct 3 which means that during normal air flow in the ventilation system, the collapsed element 5 will reduce the amount of space occupied in the duct 3 and therefore minimize the risk of turbulence as well as a pressure drop in the flow. The collapsible element 5 only takes up a certain portion of the total flow area in cross section; see Fig. 1. This proportion may be about 15-30%, and most preferred about 20-25%.
When the flow in the ventilation system switches to a back flow, e.g. in case of a fire, the gases and substances flow into the collapsible element 5 which unfolds and fully expands in such a way that the collapsible element 5 covers the whole through flow area of the duct 3 and thereby gathers or traps harmful substances (see Figs 2 and 3).
In Fig. 5 a part of a ventilation system 100 is shown. The ventilation system includes a duct 12 connected to a fire retarding backflow preventing device 1 via a fitting 10. The fire retarding backflow preventing device 1 is similar to what has previously been described with reference to Figs 1 - 4. The collapsible element 5 is shown in dotted lines in its expanded, back flow preventing mode (cf. Figs 2 and 3) With reference to Figs 6 - 12, a fire retarding backflow preventing device 1 ' according to a second embodiment is shown. The device 1 ' includes two main components, namely a duct 30 and a collapsible element 50 corresponding to the components 3 and 5 shown in Figs 1 - 5. In its first position shown in the end view of Fig. 7, the flexible element 50 is in its inactive open state where air flows in the direction of the arrow A through the duct 30. The air flow is directed in three similar channels 60A-60C past the collapsed element 50.
In its second position shown in the end view of Fig. 8, the flexible element 50 is in its closed expanded state so that air flow in the opposite direction B is prevented, whereby smoke and any harmful substances are blocked from passing through the device 1 ' (to the left in Fig. 6) and spreading on the ventilation side to the left of the device. In this second embodiment, the collapsible element 50 has - in its expanded position - the shape of a circular symmetric cone with an axis C which is coaxial with the longitudinal or centre axis C of the duct 30. Fig. 8 shows how the expanded base portion of the hollow cone is pressed against the inner wall of the duct 30, similar to the position shown in Fig. 2 of the first embodiment.
The collapsible element 50 is mounted to the duct 30 at its apex end portion 50A and at its opposite base end portion 50B. The apex end 50A is maintained at the centre of the duct 30 by means of a member 70 which extends radially and substantially perpendicularly from the inner wall of the duct 30. The supporting member 70 is preferably made of a piece of sheet metal which is folded to the shape of a T having two
flanges 70A, 70B fastened to the inner wall of the duct 30, and a leg 70C with a free end where the apex end 50A of the collapsible element 50 is attached. The flanges 70A and 70B are preferably riveted to the inner wall of the duct 30. Figs 9-11 show how a sheet metal piece is folded to form the T-shaped member 70, and Fig. 12 is a side view of the complete member 70 ready to be mounted inside the duct 30.
As shown in Fig. 8, the base end 50B of the collapsible element 50 is attached to the inner periphery of the duct 30 in three equidistant attachment points P1-P3 spaced by 120° from each other along the periphery. Thanks to this configuration, the base portion 50B of the symmetric cone is spanned around the inner periphery of the duct 30. The base portion 50B of the collapsible element 50 is attached to the duct 30 by fasteners, like rivets (not shown).
In Figs 13-14 there is shown an arrangement including a tubular body 80 with an opening or recess 81 for receiving the device 1 ' shown in Fig. 6. The device 1 ' may be regarded as an insert which is positioned in the recess 81 which may be closed by a cover member 82. Preferably, the cover member 82 is pivotably connected to the tubular body 81 and it has latching means 83 for engagement with matching latching means 84 on the tubular body 80. Hence, after insertion of the device 1 ' the recess 81 is closed by the cover member 82 and locked by the latching means 83, 84.
The arrangement 80-84 is further illustrated in Figs 15-18 where it is installed in a ventilation system, namely bridging two ventilation ducts 12A, 12B of the system. A hinge 85 between the tubular body 80 and the cover member 82 is showed in Fig. 16 and Fig. 18, respectively.
From Fig. 1 , it is understood how the device or insert 1 ' is received in the tubular body 80. The collapsible element 50 is shown in its expanded backflow preventing state, where it has the shape of a circular, symmetrical cone which is coaxial with the center axes C, C of insert 1 ' and the tubular body 80 and also with the two opposite ducts 12A, 12B on either side of the arrangement 80-84.
Figs 17-18 show how the tubular body 80 receiving the insert 1 ' is closed by the cover member 82.
A design which has been tested in practice and which has proved very good results is shown in Figs 19-23. The duct 30 of the backflow preventing device or insert
1 ' of this embodiment has external peripheral sealing elements 31, 32 for engagement with matching sealing elements 86 and 87 on the inside of the cover member 82 of the tubular body 80 when the insert 1 ' is positioned in the recess 81 and the unit is closed. The cover member 82 has an additional sealing element 88 for engagement with a lateral external portion of the tubular body 80. The tubular body 80 has two external peripheral sealing elements 90, 91 which are disposed at a distance from the respective end of the body 80 and which are configured to engage the sealing elements 86 and 87 of the cover member 82. Furthermore, the tubular body 80 has two end sealing elements 92 and 93 which seal the joint with the ducts 12A and 12B (see Figs 15 and 17). The peripheral sealing elements 90-93 are preferably of so called double-lip type, and may be made of rubber material. The sealing arrangement described above and shown in Figs 19-23 provides for secure operation with reduced risk of undesired air leakage
Preferably the end portion 30B of the duct 30, where the collapsible element 50 has its cone base end 50B, is somewhat conical outwards. Thanks to this conical shape of the duct end portion 30B, the collapsible element 50 will be smoothly applied to the inner surface of the duct end portion 30B which enhances tight application against the inner wall of the duct 30 which in turn reduces the risk of leakage in the expanded, backflow preventing state of the device (cf. Figs 6 and 8).
A flexible strap 99 has one of its ends fastened to the inside of the tubular body 80 in the recess 81 , whereas the free end of the strap 99 is used when one wishes to lift the insert 1 ' out of the recess 81 from the position shown in Fig. 20.
In Fig. 22, the member 70 supporting one apex end 50A of the collapsible element 50 is shown as well as a portion of the circular symmetric cone in its expanded position. In a variant (not shown in Fig. 22), the supporting member 70 may extend transversely and span the diameter of the duct 30. In this alternative embodiment, the opposite ends of the supporting member are fastened to the internal wall of the duct in two diagonally opposite positions.
Fig. 23 shows from the opposite end how the opposite end 50B of the collapsible element 50 is attached to the inner surface of the duct 30 and also how the cone base is expanded at this end. Various means can be used for fastening the end portion 50B of the collapsible element 50 to the inside of the duct 30.
A modified collapsible element 500 is illustrated in Fig. 24 arranged within a duct 300 schematically shown in dotted lines. As in the previous embodiments, the closed apex end 5 OA of the cone shaped element 500 is maintained at the center of the duct by the member 70 attached to the inner wall of the duct 300, whereas the opposite base cone end 50B constitutes the open end of the cone shaped element 500. In a variant, the supporting member 70 spans the diameter of the duct 300 and has its opposite ends fastened to the inner wall of the duct 300 in diagonally opposite positions (schematically shown in dotted lines). Furthermore the end portion 300B of the duct 300, where the collapsible element 500 has its cone base end, may be slightly conical outwards so that tight application of the cone base portion against the inner wall of the duct 300 is achieved in the expanded backflow preventing mode. This design reduces the risk of leakage past the cone shape.
In the end views of Figs 25 and 26, the cone element 500 is shown separately. This cone element 500 is built up by three flexible elements 500A, 500B and 500C joint together at joining lines or seams J1-J3 which form ridges of the cone shape which are directed towards the center of the same. Each one of the three segments 500A-500C defines a partial cone which has a wall portion facing the interior wall of the duct 300 and which defines a space of the hollow cone shape. Hence, the large cone 500 may be regarded as built up by three partial cone shapes each of which opens into the center of the large cone shape. This design of the collapsible element 500 has proved to be very efficient in practice.
The cross section of the segment-built cone element 500 has the shape of a three-foil clover leaf which has proved to be favourable as regards air flow in the direction of normal operation, but also for switching to the backflow prevention mode. The symmetric shape of the three-space, segment built cone element 500 provides efficient operation in both modes.
The number of segments forming the cone element 500 may vary depending on the diameter of the duct 300 and the ventilation system where the fire retarding backflow preventing device is used. The cone element may have only two segments forming the hollow cone shape, and there may also be four segments and more (not shown). In case of four partial cones forming the large cone element, the cross section
of the same may be regarded as a four-foil clover leaf. It is to be understood, though, that the inventive concept is not bound to a certain number of cone segments.
The cone segments 500A-500C consist of the same material as described above, that is a flexible fabric material with heat resistant properties. Preferably, the segments 500A-500C are sewn together along the joint lines J1-J3.
A practical example of the embodiment of Figs 24-26 is shown in Fig. 27 from which is it is clear how the segments 500A-500C are attached to the interior wall of the duct 300 at three equidistant attachment points P1-P3. Fastening means may be rivets, screws and the like.
A ventilation system 100 including devices according to embodiments of the invention is schematically shown in Fig. 28. A building 200 comprises a number of rooms R1-R5 and in one of these rooms R3 a fire F has started. Then heat and pressure increase in the room R3 and smoke is starting to spread. After a while, the backflow preventing device 1 is activated since the normal air flow is reversed. The collapsible element 5 is expanded to its cone shape and thereby blocks flow past the device 1. This blocking back flow preventing effect is shown by a cross in Fig. 28.
In the embodiments described above, the collapsible element 5, 50, 500 can be made of fabric, plastics material or any other flexible material suitable to prevent air flow in ventilation systems. Preferably, the collapsible element 5, 50, 500 is based on a heat resistant fabric material including a substrate which on one side has an airtight coating which enhances the air flow blocking effect and collects harmful substances. The property "heat resistant" may vary depending on where the device is used (type of installation, type of building, etc), and various requirements on heat resistance may apply in different countries.
One requirement which is often used is that the heat resistant material should withstand about 800 °C during 15 min, but in some installations the requirement is that the heat resistant material should withstand up to about 1000 ° during 60 min. Various standard fire curves may be applied (time-temperature). Suitable heat resistance is desired, so that the collapsible element 5, 50, 500 in its expanded backflow preventing position blocks fire gases and smoke from spreading in the system.
Practical tests performed with a fire retardant backflow preventing device designed in accordance with the basic ideas behind the concept described herein have shown that the device resists 90 min in a fire test following a temperature/time curve according to a standard referred to as EN 1363-1. The leakage through the tested device was lower than 200 m3/(hm2) and thereby it achieved the leakage criteria according to a standard referred to as EN 1366-2.
It should be appreciated that modifications are feasible without any deviation from the spirit of the invention. For instance, the inventive device is not limited to use in circular duct ventilation systems, but it can also be used in rectangular duct systems, etc. The collapsible element of the inventive device may then have other shapes, such as a pyramid shape or a wedge shape, as long as the base dimensions of the collapsible element match the dimensions of the cross section of the duct. Further, the collapsible element may have an oblique shape such that the apex or apex edge is positioned on the interior wall of the duct. It should also be mentioned that the flexible material of the collapsible material may vary as long as it fulfills its backflow preventing purpose.
Furthermore, the fastening of the collapsible element can be achieved in other ways than described herein. Alternative means can be used for supporting the apex end of the collapsible element within the duct and for attaching the base portion of the collapsible element to the inner periphery of the duct.
Although the present invention has been described above with reference to specific embodiments, it is not intended to be limited to the specific forms set forth herein. Rather, the invention is limited only by the appended claims, and other embodiments than the specific above are equally possible within the scope of these appended claims.
In the claims, the term "comprises/comprising" does not exclude the presence of other elements or steps. Additionally, although individual features may be included in different claims, these may possibly advantageously be combined, and the inclusion in different claims does not imply that a combination of features is not feasible and/or advantageous. In addition, singular references do not exclude a plurality. The terms "a", "an", "first", "second" etc do not preclude a plurality. Reference signs in the claims are
provided merely as a clarifying example and shall not be construed as limiting the scope of the claims in any way.
Claims
1. A fire retarding backflow prevention device of a ventilation system, comprising
a duct (3; 30; 300), and
a collapsible element (5; 50; 500) which is arranged within the duct and moveable between a first collapsed position allowing air flow through the duct in a first direction (A) and a second expanded position preventing harmful substances to flow through the duct in an opposite direction (B),
wherein the collapsible element (5; 50; 500) is attached to the interior wall of the duct (3; 30; 300) and extends along a longitudinal axis of the duct.
2. The device according to claim 1, wherein the collapsible element (5; 50; 500), in the second expanded position, has the shape of a cone.
3. The device according to claim 2, wherein the collapsible element (5), in the second expanded position, has the shape of a circular oblique cone.
4. The device according to claim 3, wherein the collapsible element (5) is attached to the interior wall of the duct (3) along a side or generator of the cone.
5. The device according to claim 4, wherein the collapsible element (5) is attached to the interior wall of the duct (3) in such a way that the side or generator of the cone is substantially parallel to the longitudinal axis of the duct (3).
6. The device according to any one of claims 5, wherein the collapsible element (5) is attached to the interior wall of the duct (3) along the periphery of the duct (3), preferably at points between 30° and 180° of the periphery
7. The device according to claims 2, wherein one end portion (50A) of the collapsible element (50; 500) forming the apex of the cone is maintained substantially at the center of the duct (30; 300) by means of a member (70) which extends from the interior wall of the duct (30; 300), and wherein an opposite end portion (50B) of the collapsible element (50; 500) forming the base of the cone is attached to said interior wall.
8. The device according to claims 2 or 7, wherein the collapsible element (50), in the second expanded position, has the shape of a substantially symmetric cone.
9. The device according to any one of claims 2, 7 or 8, wherein the collapsible element (50) forming the cone has an axis which is substantially coaxial with the centre axis of the duct (30)
10. The device according to any one of the claims 7 - 9, wherein said opposite end portion (50B) of the collapsible element (50) forming the base of the symmetric cone is attached to the interior wall of the duct (30) in at least two preferably equidistant attachment points on the periphery of the interior wall of the duct (30), thereby spanning the base of the symmetric cone around the inner periphery of the duct (30).
11. The device according to claim 10, wherein said opposite end of the collapsible element (50) is attached to said periphery in three attachment points (P1-P3) spaced by about 120° from each other along said periphery.
12. The device according to claim 11, wherein the collapsible element (50) in the first collapsed position defines three similar channels (60A-60C) allowing air to flow through the duct (30) in said first direction (A) past the collapsed element (50), and wherein the collapsible element (50) in the second expanded position defines said symmetric cone having the periphery of its base portion pressed against the interior wall of the duct (30) and thereby preventing air flow in said second opposite direction (B).
13. The device of any one of claims 7-12, wherein said member (70) supporting said apex of the symmetric cone comprises a piece of sheet metal which is folded substantially to the shape of a T having two flanges (70A, 70B) fastened to the interior wall of the duct (30; 300) and a leg (70C) which extends from said interior wall to the center of the duct (30; 300) and to the free end of which said apex of the symmetric cone is attached.
14. The device according to any one of the preceding claims, wherein the collapsible element (5; 50; 500) is attached to the interior wall of the duct (3; 30; 300) by means of fasteners, an adhesive or a guiding rail.
15. The device according to any one of the preceding claims, wherein the collapsible element (5; 50; 500), in an idle position of no air flow, is collapsed according to the first position allowing air flow through the duct (3; 30; 300) in said first direction (A).
16. The device according to any one of the preceding claims, wherein the collapsible element (5; 50; 500) is moveable between the first position and the second position by a change of the airflow direction.
17. The device according to any one of the preceding claims, wherein the collapsible element (5; 50; 500) is flexible and preferably comprises a fabric material with heat resistant properties.
18. The device according to claim 17, wherein said fabric material is based on a substrate which on one side has an airtight coating.
19. The device according to claim 1, wherein said collapsible element (500) comprises at least two flexible segments (500A-500C) by which the collapsible element (500) forms a hollow cone shape in said second expanded position.
20. The device of claim 19, wherein said cone shape comprises an apex end (50A) and an opposite cone base end (50B), said cone apex end (50A) being maintained substantially at the center of the duct (300) by means of a member (70) which extends from the interior wall of the duct (300), said cone base end (50B) having attachment points (P1-P3) for attachment of each cone segment (500A-500C) to the interior wall of the duct (300).
21. The device of claim 19 or 20, wherein each segment (500A-500C) of the collapsible element (500) is formed as a partial cone which has a wall portion facing the interior wall of the duct (300) and which defines a space of the hollow cone shape.
22. The device of any one of claims 19-21, wherein the segments (500A-500C) building up the collapsible element (500) are joint together along joining lines (J1-J3) extending from the cone apex (50A) to the cone base end (50B)
23. The device of claim 22, wherein each joining line (J1-J3) forms an elongate ridge of the cone shape, which is directed towards the center of the same.
24. The device of any one of claims 19-23, wherein the collapsible element (500) comprises three segments (500A-500C) defining three spaces of said cone shape.
25. The device of claim 24, wherein the cross section of said cone shape has the form of a three-foil clover leaf.
26. The device according to any one of claims 19-25, wherein the segments of the collapsible element (500) are flexible and preferably comprise a fabric material with heat resistant properties.
27. The device according to claim 26, wherein said fabric material is based on a substrate which on one side has an airtight coating.
28. An arrangement comprising a tubular body (80) with a recess (81) for receiving a device as claimed in any one of the preceding claims, wherein the tubular body (80) and the duct (3; 30; 300) of said device are coaxial after receipt of the device.
29. The arrangement according to claim 28, further comprising a cover member (82) configured to close said recess (81) after receipt of the device.
30. The arrangement according to claim 29, wherein the cover member (82) is pivotably connected to the tubular body (80) and wherein it has first latching means (83) configured to engage with matching second latching means (84) provided on the tubular body (80).
31. The arrangement according to claim 29 or 30, wherein the cover member (82) comprises internal sealing elements (86-88) configured to engage external sealing elements (90-93) of the duct (3; 30; 300) of the device and the tubular body (80), respectively.
32. A ventilation system, comprising at least one fire retarding backflow preventing device according to any one of claims 1-27.
33. The ventilation system of claim 32, further comprising at least one arrangement as claimed in any one of claims 28-31.
34. Use of a flexible element for establishing back flow preventing means in a ventilation duct, said flexible element being collapsed to a first state by normal air flow through the duct in a first direction, and expanded to a second state by air flow in a second direction opposite the first direction, whereby the flexible element serves as a back flow valve in said second state.
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DK12723508.3T DK2718632T3 (en) | 2011-05-25 | 2012-05-25 | RETURN PREVENTION DEVICE WITH FOLDING ELEMENT INTO A VENTILATION CHANNEL AND USING A FOLDABLE ELEMENT WITHIN A VENTILATION CHANNEL |
EP12723508.3A EP2718632B1 (en) | 2011-05-25 | 2012-05-25 | Backflow prevention device with collapsible element within a ventilation duct and use of a collapsable element within a ventilation duct |
Applications Claiming Priority (6)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
SE1150485-9 | 2011-05-25 | ||
SE1150485 | 2011-05-25 | ||
SE1250115-1 | 2012-02-13 | ||
SE1250115 | 2012-02-13 | ||
SE1250254-8 | 2012-03-16 | ||
SE1250254 | 2012-03-16 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2012160197A1 true WO2012160197A1 (en) | 2012-11-29 |
Family
ID=46149493
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/EP2012/059872 WO2012160197A1 (en) | 2011-05-25 | 2012-05-25 | Backflow prevention device with collapsible element within a ventilation duct and use of a collapsable element within a ventilation duct |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP2718632B1 (en) |
DK (1) | DK2718632T3 (en) |
WO (1) | WO2012160197A1 (en) |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4783045A (en) * | 1987-07-29 | 1988-11-08 | Tartaglino Jerry J | Inflatable bladder for control of fluid flow |
DE10010270A1 (en) * | 1999-06-23 | 2001-01-04 | Friatec Ag | Fireproof blocking device has housing with closure element, detachable locking unit and intumescent material |
GB2355402A (en) * | 1999-10-19 | 2001-04-25 | Advanced Air | Fire damper with telltale |
WO2001050048A1 (en) * | 2000-01-04 | 2001-07-12 | Mats Persson | Method and arrangement to accomplish a one-way flow |
WO2005023369A1 (en) | 2003-09-09 | 2005-03-17 | Fagergrens Vvs Konsult Ab | Device for preventing backflow in ventilation ducts comprised in ventilation systems |
EP2143470A1 (en) * | 2008-07-10 | 2010-01-13 | Stöbich Brandschutz GmbH | Fire partition |
-
2012
- 2012-05-25 DK DK12723508.3T patent/DK2718632T3/en active
- 2012-05-25 EP EP12723508.3A patent/EP2718632B1/en active Active
- 2012-05-25 WO PCT/EP2012/059872 patent/WO2012160197A1/en active Application Filing
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4783045A (en) * | 1987-07-29 | 1988-11-08 | Tartaglino Jerry J | Inflatable bladder for control of fluid flow |
DE10010270A1 (en) * | 1999-06-23 | 2001-01-04 | Friatec Ag | Fireproof blocking device has housing with closure element, detachable locking unit and intumescent material |
GB2355402A (en) * | 1999-10-19 | 2001-04-25 | Advanced Air | Fire damper with telltale |
WO2001050048A1 (en) * | 2000-01-04 | 2001-07-12 | Mats Persson | Method and arrangement to accomplish a one-way flow |
WO2005023369A1 (en) | 2003-09-09 | 2005-03-17 | Fagergrens Vvs Konsult Ab | Device for preventing backflow in ventilation ducts comprised in ventilation systems |
EP2143470A1 (en) * | 2008-07-10 | 2010-01-13 | Stöbich Brandschutz GmbH | Fire partition |
Also Published As
Publication number | Publication date |
---|---|
DK2718632T3 (en) | 2017-08-28 |
EP2718632B1 (en) | 2017-05-10 |
EP2718632A1 (en) | 2014-04-16 |
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