SE1850232A1 - Silencer - Google Patents

Abstract

The present invention relates to a silencer (10) for airflow (7) in ventilation, comprising an outer air-proof casing (2), which outer air-proo ing comprises an air inlet (3) at a first end (2A) and an air outlet (4) at a second end (2B), an inner through channel (5) in fluid communication with the air inlet and air outlet, and an air-permeable sound-reducing material (6) in an inner space of the outer air-proof casing between the inner through channel and the air-proof outer casing, the inner air-permeable sound-reducing material being thermal insulating and non-combustible.

Description

Sflencer TECHNICAL FIELD The present invention relates to a silencer for ventilation ducts, comprising an outer casing, aninlet, an outlet, an inner channel for letting ventilation air through the silencer, and a sound-attenuation material arranged in a space between the inner channel and the outer casing. The outer casing of the silencer is made of non-combustible material.

BACKGROUND ART There are a lot of known silencers for reducing unwanted noise in ventilation systemsemanating from air flowing through ventilation ducts and other components of the system.

One example of such a silencer is disclosed in EP 1 998 119 B1.

Some known silencers reduce the unwanted noise while fulfilling fire proof criteria in that theouter casing of the silencer is made of metal and the sound-attenuation material arranged inthe silencer are made of non-combustible material, such as mineral wool, e.g. stone or glass wool. Glass wool melts at about 400 to 500°C, and stone wool melts at about 1000 to 1500 °C.

Prior art silencers suffer from at least some disadvantages, e.g. decompose or break up too fast when exposed to excessive fire or heat.

SUMMARY OF THE INVENTION lt is, accordingly, an object of the present invention to overcome deficiencies ofthe prior art, such as indicated above.

Another object of the present invention is to increase the time during which the silencer is kept structurally intact when exposed to excessive fire and/or heat.

An additional object of the present invention is to slow down the spread of heat and fire pastor via the silencer by keeping the silencer structurally intact during a longer period of timewhile decreasing the rate of heat and fire propagation when exposed to excessive fire/heat making the silencer into a passively working firebreak.

Yet another object of the present invention is to increase the time during which the silencer is kept structurally intact when exposed to excessive fire/heat by making it in a material being 2fire proof and non-combustible and less prone to conduct heat from an external ventilation component, e.g. a ventilation duct or connector, to the outer casing of the silencer.

One other object of the present invention is to prolong the structural integrity ofthe silencerwhen exposed to excessive fire/heat by using a material that increase the resistance againstexcessive heat by being able to emit water and water vapour when the temperature exceedsabout 500°C to further prolong the heat resistance ofthe silencer. For this, gypsum being ableto give off chemically bound water at above about 500°C is used, which further emission ofwater aids in cooling ofthe silencer. Examples of suitable gypsum has a thickness of about atleast 10 to 15 mm and a heat or thermal resistance Rp of about at least 0.07 m2°C/W, and acoefficient of linear expansion of about 25x1O'6 °C'1. Suitable gypsum boards/plates have a fire resistance grade according to DIN 4102 and DIN EN 13501 of at least A2-s1, dO.

Still another object of the present invention is to decrease the rate of heat conduction so thatthe silencer is kept structurally intact for a prolonged period of time when exposed toexcessive fire/heat by using a fire proof and non-combustible material having a lower capacity of heat transmission than materials hitherto used in the outer casing ofthe silencer.

An additional object of the present invention is to make at least the gables of the outer casingofthe silencer to which any external ventilation component is mounted in a fire proof andnon-combustible material being less prone to conduct heat from the external ventilationcomponent, e.g. a ventilation duct, to the outer casing or vice versa, while keeping the silencer structurally intact for an increased period of time when exposed to excessive fire and/or heat.

The objects are achieved by means of a silencer for ventilation, as claimed in the associated in- dependent claim, preferred variants thereof being defined in associated dependent claims.

At least one of above and further objects are achieved by means of a silencer in ventilation,comprising an outer air-proof casing, which outer air-proof casing comprises an air inlet at afirst end and an air outlet at a second end, an inner through channel in fluid communicationwith the air inlet and air outlet, and an air-permeable sound-reducing material in an innerspace of the outer air-proof casing between the inner through channel and the air-proof outercasing, the air-permeable sound-reducing material also being thermal insulating and non-combustible, characterized in that the first and second casing ends of the silencer each comprises a fireproof gable made at least partly of heat/thermal insulating/resistant material, 3and to which heat insulating/thermal resistant material of the fireproof gable the air inlet and air outlet, respectively, is connected.

Further objects and features of the present invention will appear from the following definitions of aspects/examples of the invention.

According to an aspect, the silencer according to any of the former and/or latter aspects,wherein each fireproof gable comprises a first hole forming part of the air inlet or air outlet.According to another aspect, in the silencer according to any of the above and/or belowaspects the first hole is made through the heat/thermal insulating/resistant material of thefireproof gable. ln one aspect, in the silencer according to any ofthe above and/or belowaspects the first hole is configured for alignment with the inner through channel of the outerair-proof casing. ln another aspect, in the silencer according to any of the above and/or belowaspects, the first hole of the air inlet of the outer air-proof casing is configured for alignmentwith the first hole of the air outlet of the outer air-proof casing. According to a further aspect,in the silencer according to any preceding and/or subsequent aspect, the air inlet and outlet ofthe outer air-proof casing comprises an inner hollow connector with a first end adapted forair-tight connection to the inner through channel and an outer hollow connector with a firstend adapted for air-tight connection to at least one external ventilation component. Accordingto a still further aspect, in the silencer according to any of the above and/or below aspects,each connector is a flanged coupling. According to yet an aspect, in the silencer according toany preceding and/or subsequent aspect, each connector is connected with a second end tothe heat/thermal insulating/resistant material of the fireproof gable such that a heat/thermalinsulation and thermal break zone is formed between each connector and the outer air-proofcasing. According to another aspect, in the silencer according to any preceding and/or subs-equent aspect, the thermal resistant/heat insulating material of the fireproof gable is made inthe form of a plate. According to one more aspect, in the silencer according to any precedingand/or subsequent aspect, the fireproof gable is configured as a sandwich structure of orcomprising at least two plates made of different materials ofwhich at least one or a first plateis made ofthe heat/thermal insulating/resistant material. According to an additional aspect, inthe silencer according to any of the above and/or below aspects, each fireproof gablecomprises a second hole being larger than the first hole of the fireproof gable. According to one aspect, in the silencer according to any preceding and/or subsequent aspect, the second 4 hole is adapted to be in alignment with the first hole of the fireproof gable. According to onefurther aspect, in the silencer according to any of the above and/or below aspects, eachfireproof gable comprises at least another plate and a second hole in this other plate, whichother plate is configured to be an outer part ofthe outer air-proof casing and the second holeis a through hole adapted in size to at least partly expose the first plate ofthe heat/thermalinsulating/resistant material. According to still an additional aspect, in the silencer accordingto any preceding and/or subsequent aspect, each second connector end is adapted to beconnected to the exposed zone or area or surface ofthe first plate of the thermal resistantmaterial of the fireproof gable without being in physical contact with the outer air-proofcasing. According to yet a further aspect, in the silencer according to any preceding aspect, thethermal resistant material has a thermal insulation capacity of at least about 0.07 m2°C/W orbetween at least about 0.05 m2°C/W to 0.2 m2°C/W or between at least about 0.07 m2°C/W to0.15 m2°C/W. According to one aspect, the silencer according to any preceding aspectcomprises an inner channel made up by a sound attenuating material in the form of twoelongated shaped or moulded halves, which halves when put together form an enclosed holeextending along their whole lengths similar to a building block with a through channel. lnanother aspect, the silencer comprises an inner channel made of a separate perforated andelongated cylindrical tube, preferably of metal, which tube is enclosed by a sound reducingmaterial put around the inner tube between it and the outer casing in the inner space of thesilencer. ln one other aspect, the silencer comprises the inner channel made ofthe separateperforated tube being covered over its envelope surface, i.e. between its outside and the sound reducing material, with an air/sound permeable material in the form of a web/cloth.

Further objects and features of the present invention will appear from the following detailed description of aspects/examples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be explained in further details with reference to the drawings showing aspects thereof.

Figure 1A is a perspective view of a square-shaped configuration of one embodiment of a silencer according to the invention. 5Figure 1B is a perspective view of a rounded configuration of another embodiment of a silencer according to the invention.

Figure 2 is an exploded diagram in perspective of an embodiment ofthe silencer in Fig. 1A before/during assembly or after/during disassembly.

Figure 3 is a sectiona| view of the silencer in Figs. 1A or 1B before disassembly or after assembly taken along the full length of the silencer.

Figure 4 is a front or back view ofthe silencer in Figs.1A, 2, and 3 as seen from outside the silencer and towards an inlet or outlet of the silencer with fastener heads exposed.

Figure 5 is an exploded diagram in perspective of another embodiment ofthe silencer in Fig. 1A before/during assembly or after/during disassembly.

Figure 6 is a sectiona| view ofthe silencer in Figs. 1A or 1B before disassembly or after assembly taken along the full length of the silencer.

Figure 7 is a front or back view ofthe silencer in Figs.1A, 2, 3, 4, and 5 as seen from the inside of the silencer and towards an inlet or outlet of the silencer with fasteners fully exposed.

Figure 8 is a front or back view ofthe silencer in Figs. 4 and 7 as seen from outside the silencer and towards an inlet or outlet of the silencer with other fastener heads exposed.

Figure 9 is an exploded diagram in perspective view of the silencer in Figs. 4, 7, and 8 before/during assembly or after/during disassembly.

DETAILED DESCRIPTION The invention relates to a silencer 10 for connection to one or more external ventilationcomponents, such as ventilation ducts 1, to reduce noise due to air flow, fans, valves and soon. The silencer 10 is shown in figs. 1A to 9 in at least two different configurations and/orembodiments. The silencer 10 comprises an outer airproof casing 2 with two ends, a first end2A and a second end 2B. The outer airproof casing 2 ofthe silencer 10 is formed to create aninner space 2C of the silencer 10. The silencer 10 comprises at least one air inlet 3 at its firstend 2A and at least one air outlet 4 at its second end 2B. The silencer 10 also comprises acontinuous, inner channel 5 for letting through air 7 from its inlet 3 to its outlet 4. The innerchannel 5 is situated inside the outer casing 2 and its inner space 2C. The silencer 10 comprises an air permeable material 6 in its inner space 2C between outer casing 2 and inner 6 channel 5. This air permeable material 6 works as a sound-attenuation material and isarranged in the inner space 2C between inner channel 5 and outer casing 2. Silencer 10 isadapted to be part of a ventilation system comprising fans, valves, connectors, ventilationducts, heating and/or cooling batteries, and, such systems are common general knowledgeand well-known by the skilled person, hence, any components for making such a ventilation system as a whole for ventilation air flow 7 is not necessary to explain in detail herein.

The silencer 10 shown in figs. 1A to 9 basically comprises three components, the outer air-proof casing 2 made of sheet metal tube (square-shaped in figs. 1A, 2, 4, 5, and 7 to 9, androunded in figs. 1B, 3, and 6), the inner channel 5 coaxial with the outer tubular casing 2, andthe sound-attenuation material 6 filling the inner space 2C between outer casing 2 and innerchannel 5. The air-permeable sound reducing material 6 is fibrous and allows air flow 7 to passthrough the inner channel 5 ofthe silencer and is able, at the same time, to prevent looseparts of the sound-attenuation material from being carried into the inner channel and further out of the outlet 4 into the ventilation duct 1 and further into the ventilation system. ln figs. 1A and 1B, the outer silencer casing 2 comprises a gable 20 at each of its ends 2A and2B. Each gable 20 is a front or end plate defining the length ofthe silencer 10 excluding thelength of any protruding connecting part of the inlet 3 or outlet 4. Each gable 20 is attached byfasteners 30 to the silencer 10 at an associated end 2A and 2B to enclose the inner space 2Caxially from those ends (see figs. 2, 4, 5, and 7). Each gable 20 comprises an internal hollowconnector 23 (not shown in figs. 1A, 1B, but in figs. 2 to 9) adapted to fit into and be in fluidconnection with the inner channel 5 and an external hollow connector 24 adapted to fit to and be in fluid connection with an external ventilation component, e.g. a ventilation duct 1.

Each gable 20 with its internal 23 and external connector 24 has an aligned centre hole oropening 21 that extends all the way through the gable and its connectors to define/form atleast a part of the inlet 3 and outlet 4 of the silencer 10, see figs. 3, 6, 8 and 9. The externalconnector 24 is a connecting piece, which have protruding parts 24A extending outside thesilencer 10 for coupling to ventilation pipes 1 in a ventilation system of which the silencerforms part. The internal connector 23 is a connecting piece, which have protruding parts 23Aconfigured to extend in the opposite direction of the external connector 24 into the innerchannel 5 of the silencer 1 for coupling thereto. The external 24 and internal connector 23 are arranged opposite each other. The connectors 23 and 24 are facing/extending or protruding in 7 opposite directions from their associated gable 20 when assembled thereon. The external 24and internal connector 23 are arranged opposite each other at different sides of each gable20. Each of the gables 20 is connected with its internal connector 23 inserted into oppositesilencer ends 2A, 2B and fastened by fasteners 30 to the ends of the outer casing 2. Each ofthe protruding parts 24A of the external connector 24 forms an exposed outer end defining apart of an associated free end ofthe silencer 10, i.e. the openings of its inlet 3 and outlet 4before the silencer is assembled into a ventilation duct 1 or the like, i.e. when the silencer isfreestanding. Each connector 23, 24 has another end 23B and 24B adapted to be attached toopposite sides of a common gable 20. The external connector 24 has its other end 24Battached by fasteners 31 to one side of the gable 20, i.e. an external gable side facing out-wards, while the internal connector 23 has its other end 23B attached by the same fasteners31 as the external connector 24 or other fasteners to another side of the gable 20, i.e. aninternal and opposite gable side facing inwards when the silencer 10 is assembled (see its disassembled state in figs. 2 and 5 and its assembled state in figs. 1A, 1B, 3, and 6).

Each gable 20 is made up of at least two separate plates 22, 25 (see fig. 8 and 9), each platebeing made of fireproof and non-combustible material. One plate 22 is made of gypsum andforms the most important fire protection of each gable 20 and thereby the silencer 10. Theother plate 25 is made at least partly of metal and forms a stabilising part of the gable 20. Thegypsum plate 22 is thicker than the other plate 25. Gypsum plate 22 and the other plate 25 aremade to be sandwiched together and to snugly fit into an associated end 2A or 2B of the outercasing 2 enabling them to be inserted therein and fastened by the fasteners 30 (see figs. 2 to7) extending from the outside of the casing and through the casing into the gypsum plate 22and the other plate 25. The improved fire protection of the silencer 10 is accomplished bymaking a centre hole 21A through the gypsum plate 22 that is smaller than a correspondingand aligned hole 21B in the other plate, i.e. the metal plate 25 (see figs. 4, 7, 8, and 9), butwhich smaller hole 21A of the gypsum plate 22 and larger hole of the metal plate 25 correlatewith the openings 21 through the connectors 23 and 24. Size, shape and alignment of thesmall holes 21A at each end 2A, 2B of the silencer 10 are adapted so that they optimise the airflow 7. Size, shape and alignment ofthe big holes 21B at each end 2A, 2B ofthe silencer 10 areadapted so that they do not make the metal plate 25 touch, i.e. come into physical contact with any of the connectors 23, 24, in particular the external connector 24 when the external 8 connector is attached to the gypsum plate 22 and the metal plate 25 is attached to gypsumplate 22 (see fig. 8). Gypsum plate 22 forms a base or underlay for the connectors 23 and 24 tobe attached to at opposite sides of the gable 20 with the thereby commonly formed andaligned through holes or openings 21 and 21A, and the large holes 21B, after assembly. Thelarger hole 21B of the metal plate 25 is partly covered by the gypsum plate 22 when the twoplates are assembled together (see figs. 4, 7, and 8). The internal connector 23 could be anintegrated part of or be integrated in the gypsum plate 22. ln fig. 8, the large hole 21B in plate25 is indicated as a not perfectly circular hole, i.e. it has a somewhat elliptic shape but could ofcourse be circular. ln fig. 8, the small hole 21A in gypsum plate 22 is indicated by one largercircle in broken line and one smaller circle in solid line. The size of the small hole 21A couldcorrelate perfectly to the opening 21 ofthe air inlet 3 and air outlet 4, and its shape could benon-circular as the larger hole 21B, but is preferably circular. The second hole 21B has its centre axis in alignment with the centre axis ofthe first hole 21A of the fireproof gable 20.

The air-permeable sound-attenuation material 6 inside the silencer 10 is heat/thermalinsulating/resistant and non-combustible/fireproof and this is combination with the first andsecond casing ends 2A, 2B each made up of a fireproof gable 20 made at least partly ofheat/thermal insulating/resistant material 22, i.e. gypsum with high thermal insulance orinsulation capacity, see the summary and also being non-combustible/fireproof makes thesilencer 10 according to the invention able to fulfil at least the fire proof criteria of E|30 andE60, and with a protective distance of 10 mm at least El 60. This is specifically achieved in thatthe first hole 21A is made through the heat/thermal insulating/resistant material 22 of thefireproof gable 20. ln some aspects, the first hole 21, 21A is configured for alignment with theinner through channel 5 ofthe outer air-proof casing 2 and/or the first hole 21, 21A ofthe airinlet 3 is configured for alignment with the first hole 21, 21A ofthe air outlet 4. As the air inlet3 and air outlet 4 each comprises the inner hollow connector 23 with its first end 23A beingentities adapted for air-tight connection to the inner through channel 5. The same goes for theouter hollow connector 24 with its first end 24A being adapted for air-tight connection to at least one external ventilation component 1. ln an aspect, each connector 23, 24 is a flanged coupling to achieve a more stable end-to-endconnection to the gypsum plate 22 as an underlay. As each connector 23, 24 is connected with its second end 23B, 24B to the heat insulating gypsum material 22 of the fireproof gable 20 a 9 heat/thermal insulation and thermal/break zone and/or area and/or volume and/or surface isformed between each connector and the outer air-proof casing 2. ln other words, the fire-proof gable 20 is at least partly or wholly configured as a sandwich structure comprising the atleast two plates 22, 25 made of different materials, i.e. at least gypsum and/or metal, of whichat least the first plate 22 is made of heat/thermal insulating/resistant gypsum material. Eachfireproof gable 20 comprises the second hole 21B (in metal plate 25) being larger than the firsthole 21A of the fireproof gable, i.e. in the gypsum plate 22. The second hole 21B is adapted to be in alignment with the first hole 21A ofthe fireproof gypsum plate 22. ln one aspect, the hole 21B in the metal plate 25 is a through hole adapted in size to at leastpartly expose the first gypsum plate 22 after assembly together. The improved fire protectionof the silencer 10 is accomplished in that each second connector end 23B, 24B is adapted tobe connected to the exposed zone or area or surface of the first gypsum plate 22 withoutbeing in physical contact with the outer air-proof casing 2 and/or the metal plate 25. Thefasteners 30 and 31 are arranged so that no physical contact between outer air-proof casing 2and the metal plate 25 and the connectors 23, 24 and/or the fasteners themselves occurs to further hindering/slowing down heat and fire propagation via/in the silencer 10.

The gypsum material 22 has a thermal insulation capacity corresponding to a heat or thermalresistance Rp of about at least 0.07 m2°C/W; preferably between at least about 0.05 m2°C/Wto 0.2 m2°C/W; more preferred between at least about 0.07 m2°C/W to 0.18 m2°C/W, and most preferred between at least about 0.07 m2°C/W to 0.15 m2°C/W or about 0.07 m2°C/W. ln figs. 2 and 3, the inner channel 5 is made up by surrounding it with the sound attenuatingmaterial 6 in the form of two elongated halves, an upper half 6' and a lower half 6”. Each half6' and 6" has a U- or cup-shaped cross-section and are adapted to be put together with thelegs of their Uzs abutting against each other, whereby a through hole in the form ofthe innerchannel 5 is formed there through, i.e. the inner channel 5 is formed by the inner surface ofthe opening through the halves 6' and 6" .The two halves 6' and 6" are formed into twosubstantially shape stable entities or pieces of sound reducing material, preferably stone woolfor fire/heat resistance, e.g. by moulding. A first end 6A and a second end 6B ofthe halves 6'and 6" and the halves themselves (figs. 2 and 3) are formed to make the inner channel 5 and its first and second end to fit securely and snugly with one internal connector 23 (i.e. a first gable 20) at the first end 6A and to fit securely and snugly with a second internal connector 23 (i.e. a second gable 20) at the second end 6B inside the silencer 10. ln figs. 5 and 6, the inner channel 5 is made of a separate perforated and elongated cylindricaltube, preferably of metal, which tube 5 is wrapped or enclosed or surrounded with the soundreducing material 6, e.g. in the form of loose stone wool or mats put around the inner tube 5between it and the outer casing 2 in the inner space 2C. After assembly of the silencer 10 athrough hole in the form ofthe inner channel tube 5 is formed there through. A first end 5Aand a second end 5B ofthe inner tube channel 5 (figs. 5 and 6) are adapted to fit securely andsnugly with one internal connector 23 (= a first gable 20) at the first end 5A and to fit securelyand snugly with a second internal connector 23 (= a second gable 20) at the second end 5Binside the silencer. The tubular inner channel 5 in figs. 5 and 6 is made to prevent loose partsof the sound-reducing material 6 from being carried into it through its perforation and to theoutlet 4 out into the ventilation duct 1 and further into the ventilation system. The preventionof parts of the sound attenuating material 6 coming loose and being transported furtherdownstream of the silencer 10 is in one aspect improved by covering the external/envelopesurface of the inner tube channel 5, i.e. between its outside and the sound reducing material6, with some kind of air/sound permeable material 8, such as a porous fabric or cloth 8 or thelike, to make the inner channel 5 less prone to let through any sound reducing material 6 viaits perforations from the inner space 2C and further into and downstream in the ventilationsystem. This fabric or cloth 8 is preferably a non-woven synthetic material 8, such as Polyester,e.g. POLDUK, working as an additional filter 8 besides the more coarse perforations oftheinner channel 5. This additional filter 8 is a screen cloth or filtration fabric with smaller meshthan the perforated inner channel 5. Each pore or opening ofthe filter 8 is smaller in size thaneach perforation of the inner channel 5. The filter 8 has more openings per surface unit/areacompared to the inner channel 5. The filter 8 lets through air and thereby sound to ”help” the silencer 10 while not letting through any loose parts of the sound attenuation material 6.

Each fireproof gable 20 is made at least partly of fireproof material and adapted to function asa thermal barrier/firebreak between the in-/outlets 3, 4 of air and the outer air-proof casing 2.Each hole 21, 21A, 21B of each gable 20 enables air 7 to be let in or out ofthe silencer 10 as itis made through the fireproof material of each fireproof gable 20, which fireproof material is made in the form ofthe plates 22 and 25. Each connector 23, 24 of the gable 20 forms at least 11 a part of the air inlet 3 or air outlet 4 of the silencer 10. Each connector 23, 24 is connectedwith its second end 23B, 24B to the heat insulating and thermal resistant gypsum gablematerial 22 in such a way that a heat insulation and firebreak zone/area/volume/surface isformed between each connector and the outer air-proof casing 2. Each connector 23, 24 isconnected with its second end 23B, 24B by fasteners 31 to the thermal resistant gypsum plate22 such that each connector is physically and thermally separated from each other and theouter air-proof casing 2, i.e. the gypsum plate 22 forms a firebreak and distance between theconnectors 23, 24 and between the connectors and the outer casing 2. Each connector 23, 24is connected with its second end 23B, 24B to the thermal resistant gypsum gable plate 22 insuch a way that a distance is created both in the longitudinal direction and the radial, i.e.sideways and in the width and breadth direction ofthe silencer 10 between the connectorsand the outer air-proof casing 2 increasing/prolonging the thermal resistivity of each fireproof gable 20 and thereby the silencer 10. ln fig. 9, the gable 20 is shown with the gypsum plate 22 and metal plate 25 being squareshaped in their planes of extension, however, the gypsum plate 22 and the metal plate 25could of course be formed with rounded shapes, e.g. extend in planes of extension beingcircular or elliptic as understood when viewing the gables 20 shown in fig. 1B and all the other cylindrically shaped parts ofthe silencer, such as the outer casing 2 and its inner space 2C.

Claims (13)

1.

2. CLAll\/IS A silencer (10) for airflow (7) in ventilation, comprising an outer air-proof casing (2),which outer air-proof casing comprises an air inlet (3) at a first end (2A) and an air outlet(4) at a second end (2B), an inner through channel (5) in fluid communication with theair inlet (3) and air outlet (4), and an air-permeable sound-reducing material (6) in aninner space (2C) of the outer air-proof casing between the inner through channel (5) andthe air-proof outer casing, the air-permeable sound-reducing material (6) also beingthermal insulating and non-combustible, c h a r a c t e r i z e d in that the first and secondcasing ends (2A, 2B) of the silencer (10) each comprises a fireproof gable (20) made atleast partly of thermal resistant material (22), and to which thermal resistant material of the fireproof gable the air inlet (3) and air outlet (4), respectively, is connected. A silencer (10) according to claim 1, wherein each fireproof gable (20) comprises a first hole (21, 21A, 21B) forming part of the air inlet (3) or air outlet (4). A silencer (10) according to claim 2, wherein the first hole (21, 21A) is made through the thermal resistant material (22) ofthe fireproof gable (20). A silencer (10) according to claim 2 or 3, wherein the first hole (21, 21A, 21B) is configured for alignment with the inner through channel (5) of outer air-proof casing (2). A silencer (10) according to claim 2, 3 or 4, wherein the first hole (21, 21A, 21B) ofthe airinlet (3) of the outer air-proof casing (2) is configured for alignment with the first hole (21, 21A, 21B) of the air outlet (4) of the outer air-proof casing. A silencer (10) according to any preceding claim, wherein the air inlet (3) and outlet (4)ofthe outer air-proof casing (2) comprises an inner hollow connector (23) with a firstend (23A) adapted for air-tight connection to the inner through channel (5) and an outerhollow connector (24) with a first end (24A) adapted for air-tight connection to at least one external ventilation component (1). A silencer (10) according to claim 6, wherein each connector (23, 24) is a flanged coupling. 8. 5 9.10.10 11.12.15 1

3.20 1

4.1

5. 13A silencer (10) according to claim 6 or 7, wherein each connector (23, 24) is connectedwith a second end (23B, 24B) to the thermal resistant material (22) of the fireproof gable(20) such that a heat insulation and thermal break zone is formed between each connector and the outer air-proof casing (2). A silencer (10) according to any preceding claim, wherein the thermal resistant material (22) of the fireproof gable (20) is made in the form of a plate. A silencer (10) according to any preceding claim, wherein the fireproof gable (20) isconfigured as a sandwich structure of at least two plates (22, 25) made of different materials ofwhich at least one plate is made of the thermal resistant material (22). A silencer (10) according to any of claims 2 to 10 when claims 6, 9 or 10 is dependent onclaim 2, wherein each fireproof gable (20) comprises a second hole (21B) being larger than the first hole (21A) of the fireproof gable. A silencer (10) according to claim 10, wherein the second hole (21B) is adapted to be in alignment with the first hole (21A) of the fireproof gable (20). A silencer (10) according to any of claims 10 to 12 when claim 10 is dependent on claim2, wherein each fireproof gable (20) comprises at least another plate (25) and a secondhole (21B) in this other plate, which other plate is configured to be an outer part oftheouter air-proof casing (2) and the second hole is a through hole adapted in size to at least partly expose the first plate (22) of the thermal resistant material. A silencer (10) according to claim 13 when any of claims 9 to 13 is dependent on claim 8,wherein each second connector end (23B, 24B) is adapted to be connected to theexposed zone of the first plate (22) of the thermal resistant material of the fireproof gable (20) without being in physical contact with the outer air-proof casing (2). A silencer (10) according to any preceding claim, wherein the thermal resistant material(22) has a thermal insulation capacity of at least about 0.07 m2°C/W or between at leastabout 0.05 m2°C/W to 0.2 m2°C/W or between at least about 0.07 m2°C/W to 0.15m2°c/w.