GB1574480A - Sound absorbing device - Google Patents

Sound absorbing device Download PDF

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Publication number
GB1574480A
GB1574480A GB5205077A GB5205077A GB1574480A GB 1574480 A GB1574480 A GB 1574480A GB 5205077 A GB5205077 A GB 5205077A GB 5205077 A GB5205077 A GB 5205077A GB 1574480 A GB1574480 A GB 1574480A
Authority
GB
United Kingdom
Prior art keywords
wall
sound
strip
passage
continuous
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
GB5205077A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
EUROVIB ACOUSTIC PRODUCTS
Original Assignee
EUROVIB ACOUSTIC PRODUCTS
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by EUROVIB ACOUSTIC PRODUCTS filed Critical EUROVIB ACOUSTIC PRODUCTS
Priority to GB5205077A priority Critical patent/GB1574480A/en
Publication of GB1574480A publication Critical patent/GB1574480A/en
Expired legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
    • F01N13/18—Construction facilitating manufacture, assembly, or disassembly
    • F01N13/1838—Construction facilitating manufacture, assembly, or disassembly characterised by the type of connection between parts of exhaust or silencing apparatus, e.g. between housing and tubes, between tubes and baffles
    • F01N13/1844—Mechanical joints
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N1/00—Silencing apparatus characterised by method of silencing
    • F01N1/24—Silencing apparatus characterised by method of silencing by using sound-absorbing materials
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
    • F01N13/18—Construction facilitating manufacture, assembly, or disassembly
    • F01N13/1838—Construction facilitating manufacture, assembly, or disassembly characterised by the type of connection between parts of exhaust or silencing apparatus, e.g. between housing and tubes, between tubes and baffles
    • F01N13/1844—Mechanical joints
    • F01N13/185—Mechanical joints the connection being realised by deforming housing, tube, baffle, plate, or parts thereof
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
    • F16L55/00—Devices or appurtenances for use in, or in connection with, pipes or pipe systems
    • F16L55/02—Energy absorbers; Noise absorbers
    • F16L55/033—Noise absorbers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2310/00—Selection of sound absorbing or insulating material
    • F01N2310/02—Mineral wool, e.g. glass wool, rock wool, asbestos or the like
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2450/00—Methods or apparatus for fitting, inserting or repairing different elements
    • F01N2450/20—Methods or apparatus for fitting, inserting or repairing different elements by mechanical joints, e.g. by deforming housing, tube, baffle plate or parts thereof
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2470/00—Structure or shape of gas passages, pipes or tubes
    • F01N2470/02—Tubes being perforated
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2470/00—Structure or shape of gas passages, pipes or tubes
    • F01N2470/24—Concentric tubes or tubes being concentric to housing, e.g. telescopically assembled
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2530/00—Selection of materials for tubes, chambers or housings
    • F01N2530/26—Multi-layered walls

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Gas Separation By Absorption (AREA)
  • Treating Waste Gases (AREA)

Description

(54) SOUND ABSORBING DEVICE (71) We, EUROVIB (ACOUSTIC PRO DUCTS) LIMITED, of 1 Shortlands Road, Kingston upon Thames, Surrey, a British Company, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: - The present invention relates to sound absorbing devices for reducing the noise in gas streams, for example streams of air in ventilation systems.
It is known to pass gas streams containing noise along ducts, the wall of which include sound absorbing material. The outer wall of such a duct is usually made from sheet metal rolled to form a circular cross sectional duct and welded along the longitudinal joint between the edges of the sheet. This construction requires a sheet of metal of the required length of the duct to be cut and then shaped as required. If any gaps are left in the welded joint these can provide passages for noise to escape from the device. The sound absorbent material is usually located inside the outer wall.
In known sound absorbing devices, the gas stream makes direct contact with the sound absorbent material. This can result in chemical reaction between the gas and the sound absorbent material taking place and the deposit on the sound absorbent material of particles carried within the gas stream. Each of these factors tends to reduce the sound absorbing properties of the sound absorbent material.
The object of the present invention is to provide an improved sound absorbing device.
According to the present invention a sound absorbing device comprises a duct having a rigid outer wall formed from a continuous strip of metal shaped into a helical configuration with adjacent edges interlocked so as to form a continuous rigid wall and an annular mass of sound ab sorbent material located within said outer wall and forming a passage extending along said duct.
According to a preferred embodiment of the invention a sheet of sound transmitting and liquid and gas impervious material extends over the surface of said annular mass of sound absorbent material forming said passage.
In order that the invention may be more readily understood reference will now be made to the accompanying drawings in which: - FIG. 1 is a perspective view of a sound absorbing device embodying the invention; FIG. 2 is a side view of the device illustrated in Fig. 1 sectional along an axial plane; FIG. 3 is an enlarged view of the region A in Fig. 2; FIG. 4 is a plan view of the region A; and FIG. 5 is an end view of the device illustrated in Figs. 1 and 2 modified by the addition of an internal axially extending pod.
The sound absorbing device illustrated in Figs. 1 and 2 consists of a cylindrical duct 1 formed with an axial passage 2 along which a gas stream may be passed. The duct 1 has an outer wall 3 formed from a continuous strip of metal shaped into a helical configuration. The adjacent edges of the strip are shaped so that they are interlocked as described below with reference to Figs. 3 and 4, and the strip forms a continuous outer wall for the duct.
Inside the outer wall 3 is a mass 4 of sound absorbent material, for example glass fibre or other mineral wool. The mass 4 is annular in cross section so that it does not extend into the axial passage 2. The mass 4 is retained in position by an inner wall 5 formed from a single strip of metal shaped into a helical configuration with adjacent edges interlocked, by the same arrangement as is used for the outer wall 3. The inner wall 5 is formed with a plurality of perforations 6.
Between the mass 4 of sound absorbent material and the inner wall 5 is located a thin sheet 7 - of material which is sound transmitting but is impervious to liquid or gas. A suitable material is a polyethylene terephthalate known as Melinex (Registered Trade Mark).
When a stream of gas passes along the passage 2 any noise in the gas will be transmitted through the perforations 6 in the inner wall 5 and through the sheet 7 into the sound absorbent material 4 where the noise will be absorbed. However, since the thin sheet 7 is impervious to liquids and gases and to particles, there will be no transfer of liquids or gases or particles from the gas stream to the sound absorbent material 4. Therefore, the sound absorbing properties of the material 4 will not be affected by impurities. Particles or liquids in the gas stream may become trapped in the perforations 6 or attached to the surface of the inner wall 5 or the sheet 7 and these particles and liquids can be removed by passing a cleaning fluid, such as water or steam, along the duct.
The construction of the outer wall 3 is more clearly illustrated in Figs. 3 and 4 which show the way in which adjacent edges of the single strip of metal 10 forming the outer wall 3 are shaped so that they interlock together. One edge 11 of the strip 10 is bent to form a ridge 12 with a U-shaped cross section, one arm 13 of the U extending substantially parallel to the outer surface 14 of the sheet and spaced therefrom. The other edge 15 of the strip is bent to form a ridge 16 having a substantially C-shaped cross section. This ridge 16 projects above the outer surface 14 of the strip 11. One arm 17 of the C extends substantially parallel to the outer surface 14 and is spaced from the central portion 18 of the C.
The two ridges 12 and 16 are adapted to interlock, as illustrated, the outer arm 13 of ridge 12 engaging within the hollow formed within the ridge 16. By compressing together the two ridges the adjacent edges of the strip 10 are securely held together.
Since the ridges interlock closely there is no gap between the adjacent edges of the strip. Hence, the strip 10 is formed into a continuous outer wall 3 which is very strong and rigid and no noise is transmitted through the wall.
The construction of the inner wall 5 is substantially identical and, therefore, the inner wall is continuous, except for the perforations 6 in the sheet forming the inner wall.
Fig. 4 is a plan view of the region A and illustrates the outer surface of the ridge 16 when the adjacent edges of the strip 10 are securely interlocked together.
The inner and outer walls can each be formed by a continuous process which bends the edges of the strip 10 to form the ridges 12 and 16 and links the ridges together to form a continuous wall which has no apertures in it through which sound can escape, and which is very strong and rigid.
The sheet 7 is also a continuous strip of thin material which is wound over the outer surface of the inner wall 5 in a spiral with adjacent edges overlapping in order to provide a continuous membrane preventing the passage of liquids, gases or particles from a gas stream passing along the passage 2 into the sound absorbent material 4.
Fig. 5 illustrates an alternative form of construction of the sound absorbing device in which a pod 21 is located within the passage 2. The pod comprises an axially extending cylindrical duct 22 supported on legs 23 bolted to the inner surface of inner wall 5. The cylinder 22 has an outer wall 24 and inner wall 25 each formed by the same construction as the walls 3 and 5 together with a mass 26 of sound absorbent material similar to the material of the mass 4. The walls 24 and 25 are perforated and the mass 26 of sound absorbent material is surrounded by a sheet of moisture impervious material like the material of the sheet 7. The pod 21 provides additional sound absorption.
In practice, the sound absorbing device described may be supplied with the pod 21 as an optional feature, the pod being stored within the passage 2 for transport, together with its fixing bolts.
WHAT WE CLAIM IS:- 1. A sound absorbing device comprising a duct having a rigid outer wall formed from a continuous strip of metal shaped into a helical configuraiton with adjacent edges interlocked so as to form a continuous rigid wall and an annular mass of sound absorbent material located within said outer wall and forming a passage extending axially along said duct.
2. A device as claimed in claim 1 comprising a sheet of sound transmitting and liquid and gas impervious material extending over the surface of said annular mass of sound absorbent material forming said passage.
3. A device as claimed in either of the preceding claims in which said duct has a perforated inner wall extending along the passage, said sound absorbent material
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (11)

  1. **WARNING** start of CLMS field may overlap end of DESC **.
    4 is retained in position by an inner wall 5 formed from a single strip of metal shaped into a helical configuration with adjacent edges interlocked, by the same arrangement as is used for the outer wall 3. The inner wall 5 is formed with a plurality of perforations 6.
    Between the mass 4 of sound absorbent material and the inner wall 5 is located a thin sheet 7 - of material which is sound transmitting but is impervious to liquid or gas. A suitable material is a polyethylene terephthalate known as Melinex (Registered Trade Mark).
    When a stream of gas passes along the passage 2 any noise in the gas will be transmitted through the perforations 6 in the inner wall 5 and through the sheet 7 into the sound absorbent material 4 where the noise will be absorbed. However, since the thin sheet 7 is impervious to liquids and gases and to particles, there will be no transfer of liquids or gases or particles from the gas stream to the sound absorbent material 4. Therefore, the sound absorbing properties of the material 4 will not be affected by impurities. Particles or liquids in the gas stream may become trapped in the perforations 6 or attached to the surface of the inner wall 5 or the sheet 7 and these particles and liquids can be removed by passing a cleaning fluid, such as water or steam, along the duct.
    The construction of the outer wall 3 is more clearly illustrated in Figs. 3 and 4 which show the way in which adjacent edges of the single strip of metal 10 forming the outer wall 3 are shaped so that they interlock together. One edge 11 of the strip 10 is bent to form a ridge 12 with a U-shaped cross section, one arm 13 of the U extending substantially parallel to the outer surface 14 of the sheet and spaced therefrom. The other edge 15 of the strip is bent to form a ridge 16 having a substantially C-shaped cross section. This ridge 16 projects above the outer surface 14 of the strip 11. One arm 17 of the C extends substantially parallel to the outer surface 14 and is spaced from the central portion 18 of the C.
    The two ridges 12 and 16 are adapted to interlock, as illustrated, the outer arm 13 of ridge 12 engaging within the hollow formed within the ridge 16. By compressing together the two ridges the adjacent edges of the strip 10 are securely held together.
    Since the ridges interlock closely there is no gap between the adjacent edges of the strip. Hence, the strip 10 is formed into a continuous outer wall 3 which is very strong and rigid and no noise is transmitted through the wall.
    The construction of the inner wall 5 is substantially identical and, therefore, the inner wall is continuous, except for the perforations 6 in the sheet forming the inner wall.
    Fig. 4 is a plan view of the region A and illustrates the outer surface of the ridge 16 when the adjacent edges of the strip 10 are securely interlocked together.
    The inner and outer walls can each be formed by a continuous process which bends the edges of the strip 10 to form the ridges 12 and 16 and links the ridges together to form a continuous wall which has no apertures in it through which sound can escape, and which is very strong and rigid.
    The sheet 7 is also a continuous strip of thin material which is wound over the outer surface of the inner wall 5 in a spiral with adjacent edges overlapping in order to provide a continuous membrane preventing the passage of liquids, gases or particles from a gas stream passing along the passage 2 into the sound absorbent material 4.
    Fig. 5 illustrates an alternative form of construction of the sound absorbing device in which a pod 21 is located within the passage 2. The pod comprises an axially extending cylindrical duct 22 supported on legs 23 bolted to the inner surface of inner wall 5. The cylinder 22 has an outer wall 24 and inner wall 25 each formed by the same construction as the walls 3 and 5 together with a mass 26 of sound absorbent material similar to the material of the mass 4. The walls 24 and 25 are perforated and the mass 26 of sound absorbent material is surrounded by a sheet of moisture impervious material like the material of the sheet 7. The pod 21 provides additional sound absorption.
    In practice, the sound absorbing device described may be supplied with the pod 21 as an optional feature, the pod being stored within the passage 2 for transport, together with its fixing bolts.
    WHAT WE CLAIM IS:- 1. A sound absorbing device comprising a duct having a rigid outer wall formed from a continuous strip of metal shaped into a helical configuraiton with adjacent edges interlocked so as to form a continuous rigid wall and an annular mass of sound absorbent material located within said outer wall and forming a passage extending axially along said duct.
  2. 2. A device as claimed in claim 1 comprising a sheet of sound transmitting and liquid and gas impervious material extending over the surface of said annular mass of sound absorbent material forming said passage.
  3. 3. A device as claimed in either of the preceding claims in which said duct has a perforated inner wall extending along the passage, said sound absorbent material
    being located between said inner and outer walls.
  4. 4. A device as claimed in claim 3 in which said inner wall is formed from a continuous strip of metal shaped into a helical configuration with adjacent edges interlocked so as to form a continuous wall.
  5. 5. A device as claimed in any one of claims 1, 2 or 4 in which, for each continuous strip of metal, the two edges are each formed with a ridge, the two ridges having cross sections such that they interlock to form a continuous wall.
  6. 6. A device as claimed in claim 5 in which one ridge has a substantially Ushaped cross section and the other ridge has a substantially C-shaped cross section.
  7. 7. A device as claimed in any one of the preceding claims comprising an additional sound absorbing unit extending axially within said passage.
  8. 8. A device as claimed in claim 7 in which said additional sound absorbing unit comprises an additional duct having an outer wall and an additional annular mass of sound absorbent material located within said outer wall and forming a passage extending axially along said additional duct.
  9. 9. A device as claimed in claim 8 comprising a sheet of sound transmitting and liquid and gas impervious material extending over the surface of said additional annular mass of sound absorbent material forming said passage.
  10. 10. A sound absorbing device substantially as described with reference to Figs.
    1, 2, 3 and 4 of the accompanying drawings.
  11. 11. A sound absorbing device substantially as described with reference to Fig. 5 of the accompanying drawings.
GB5205077A 1977-12-14 1977-12-14 Sound absorbing device Expired GB1574480A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB5205077A GB1574480A (en) 1977-12-14 1977-12-14 Sound absorbing device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB5205077A GB1574480A (en) 1977-12-14 1977-12-14 Sound absorbing device

Publications (1)

Publication Number Publication Date
GB1574480A true GB1574480A (en) 1980-09-10

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Family Applications (1)

Application Number Title Priority Date Filing Date
GB5205077A Expired GB1574480A (en) 1977-12-14 1977-12-14 Sound absorbing device

Country Status (1)

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GB (1) GB1574480A (en)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0092589A1 (en) * 1981-11-05 1983-11-02 Mitsubishi Denki Kabushiki Kaisha Exhaust silencer for internal combustion engine
EP0176657A1 (en) * 1984-09-20 1986-04-09 Mitsubishi Denki Kabushiki Kaisha Muffler for exhaust gas from internal combustion engine
GB2253035A (en) * 1991-02-18 1992-08-26 Zanussi Elettrodomestici Silenced tumble dryer
WO1998032551A1 (en) * 1997-01-27 1998-07-30 Lindab Ab Double-walled structure and method and arrangement for producing the same
US5911457A (en) * 1997-01-27 1999-06-15 Lindab Ab Method for producing a double-walled structure
WO2000003129A1 (en) * 1998-07-10 2000-01-20 Lindab Ab Double-walled structure in a ventilation duct system
US6062270A (en) * 1997-01-27 2000-05-16 Lindab Ab Double-walled structure in a ventilation duct system
GB2335248B (en) * 1998-03-07 2002-12-31 Crp Group Ltd Protection of underwater elongate members
US6543575B1 (en) 2000-06-14 2003-04-08 Lindab Ab Double-walled structure and connection arrangement
GB2386935A (en) * 2002-03-15 2003-10-01 Smiths Group Plc Ducting with sound absorbing properties
EP3473910A1 (en) * 2017-10-23 2019-04-24 Hamilton Sundstrand Corporation Duct assembly having internal noise reduction features, thermal insulation and leak detection

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0092589A1 (en) * 1981-11-05 1983-11-02 Mitsubishi Denki Kabushiki Kaisha Exhaust silencer for internal combustion engine
EP0092589A4 (en) * 1981-11-05 1984-03-29 Mitsubishi Electric Corp Exhaust silencer for internal combustion engine.
US4523662A (en) * 1981-11-05 1985-06-18 Mitsubishi Denki Kabushiki Kaisha Muffler for exhaust gas from an internal combustion engine
EP0161692A2 (en) * 1981-11-05 1985-11-21 Mitsubishi Denki Kabushiki Kaisha Sound-absorbing device for use as muffler for exhaust gas from an internal combustion engine
EP0161692A3 (en) * 1981-11-05 1986-02-26 Mitsubishi Denki Kabushiki Kaisha Sound-absorbing device for use as muffler for exhaust gas from an internal combustion engine
EP0176657A1 (en) * 1984-09-20 1986-04-09 Mitsubishi Denki Kabushiki Kaisha Muffler for exhaust gas from internal combustion engine
US4700805A (en) * 1984-09-20 1987-10-20 Mitsubishi Denki Kabushiki Kaisha Muffler for exhaust gas from internal combustion engine
GB2253035A (en) * 1991-02-18 1992-08-26 Zanussi Elettrodomestici Silenced tumble dryer
GB2253035B (en) * 1991-02-18 1995-02-08 Zanussi Elettrodomestici Laundry drying machine with silencer
US5911457A (en) * 1997-01-27 1999-06-15 Lindab Ab Method for producing a double-walled structure
WO1998032551A1 (en) * 1997-01-27 1998-07-30 Lindab Ab Double-walled structure and method and arrangement for producing the same
US6062270A (en) * 1997-01-27 2000-05-16 Lindab Ab Double-walled structure in a ventilation duct system
CZ300247B6 (en) * 1997-01-27 2009-04-01 Lindab Ab Double-walled structure, method for producing thereof, arrangement for producing such double-walled structure and double-walled silencer
GB2335248B (en) * 1998-03-07 2002-12-31 Crp Group Ltd Protection of underwater elongate members
WO2000003129A1 (en) * 1998-07-10 2000-01-20 Lindab Ab Double-walled structure in a ventilation duct system
US6543575B1 (en) 2000-06-14 2003-04-08 Lindab Ab Double-walled structure and connection arrangement
GB2386935A (en) * 2002-03-15 2003-10-01 Smiths Group Plc Ducting with sound absorbing properties
US6679296B2 (en) 2002-03-15 2004-01-20 Smiths Group Plc Ducting
GB2386935B (en) * 2002-03-15 2004-11-17 Smiths Group Plc Ducting
EP3473910A1 (en) * 2017-10-23 2019-04-24 Hamilton Sundstrand Corporation Duct assembly having internal noise reduction features, thermal insulation and leak detection

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