Elastomer or Fluoropolymers coated fabrics can be used as single or multilayer execution based on the temperature and pressure of the flow media. In multilayer fabric construction, coated or laminated fabrics are used as basic fabric and applied as outer most layers. Then it is further backed up by various types of non woven fabrics in multilayer construction.
Boson Group manufactures make Fabric Expansion Bellows that are exceptionally flexible. Compared to steel and rubber bellows it can absorb misalignment in multiple direction— Axial, Lateral, Angular and Torsional.
It is strongly recommended that at the time of installation of the bellows, if any torsional misalignment is found between any two jointing ducts, this should be corrected and fixed, and then only should the bellow be installed. During operation if any torsional misalignment develops, then it can be accommodated by the fabric bellow up to a certain limit.
Usage of Fabric Bellow:
• Can be used for insulation
• Can support ducts or pipelines with greater amount of misalignment
• Flow media will be dry like air or gas
Advantages of Fabric Expansion bellow.
• Used for abrasion resistance
• Reactive forces are practically nil
• Mechanical load can be avoided
• VF or fabric selection, various options are available
• Compare to Metallic and Rubber bellow it offers almost unlimited flexibility
• Can absorb movements in multi direction—
 Axial movement (compression and extension)
 Lateral movement
 Angular rotation
 Torsional rotation
• Design has multiple options for selection
• For installation space requirements are very less
• Can be custom based considering prevailing duty conditions
• Easy to transport and easy to install
• Fabric part can be replaced in the running condition i.e. without taking any shut down.
A Fabric Expansion Bellow can readily accommodate the torsional movement of duct or pipeline which is practically not possible in the case of Metallic or Rubber Expansion Bellows. This is a major difference between a Metallic or Rubber bellow and Fabric Bellow.
A Fabric Expansion Bellow can absorb the system vibration and also capable of reducing or eliminating noise produced by the connected equipment.
For example, a fabric expansion bellow is used as inlet and outlet connection of ID/FD fan primarily to absorb vibration and to eliminate the noise of the Connected Fan.
Sizes
Any sizes, practically there is no limitations in dimensions. Fabric expansion bellows can be supplied with or without steel parts.
In the case of without steel parts, only fabrics can be supplied in open or closed belt condition.
Types
Fabric Expansion Bellow can be of both Round and Rectangular shape. This can be designed for temperature maximum 1200 deg C and pressure up to 2000 mm wg.
Bolster is made out from several layers of glass wool or ceramic wool and encased in woven glass fabric. It is further encased in SS wire mesh for higher pressure even.