Circular Flexible Connector for Ventilation Systems

A circular galvanized steel flexible connector (fabric duct vibration isolator series VASMI) is a specialized protective fitting engineered to decouple rigid mechanical links within air distribution networks. This component is typically positioned at the junction between a source of dynamic movement (such as an inline duct fan, central air handling unit, or supply ventilation module) and the primary ducting mainline. The circular flexible insert effectively resolves the challenge of mechanical vibration propagation along the duct run by absorbing axial and radial oscillations and preventing them from transferring onto rigid galvanized pipes. This significantly dampens low-frequency structural hum inside building rooms, safeguards hanger assemblies from incremental loosening, and extends the overall service life of the HVAC equipment.

The rigid connection sleeves are formed on automated industrial machinery from high-grade structural galvanized sheet steel, grade DX51D, carrying a dense protective zinc coating mass of Z275 (275 g/m²). A heavy-duty, multi-layer technical polymer fabric (PVC composite) is utilized as the flexible compensating core, anchored securely to the steel collars via a durable mechanical lock seam with multi-point stamping. The structural design preserves excellent flexibility across a wide operating temperature spectrum and resists surface wear under continuous directional air stream velocity pressure.

Key Benefits of the VASMI Flexible Connector

• Efficient elimination of structural noise and resonating hums: The heavy-duty polymer fabric sleeve fully dampens mechanical micro-vibrations generated by the fan motor. This eliminates the risk of an acoustic resonance developing through walls and ceilings, guaranteeing acoustic comfort inside residential apartments, corporate offices, and commercial halls.
• Safeguarding the duct network from depressurization: The pliable center core easily compensates for minor axial misalignments and thermal expansion cycles of the sheet metal. This shields steel pipe junctions from developing fatigue cracks and prevents mounting screws from backing out of duct hangers under continuous vibration.
• High-standard channel airtightness without static pressure drops: The multi-layer pliable sleeve features absolute air impermeability. Combined with a precision mechanical lock seam for steel-to-fabric interfacing, this configuration ensures system compliance with rigid Airtightness Class C metrics, minimizing static pressure drop losses.
• Rapid inline assembly with male connection collars: Sized with a calibrated male nipple profile, the rigid ports slide smoothly inside straight round ducts. Integrated center stop beads accurately restrict the insertion depth, ensuring clean alignment and preventing assembly tilting during joint execution.

Technical Specifications and Dimensional Data

The linear variables, mounting tolerances, and nominal port diameter calibrations of the VASMI series fully comply with European standards EN 1505:2000 and EN 1506:2007 for sheet metal ventilation tracks. The pliable connector sleeve does not restrict the net free area of the duct path, preventing performance drops in the ventilation system.

• Collar Sleeve Material: Galvanized steel DX51D with a Z275 zinc passivation coating
• Flexible Core Material: Wear-resistant multi-layer technical polymer fabric (PVC composite)
• Connection Interface Type: Double male nipple profile calibrated for inline sliding inside duct runs
• Custom Material Configurations: Flanges can be manufactured from stainless steel grade AISI 304 for facilities governed by strict sanitary-hygienic or high-temperature operational criteria

Assembly and Load Allocation Guidelines

The flexible connector must be integrated directly downstream of the fan unit or air handling apparatus prior to the start of the rigid duct mainline. The male connection collars slide inside standard round pipes until they sit flush against the pre-rolled center stop beads. Secure the joint points mechanically using quick-release ventilation clamps, blind structural rivets, or self-tapping sheet metal screws. During duct track assembly, it is strictly forbidden to utilize the flexible connector as a load-bearing element to support the dead weight of the pipes. All ducts preceding and following the vibration isolator must be anchored independently to independent ceiling drop rods or wall brackets. External joint lines must be wrapped with high-adhesion aluminum duct tape to preserve the design leakage category.