Round Iris Damper for Ventilation Systems

A round galvanized steel iris damper (IRIS Handling-measuring series) is a precision-engineered HVAC component designed for the accurate volume regulation and systematic measurement of airflow within circular duct networks. Unlike standard single-blade butterfly or throttle valves, this device alters its net free area concentrically, operating on the mechanical principle of a photographic camera aperture. This advanced configuration ensures that the air stream remains centered along the duct axis, which effectively resolves the critical challenge of localized wall turbulence and dynamic whistling noise during air throttling, allowing balancing engineers to achieve a stable and quiet distribution of supply or extract air across residential buildings, corporate offices, and laboratory environments.

The external lens-shaped casing and internal overlapping iris blades are manufactured on high-speed automated production lines from premium galvanized sheet steel, providing exceptional mechanical resistance against network static pressure deformations. The robust internal mechanics guarantee smooth blade travel without friction jams, ensuring a perfectly round concentric opening at any throttle position. Sized with standard male clearance tolerances, the component arrives fully ready for direct inline integration into circular air distribution frameworks.

Key Benefits of the Iris Balancing Damper

• Precision airflow modulation without aerodynamic noise: The uniform concentric movement of the steel blades ensures the moving air jet remains centered within the duct run. This effectively prevents severe air vortexes from colliding with the pipe walls, dramatically reducing system acoustic noise even under heavy throttling conditions.
• Integrated infrastructure for airflow volume measurement: The damper housing comes equipped with two pre-installed measuring nozzles designed to connect directly to a differential manometer. By measuring the pressure drop across the internal orifice plate and cross-referencing the calibration chart, technicians can determine the exact volumetric airflow in real time, vastly simplifying system commissioning.
• Intuitive mechanical adjustment with position lock: The housing features a highly legible graduated alignment scale combined with a robust manual control handle and integrated lock lever. This setup allows technicians to easily set the calculated design parameters, lock the blade layout to prevent accidental shifting, and rapidly return to the baseline setting after maintenance.
• Airtight inline installation without external liquid mastics: Both male connection ports feature factory-installed double-lipped EPDM rubber gaskets. Upon insertion into standard straight ducts, the elastomeric blades tightly expand against the inner pipe walls, forming a dense junction that cuts leakage and eliminates the need for exterior duct tapes or liquid silicones.

Technical Specifications and Dimensional Data

The linear variables, installation tolerances, and nominal port calibrations of the IRIS series comply fully with European standards EN 1505 and EN 1506:2007 for circular sheet metal air distribution ducting and fittings. The unit is shipped complete with an integrated lockable manual control lever.

• Housing Construction Material: Industrial-grade galvanized sheet steel
• Diaphragm Blade Material: Heavy-duty wear-resistant carbon steel
• Connection Interface Type: Double male profile with pre-fitted EPDM gaskets
• Adjustment Method: Manual control lever with position locking screw and calibration scale

Assembly and Operational Placement Recommendations

Install the iris damper within ventilation duct segments that remain fully accessible for subsequent manual handle adjustment, scale reading, and differential manometer tube connection. The male-profile collars slide directly inside straight round ducts until they sit flush against the pre-rolled stop beads. Secure the overlapping junction mechanically using standard blind structural rivets or self-tapping sheet metal screws. To ensure absolute measurement accuracy when reading pressure drops, the damper must be mounted on a straight run of pipe. The straight duct length upstream of the damper (flow entry side) must measure at least four nominal duct diameters, while the straight duct length immediately downstream of the unit must span at least one nominal diameter.