Non-return (Backdraft) dampers with double EPDM gasket

The DAOSL dampers are designed for ventilation ductwork systems
which require air tightness class D according to EN 12237 requirements.

These dampers feature a split flap closure and are designed as non-return
dampers which allows a single air flow direction only. The damper closure
has approximately air tightness class 2 as per EN 1751:2002, without full
class compliance.

Both closure flaps are made of light-weight aluminium sheet and hinged on a
steel bar with springs which keep the flaps closed when there is no air flow.
This damper is often installed upstream of an air intake or an air exhaust
unit to prevent the air backflow.